Eur Arch Paediatr Dent DOI 10.1007/s40368-014-0150-z
ORIGINAL SCIENTIFIC ARTICLE
Evaluation of a treatment protocol for unerupted maxillary central incisors: retrospective clinical study of 46 children N. N. Lygidakis • K. Chatzidimitriou • N. Theologie-Lygidakis • N. A. Lygidakis
Received: 11 May 2014 / Accepted: 5 September 2014 Ó European Academy of Paediatric Dentistry 2014
Abstract Aim To evaluate the clinical outcome of a treatment protocol performed in children with unerupted permanent maxillary central incisors, including surgical removal of any related obstruction and traction initiation in one stage, under fully repositioned flap, combined with pre- and postoperative orthodontics for space creation and final alignment. Methods Forty-six patients aged 7.3–12.7 years (mean = 9.44 ± 1.36) having 54 impacted maxillary central incisors were reviewed. The study group included 37 patients fully treated by us and nine referrals with eruption failure of impacted incisors following previous surgical removal of various obstructions. Detailed patient’s clinical and radiographic data were recorded. Results Aetiology of unerupted incisors included 9 patients with odontomas, 24 with supernumerary teeth, 1 with skeletal lack of space, 1 with a dentigerous cyst, 4 with dilaceration, 1 with severe incisor MIH, 5 with luxation injuries to primary predecessors and 1 with coexisting dilaceration and odontoma. The total treatment time following the standardised protocol ranged from 5 to 21 months (mean 9.88 ± 3.10), while the time needed using different approaches (no pre-operative orthodontics or obstruction removal and then to wait over an assessment period) ranged from 12 to 18 months (mean 15 ± 2.12) and 17 to 30 months (mean 23.73 ± 5.14), respectively (p \ 0.05). The time needed for full alignment depended on the inclination, the height of the impacted tooth
N. N. Lygidakis K. Chatzidimitriou N. Theologie-Lygidakis N. A. Lygidakis (&) Private Paediatric Dental Clinic, 2 Papadiamantopoulou Street, 11528 Athens, Greece e-mail: [email protected]; [email protected]
(p = 0.001) and the patient’s age (p = 0.002). Additionally, the absence of pre-operative orthodontics for space creation dramatically increased treatment time (p = 0.018). In contrast, the maturity of the impacted tooth and the developmental stage of the anterior teeth did not affect treatment time. Finally, when the location of the impacted tooth and the space availability allowed waiting for spontaneous eruption, treatment time was not statistically different from that of the main treatment protocol (p = 0.545). Conclusions The studied treatment protocol appears ideal for successful results and minimum treatment time. Space creation followed by surgical removal of any obstruction together with orthodontic traction initiation produces excellent results, while waiting for spontaneous eruption is indicated only in cases of favourable patient’s age and tooth location. Treatment initiation with operation in the absence of the required eruption space is not recommended, whereas in unfavourable cases obstruction removal without simultaneous orthodontic traction increases dramatically the total treatment time and requires an unnecessary second operation for traction. Keywords Treatment Impacted Unerupted Maxillary central incisors
Introduction Eruption anomalies belong to the dental anomalies spectrum and include changes of normal tooth eruption, as those of accelerated, delayed, failed or deviated ectopic eruption. These anomalies are related to general and/or local aetiologic factors (Brin et al. 1982; Valladares et al. 1995).
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Although an impaction of other permanent teeth is rarely diagnosed during the early mixed dentition period, an unerupted central incisor can be usually diagnosed on time following the delay in the eruption of the tooth. Many patients with unerupted maxillary central incisors are referred to paediatric dentists or orthodontists by general dental practitioners, because parents are concerned about a missing incisor in the early mixed dentition, even though its occurrence is less frequent (Lin 1999; Becker 2002). The frequency of maxillary central incisor impaction has been found in the range of 0.03–1.96 % (Mead 1930; Grover and Lorton 1985). Several contributing factors have been suggested that impede maxillary central incisor eruption. These could be supernumerary teeth, trauma to primary teeth/dilaceration, congenitally displaced incisor, ectopic development, cysts, tumours, odontomas, over-retained or early lost primary teeth, dense mucoperiosteum, tooth agenesis, syndromes, lack of space, ankylosis and abnormal morphology (Huber et al. 2008). The anterior maxilla is a highly demanding aesthetic area and consequently treatment of unerupted maxillary incisors requires a well-synchronised and multidisciplinary approach to obtain an acceptable aesthetic and functional result as soon as possible. She clinical management of this condition is variable. A comprehensive evaluation must include assessment of whether space is available or can be made available in the arch for alignment of the unerupted teeth, patient’s age and dental developmental stage, timing of surgical intervention, length and cost of orthodontic treatment, oral hygiene status and others. There are several treatment options open to a patient with an unerupted permanent incisor. She most conservative management would be the extraction of any obstruction, the creation of space and the observation for spontaneous eruption (Huber et al. 2008). Spontaneous eruption in 54–74 % of the cases of unerupted incisors has been reported following the removal of any obstruction, without any further treatment (Mason et al. 2000). However, in many cases surgical exposure of the impacted teeth and orthodontic traction into the line of occlusion is the most indicated approach (Ferguson 1990). Surgical procedures involve either exposure and packing of the area prior to placing an orthodontic attachment in a later visit or a one-step exposure and orthodontic attachment placement using a fully repositioned mucoperiosteal flap (Bishara 1992). Both methods have advantages and disadvantages and their use depends on the operator’s experience, while other methods such as the one with a magnet system have been described with good results (Cole et al. 2003). However, as most of the successful cases regarding the orthodontic traction of unerupted maxillary central incisors include short-term case reports (Duncan and Ashrafi 1983; Crawford 1997;
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Lin 1999; Tanaka et al. 2001; Macias et al. 2003), there is lack of evidence-based information about the immediate and long-term results. The purpose of this retrospective study was to evaluate the clinical outcome of a treatment protocol performed in a large cohort of children with unerupted permanent maxillary central incisors, including surgical removal of any related obstruction and orthodontic traction initiation in one stage, under fully repositioned flap, combined with pre-operative orthodontics for space creation if unavailable. In particular, the study investigated (a) the aetiology of impaction, (b) the treatment time related to different parameters such as the age of the patient, the position of the unerupted incisors, their developmental stage, the anterior occlusal development and finally (c) the total treatment time following our method as compared to that needed using different approaches.
Materials and methods Cases analysed were treated in a paediatric dental clinic over the last 15 years. During this period, 46 patients presented with 54 impacted maxillary central incisors. All patients had full clinical and radiological records and scheduled recalls at least 2 years following treatment. Nine more patients with missing data from their records were excluded from the study. The clinical diagnosis was confirmed by radiographs. The study group consisted of 37 patients fully treated by the authors and 9 patients with unerupted incisor/s referred to us following a previous operation for the removal of any obstruction related to impaction. Treatment approach followed (a)
A standardised treatment approach was used in the great majority of the young patients. Initially, clinical and panoramic radiographic evaluation of the patients recorded the maturity and position of the unerupted teeth including the degree of angulation and the distance from the occlusal plane. A treatment schedule was initiated with fixed orthodontic appliances to align the adjacent teeth and create adequate space for the impacted tooth, if unavailable. At that time, the position and maturity of the tooth/teeth was again evaluated with different periapical and occlusal radiographs applying Clark’s technique (Jacobs 1999). In few cases of severe impaction, a dental scan was also prescribed. The surgery was performed under local analgesia (LA) according to a standard protocol, when location
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Fig. 1 A male, 10.6 years old, with an unerupted right central incisor, resulting from a conical supernumerary. a Clinical appearance at the first examination, b OPG revealing the supernumerary, c 4 months pre-operative orthodontics for alignment and space creation, d closed flap operation under LA, removal of supernumerary
and bracket attachment, e traction into occlusion, f periapical radiograph to evaluate traction progress, g incisor into occlusion 5 months later (note recessed gingiva), and h 6 years follow-up (note enhanced gingiva without any intervention)
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Fig. 2 A male 9.2 years old, with an unerupted right central incisor, resulting from a tuberculated supernumerary. a Clinical appearance at first examination, b OPG revealing the supernumerary, c 4 months pre-operative orthodontics for adjacent teeth alignment and space
improvement, d closed flap operation under LA for the removal of supernumerary, e incisor starting to erupt, f incisor into full occlusion 5 months later, g OPG to evaluate alignment, and h 6 months followup revealing a satisfactory result
(height/angle) and maturity of the unerupted tooth/ teeth were considered unfavourable. A mucoperiosteal flap was raised, any obstruction was removed and a small round orthodontic attachment was bonded to the impacted tooth, while the flap was
repositioned in place (closed method). Orthodontic traction with light forces was initiated 1 week following suture removal and treatment completed when incisors were stabilised with SS wire in full alignment (Fig. 1a–h).
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(b)
Alternative treatment approaches evaluated in the present study included: (1) orthodontic space creation or improvement, operation for obstruction removal and an intentional wait for spontaneous eruption in cases of favourable patient’s age and maturity and location of the unerupted teeth (Fig. 2a–h), (2) operation for obstruction removal and attachment placement, followed by orthodontic treatment for space creation, traction and alignment and (3) operation for obstruction removal and unjustified wait for spontaneous eruption.
