Surgical orthodontic treatment of anterior ske etal open bite using small plate internal fixation
Creed S. Haymond ~, Paul J. W. Stoelinga 1, Peter A. Blijdorp ~, Robbert J. Leenen 2, Nico M. Merkens 2 1Dept. of Oral and Maxillofacial Surgery 'Rynstate' Hospital, Arnhem and 2Orthodontists (private practice), Arnhem, The Netherlands
One to five year follow-up C. S. Haymond, P J. W. Stoelinga, P. A. BlO'dorp, R. J. Leenen, N. M. Merkens: Surgical orthodontic treatment of anterior skeletal open bite using small plate internal fixation. One to five year follow-up. J. Oral Maxillofac. Surg. 1991; 20: 223~27. Abstract. Thirty-eight patients with skeletal open bite were studied retrospectively to assess stability of surgical-orthodontic treatment when small plate internal fixation was used. 86% of the sample population showed stable clinical results. Follow-up was from 1 5 years. Only 1 patient experienced skeletal relapse (3%) and 5 patients (13%) dento-alveolar relapse. Fifty percent o f relapses were due to transverse relapse of orthodontically expanded maxillary arches. N o relapse was seen with surgically assisted orthodontic expansion or surgical expansion at the time of osteotomy. Stable results can be achieved in treating skeletal open bite when small plate internal fixation is used and proper consideration given to the cause of skeletal open bite when planning treatment.
The results of surgical-orthodontic treatment of skeletal anterior open bite are known to be somewhat unpredictable. High rates of relapse have been reported, but these studies were based on patients not treated with rigid fixation ~, 4, 5, ~, 9, H, 12, 15, 16, 17. In addition, the skeletal diagnosis upon which the treatment was based is not always clear in these studies. M a n y authors have categorized the skeletal morphologic characteristics o f open bite deformities 3' 5, 6, 7, 10,13,14 These include, but are not limited to: - increased mandibular plane and gonial angles increased anterior facial height increased lower facial height - increased maxillary and mandibular posterior dentoalveolar height - divergent occlusal planes downward and backward position of mandible - normal or decreased posterior facial height There is general agreement that the cause of skeletal open bite is located below the maxillary palatal plane and is indeed multifactorial. Based on these characteristics, ELLIS
has described components of adult Class II and III skeletal open bites 6' 7 He emphasizes that in either Class II or Class III, both the maxilla and mandible may be involved. A proper diagnosis is therefore of p a r a m o u n t importance because, to correct this deformity, treatment must be directed towards both the maxilla and mandible. The purpose of this study is to document the stability or instability of surgical-orthodontic treatment of anterior open bite using small plate internal fixation, and to identify relapse patterns and sites of relapse.
Key words: orthognathic surgery; open bite; Le Fort I osteotomy; rigid fixation; sagittal split osteotomy; small plates. Accepted for publication 19 March 1991
orthodontic maxillary expansion had occurred as a result of pre-operative alignment of the maxillary arch. Four of these patients had pre-operative bicuspid extraction. Alignment of the arch had caused an increase in the transverse dimension in the bicuspid area (Fig. 3). Two patients received surgically assisted orthodontic expansion approximately 1 year before surgery, and 11 were expanded surgically at the time of the Le Fort I osteotomy. In total, 21 of 38 patients received some type of maxillary expansion. The patients were classified into 4 groups according to characteristics as described by ELLIS 6 ,7, and to treatment given:
Group 1 (n= 15). Maxillary posterior dentoMaterial and methods Tlae records of 38 patients treated for anterior skeletal open bite were studied retrospectively. All patients were treated at the Rynstate Hospital between 1985 and 1989. The sample consisted of 31 females and 7 males. Ages ranged from 16 to 44 years with a mean age of 26.4 years. Patients with clefts were not included in the study. All patients received pre- and postoperative orthodontic treatment. Fifteen patients had extraction of 4 bicuspids in both maxilla and mandible, and 3 had extraction of 2 bicuspids only in the maxilla. In 8 patients, some degree of
alveolar hyperplasia only, treated with Le Fort I intrusion osteotomy. Group 2 (n = 16): Maxillary posterior dentoalveolar hyperplasia and mandibular hypoplasia treated with Le Fort I intrusion osteotomy and advancement of the mandible using bilateral sagittal split osteotomies. Group 3 (n=4): Maxillary posterior dentoalveolar hyperplasia and mandibular hyperplasia treated with Le Fort I intrusion and sagittal split setback osteotomies. Group 4 (n= 3): Isolated mandibular hyperplasia treated with bilateral sagittal split setback (2 cases), or mandibular step setback osteotomies (1 case).
224
H a y m o n d et al.
The Le Fort I osteotomies were performed as described by BELLz. After downfracturing of the maxilla, the appropriate amount of bone was removed at the lateral and medial sinus wall to allow for intrusion. If expansion was necessary a U-shaped osteotomy was carried out on the palate combined with a midline split in the alveolar part. For those expanded surgically, segments were stabilized with an acrylic splint wired to the maxillary teeth for a period of 6 weeks. The osteotomy sites were grafted using either porous hydroxylapatite blocks, or autogenous bone. Excess bone removed from the maxilla was used in most cases. Champy c~ small plates were used for fixation usually using four 4-hole L-shaped plates. Two plates were placed alongside the piriform rim and 2 at the zygomatic crest. If a sagittal split osteotomy was performed, two 4-hole straight plates were placed in the mandible as previously described by RUBENS et al. 19. No intermaxillary fixation was used postoperatively, except for light guiding elastics. Records included lateral cephalometric radiographs taken at 3 time intervals. Preoperatively: T1; immediately postoperatively: T2; and 1-5 years postoperatively: T3. Dental casts were made before orthodontic treatment, before surgical treatment and at the final clinical examination. Transverse maxillary dimension was measured on all casts,
Table 1. Changes in cephalometric landmarks, measured in ram, from T ~ T 3 for the 6 patients showing post-operative relapse. One patient had skeletal relapse, 5 had dento-alveolar relapse only. Patients
Overbite
Overjet
Anterior facial height
1
- 2
+ 7
+
2 3 4 5 6
-2 - 2 - 1 -1 - 11/2
+2 + 1/2 +2 -1 - 1
+ 1 +2 +3 +3 +2
measuring at cusp tips of canines and mesial pits of 1st premolars and 2nd molars. Open bite was defined as no vertical overlap of maxillary and mandibular incisors in centric occlusion as documented on lateral cephalometric radiographs and by clinical examination. All cephalograms were traced by one author (C.H.). The following cephalometric parameters were used: (Fig. 1) overbite - distance between lines drawn from incisal edges of maxillary and mandibular incisors perpendicular to the NME line overjet - distance between lines drawn from incisal edges perpendicular to functional occlusal plane
maxillary molar vertical position length of line drawn from occlusal plane perpendicular to SN at 1st molar position A point: most posterior bony point between maxillary incisors and anterior nasal spine B point: most posterior bony point between mandibular incisors and menton. Treatment was considered successful if the occlusion was closed with < 2 mm decrease in overbite, unless this decrease had resulted in an end-to-end or negative overbite relationship. This allows for tracing error and orthodontic tooth movement.
Results
4"
B point
NC NC NC NC NC NC
NC NC 3 + 1/2 NC NC
(NC = N o change)
anterior facial height - nasion to menton mandibular molar vertical position length of line drawn from occlusal plane to mandibular plane at 1st molar position
Fig. 1. Cephalometric landmarks and measurements used to evaluate stability of surgical and orthodontic correction. A point; B point; OB: overbite; OJ: overjet; NA-ME line: anterior facial height; Max MVP: maxillary molar vertical position; Mand MVP: mandibular molar vertical position.
1/2
A point
According to the a b o v e defined criteria, 32 of 38 p a t i e n t s (84%) were clinically stable a t final e x a m i n a t i o n . All stable patients h a d a Class I occlusion with adequate interdigitation and a normal transverse relationship (Fig. 2). Six patients (16%) s h o w e d relapse to a n endto-end, or negative overbite relationship. C e p h a l o m e t r i c analysis o f p a t i e n t s with relapse showed a n increase in total
a n t e r i o r facial height varying f r o m 0.5 3 m m ( a v e r a g e , l . 9 mm). C o m m o n characteristics included increase in lower facial height a n d vertical maxillary m o l a r position. N o significant change was seen in maxillary p o s i t i o n at A - p o i n t or in palatal plane. One p a t i e n t showed skeletal relapse, w h i c h occurred in the mandible. The others s h o w e d d e n t o - a l v e o l a r relapse only. Table 1 shows the d a t a o n skeletal a n d dental characteristics o f p a t i e n t s experiencing relapse. T h r e e p a t i e n t s with dento-alveolar relapse h a d 4 bicuspids extracted. O r t h o d o n t i c a l i g n m e n t h a d led to a n increased transverse d i m e n s i o n in the bicuspid area. T h e m e a s u r e m e n t s o n the final models showed s u b s e q u e n t decrease o f arch width. The r e m a i n i n g 2 patients h a d flaring o f their maxillary a n t e r i o r teeth a n d c o n t i n u i n g e r u p t i o n of the maxillary first molars. F o u r patients with relapse were f r o m G r o u p 2, a n d 2 f r o m G r o u p 1. N o relapse was seen in patients f r o m G r o u p s 3 or 4. N o n e o f the patients w h o received surgically assisted o r t h o d o n t i c e x p a n s i o n or surgical e x p a n s i o n at the time o f o s t e o t o m y showed relapse.