Evaluation methodology Clinical The records of the patients were reviewed and data concerning their gender, age, maturity and location of the unerupted incisor/s, anterior developmental steps lost, aetiology of impaction, surgical and orthodontic procedures, treatment duration and complications were recorded. Developmental steps lost were the ones resulting from the disturbance of the normal eruption sequence in the anterior area. As normal anterior eruption sequence starts with that of the mandibular central incisors followed by the maxillary central incisors, the mandibular lateral incisors and then the maxillary lateral incisors, in the absence of central incisor/s when the mandibular lateral incisors erupt one step has been lost and when the maxillary lateral incisors erupt two steps have been lost (Fig. 3). If the aetiology of impaction was a supernumerary tooth or an odontoma, it was further classified accordingly (conical, tuberculated, supplemental, compound and complex, respectively). Preoperative orthodontic treatment time was calculated as needed for space creation, if unavailable. Actual treatment time was considered as starting from the day of operation and traction initiation until the engagement of a rectangular wire 16 9 22 SS in the bracket of the exposed tooth in full alignment. Radiographic To determine the position of the impacted incisor/s, orthopantomographs (OPGs) were reviewed at the beginning of the treatment period. All OPGs were taken in the same radiology practice with the same OPG unit (PlanmecaÒ ProMax) always using the same radiographic parameters. The degree of angulation from the angle of the long axis of the unerupted incisor to the mid-sagittal line and the vertical distance from the occlusal line of the affected side to the mesial aspect of the incisal edge of the unerupted incisor were recorded (Fig. 4). In cases of two unerupted incisors, two occlusal lines were drawn, one in each quadrant. In the four cases of dilacerated teeth, the vertical line of the impaction was considered to be the one of the crown. The described radiographic evaluation procedure was used
Fig. 3 Eruption sequence and developmental steps lost in the anterior area of permanent dentition
Fig. 4 Methodology of the radiographic evaluation in an 8-year-old boy with an unerupted left central incisor resulting from a tuberculated supernumerary tooth. a The degree of angulation from the angle of the long axis of the unerupted incisor to the mid-sagittal line and b the vertical distance from the occlusal line of the affected side to the mesial aspect of the incisal edge of the unerupted incisor
as a simple and easily reproducible method. Periapical and occlusal radiographs for determination of the site of the unerupted tooth at the time of exposure using Clark’s method were taken at the clinic using a BelmontÒ unit with long-cone paralleling technique. The maturity of the nonerupted maxillary incisor teeth was assessed in five groups according to the length and width of the root as in Cvek’s classification (Cvek 1992).The first two authors made the measurements in the OPGs being previously calibrated using 20 radiographs, and the inter-and intra-examiner reproducibility was calculated and found to be high in all parameters examined (kappa = 0.91–0.94). Statistical analysis Statistical analysis of the results was performed using the SPSS v.15.0 statistical package. Descriptive statistics and parametric (Pearson correlation/coefficient) and non-
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Fig. 5 Different aetiological factors resulting in unerupted incisors in the 46 patients. Asterisk indicates a patient having an odontoma together with a dilacerated incisor
parametric (Kruskal–Wallis one-way analysis of variance, Mann–Whitney U test) analyses were applied. Statistical significance was considered at the level of p \ 0.05. Results Study group demographics The study group of 46 patients comprised 34 males and 12 females aged 7.3–12.7 years with a mean age of 9.44 ± 1.36. The study group included 37 patients diagnosed and fully treated by us and 9 referrals with persistent eruption failure of central incisors following previous surgical removal of various obstructions by other clinicians. Of the total 46 patients, 38 had 1 unerupted maxillary central incisor and a further 8 had 2; therefore, the total number studied was 54 unerupted maxillary incisors. Teeth involved were 26 right and 28 left maxillary permanent central incisors. Aetiology of unerupted incisors The aetiology of the unerupted central incisors in the 46 patients was the presence of the following factors: 10 (21.7 %) cases with odontomas (8 compound, 2 complex), 24 (52.17 %) with supernumerary teeth (16 cases with 1, 7 cases with 2, 1 case with 3, altogether 16 conical, 14 tuberculated, 3 supplementary teeth). There were 5 children with previous trauma to primary predecessors resulting in malpositioned incisors, 1 with congenital lack of space, 1 with dentigerous cyst, 1 with severe MIH of the incisor and 5 (10.8 %) with dilaceration. In one of the patients, there was a combination of a compound odontoma with a dilacerated incisor (Fig. 5).
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Treatment groups and relevant total treatment time Total treatment time included pre-operative orthodontics and lasted until the full alignment of the unerupted teeth in occlusion. The study group was further divided into four different subgroups according to the total management options to better evaluate the treatment results (Fig. 6): Subgroup 1 Following diagnosis, simple orthodontics for adjacent teeth alignment and space creation (if needed), and operation for obstruction removal together with placement of a wired orthodontic bracket, traction and orthodontic alignment to occlusion were performed. Twenty-four patients with 25 unerupted teeth (mean total treatment time 9.88 ± 3.10 months) were included. Subgroup 2 Following diagnosis, simple orthodontics for adjacent teeth alignment and space creation (if needed), operation for obstruction removal, intentional wait for eruption and orthodontic alignment to occlusion if necessary were performed. Eight patients with nine unerupted teeth (mean total treatment time 8.22 ± 3.92 months) were included. Subgroup 3 Initiation of the treatment with an operation for obstruction removal together with placement of a wired orthodontic bracket, then teeth bracketing for space creation simultaneously to traction of the unerupted teeth and alignment into occlusion were performed. Five patients with five unerupted incisors (mean total treatment time 15 ± 2.12 months) were included. Subgroup 4 Treatment was initiated with an operation for obstruction removal and wait for spontaneous eruption. Following persistent eruption failure, preoperative orthodontics for space creation, second operation for uncovering and placement of a wired orthodontic attachment, traction of the unerupted teeth and alignment into occlusion were performed. Nine patients
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Time in months
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Fig. 6 Analysis of treatment time (mean ± SD) in the four different subgroups of the 46 patients with 54 unerupted insicors
with 15 unerupted teeth (mean total treatment time 23.73 ± 5.14 months) were included. Analysis of the different treatment time steps is shown in Fig. 6. In the first three subgroups, the whole treatment approach, from diagnosis until full alignment into the occlusion of the unerupted incisors in the mouth, was undertaken. In the fourth subgroup, total treatment time was rather ‘total attendance time’ as the first operation for obstruction removal was performed by other clinicians and our treatment followed a referral for unerupted incisors. Finally, the first subgroup was considered as the main treatment protocol and therefore treatment results for the remaining three groups were compared to that. Correlation of treatment time to treatment subgroup For the total of 46 patients, the actual orthodontic treatment time, from the day of the obstruction removal and/or traction initiation until the day of the unerupted tooth alignment, ranged from 3 to 18 months (mean 7 ± 3.56). In addition, time needed for pre-operative simple orthodontics for adjacent teeth alignment and space creation ranged from 2 to 12 months (mean 3 ± 2.70). Total treatment time from the diagnosis until teeth alignment ranged from 4 to 21 months (mean 10 ± 3.97). In the last calculation, time that elapsed from the first operation by other clinicians to the initiation of our treatment for the nine patients of the fourth subgroup was excluded. This subgroup was characterised by an initial misdiagnosis and unnecessary long-term time engagement of the young patients.
Statistical analysis of the total treatment time needed for the four different approaches revealed a significant time difference (Mann–Whitney 17, p \ 0.05). The worse result was for the fourth treatment option and the best for the first and second options. The absence of pre-operative simple orthodontics for space creation, as in the third option, dramatically increased treatment time (Mann–Whitney 215, p = 0.018). Finally, when the maturity, the location of the impacted tooth and the space availability allowed waiting for spontaneous eruption as in the second option, treatment time was not statistically different from that of our main treatment protocol as in the first option (Mann– Whitney 140, p = 0.545). Surgical procedure and complications All 46 patients undertook an operation for obstruction removal and/or uncovering the unerupted incisors under local analgesia. The great majority received the closed surgical technique, a mucoperiosteal flap fully repositioned, for (a) the removal of any obstruction, (b) the attachment of an orthodontic bracket for traction initiation or (c) a combination of both. Of the 46 patients, 37 (subgroups 1, 2, 3) who were initially diagnosed by us received the following operations: 35 patients, a fully repositioned flap; 1, an apically repositioned flap; and 1, a marsupialisation technique having a dentigerous cyst. These operations were performed in 8 patients for obstruction removal alone (supernumerary teeth or a cyst), in 11 for placement of an orthodontic attachment for traction initiation alone (cases with dilaceration, MIH, primary teeth trauma, lack
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Fig. 7 Different types of surgical procedures applied in the four different subgroups of the 46 patients. Asterisk indicates a patient in the first subgroup having two scheduled operations: a first one for a complex odontoma removal and a second for traction and final alignment
of space) and the remaining 17 for a combination of the above (Fig. 7). Finally in one case with an extremely dislocated incisor in the first subgroup, a previous operation for a complex odontoma removal preceded until the tooth moved to a more favourable position allowing for a second operation for traction and final alignment. In the 9 patients of the 4th subgroup, 2 patients received the apically repositioned flap and the remaining 7 the closed technique, all for placement of an orthodontic bracket and initiation of traction as any obstruction was removed previously. In all 4 subgroups, 49 of the unerupted incisors were surgically treated with the closed technique, 4 with an apically repositioned flap and 1 with marsupialisation. Concerning complications from the total of 54 unerupted incisors, 18 presented with some type of complication that required additional treatment. All 18 had received the closed surgical technique. Eleven of them needed a later minimal gingivectomy to remove gingival overgrowth and drifting during orthodontic traction and 3 erupted in an unusual position, 2 vertically and 1 palatally, requiring additional orthodontic adjustments. Finally, mild recession of the gingival margin at the end of treatment was observed in 6 incisors, but in all of them it spontaneously improved a few years later.