Discussion
This study o f 38 p a t i e n t s treated for skeletal o p e n b i t e w i t h c o m b i n e d o r t h o dontic-surgical t h e r a p y using small plate internal fixation showed t h a t 8 4 % o f the patients h a d a stable result w h e n e x a m i n e d 1-5 years post operatively. DENISON et al. 5 r e p o r t 4 2 % relapse which, as in this study, was m a i n l y dento-alveolar r a t h e r t h a n skeletal relapse. They make, however, n o m e n t i o n o f fixa t i o n m e t h o d s used at the time o f surgery, n o r are transverse relationships discussed. REITZICK et al. 18 claim stable results o n 20 consecutively treated p a t i e n t s with a n t e r i o r skeletal open bite. They exclusively used inverted-L m a n d i b u l a r
Treatment o f skeletal open bite autogenous bone and stabilized with 4 small plates. Their criteria for success, however, are not well defined. Since many patients with open bite also dis-
play maxillary vertical hyperplasia with a high smiling line, a treatment exclusively directed towards correction in the mandible seems to ignore im-
Fig. 2. A-B: Pre-operative frontal and profile views of patient from Group 2, demonstrating typical facial features of patients with maxillary posterior dento-alveolar hyperplasia and mandibular hypoplasia. These may include lip incompetence, mandibular retrusion and a long face. C-D: Post-operative views of the same patient 1.5 years post Le Fort I intrusion osteotomy, bilateral sagittal split advancement osteotomies and advancement genioplasty. Note balance in facial features and improved lip posture. E: Pre-operative occlusion. F: Stable Class I occlusion 2 yeas postoperatively.
225
in the mandible seems to ignore important esthetic aspects. Most clinicians will agree that the open bite deformity often requires bimaxillary surgery to achieve optimal functional and esthetic results. Fifty percent of the patients experiencing post treatment relapse, had presurgical extraction 4 bicuspids. Alignment of the teeth had resulted in rounding of the arches and subsequent increase in transverse dimension in the bicuspid area (Fig. 3). Postoperatively, some decrease in the transverse dimension had occurred because of palatal inclination of the bicuspids and molars (Fig. 3). Other authors have found a decrease in maxillary arch width in patients experiencing relapse. Many patients with open bite tend to have a narrow maxillary arch which often requires pre-operative expansion if the teeth are to be properly aligned. This tends, however, to partially close the anterior open bite. Postoperative decrease in the transverse dimension of the maxillary arch produces not only medial but also inferior movement of molars. This dento-alveolar relapse then displaces the mandible inferiorly, increasing anterior facial height and re-opening the bite anteriorly. This occurred in 3 of the patients experiencing relapse. Orthodontic extrusion of anterior teeth may not be capable of compensating fo r re-opening of the bite as there is often pre-existing anterior dento-alveolar hyperplasia and/or over eruption of incisors. Orthodontic compensation is also not desirable as it merely camouflages the deformity and the results are often unnatural in appearance. As ELLIS states 6, 7: "A basic treatment principle (..) is to correct rather than camouflage the existing deformity". It is of interest to note that neither of the 2 patients who underwent surgically assisted orthodontic expansion of the maxilla prior to Le Fort I osteotomy nor any of those who had surgical expansion at the time of surgery had open bite relapse. Although the samples are too small to draw decisive conclusions, it does raise an interesting question about how maxillary expansion in open bite cases should be accomplished. Surgical expansion or surgically assisted orthodontic expansion may be the method of choice for these patients. In both techniques buccal tilting of the bicusp i d s and molars is avoided: It is likely that pure orthodontic movements in a transverse direction are more prone to
226
Haymond et al. treatment is given accordingly. Wellcontrolled, prospective research is needed to document exact m o v e m e n t of dento-alveolar segments during the orthodontic and surgical phases o f treatment, and to study its relationship to stability o f treatment. References 1. ARVYSTAS MG. Treatment of anterior open bite deformity. Am J Orthod 1977: 72: 147-64. 2. BELLWH, PROFFITWR, WHITE RR Surgical correction of dentofacial deformities. Vol. II. Philadelphia: WB Saunders, 1980: 1058-209. 3. CABGUAKISU TJ. Skeletal morphologic
features of anterior open bite. Am J Orthod 1984: 85: 28-36. 4. DATTILO D J, BRAWN TW, SOTEREANOS GC. The inverted L osteotomy for treatment of skeletal open bite deformities. J Oral Maxillofac Surg 1985: 43: 44043. 5. DENISON TF, KOKICH NG, SHAPIROPA.