significant correlations were found in other parameters evaluated such as the maturity of the unerupted incisors (Pearson’s 0.093, p = 0.505) and the anterior developmental steps lost (Kruskal–Wallis 7.48, p = 0.058). Finally, it was noted that there was no statistically significantly correlation between the age of the patients and the degree of maturity of the unerupted incisors (Pearson’s 0.201, p = 0.146). Additional correlations of treatment time within the four subgroups As shown previously, the first and second subgroups showed better results regarding the total treatment time of the patients. Further however, statistical analysis of the various evaluated parameters within the four different treatment subgroups revealed the following additional findings, when the main treatment protocol of the first subgroup was compared to the others: a.
Total group correlations of treatment time to evaluated parameters b. In the 46 patients, the total treatment time needed for alignment of the unerupted incisors was statistically significantly correlated to their age (Pearson’s correlation 0.416, p = 0.002) and the impaction height (Pearson 0.449, p = 0.001) and angle (Pearson 0.583, p = 0.000) of the unerupted incisors. On the contrary, no statistically
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Unerupted teeth location (height and angle) and age of the patients were again statistically significantly related to treatment time (always p \ 0.005) in the first, third and fourth subgroups, but not in the second when compared with the first, which shared exactly the same treatment methodology with the exception of the unerupted incisors orthodontic traction (Pearson’s test for height 0.630, p = 0.129; for angle 0.551, p = 0.20; and for age 0.228, p = 0.623) The anterior developmental steps lost were again not statistically significantly related to treatment time (p \ 0.005) in the first, second and fourth subgroups, but not in the third when compared to the first, which shared the same treatment methodology with the exception of the pre-operative orthodontics for space creation (Kruskal–Wallis 6.663, p = 0.036)
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Discussion The present study reviewed 46 patients, of whom 37 were fully treated by us. The strong male bias for unerupted incisors in this retrospective study (73.9 %) is in agreement with previous studies (Patchett et al. 2001; Foley 2004) and may reflect the higher prevalence of supernumerary teeth in males (Mitchell and Bennett 1992). In 5 of those 37 patients, treatment was initiated with surgical removal of the obstruction and ligation of the unerupted incisor followed by orthodontic space creation and traction for alignment (Third subgroup). Since these cases were treated before 2000, at the start of our experience without any similar reference in the literature, it was decided to follow a different approach in future patients as treatment time appeared prolonged, resulting from the initial absence of the required space for eruption. The standardised treatment plan that was followed since then in the majority of our patients included simple fixed orthodontic treatment for adjacent teeth alignment and space creation, operation for obstruction removal together with placement of a wired orthodontic attachment in cases of unfavourable tooth position, traction and orthodontic alignment to occlusion (first subgroup). Alternatively, when the unerupted tooth revealed a favourable position, spontaneous eruption was anticipated following the operation (second subgroup). The results of the present study clearly showed the predominance of such a comprehensive approach, as statistically significantly less treatment time was needed following this treatment plan. However, to our knowledge there are no similar clinical studies showing the results of this comprehensive approach including pre-operative orthodontics and one-step operation in patients with unerupted maxillary central incisors. The essential existence of sufficient space prior to operation has been highlighted before (Di Biase 1971; Mitchell and Bennett 1992; Suri et al. 2004; Leyland et al. 2006; Huber et al. 2008), while Bryan et al. (2005) suggested that extraction of primary canines at the time of supernumerary removal may result in creating the necessary space for eruption. The most conservative clinical management would be the extraction of any obstruction, the creation of space if necessary and the observation for spontaneous eruption, only in cases in which the location and the root maturity of the unerupted teeth were favourable. Between 37 and 72 % of the teeth, depending on the degree of root maturity, have been reported to erupt spontaneously without any further treatment after the removal of any obstruction (Mason et al. 2000). In the second subgroup, 8 patients were treated following this approach and all their 9 impacted teeth erupted spontaneously, following careful evaluation of the favourable location and maturity of the tooth and providing that sufficient eruption space existed.
In a case of insufficient or even questionable anterior space, orthodontic intervention should be preceded as in all our cases of spontaneous eruption, in contrast to another approach where space creation followed the obstruction removal and possible traction. The former approach appears better, because statistically significantly less treatment time is required, as shown in the results of the present study when comparing the second and third subgroups. In addition, young patients are introduced to treatment with milder simple orthodontic procedures as compared to more aggressive surgical procedures. As a result, the patient’s collaboration is gradually enhanced and the operation can be performed under local analgesia. The initiation of the treatment with the operation for obstruction removal and monitoring for spontaneous eruption (subgroup 4) appears to be an incorrect approach when clinical and radiographic findings are not favourable. Following supernumerary removal, 63 % of the incisors with mature roots failed to erupt, while even in those cases with immature roots 28 % eruption failure occurs (Mason et al. 2000). In addition Leyland et al. (2006) reported that regardless of root development, only 49 % of teeth erupted depended only on the space available. The type of supernumerary teeth may well affect the ability of spontaneous eruption. Unerupted incisors associated with tuberculate supernumerary teeth were twice less likely to erupt as compared to those associated with conical ones (Mitchell and Bennett 1992; Patchett et al. 2001). This unnecessary delay in the treatment of the unerupted incisors may result in additional problems such as cyst formation, ankylosis, external tooth resorption and periodontal problems (Huber et al. 2008), while maxillary canine impaction resulting from the adjacent laterals’ displacement may happen in 58.7 % of the cases (Chaushu et al. 2003). However, under certain circumstances of very severely displaced unerupted incisors, as in one of our cases, the treatment plan may include a first operation for the removal of the obstruction and, then when tooth location becomes more favourable, a second operation for traction and alignment. An important step in the treatment plan is the surgical removal of any obstruction and at the same time the exposure of the unerupted tooth, which can be performed using either an open or a closed technique as previously described (Becker et al. 2002). In the great majority of our cases (42 of 46 patients), the closed technique was used. Three more patients received an apically repositioned flap (Vanarsdall and Corn 1977) and one more, having a dentigerous cyst, a marsupialisation approach. The advantages claimed for the closed versus open technique for the uncovering of unerupted incisors include superior aesthetics and periodontal health in addition to shorter clinical crowns and increased bone support (Becker et al. 2002; Chaushu et al. 2003, 2009). However, as it has been
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previously reported in relation to the closed technique, a complication, namely gingival overgrowth and drifting, may follow almost 50 % of the teeth forced to erupt, presumably as the result of a ‘‘forced eruption phenomenon’’ that generates an increased amount of crestal bone, when compared to normal eruption (Kohavi et al. 1984). In the present study, minimal gingivectomy was necessary in only 11 of the 49 (22.4 %) incisors that received the closed technique, for removing the gingival attachment overgrowth and drifting and facilitate the final aesthetic alignment of the unerupted tooth. For the 46 patients treated by us, the mean treatment time from the operation date until the day of the full alignment of the unerupted incisor was 7 ± 3.56 months, while if pre-operative orthodontics for space creation was included the mean total treatment time increased to 10 ± 3.97 months. Mason et al. (2000) reported that the mean spontaneous eruption time for the incisors after the initial operation was 11 months, Bryan et al. (2005) reported 9.2 months and Leyland et al. (2006) reported 6–18 months. Di Biase (1971) reported eruption time up to 18 months provided that teeth were not displaced and the follicle had not been disturbed during the surgical procedure. Since these studies did not include any pre-operative orthodontics for space creation or traction, they can only be compared with the post-operative time needed for the eruption in the second subgroup in our study (5.88 ± 2.61 months, see Fig. 6), where the teeth were allowed to erupt spontaneously following the removal of the obstruction. In the present study, the total treatment time was statistically significantly related to the patient’s age and the impaction height and angle of the incisor in all subgroups with the exception of the second subgroup, where the incisors erupted spontaneously without orthodontic traction. The latter partly supported the results of Bryan et al. (2005) who found that there was no statistically significant association between tooth eruption and the angle of the long axis, but there was with vertical height. Concerning the importance of age, the root and occlusal development, in the same second subgroup the total treatment time was not statistically significantly associated with neither of them, a finding in accordance with the results of Bryan et al. (2005). On the contrary, Mason et al. (2000) found that the difference in the proportion of teeth that erupted was significant between the immature and mature, while Foley et al. (2004) indicated that 89 % of incisors with immature apices subsequently erupted, compared with only 19 % of mature ones. In addition, Leyland et al. (2006) reported that patients’ age was related to eruption time. Differences regarding the role of the age and root maturity may reflect the smaller size and difference in age