Fig. 3. Example of how orthodontic expansion due to rounding of the anterior arch and space closure after bicuspid extraction can cause relapse of the open bite. A: Pre-operative dental relationship. B: Post-0perative dental relationship (1.5 years) showing relapse to an end-to-end anterior position. C: Pre-orthodontic and presurgical dental casts. Note expansion in canine and molars areas as a result of rounding of the anterior arch and alignment of teeth following extraction of 4 bicuspids: The anterior teeth are moved posteriorly and the canines expanded. Molars are moved anteriorly, occupying a more anterior position in the arch which requires expansion by tilting to haaintain the transverse relationship. D: Dental casts made 1.5 years postoperatively. Note the decrease in transverse dimension in both canine and molar areas. This opens the bite anteriorly.
the result of surgical and surgically assisted expansion. Another important orthodontic consideration when 'treating skeletal open bite is the inclination of maxillary anterior teeth. If surgical posterior maxillary intrusion is anticipated, attention should be given to this inclination, because posterior intrusion, and hence tilting of the maxilla will place the anterior teeth in a more orthognathic position. It is therefore often necessary to accentuate the proclination of maxillary anterior teeth before surgery. Bicuspid extraction to gain space for alignment of a crowded maxillary arch is at times contraindicated because o f the tendency of maxillary anterior teeth to be upright rather than protrude. Some cases may re-open because of continued eruption o f maxillary molars. This may be a reason to over-
close the anterior teeth through extra counter-clockwise rotation of the mandible and open the posterior occlusion at the time of surgery. This opening of the posterior occlusion should be supported by a thick acrylic wafer. The posterior occlusion should be closed postoperatively by gradual grinding of the acrylic from posterior to anterior, combined with vertical traction with elastic bands. It can be concluded from this study that in the majority of cases predictably stable results can be achieved when treating skeletal open bite with a coordinated surgical and orthodontic approach and when small plate internal fixation is used. Stable and esthetically acceptable results can only be expected when proper consideration is given to the cause of the deformity and when treatment is given accordingly. Well-
Stability of maxillary surgery in open bite versus non open bite malocclusions. Angle Orthod 1989: 59:5 10. 6. ELLISE, MCNAMARAJA JR. Components of adult Class III open bite malocclusion. Am J Orthod 1984: 86: 277-90. 7. ELLISE, MCNAMARAJA JR. Components of adult Class II open bite malocclusion. J Oral Maxillofac, Surg 1985: 43:92 105. 8. EPKER BN, FISH LC. Surgical-orthodontic correction of open bite deformity. Am J Orthod 1977: 71: 278-99. 9. EPKER BN, FISH LC. The surgical-orthodontic correction of Class II1 skeletal open bite. Am J Orthod 1978: 73: 60118. 10. JARABAKJR. Open bite-skeletal morphology. Fortschr Kieferorthop 1983: 44: 122-33. 11. K~AHNBERGKE, WIDMARK G. Surgical treatment of the open bite deformity. Surgical correction of combined mandibular prognathism and open bite by oblique sliding osteotomy of the mandibular rami. Int J Oral Maxillofac Surg 1988: 17: 45-8. 12. LELLO GE. Skeletal open bite correction by combined Le Fort I osteotomy and bilateral sagittal split of the mandibular ramus. J Cranio-Maxillofac Surg 1987: 15: 132-6. 13. LOPEZ-GAVITO G, WALLEN TR, LITTLE RM, JOONEDELPHDR. Anterior open bite malocclusion: a longitudinal 10 year postretention evaluation of orthodontically treated patie~ats. Am J Orthod 1985: 87: 175-86. 14. NANDASK. Patterns of vertical growth in the face.,Am J Orthod Dentofac Orthop 1988: 93: 103-16. 15. NEM~TH RB, ISAACSONRJ. Vertical anterior relapse. Am J Orthod 1974: 65: 565-85.
Treatment o f skeletal open bite dontic correction of severe mandibular retrusion. Am J Orthod 1971: 59: 244. 17. POULTONDR, WAREWH. Surgical orthodontic correction of severe mandibular retrusion. Part II. Am J Orthod 1973: 63: 237. 18. REITZIK M, BARER PG, WAINWRIGHT WM, LORE B. The surgical treatment of skeletal open bite deformities with rigid
internal fixation in the mandible. Am J Orthod Dentofacial Orthop 1990: 97: 52-7. 19. RUBENS BC, STOELINGA PJW, BLHDORP PA, SCHOENAERSJHA, POLITIS C. ~Skeletal stability following sagittal split osteotomy using monocortical miniplate internal fixation. Int J Oral Maxillofac Surg 1988: I7: 371-76.