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cohorts studied. In the present study patients belonging to the second subgroup had a limited age span (7.6–9.2 years) compromising the statistical result. Finally as there were no previous studies examining the treatment time required in cases where comprehensive orthodontic surgical approach was followed, our results from the first, third and fourth subgroups cannot be compared to other studies. The recording and evaluation of the lost anterior developmental (eruption) steps, as detailed in ‘‘Materials and methods’’, have been reported for the first time in the dental literature, although to our experience they comprise a very valuable clinical tool for determining the time for treatment initiation. When an eruption step has been lost or the tooth has delayed eruption for more than 6 months after contralateral eruption (Kluemper et al. 2000), the clinician should further examine the case and treat accordingly. The significance of the steps lost is clearly shown in the results of the treatment time in the third subgroup where no preoperative orthodontics for space creation was applied. The more developmental steps lost, the more is the treatment time needed (see results in ‘‘Additional correlations of treatment time within the 4 subgroups’’) as available space might be compromised with the eruption and migration of laterals. The reliability of various parameters used in clinical studies is always questionable. Our previously described method for impacted canines (Lygidakis et al. 2001) was modified and used as a simple and easily reproducible one, as there is no single standardised method for classifying impacted teeth in either OPGs or lateral cephalographs (Iramaneerat et al. 1998). The standardised parameters of the present study included the patient’s chronological age, the degree of angulation and height of the unerupted maxillary incisor, tooth maturity and the anterior developmental steps lost. Our preference of using the chronological age of patients instead of dental age is in accordance with similar previous studies (Betts and Camilleri 1999; Mason et al. 2000; Bryan et al. 2005). In the present study, the maturity of the unerupted incisor was classified into five different stages using the Cvek’s assessment as in the studies of Mason et al. (2000) and Foley (2004). Concerning the radiographic location of the unerupted incisor in the present study, the degree of angulation was determined as the angle of the long axis of the unerupted tooth to the mid-sagittal line, an approach also used previously by Bryan et al. (2005). The same authors recorded the vertical distance from the nasal spine, while others from the palatal plane (Chaushu et al. 2003). In our study we preferred to calculate the height of the unerupted incisor as the vertical distance from the occlusal line of the affected side to the mesial aspect of the incisal edge of the impacted incisor, as used in a previous study but for
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impacted canines (Lygidakis et al. 2001). It should be noted, however, that true linear radiographic measurements of teeth are inconclusive when performed on panoramic radiographs, being influenced by many diverse parameters, while angular measurements appear much more reliable (Christen and Segrest 1968; Stramotas et al. 2000). The identification of anatomical structures can also be problematic, but despite these limitations the use of panoramic films in previous and the present study is justified because only the significance of the differences are analysed, and not the absolute values (Chaushu et al. 2003). In addition, in the present study radiographs were always in the same dental radiology practice using the same unit with the same parameters. Finally, the literature reports several causes of failure or delayed eruption of maxillary incisors. The most commonly reported cause of eruption delay of the maxillary incisors is the presence of a supernumerary tooth (Bishara 1971; Munns 1981; Buchanan and Jenkins 1997). In the present study, 52.17 % of our patients had supernumerary teeth and 54.16 % of them revealed tuberculated supernumerary teeth. Previous studies have reported that 56–86 % of the cases with unerupted incisors are a result of supernumerary teeth, while tuberculated supernumeraries are more likely to impede eruption (Mitchell and Bennett 1992; Betts and Camilleri 1999; Mason et al. 2000). While supernumerary teeth are the most common cause of delayed eruption of maxillary incisors, eruption failure can also be caused by other anomalies. Odontomas were present in 21.7 % of our patients, a percentage higher than the 9–12 % found in other studies (Mason et al. 2000; Leyland et al. 2006), while a further 10.8 % had a dilacerated incisor, which is in accordance with the study of Betts and Camilleri (1999). Eruption failure may also occur if cysts develop in the eruptive path of incisors (Bodenham 1967), such as the dentigerous cyst which was present in one of our patients. Of the patients, 10.8 % had a history of trauma to the primary teeth resulting in the malposition of the successor incisor, a higher rate compared to those reported previously by Brin et al. (1988) and Betts and Camilleri (1999), but lower than the 16.7 % reported recently by Altun et al. (2009). Finally, in one of the patients, the incisor failed to erupt due to severe MIH, a phenomenon that has not been referred previously for affected incisors, but only for molars (Lygidakis et al. 2010).
Conclusions The results are as follows: Precise clinical and radiographic diagnosis and treatment plan are necessary for the treatment of the unerupted incisors resulting from the presence
of an obstruction. Pre-operative space creation if unavailable is mandatory. Following the removal of the obstruction, if the location of the unerupted tooth is favourable, spontaneous eruption would be anticipated; otherwise, a one-step operation including obstruction removal and initiation of orthodontic traction is recommended. In such cases, treatment time is statistically significantly related to the age, height and angulation of the unerupted teeth. Treatment initiation with the one-step operation in the absence of the required space for eruption may need as much as double treatment time; therefore, it is not recommended. In cases of unfavourable unerupted teeth location, the removal of the obstruction without simultaneous orthodontic traction increases dramatically the total treatment time and requires an unnecessary second operation for traction. Acknowledgments The authors wish to thank Mrs Eirini Stamatopoulou, MSc, Biostatistician, for performing the statistical analyses. Dr K. Chatzidimitriou is a Hellenic State Scholarships Foundation scholar. Ethical standard The authors state that the study has been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. Also, the presented patients and their parents had given their informed consent prior to the inclusion in the study.
References Altun C, Cehreli ZC, Gu¨ven G, Acikel C. Traumatic intrusion of primary teeth and its effects on the permanent successors: a clinical follow-up study. Oral Surg Oral Med OralPathol Oral Radiol Endod. 2009;107(4):493–8. Becker A, Brin I, Ben-Bassat Y, Zilberman Y, Chaushu S. Closederuption surgical technique for impacted maxillary incisors: a postorthodontic periodontal evaluation. Am J Orthod Dentofac Orthop. 2002;122:9–14. Becker A. Early treatment for impacted maxillary incisors. Am J Orthod Dentofac Orthop. 2002;121:586–7. Betts A, Camilleri GE. A review of 47 cases of unerupted maxillary incisors. Int J Paediatr Dent. 1999;9(4):285–92. Bishara SE. Impacted maxillary canines: a review. Am J Orthod Dentofac Orthop. 1992;101:159–71. Bishara SE. Treatment of unerupted incisors. Am J Orthod. 1971;59:443–7. Bodenham RS. The treatment and prognosis of unerupted maxillary incisors associated with the presence of supernumerary teeth. Brit Dent J. 1967;123:173–7. Brin I, Zilberman Y, Azaz B. The unerupted maxillary central incisor: review of its etiology and treatment. J Dent Child. 1982;5:352–6. Brin I, Ben Bassat Y, Zilberman Y, Fuks A. Effect of trauma to the primary incisors on the alignment of their permanent successors in Israelis. Community Dent Oral Epidemiol. 1988;16:104–8. Bryan RA, Cole BO, Welbury RR. Retrospective analysis of factors influencing the eruption of delayed permanent incisors after supernumerary tooth removal. Eur J Paediatr Dent. 2005;6(2):84–9. Buchanan S, Jenkins CR. Riga-Fedes syndrome: natal or neonatal teeth associated with tongue ulceration. Case report. Aust Dent J. 1997;42:225–7.
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Eur Arch Paediatr Dent Chaushu S, Zilberman Y, Becker A. Maxillary incisor impaction and its relationship to canine displacement. Am J Orthod Dentofac Orthop. 2003;124:144–50. Chaushu S, Dykstein N, Ben-Bassat Y, Becker A. Periodontal status of impacted maxillary incisors uncovered by 2 different surgical techniques. J Oral Maxillofac Surg. 2009;67(1):120–4. Christen A, Segrest V. Distortion and artifacts encountered in panorex radiography. J Am Dent Assoc. 1968;77:1096–101. Cole BO, Shaw AJ, Hobson RS, et al. The role of magnets in the management of unerupted teeth in children and adolescents. Int J Paediatr Dent. 2003;13(3):204–7. Crawford LB. Impacted maxillary central incisor in mixed dentition treatment. Am J Orthod Dentofac Orthop. 1997;112:1–7. Cvek M. Prognosis of luxated non-vital maxillary incisors treated with calcium hydroxide and filled with gutta-percha. A retrospective clinical study. Endod Dent Traumatol. 1992;8(2):45–55. Di Biase DD. The effects of variations in tooth morphology and position on eruption. Dent Pract Dent Record. 1971;22:95–108. Duncan WK, Ashrafi MH. Management of the nonerupted maxillary anterior tooth. JADA. 1983;106:640–4. Ferguson JW. Management of the unerupted maxillary canine. Br Dent J. 1990;169:11–7. Foley J. Surgical removal of supernumerary teeth and the fate of incisor eruption. Eur J Paediatr Dent. 2004;5(1):35–40. Grover PS, Lorton L. The incidence of unerupted permanent teeth and related clinical cases. Oral Surg Oral Med Oral Pathol. 1985;59:420–5. Huber KL, Suri L, Taneja P. Eruption disturbances of the maxillary incisors: a literature review. J ClinPediatr Dent. 2008;32(3):221–30. Iramaneerat S, Cunningham SJ, Horrocks EN. The effect of two alternative methods of canine exposure upon subsequent duration of orthodontic treatment. Inter J Paed Dent. 1998;8:123–9. Jacobs SG. Radiographic localization of unerupted maxillary anterior teeth using the vertical tube shift technique: the history and application of the method with some case reports. Am J Orthod Dentofac Orthop. 1999;116(4):415–23. Kluemper GT, Beeman CS, Hicks EP. Early orthodontic treatment: what are the imperatives? JADA. 2000;131(5):613–20. Kohavi D, Zilberman Y, Becker A. Periodontal status following the alignment of buccally ectopic maxillary canine teeth. Am J Orthod. 1984;85:78. Leyland L, Batra P, Wong F, Llewelyn R. A retrospective evaluation of the eruption of impacted permanent incisors after extraction of supernumerary teeth. J ClinPediatr Dent. 2006;30(3):225–31.