Address:
Dr. P. J. W. Stoelinga Rynstate Ziekenhu& GZ Dept. of OMF Surgery Wagnerlaan 55, 6815 AD Arnhem The Netherlands"
227
Creed S. Haymond ~, Paul J. W. Stoelinga 1, Peter A. Blijdorp ~, Robbert J. Leenen 2, Nico M. Merkens 2 1Dept. of Oral and Maxillofacial Surgery 'Rynstate' Hospital, Arnhem and 2Orthodontists (private practice), Arnhem, The Netherlands
One to five year follow-up C. S. Haymond, P J. W. Stoelinga, P. A. BlO'dorp, R. J. Leenen, N. M. Merkens: Surgical orthodontic treatment of anterior skeletal open bite using small plate internal fixation. One to five year follow-up. J. Oral Maxillofac. Surg. 1991; 20: 223~27. Abstract. Thirty-eight patients with skeletal open bite were studied retrospectively to assess stability of surgical-orthodontic treatment when small plate internal fixation was used. 86% of the sample population showed stable clinical results. Follow-up was from 1 5 years. Only 1 patient experienced skeletal relapse (3%) and 5 patients (13%) dento-alveolar relapse. Fifty percent o f relapses were due to transverse relapse of orthodontically expanded maxillary arches. N o relapse was seen with surgically assisted orthodontic expansion or surgical expansion at the time of osteotomy. Stable results can be achieved in treating skeletal open bite when small plate internal fixation is used and proper consideration given to the cause of skeletal open bite when planning treatment.
The results of surgical-orthodontic treatment of skeletal anterior open bite are known to be somewhat unpredictable. High rates of relapse have been reported, but these studies were based on patients not treated with rigid fixation ~, 4, 5, ~, 9, H, 12, 15, 16, 17. In addition, the skeletal diagnosis upon which the treatment was based is not always clear in these studies. M a n y authors have categorized the skeletal morphologic characteristics o f open bite deformities 3' 5, 6, 7, 10,13,14 These include, but are not limited to: - increased mandibular plane and gonial angles increased anterior facial height increased lower facial height - increased maxillary and mandibular posterior dentoalveolar height - divergent occlusal planes downward and backward position of mandible - normal or decreased posterior facial height There is general agreement that the cause of skeletal open bite is located below the maxillary palatal plane and is indeed multifactorial. Based on these characteristics, ELLIS
has described components of adult Class II and III skeletal open bites 6' 7 He emphasizes that in either Class II or Class III, both the maxilla and mandible may be involved. A proper diagnosis is therefore of p a r a m o u n t importance because, to correct this deformity, treatment must be directed towards both the maxilla and mandible. The purpose of this study is to document the stability or instability of surgical-orthodontic treatment of anterior open bite using small plate internal fixation, and to identify relapse patterns and sites of relapse.
Key words: orthognathic surgery; open bite; Le Fort I osteotomy; rigid fixation; sagittal split osteotomy; small plates. Accepted for publication 19 March 1991
orthodontic maxillary expansion had occurred as a result of pre-operative alignment of the maxillary arch. Four of these patients had pre-operative bicuspid extraction. Alignment of the arch had caused an increase in the transverse dimension in the bicuspid area (Fig. 3). Two patients received surgically assisted orthodontic expansion approximately 1 year before surgery, and 11 were expanded surgically at the time of the Le Fort I osteotomy. In total, 21 of 38 patients received some type of maxillary expansion. The patients were classified into 4 groups according to characteristics as described by ELLIS 6 ,7, and to treatment given:
Group 1 (n= 15). Maxillary posterior dentoMaterial and methods Tlae records of 38 patients treated for anterior skeletal open bite were studied retrospectively. All patients were treated at the Rynstate Hospital between 1985 and 1989. The sample consisted of 31 females and 7 males. Ages ranged from 16 to 44 years with a mean age of 26.4 years. Patients with clefts were not included in the study. All patients received pre- and postoperative orthodontic treatment. Fifteen patients had extraction of 4 bicuspids in both maxilla and mandible, and 3 had extraction of 2 bicuspids only in the maxilla. In 8 patients, some degree of
alveolar hyperplasia only, treated with Le Fort I intrusion osteotomy. Group 2 (n = 16): Maxillary posterior dentoalveolar hyperplasia and mandibular hypoplasia treated with Le Fort I intrusion osteotomy and advancement of the mandible using bilateral sagittal split osteotomies. Group 3 (n=4): Maxillary posterior dentoalveolar hyperplasia and mandibular hyperplasia treated with Le Fort I intrusion and sagittal split setback osteotomies. Group 4 (n= 3): Isolated mandibular hyperplasia treated with bilateral sagittal split setback (2 cases), or mandibular step setback osteotomies (1 case).
224
H a y m o n d et al.