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Lin YTJ. Treatment of an impacted dilacerated maxillary central incisor. Am J Orthod Dentofac Orthop. 1999;115:406–9. Lygidakis NA, Theologie-Lygidakis N, Dimopoulos AS. Orhtodontic-surgical management of unerupted permanent teeth using the fully repositioned flap technique. Part 1. Results, treatment time and post-treatment stability in 90 cases. Eur J Paediatr Dent. 2001;2(3):119–27. Lygidakis NA, Wong F, Ja¨levik B, et al. Best Clinical Practice Guidance for clinicians dealing with children presenting with Molar-Incisor-Hypomineralisation (MIH). Eur Arch Paediatr Dent. 2010;11(2):75–81. Macias E, Carlos F, Cobo J. Posttraumatic impaction of both maxillary central incisors. Am J Orthod Dentofac Orthop. 2003;124:331–8. Mason C, Azam N, Holt RD, Rule DC. A retrospective study of unerupted maxillary incisors associated with supernumerary teeth. Br J Oral Maxillofac Surg. 2000;38(1):62–5. Mead SV. Incidence of impacted teeth. Int Orthod. 1930;16:885–90. Mitchell L, Bennett TG. Supernumerary teeth causing delayed eruption— a retrospective study. Br J Orthod. 1992;19:41–6. Munns D. Unerupted incisors. Br J Orthod. 1981;8:39–42. Patchett CL, Crawford PJ, Cameron AC, Stephens CD. The management of supernumerary teeth in childhood–a retrospective study of practice in Bristol Dental Hospital, England and Westmead Dental Hospital, Sydney, Australia. Int J Paediatr Dent. 2001;11(4):259–65. Stramotas S, Geenty JP, Darendeliler MA, et al. The reliability of crown-root ratio, linear and angular measurements on panoramic radiographs. Clin Orthod Res. 2000;3:182–91. Suri L, Gagari E, Vastardis H. Delayed tooth eruption: pathogenesis, diagnosis, and treatment. A literature review. Am J Orthod Dentofac Orthop. 2004;126(4):432–45. Tanaka E, Watanabe M, Nagaoka K, Yamaguchi K, Tanne K. Orthodontic traction of an impacted maxillary central incisor. J Clin Orthod. 2001;35:375–8. ValladaresNeto J, Silva FA, Kaadi OB. Delayed eruption of permanent incisor associated to prolonged retention of deciduous predecessor: obstructive, traumatic, developmental or idiopathic? Rev Odontol Bras Cent. 1995;5:4–10. Vanarsdall RL, Corn H. Soft-tissue management of labially positioned unerupted teeth. Am J Orthod. 1977;72:53–64.
ORIGINAL SCIENTIFIC ARTICLE
Evaluation of a treatment protocol for unerupted maxillary central incisors: retrospective clinical study of 46 children N. N. Lygidakis • K. Chatzidimitriou • N. Theologie-Lygidakis • N. A. Lygidakis
Received: 11 May 2014 / Accepted: 5 September 2014 Ó European Academy of Paediatric Dentistry 2014
Abstract Aim To evaluate the clinical outcome of a treatment protocol performed in children with unerupted permanent maxillary central incisors, including surgical removal of any related obstruction and traction initiation in one stage, under fully repositioned flap, combined with pre- and postoperative orthodontics for space creation and final alignment. Methods Forty-six patients aged 7.3–12.7 years (mean = 9.44 ± 1.36) having 54 impacted maxillary central incisors were reviewed. The study group included 37 patients fully treated by us and nine referrals with eruption failure of impacted incisors following previous surgical removal of various obstructions. Detailed patient’s clinical and radiographic data were recorded. Results Aetiology of unerupted incisors included 9 patients with odontomas, 24 with supernumerary teeth, 1 with skeletal lack of space, 1 with a dentigerous cyst, 4 with dilaceration, 1 with severe incisor MIH, 5 with luxation injuries to primary predecessors and 1 with coexisting dilaceration and odontoma. The total treatment time following the standardised protocol ranged from 5 to 21 months (mean 9.88 ± 3.10), while the time needed using different approaches (no pre-operative orthodontics or obstruction removal and then to wait over an assessment period) ranged from 12 to 18 months (mean 15 ± 2.12) and 17 to 30 months (mean 23.73 ± 5.14), respectively (p \ 0.05). The time needed for full alignment depended on the inclination, the height of the impacted tooth
N. N. Lygidakis K. Chatzidimitriou N. Theologie-Lygidakis N. A. Lygidakis (&) Private Paediatric Dental Clinic, 2 Papadiamantopoulou Street, 11528 Athens, Greece e-mail: [email protected]; [email protected]
(p = 0.001) and the patient’s age (p = 0.002). Additionally, the absence of pre-operative orthodontics for space creation dramatically increased treatment time (p = 0.018). In contrast, the maturity of the impacted tooth and the developmental stage of the anterior teeth did not affect treatment time. Finally, when the location of the impacted tooth and the space availability allowed waiting for spontaneous eruption, treatment time was not statistically different from that of the main treatment protocol (p = 0.545). Conclusions The studied treatment protocol appears ideal for successful results and minimum treatment time. Space creation followed by surgical removal of any obstruction together with orthodontic traction initiation produces excellent results, while waiting for spontaneous eruption is indicated only in cases of favourable patient’s age and tooth location. Treatment initiation with operation in the absence of the required eruption space is not recommended, whereas in unfavourable cases obstruction removal without simultaneous orthodontic traction increases dramatically the total treatment time and requires an unnecessary second operation for traction. Keywords Treatment Impacted Unerupted Maxillary central incisors
Introduction Eruption anomalies belong to the dental anomalies spectrum and include changes of normal tooth eruption, as those of accelerated, delayed, failed or deviated ectopic eruption. These anomalies are related to general and/or local aetiologic factors (Brin et al. 1982; Valladares et al. 1995).
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Although an impaction of other permanent teeth is rarely diagnosed during the early mixed dentition period, an unerupted central incisor can be usually diagnosed on time following the delay in the eruption of the tooth. Many patients with unerupted maxillary central incisors are referred to paediatric dentists or orthodontists by general dental practitioners, because parents are concerned about a missing incisor in the early mixed dentition, even though its occurrence is less frequent (Lin 1999; Becker 2002). The frequency of maxillary central incisor impaction has been found in the range of 0.03–1.96 % (Mead 1930; Grover and Lorton 1985). Several contributing factors have been suggested that impede maxillary central incisor eruption. These could be supernumerary teeth, trauma to primary teeth/dilaceration, congenitally displaced incisor, ectopic development, cysts, tumours, odontomas, over-retained or early lost primary teeth, dense mucoperiosteum, tooth agenesis, syndromes, lack of space, ankylosis and abnormal morphology (Huber et al. 2008). The anterior maxilla is a highly demanding aesthetic area and consequently treatment of unerupted maxillary incisors requires a well-synchronised and multidisciplinary approach to obtain an acceptable aesthetic and functional result as soon as possible. She clinical management of this condition is variable. A comprehensive evaluation must include assessment of whether space is available or can be made available in the arch for alignment of the unerupted teeth, patient’s age and dental developmental stage, timing of surgical intervention, length and cost of orthodontic treatment, oral hygiene status and others. There are several treatment options open to a patient with an unerupted permanent incisor. She most conservative management would be the extraction of any obstruction, the creation of space and the observation for spontaneous eruption (Huber et al. 2008). Spontaneous eruption in 54–74 % of the cases of unerupted incisors has been reported following the removal of any obstruction, without any further treatment (Mason et al. 2000). However, in many cases surgical exposure of the impacted teeth and orthodontic traction into the line of occlusion is the most indicated approach (Ferguson 1990). Surgical procedures involve either exposure and packing of the area prior to placing an orthodontic attachment in a later visit or a one-step exposure and orthodontic attachment placement using a fully repositioned mucoperiosteal flap (Bishara 1992). Both methods have advantages and disadvantages and their use depends on the operator’s experience, while other methods such as the one with a magnet system have been described with good results (Cole et al. 2003). However, as most of the successful cases regarding the orthodontic traction of unerupted maxillary central incisors include short-term case reports (Duncan and Ashrafi 1983; Crawford 1997;
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Lin 1999; Tanaka et al. 2001; Macias et al. 2003), there is lack of evidence-based information about the immediate and long-term results. The purpose of this retrospective study was to evaluate the clinical outcome of a treatment protocol performed in a large cohort of children with unerupted permanent maxillary central incisors, including surgical removal of any related obstruction and orthodontic traction initiation in one stage, under fully repositioned flap, combined with pre-operative orthodontics for space creation if unavailable. In particular, the study investigated (a) the aetiology of impaction, (b) the treatment time related to different parameters such as the age of the patient, the position of the unerupted incisors, their developmental stage, the anterior occlusal development and finally (c) the total treatment time following our method as compared to that needed using different approaches.
Materials and methods Cases analysed were treated in a paediatric dental clinic over the last 15 years. During this period, 46 patients presented with 54 impacted maxillary central incisors. All patients had full clinical and radiological records and scheduled recalls at least 2 years following treatment. Nine more patients with missing data from their records were excluded from the study. The clinical diagnosis was confirmed by radiographs. The study group consisted of 37 patients fully treated by the authors and 9 patients with unerupted incisor/s referred to us following a previous operation for the removal of any obstruction related to impaction. Treatment approach followed (a)
A standardised treatment approach was used in the great majority of the young patients. Initially, clinical and panoramic radiographic evaluation of the patients recorded the maturity and position of the unerupted teeth including the degree of angulation and the distance from the occlusal plane. A treatment schedule was initiated with fixed orthodontic appliances to align the adjacent teeth and create adequate space for the impacted tooth, if unavailable. At that time, the position and maturity of the tooth/teeth was again evaluated with different periapical and occlusal radiographs applying Clark’s technique (Jacobs 1999). In few cases of severe impaction, a dental scan was also prescribed. The surgery was performed under local analgesia (LA) according to a standard protocol, when location
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Fig. 1 A male, 10.6 years old, with an unerupted right central incisor, resulting from a conical supernumerary. a Clinical appearance at the first examination, b OPG revealing the supernumerary, c 4 months pre-operative orthodontics for alignment and space creation, d closed flap operation under LA, removal of supernumerary
and bracket attachment, e traction into occlusion, f periapical radiograph to evaluate traction progress, g incisor into occlusion 5 months later (note recessed gingiva), and h 6 years follow-up (note enhanced gingiva without any intervention)
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Fig. 2 A male 9.2 years old, with an unerupted right central incisor, resulting from a tuberculated supernumerary. a Clinical appearance at first examination, b OPG revealing the supernumerary, c 4 months pre-operative orthodontics for adjacent teeth alignment and space
improvement, d closed flap operation under LA for the removal of supernumerary, e incisor starting to erupt, f incisor into full occlusion 5 months later, g OPG to evaluate alignment, and h 6 months followup revealing a satisfactory result
(height/angle) and maturity of the unerupted tooth/ teeth were considered unfavourable. A mucoperiosteal flap was raised, any obstruction was removed and a small round orthodontic attachment was bonded to the impacted tooth, while the flap was
repositioned in place (closed method). Orthodontic traction with light forces was initiated 1 week following suture removal and treatment completed when incisors were stabilised with SS wire in full alignment (Fig. 1a–h).
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(b)
Alternative treatment approaches evaluated in the present study included: (1) orthodontic space creation or improvement, operation for obstruction removal and an intentional wait for spontaneous eruption in cases of favourable patient’s age and maturity and location of the unerupted teeth (Fig. 2a–h), (2) operation for obstruction removal and attachment placement, followed by orthodontic treatment for space creation, traction and alignment and (3) operation for obstruction removal and unjustified wait for spontaneous eruption.
Evaluation methodology Clinical The records of the patients were reviewed and data concerning their gender, age, maturity and location of the unerupted incisor/s, anterior developmental steps lost, aetiology of impaction, surgical and orthodontic procedures, treatment duration and complications were recorded. Developmental steps lost were the ones resulting from the disturbance of the normal eruption sequence in the anterior area. As normal anterior eruption sequence starts with that of the mandibular central incisors followed by the maxillary central incisors, the mandibular lateral incisors and then the maxillary lateral incisors, in the absence of central incisor/s when the mandibular lateral incisors erupt one step has been lost and when the maxillary lateral incisors erupt two steps have been lost (Fig. 3). If the aetiology of impaction was a supernumerary tooth or an odontoma, it was further classified accordingly (conical, tuberculated, supplemental, compound and complex, respectively). Preoperative orthodontic treatment time was calculated as needed for space creation, if unavailable. Actual treatment time was considered as starting from the day of operation and traction initiation until the engagement of a rectangular wire 16 9 22 SS in the bracket of the exposed tooth in full alignment. Radiographic To determine the position of the impacted incisor/s, orthopantomographs (OPGs) were reviewed at the beginning of the treatment period. All OPGs were taken in the same radiology practice with the same OPG unit (PlanmecaÒ ProMax) always using the same radiographic parameters. The degree of angulation from the angle of the long axis of the unerupted incisor to the mid-sagittal line and the vertical distance from the occlusal line of the affected side to the mesial aspect of the incisal edge of the unerupted incisor were recorded (Fig. 4). In cases of two unerupted incisors, two occlusal lines were drawn, one in each quadrant. In the four cases of dilacerated teeth, the vertical line of the impaction was considered to be the one of the crown. The described radiographic evaluation procedure was used
Fig. 3 Eruption sequence and developmental steps lost in the anterior area of permanent dentition
Fig. 4 Methodology of the radiographic evaluation in an 8-year-old boy with an unerupted left central incisor resulting from a tuberculated supernumerary tooth. a The degree of angulation from the angle of the long axis of the unerupted incisor to the mid-sagittal line and b the vertical distance from the occlusal line of the affected side to the mesial aspect of the incisal edge of the unerupted incisor
as a simple and easily reproducible method. Periapical and occlusal radiographs for determination of the site of the unerupted tooth at the time of exposure using Clark’s method were taken at the clinic using a BelmontÒ unit with long-cone paralleling technique. The maturity of the nonerupted maxillary incisor teeth was assessed in five groups according to the length and width of the root as in Cvek’s classification (Cvek 1992).The first two authors made the measurements in the OPGs being previously calibrated using 20 radiographs, and the inter-and intra-examiner reproducibility was calculated and found to be high in all parameters examined (kappa = 0.91–0.94). Statistical analysis Statistical analysis of the results was performed using the SPSS v.15.0 statistical package. Descriptive statistics and parametric (Pearson correlation/coefficient) and non-
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Fig. 5 Different aetiological factors resulting in unerupted incisors in the 46 patients. Asterisk indicates a patient having an odontoma together with a dilacerated incisor
parametric (Kruskal–Wallis one-way analysis of variance, Mann–Whitney U test) analyses were applied. Statistical significance was considered at the level of p \ 0.05. Results Study group demographics The study group of 46 patients comprised 34 males and 12 females aged 7.3–12.7 years with a mean age of 9.44 ± 1.36. The study group included 37 patients diagnosed and fully treated by us and 9 referrals with persistent eruption failure of central incisors following previous surgical removal of various obstructions by other clinicians. Of the total 46 patients, 38 had 1 unerupted maxillary central incisor and a further 8 had 2; therefore, the total number studied was 54 unerupted maxillary incisors. Teeth involved were 26 right and 28 left maxillary permanent central incisors. Aetiology of unerupted incisors The aetiology of the unerupted central incisors in the 46 patients was the presence of the following factors: 10 (21.7 %) cases with odontomas (8 compound, 2 complex), 24 (52.17 %) with supernumerary teeth (16 cases with 1, 7 cases with 2, 1 case with 3, altogether 16 conical, 14 tuberculated, 3 supplementary teeth). There were 5 children with previous trauma to primary predecessors resulting in malpositioned incisors, 1 with congenital lack of space, 1 with dentigerous cyst, 1 with severe MIH of the incisor and 5 (10.8 %) with dilaceration. In one of the patients, there was a combination of a compound odontoma with a dilacerated incisor (Fig. 5).
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Treatment groups and relevant total treatment time Total treatment time included pre-operative orthodontics and lasted until the full alignment of the unerupted teeth in occlusion. The study group was further divided into four different subgroups according to the total management options to better evaluate the treatment results (Fig. 6): Subgroup 1 Following diagnosis, simple orthodontics for adjacent teeth alignment and space creation (if needed), and operation for obstruction removal together with placement of a wired orthodontic bracket, traction and orthodontic alignment to occlusion were performed. Twenty-four patients with 25 unerupted teeth (mean total treatment time 9.88 ± 3.10 months) were included. Subgroup 2 Following diagnosis, simple orthodontics for adjacent teeth alignment and space creation (if needed), operation for obstruction removal, intentional wait for eruption and orthodontic alignment to occlusion if necessary were performed. Eight patients with nine unerupted teeth (mean total treatment time 8.22 ± 3.92 months) were included. Subgroup 3 Initiation of the treatment with an operation for obstruction removal together with placement of a wired orthodontic bracket, then teeth bracketing for space creation simultaneously to traction of the unerupted teeth and alignment into occlusion were performed. Five patients with five unerupted incisors (mean total treatment time 15 ± 2.12 months) were included. Subgroup 4 Treatment was initiated with an operation for obstruction removal and wait for spontaneous eruption. Following persistent eruption failure, preoperative orthodontics for space creation, second operation for uncovering and placement of a wired orthodontic attachment, traction of the unerupted teeth and alignment into occlusion were performed. Nine patients
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Time in months
.