The Le Fort I osteotomies were performed as described by BELLz. After downfracturing of the maxilla, the appropriate amount of bone was removed at the lateral and medial sinus wall to allow for intrusion. If expansion was necessary a U-shaped osteotomy was carried out on the palate combined with a midline split in the alveolar part. For those expanded surgically, segments were stabilized with an acrylic splint wired to the maxillary teeth for a period of 6 weeks. The osteotomy sites were grafted using either porous hydroxylapatite blocks, or autogenous bone. Excess bone removed from the maxilla was used in most cases. Champy c~ small plates were used for fixation usually using four 4-hole L-shaped plates. Two plates were placed alongside the piriform rim and 2 at the zygomatic crest. If a sagittal split osteotomy was performed, two 4-hole straight plates were placed in the mandible as previously described by RUBENS et al. 19. No intermaxillary fixation was used postoperatively, except for light guiding elastics. Records included lateral cephalometric radiographs taken at 3 time intervals. Preoperatively: T1; immediately postoperatively: T2; and 1-5 years postoperatively: T3. Dental casts were made before orthodontic treatment, before surgical treatment and at the final clinical examination. Transverse maxillary dimension was measured on all casts,
Table 1. Changes in cephalometric landmarks, measured in ram, from T ~ T 3 for the 6 patients showing post-operative relapse. One patient had skeletal relapse, 5 had dento-alveolar relapse only. Patients
Overbite
Overjet
Anterior facial height
1
- 2
+ 7
+
2 3 4 5 6
-2 - 2 - 1 -1 - 11/2
+2 + 1/2 +2 -1 - 1
+ 1 +2 +3 +3 +2
measuring at cusp tips of canines and mesial pits of 1st premolars and 2nd molars. Open bite was defined as no vertical overlap of maxillary and mandibular incisors in centric occlusion as documented on lateral cephalometric radiographs and by clinical examination. All cephalograms were traced by one author (C.H.). The following cephalometric parameters were used: (Fig. 1) overbite - distance between lines drawn from incisal edges of maxillary and mandibular incisors perpendicular to the NME line overjet - distance between lines drawn from incisal edges perpendicular to functional occlusal plane
maxillary molar vertical position length of line drawn from occlusal plane perpendicular to SN at 1st molar position A point: most posterior bony point between maxillary incisors and anterior nasal spine B point: most posterior bony point between mandibular incisors and menton. Treatment was considered successful if the occlusion was closed with < 2 mm decrease in overbite, unless this decrease had resulted in an end-to-end or negative overbite relationship. This allows for tracing error and orthodontic tooth movement.
Results
4"
B point
NC NC NC NC NC NC
NC NC 3 + 1/2 NC NC
(NC = N o change)
anterior facial height - nasion to menton mandibular molar vertical position length of line drawn from occlusal plane to mandibular plane at 1st molar position
Fig. 1. Cephalometric landmarks and measurements used to evaluate stability of surgical and orthodontic correction. A point; B point; OB: overbite; OJ: overjet; NA-ME line: anterior facial height; Max MVP: maxillary molar vertical position; Mand MVP: mandibular molar vertical position.
1/2
A point
According to the a b o v e defined criteria, 32 of 38 p a t i e n t s (84%) were clinically stable a t final e x a m i n a t i o n . All stable patients h a d a Class I occlusion with adequate interdigitation and a normal transverse relationship (Fig. 2). Six patients (16%) s h o w e d relapse to a n endto-end, or negative overbite relationship. C e p h a l o m e t r i c analysis o f p a t i e n t s with relapse showed a n increase in total
a n t e r i o r facial height varying f r o m 0.5 3 m m ( a v e r a g e , l . 9 mm). C o m m o n characteristics included increase in lower facial height a n d vertical maxillary m o l a r position. N o significant change was seen in maxillary p o s i t i o n at A - p o i n t or in palatal plane. One p a t i e n t showed skeletal relapse, w h i c h occurred in the mandible. The others s h o w e d d e n t o - a l v e o l a r relapse only. Table 1 shows the d a t a o n skeletal a n d dental characteristics o f p a t i e n t s experiencing relapse. T h r e e p a t i e n t s with dento-alveolar relapse h a d 4 bicuspids extracted. O r t h o d o n t i c a l i g n m e n t h a d led to a n increased transverse d i m e n s i o n in the bicuspid area. T h e m e a s u r e m e n t s o n the final models showed s u b s e q u e n t decrease o f arch width. The r e m a i n i n g 2 patients h a d flaring o f their maxillary a n t e r i o r teeth a n d c o n t i n u i n g e r u p t i o n of the maxillary first molars. F o u r patients with relapse were f r o m G r o u p 2, a n d 2 f r o m G r o u p 1. N o relapse was seen in patients f r o m G r o u p s 3 or 4. N o n e o f the patients w h o received surgically assisted o r t h o d o n t i c e x p a n s i o n or surgical e x p a n s i o n at the time o f o s t e o t o m y showed relapse.