-
.
.
-
. .
.
Fig. 6 Analysis of treatment time (mean ± SD) in the four different subgroups of the 46 patients with 54 unerupted insicors
with 15 unerupted teeth (mean total treatment time 23.73 ± 5.14 months) were included. Analysis of the different treatment time steps is shown in Fig. 6. In the first three subgroups, the whole treatment approach, from diagnosis until full alignment into the occlusion of the unerupted incisors in the mouth, was undertaken. In the fourth subgroup, total treatment time was rather ‘total attendance time’ as the first operation for obstruction removal was performed by other clinicians and our treatment followed a referral for unerupted incisors. Finally, the first subgroup was considered as the main treatment protocol and therefore treatment results for the remaining three groups were compared to that. Correlation of treatment time to treatment subgroup For the total of 46 patients, the actual orthodontic treatment time, from the day of the obstruction removal and/or traction initiation until the day of the unerupted tooth alignment, ranged from 3 to 18 months (mean 7 ± 3.56). In addition, time needed for pre-operative simple orthodontics for adjacent teeth alignment and space creation ranged from 2 to 12 months (mean 3 ± 2.70). Total treatment time from the diagnosis until teeth alignment ranged from 4 to 21 months (mean 10 ± 3.97). In the last calculation, time that elapsed from the first operation by other clinicians to the initiation of our treatment for the nine patients of the fourth subgroup was excluded. This subgroup was characterised by an initial misdiagnosis and unnecessary long-term time engagement of the young patients.
Statistical analysis of the total treatment time needed for the four different approaches revealed a significant time difference (Mann–Whitney 17, p \ 0.05). The worse result was for the fourth treatment option and the best for the first and second options. The absence of pre-operative simple orthodontics for space creation, as in the third option, dramatically increased treatment time (Mann–Whitney 215, p = 0.018). Finally, when the maturity, the location of the impacted tooth and the space availability allowed waiting for spontaneous eruption as in the second option, treatment time was not statistically different from that of our main treatment protocol as in the first option (Mann– Whitney 140, p = 0.545). Surgical procedure and complications All 46 patients undertook an operation for obstruction removal and/or uncovering the unerupted incisors under local analgesia. The great majority received the closed surgical technique, a mucoperiosteal flap fully repositioned, for (a) the removal of any obstruction, (b) the attachment of an orthodontic bracket for traction initiation or (c) a combination of both. Of the 46 patients, 37 (subgroups 1, 2, 3) who were initially diagnosed by us received the following operations: 35 patients, a fully repositioned flap; 1, an apically repositioned flap; and 1, a marsupialisation technique having a dentigerous cyst. These operations were performed in 8 patients for obstruction removal alone (supernumerary teeth or a cyst), in 11 for placement of an orthodontic attachment for traction initiation alone (cases with dilaceration, MIH, primary teeth trauma, lack
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Fig. 7 Different types of surgical procedures applied in the four different subgroups of the 46 patients. Asterisk indicates a patient in the first subgroup having two scheduled operations: a first one for a complex odontoma removal and a second for traction and final alignment
of space) and the remaining 17 for a combination of the above (Fig. 7). Finally in one case with an extremely dislocated incisor in the first subgroup, a previous operation for a complex odontoma removal preceded until the tooth moved to a more favourable position allowing for a second operation for traction and final alignment. In the 9 patients of the 4th subgroup, 2 patients received the apically repositioned flap and the remaining 7 the closed technique, all for placement of an orthodontic bracket and initiation of traction as any obstruction was removed previously. In all 4 subgroups, 49 of the unerupted incisors were surgically treated with the closed technique, 4 with an apically repositioned flap and 1 with marsupialisation. Concerning complications from the total of 54 unerupted incisors, 18 presented with some type of complication that required additional treatment. All 18 had received the closed surgical technique. Eleven of them needed a later minimal gingivectomy to remove gingival overgrowth and drifting during orthodontic traction and 3 erupted in an unusual position, 2 vertically and 1 palatally, requiring additional orthodontic adjustments. Finally, mild recession of the gingival margin at the end of treatment was observed in 6 incisors, but in all of them it spontaneously improved a few years later.
significant correlations were found in other parameters evaluated such as the maturity of the unerupted incisors (Pearson’s 0.093, p = 0.505) and the anterior developmental steps lost (Kruskal–Wallis 7.48, p = 0.058). Finally, it was noted that there was no statistically significantly correlation between the age of the patients and the degree of maturity of the unerupted incisors (Pearson’s 0.201, p = 0.146). Additional correlations of treatment time within the four subgroups As shown previously, the first and second subgroups showed better results regarding the total treatment time of the patients. Further however, statistical analysis of the various evaluated parameters within the four different treatment subgroups revealed the following additional findings, when the main treatment protocol of the first subgroup was compared to the others: a.
Total group correlations of treatment time to evaluated parameters b. In the 46 patients, the total treatment time needed for alignment of the unerupted incisors was statistically significantly correlated to their age (Pearson’s correlation 0.416, p = 0.002) and the impaction height (Pearson 0.449, p = 0.001) and angle (Pearson 0.583, p = 0.000) of the unerupted incisors. On the contrary, no statistically
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Unerupted teeth location (height and angle) and age of the patients were again statistically significantly related to treatment time (always p \ 0.005) in the first, third and fourth subgroups, but not in the second when compared with the first, which shared exactly the same treatment methodology with the exception of the unerupted incisors orthodontic traction (Pearson’s test for height 0.630, p = 0.129; for angle 0.551, p = 0.20; and for age 0.228, p = 0.623) The anterior developmental steps lost were again not statistically significantly related to treatment time (p \ 0.005) in the first, second and fourth subgroups, but not in the third when compared to the first, which shared the same treatment methodology with the exception of the pre-operative orthodontics for space creation (Kruskal–Wallis 6.663, p = 0.036)
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Discussion The present study reviewed 46 patients, of whom 37 were fully treated by us. The strong male bias for unerupted incisors in this retrospective study (73.9 %) is in agreement with previous studies (Patchett et al. 2001; Foley 2004) and may reflect the higher prevalence of supernumerary teeth in males (Mitchell and Bennett 1992). In 5 of those 37 patients, treatment was initiated with surgical removal of the obstruction and ligation of the unerupted incisor followed by orthodontic space creation and traction for alignment (Third subgroup). Since these cases were treated before 2000, at the start of our experience without any similar reference in the literature, it was decided to follow a different approach in future patients as treatment time appeared prolonged, resulting from the initial absence of the required space for eruption. The standardised treatment plan that was followed since then in the majority of our patients included simple fixed orthodontic treatment for adjacent teeth alignment and space creation, operation for obstruction removal together with placement of a wired orthodontic attachment in cases of unfavourable tooth position, traction and orthodontic alignment to occlusion (first subgroup). Alternatively, when the unerupted tooth revealed a favourable position, spontaneous eruption was anticipated following the operation (second subgroup). The results of the present study clearly showed the predominance of such a comprehensive approach, as statistically significantly less treatment time was needed following this treatment plan. However, to our knowledge there are no similar clinical studies showing the results of this comprehensive approach including pre-operative orthodontics and one-step operation in patients with unerupted maxillary central incisors. The essential existence of sufficient space prior to operation has been highlighted before (Di Biase 1971; Mitchell and Bennett 1992; Suri et al. 2004; Leyland et al. 2006; Huber et al. 2008), while Bryan et al. (2005) suggested that extraction of primary canines at the time of supernumerary removal may result in creating the necessary space for eruption. The most conservative clinical management would be the extraction of any obstruction, the creation of space if necessary and the observation for spontaneous eruption, only in cases in which the location and the root maturity of the unerupted teeth were favourable. Between 37 and 72 % of the teeth, depending on the degree of root maturity, have been reported to erupt spontaneously without any further treatment after the removal of any obstruction (Mason et al. 2000). In the second subgroup, 8 patients were treated following this approach and all their 9 impacted teeth erupted spontaneously, following careful evaluation of the favourable location and maturity of the tooth and providing that sufficient eruption space existed.