Discussion
This study o f 38 p a t i e n t s treated for skeletal o p e n b i t e w i t h c o m b i n e d o r t h o dontic-surgical t h e r a p y using small plate internal fixation showed t h a t 8 4 % o f the patients h a d a stable result w h e n e x a m i n e d 1-5 years post operatively. DENISON et al. 5 r e p o r t 4 2 % relapse which, as in this study, was m a i n l y dento-alveolar r a t h e r t h a n skeletal relapse. They make, however, n o m e n t i o n o f fixa t i o n m e t h o d s used at the time o f surgery, n o r are transverse relationships discussed. REITZICK et al. 18 claim stable results o n 20 consecutively treated p a t i e n t s with a n t e r i o r skeletal open bite. They exclusively used inverted-L m a n d i b u l a r
Treatment o f skeletal open bite autogenous bone and stabilized with 4 small plates. Their criteria for success, however, are not well defined. Since many patients with open bite also dis-
play maxillary vertical hyperplasia with a high smiling line, a treatment exclusively directed towards correction in the mandible seems to ignore im-
Fig. 2. A-B: Pre-operative frontal and profile views of patient from Group 2, demonstrating typical facial features of patients with maxillary posterior dento-alveolar hyperplasia and mandibular hypoplasia. These may include lip incompetence, mandibular retrusion and a long face. C-D: Post-operative views of the same patient 1.5 years post Le Fort I intrusion osteotomy, bilateral sagittal split advancement osteotomies and advancement genioplasty. Note balance in facial features and improved lip posture. E: Pre-operative occlusion. F: Stable Class I occlusion 2 yeas postoperatively.
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in the mandible seems to ignore important esthetic aspects. Most clinicians will agree that the open bite deformity often requires bimaxillary surgery to achieve optimal functional and esthetic results. Fifty percent of the patients experiencing post treatment relapse, had presurgical extraction 4 bicuspids. Alignment of the teeth had resulted in rounding of the arches and subsequent increase in transverse dimension in the bicuspid area (Fig. 3). Postoperatively, some decrease in the transverse dimension had occurred because of palatal inclination of the bicuspids and molars (Fig. 3). Other authors have found a decrease in maxillary arch width in patients experiencing relapse. Many patients with open bite tend to have a narrow maxillary arch which often requires pre-operative expansion if the teeth are to be properly aligned. This tends, however, to partially close the anterior open bite. Postoperative decrease in the transverse dimension of the maxillary arch produces not only medial but also inferior movement of molars. This dento-alveolar relapse then displaces the mandible inferiorly, increasing anterior facial height and re-opening the bite anteriorly. This occurred in 3 of the patients experiencing relapse. Orthodontic extrusion of anterior teeth may not be capable of compensating fo r re-opening of the bite as there is often pre-existing anterior dento-alveolar hyperplasia and/or over eruption of incisors. Orthodontic compensation is also not desirable as it merely camouflages the deformity and the results are often unnatural in appearance. As ELLIS states 6, 7: "A basic treatment principle (..) is to correct rather than camouflage the existing deformity". It is of interest to note that neither of the 2 patients who underwent surgically assisted orthodontic expansion of the maxilla prior to Le Fort I osteotomy nor any of those who had surgical expansion at the time of surgery had open bite relapse. Although the samples are too small to draw decisive conclusions, it does raise an interesting question about how maxillary expansion in open bite cases should be accomplished. Surgical expansion or surgically assisted orthodontic expansion may be the method of choice for these patients. In both techniques buccal tilting of the bicusp i d s and molars is avoided: It is likely that pure orthodontic movements in a transverse direction are more prone to
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Haymond et al. treatment is given accordingly. Wellcontrolled, prospective research is needed to document exact m o v e m e n t of dento-alveolar segments during the orthodontic and surgical phases o f treatment, and to study its relationship to stability o f treatment. References 1. ARVYSTAS MG. Treatment of anterior open bite deformity. Am J Orthod 1977: 72: 147-64. 2. BELLWH, PROFFITWR, WHITE RR Surgical correction of dentofacial deformities. Vol. II. Philadelphia: WB Saunders, 1980: 1058-209. 3. CABGUAKISU TJ. Skeletal morphologic
features of anterior open bite. Am J Orthod 1984: 85: 28-36. 4. DATTILO D J, BRAWN TW, SOTEREANOS GC. The inverted L osteotomy for treatment of skeletal open bite deformities. J Oral Maxillofac Surg 1985: 43: 44043. 5. DENISON TF, KOKICH NG, SHAPIROPA.
Fig. 3. Example of how orthodontic expansion due to rounding of the anterior arch and space closure after bicuspid extraction can cause relapse of the open bite. A: Pre-operative dental relationship. B: Post-0perative dental relationship (1.5 years) showing relapse to an end-to-end anterior position. C: Pre-orthodontic and presurgical dental casts. Note expansion in canine and molars areas as a result of rounding of the anterior arch and alignment of teeth following extraction of 4 bicuspids: The anterior teeth are moved posteriorly and the canines expanded. Molars are moved anteriorly, occupying a more anterior position in the arch which requires expansion by tilting to haaintain the transverse relationship. D: Dental casts made 1.5 years postoperatively. Note the decrease in transverse dimension in both canine and molar areas. This opens the bite anteriorly.
the result of surgical and surgically assisted expansion. Another important orthodontic consideration when 'treating skeletal open bite is the inclination of maxillary anterior teeth. If surgical posterior maxillary intrusion is anticipated, attention should be given to this inclination, because posterior intrusion, and hence tilting of the maxilla will place the anterior teeth in a more orthognathic position. It is therefore often necessary to accentuate the proclination of maxillary anterior teeth before surgery. Bicuspid extraction to gain space for alignment of a crowded maxillary arch is at times contraindicated because o f the tendency of maxillary anterior teeth to be upright rather than protrude. Some cases may re-open because of continued eruption o f maxillary molars. This may be a reason to over-
close the anterior teeth through extra counter-clockwise rotation of the mandible and open the posterior occlusion at the time of surgery. This opening of the posterior occlusion should be supported by a thick acrylic wafer. The posterior occlusion should be closed postoperatively by gradual grinding of the acrylic from posterior to anterior, combined with vertical traction with elastic bands. It can be concluded from this study that in the majority of cases predictably stable results can be achieved when treating skeletal open bite with a coordinated surgical and orthodontic approach and when small plate internal fixation is used. Stable and esthetically acceptable results can only be expected when proper consideration is given to the cause of the deformity and when treatment is given accordingly. Well-
Stability of maxillary surgery in open bite versus non open bite malocclusions. Angle Orthod 1989: 59:5 10. 6. ELLISE, MCNAMARAJA JR. Components of adult Class III open bite malocclusion. Am J Orthod 1984: 86: 277-90. 7. ELLISE, MCNAMARAJA JR. Components of adult Class II open bite malocclusion. J Oral Maxillofac, Surg 1985: 43:92 105. 8. EPKER BN, FISH LC. Surgical-orthodontic correction of open bite deformity. Am J Orthod 1977: 71: 278-99. 9. EPKER BN, FISH LC. The surgical-orthodontic correction of Class II1 skeletal open bite. Am J Orthod 1978: 73: 60118. 10. JARABAKJR. Open bite-skeletal morphology. Fortschr Kieferorthop 1983: 44: 122-33. 11. K~AHNBERGKE, WIDMARK G. Surgical treatment of the open bite deformity. Surgical correction of combined mandibular prognathism and open bite by oblique sliding osteotomy of the mandibular rami. Int J Oral Maxillofac Surg 1988: 17: 45-8. 12. LELLO GE. Skeletal open bite correction by combined Le Fort I osteotomy and bilateral sagittal split of the mandibular ramus. J Cranio-Maxillofac Surg 1987: 15: 132-6. 13. LOPEZ-GAVITO G, WALLEN TR, LITTLE RM, JOONEDELPHDR. Anterior open bite malocclusion: a longitudinal 10 year postretention evaluation of orthodontically treated patie~ats. Am J Orthod 1985: 87: 175-86. 14. NANDASK. Patterns of vertical growth in the face.,Am J Orthod Dentofac Orthop 1988: 93: 103-16. 15. NEM~TH RB, ISAACSONRJ. Vertical anterior relapse. Am J Orthod 1974: 65: 565-85.
Treatment o f skeletal open bite dontic correction of severe mandibular retrusion. Am J Orthod 1971: 59: 244. 17. POULTONDR, WAREWH. Surgical orthodontic correction of severe mandibular retrusion. Part II. Am J Orthod 1973: 63: 237. 18. REITZIK M, BARER PG, WAINWRIGHT WM, LORE B. The surgical treatment of skeletal open bite deformities with rigid
internal fixation in the mandible. Am J Orthod Dentofacial Orthop 1990: 97: 52-7. 19. RUBENS BC, STOELINGA PJW, BLHDORP PA, SCHOENAERSJHA, POLITIS C. ~Skeletal stability following sagittal split osteotomy using monocortical miniplate internal fixation. Int J Oral Maxillofac Surg 1988: I7: 371-76.
Address:
Dr. P. J. W. Stoelinga Rynstate Ziekenhu& GZ Dept. of OMF Surgery Wagnerlaan 55, 6815 AD Arnhem The Netherlands"
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