In a case of insufficient or even questionable anterior space, orthodontic intervention should be preceded as in all our cases of spontaneous eruption, in contrast to another approach where space creation followed the obstruction removal and possible traction. The former approach appears better, because statistically significantly less treatment time is required, as shown in the results of the present study when comparing the second and third subgroups. In addition, young patients are introduced to treatment with milder simple orthodontic procedures as compared to more aggressive surgical procedures. As a result, the patient’s collaboration is gradually enhanced and the operation can be performed under local analgesia. The initiation of the treatment with the operation for obstruction removal and monitoring for spontaneous eruption (subgroup 4) appears to be an incorrect approach when clinical and radiographic findings are not favourable. Following supernumerary removal, 63 % of the incisors with mature roots failed to erupt, while even in those cases with immature roots 28 % eruption failure occurs (Mason et al. 2000). In addition Leyland et al. (2006) reported that regardless of root development, only 49 % of teeth erupted depended only on the space available. The type of supernumerary teeth may well affect the ability of spontaneous eruption. Unerupted incisors associated with tuberculate supernumerary teeth were twice less likely to erupt as compared to those associated with conical ones (Mitchell and Bennett 1992; Patchett et al. 2001). This unnecessary delay in the treatment of the unerupted incisors may result in additional problems such as cyst formation, ankylosis, external tooth resorption and periodontal problems (Huber et al. 2008), while maxillary canine impaction resulting from the adjacent laterals’ displacement may happen in 58.7 % of the cases (Chaushu et al. 2003). However, under certain circumstances of very severely displaced unerupted incisors, as in one of our cases, the treatment plan may include a first operation for the removal of the obstruction and, then when tooth location becomes more favourable, a second operation for traction and alignment. An important step in the treatment plan is the surgical removal of any obstruction and at the same time the exposure of the unerupted tooth, which can be performed using either an open or a closed technique as previously described (Becker et al. 2002). In the great majority of our cases (42 of 46 patients), the closed technique was used. Three more patients received an apically repositioned flap (Vanarsdall and Corn 1977) and one more, having a dentigerous cyst, a marsupialisation approach. The advantages claimed for the closed versus open technique for the uncovering of unerupted incisors include superior aesthetics and periodontal health in addition to shorter clinical crowns and increased bone support (Becker et al. 2002; Chaushu et al. 2003, 2009). However, as it has been
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previously reported in relation to the closed technique, a complication, namely gingival overgrowth and drifting, may follow almost 50 % of the teeth forced to erupt, presumably as the result of a ‘‘forced eruption phenomenon’’ that generates an increased amount of crestal bone, when compared to normal eruption (Kohavi et al. 1984). In the present study, minimal gingivectomy was necessary in only 11 of the 49 (22.4 %) incisors that received the closed technique, for removing the gingival attachment overgrowth and drifting and facilitate the final aesthetic alignment of the unerupted tooth. For the 46 patients treated by us, the mean treatment time from the operation date until the day of the full alignment of the unerupted incisor was 7 ± 3.56 months, while if pre-operative orthodontics for space creation was included the mean total treatment time increased to 10 ± 3.97 months. Mason et al. (2000) reported that the mean spontaneous eruption time for the incisors after the initial operation was 11 months, Bryan et al. (2005) reported 9.2 months and Leyland et al. (2006) reported 6–18 months. Di Biase (1971) reported eruption time up to 18 months provided that teeth were not displaced and the follicle had not been disturbed during the surgical procedure. Since these studies did not include any pre-operative orthodontics for space creation or traction, they can only be compared with the post-operative time needed for the eruption in the second subgroup in our study (5.88 ± 2.61 months, see Fig. 6), where the teeth were allowed to erupt spontaneously following the removal of the obstruction. In the present study, the total treatment time was statistically significantly related to the patient’s age and the impaction height and angle of the incisor in all subgroups with the exception of the second subgroup, where the incisors erupted spontaneously without orthodontic traction. The latter partly supported the results of Bryan et al. (2005) who found that there was no statistically significant association between tooth eruption and the angle of the long axis, but there was with vertical height. Concerning the importance of age, the root and occlusal development, in the same second subgroup the total treatment time was not statistically significantly associated with neither of them, a finding in accordance with the results of Bryan et al. (2005). On the contrary, Mason et al. (2000) found that the difference in the proportion of teeth that erupted was significant between the immature and mature, while Foley et al. (2004) indicated that 89 % of incisors with immature apices subsequently erupted, compared with only 19 % of mature ones. In addition, Leyland et al. (2006) reported that patients’ age was related to eruption time. Differences regarding the role of the age and root maturity may reflect the smaller size and difference in age
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cohorts studied. In the present study patients belonging to the second subgroup had a limited age span (7.6–9.2 years) compromising the statistical result. Finally as there were no previous studies examining the treatment time required in cases where comprehensive orthodontic surgical approach was followed, our results from the first, third and fourth subgroups cannot be compared to other studies. The recording and evaluation of the lost anterior developmental (eruption) steps, as detailed in ‘‘Materials and methods’’, have been reported for the first time in the dental literature, although to our experience they comprise a very valuable clinical tool for determining the time for treatment initiation. When an eruption step has been lost or the tooth has delayed eruption for more than 6 months after contralateral eruption (Kluemper et al. 2000), the clinician should further examine the case and treat accordingly. The significance of the steps lost is clearly shown in the results of the treatment time in the third subgroup where no preoperative orthodontics for space creation was applied. The more developmental steps lost, the more is the treatment time needed (see results in ‘‘Additional correlations of treatment time within the 4 subgroups’’) as available space might be compromised with the eruption and migration of laterals. The reliability of various parameters used in clinical studies is always questionable. Our previously described method for impacted canines (Lygidakis et al. 2001) was modified and used as a simple and easily reproducible one, as there is no single standardised method for classifying impacted teeth in either OPGs or lateral cephalographs (Iramaneerat et al. 1998). The standardised parameters of the present study included the patient’s chronological age, the degree of angulation and height of the unerupted maxillary incisor, tooth maturity and the anterior developmental steps lost. Our preference of using the chronological age of patients instead of dental age is in accordance with similar previous studies (Betts and Camilleri 1999; Mason et al. 2000; Bryan et al. 2005). In the present study, the maturity of the unerupted incisor was classified into five different stages using the Cvek’s assessment as in the studies of Mason et al. (2000) and Foley (2004). Concerning the radiographic location of the unerupted incisor in the present study, the degree of angulation was determined as the angle of the long axis of the unerupted tooth to the mid-sagittal line, an approach also used previously by Bryan et al. (2005). The same authors recorded the vertical distance from the nasal spine, while others from the palatal plane (Chaushu et al. 2003). In our study we preferred to calculate the height of the unerupted incisor as the vertical distance from the occlusal line of the affected side to the mesial aspect of the incisal edge of the impacted incisor, as used in a previous study but for
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impacted canines (Lygidakis et al. 2001). It should be noted, however, that true linear radiographic measurements of teeth are inconclusive when performed on panoramic radiographs, being influenced by many diverse parameters, while angular measurements appear much more reliable (Christen and Segrest 1968; Stramotas et al. 2000). The identification of anatomical structures can also be problematic, but despite these limitations the use of panoramic films in previous and the present study is justified because only the significance of the differences are analysed, and not the absolute values (Chaushu et al. 2003). In addition, in the present study radiographs were always in the same dental radiology practice using the same unit with the same parameters. Finally, the literature reports several causes of failure or delayed eruption of maxillary incisors. The most commonly reported cause of eruption delay of the maxillary incisors is the presence of a supernumerary tooth (Bishara 1971; Munns 1981; Buchanan and Jenkins 1997). In the present study, 52.17 % of our patients had supernumerary teeth and 54.16 % of them revealed tuberculated supernumerary teeth. Previous studies have reported that 56–86 % of the cases with unerupted incisors are a result of supernumerary teeth, while tuberculated supernumeraries are more likely to impede eruption (Mitchell and Bennett 1992; Betts and Camilleri 1999; Mason et al. 2000). While supernumerary teeth are the most common cause of delayed eruption of maxillary incisors, eruption failure can also be caused by other anomalies. Odontomas were present in 21.7 % of our patients, a percentage higher than the 9–12 % found in other studies (Mason et al. 2000; Leyland et al. 2006), while a further 10.8 % had a dilacerated incisor, which is in accordance with the study of Betts and Camilleri (1999). Eruption failure may also occur if cysts develop in the eruptive path of incisors (Bodenham 1967), such as the dentigerous cyst which was present in one of our patients. Of the patients, 10.8 % had a history of trauma to the primary teeth resulting in the malposition of the successor incisor, a higher rate compared to those reported previously by Brin et al. (1988) and Betts and Camilleri (1999), but lower than the 16.7 % reported recently by Altun et al. (2009). Finally, in one of the patients, the incisor failed to erupt due to severe MIH, a phenomenon that has not been referred previously for affected incisors, but only for molars (Lygidakis et al. 2010).
Conclusions The results are as follows: Precise clinical and radiographic diagnosis and treatment plan are necessary for the treatment of the unerupted incisors resulting from the presence
of an obstruction. Pre-operative space creation if unavailable is mandatory. Following the removal of the obstruction, if the location of the unerupted tooth is favourable, spontaneous eruption would be anticipated; otherwise, a one-step operation including obstruction removal and initiation of orthodontic traction is recommended. In such cases, treatment time is statistically significantly related to the age, height and angulation of the unerupted teeth. Treatment initiation with the one-step operation in the absence of the required space for eruption may need as much as double treatment time; therefore, it is not recommended. In cases of unfavourable unerupted teeth location, the removal of the obstruction without simultaneous orthodontic traction increases dramatically the total treatment time and requires an unnecessary second operation for traction. Acknowledgments The authors wish to thank Mrs Eirini Stamatopoulou, MSc, Biostatistician, for performing the statistical analyses. Dr K. Chatzidimitriou is a Hellenic State Scholarships Foundation scholar. Ethical standard The authors state that the study has been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. Also, the presented patients and their parents had given their informed consent prior to the inclusion in the study.
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