Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
Contents lists available at ScienceDirect
Journal of Cranio-Maxillo-Facial Surgery journal homepage: www.jcmfs.com
Skeletal and soft tissue changes and stability in cleft lip and palate patients after distraction osteogenesis using a new intraoral maxillary device Edward Ansari a, *, Catherine Tomat a, Natacha Kadlub a, b, Patrick A. Diner a, Thomas Bellocq a, Marie-Paule Vazquez a, b, Arnaud Picard a, b a b
Department of Maxillofacial and Plastic Surgery, Necker Children's Hospital, AP-HP, Universit e Paris 5, Paris, France Centre de Recherche des Cordeliers, INSERM, UMRS872, equipe 5, 75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 2 November 2014 Accepted 9 December 2014 Available online 17 December 2014
Background: The authors have recently reported on the use of an internal maxillary distraction device. In this study, we report on the hard and soft tissue movements achieved with this intraoral distraction device, and the stability changes after distraction osteogenesis for maxillary hypoplasia in patients with cleft lip and palate. Methods: Ten male patients with severe hypoplasia of the maxilla, with complete uni- or bilateral cleft lip and palate were included. The mean age of the patients at the time of operation was 11.91 years (±3.41). To evaluate the distraction process and stability, superimpositions on the preoperative lateral cephalograms were performed. The mean follow-up (FU) was 15.42 months (±3.94). Results: Cephalometric measurements at all of the maxillary hard and soft tissue points improved significantly. Maxillary point A was advanced by 8.25 mm (±3.17; P < 0.001). After distraction soft tissue point A0 had advanced 7.10 mm (±2.69; P < 0.001). The soft tissue to hard tissue ratio at point A was 0.86:1 after distraction. Maxillary horizontal relapse at point A was 14.1% at FU. Vertical relapse was not significant. Conclusion: This rigid intraoral distraction device can be successfully used in the correction of severe maxillary hypoplasia. The marked aesthetic improvement and low psychological encumbrance make this device viable for the treatment of cleft-related hypoplasia of the maxilla. © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Keywords: Hard tissue Intraoral device Maxillary distraction Soft tissue Stability
1. Introduction Traditionally, maxillary hypoplasia has been corrected with orthognathic surgery. This type of surgery encounters technical difficulties. This is especially seen in the treatment of patients with cleft lip and palate, who often have scarring from previous operations and concurrent hypoplasia of the maxilla, which requires large maxillary advancement. Various reports have noted a relapse or partial regression towards the pre-operative state in Le Fort I maxillary advancements (Hochban et al., 1993, Ayliffe et al., 1995). In conventional orthognathic surgery, autogenous bone grafting is often essential to fill a significant osteotomy gap for bone healing * Corresponding author. The French Center for Cleft Lip and Palate, Department of ^pital Necker e Enfants Malades, 149 Rue de Plastic and Maxillofacial Surgery, The Ho Sevres, 75015 Paris, France. Tel.: þ33 1 44736935; fax: þ33 1 44736936. E-mail address: [email protected] (E. Ansari).
(Cheung et al., 2006), however donor site morbidities, resorption and infection can occur and potentiate a relapse. Moreover conventional surgery is not recommended in growing patients due to the tooth buds and the need for tremendous mobilization. Distraction osteogenesis (DO), a method of gradual bone distraction, has been advocated as a viable alternative for large maxillary advancements. Various studies have reported improved results with the use of DO over conventional orthognathic surgery (Chua and Cheung, 2012; Molina et al., 1998) and have demonstrated a decreased relapse (Chua and Cheung, 2012; Cheung and Chua, 2006), especially with large maxillary advancements. Furthermore, it has been demonstrated that DO induces gradual bone formation (Kusnoto et al., 2001; Swennen et al., 2001) and improves the surrounding soft tissue profile (Chua and Cheung, 2012). In this manner, it contributes to more stable and aesthetically refined results, thereby offering possibilities conventional osteotomy cannot.
http://dx.doi.org/10.1016/j.jcms.2014.12.006 1010-5182/© 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
324
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
The use of external distraction devices has been studied extensively (Molina et al., 1998; Polley and Figueroa, 1997). Although rigid external distractors (RED) still have a place in certain applications, a wide variety of intraoral distractors are now available; these distractors are small and compact, with augmented patient comfort and acceptance. In 2011 we described our experience with a new intraoral maxillary distraction device (Picard et al., 2011) which has been the preferred treatment at our institution since 2004 to correct severe maxillary hypoplasia. This rigid intraoral device (RID) has the advantage of being easy to surgically implement due to its single miniplate fixation. Another major advantage, which is absent for other intraoral devices, is to have an unlimited distraction capacity. This characteristic allows it to always achieve the desired advancement, despite the lack of correlation between real bone advancement and the advancement measured on the device. In this cephalometric study we evaluate the skeletal and soft tissue changes and stability in patients with cleft lip and palate after DO with this RID. 2. Materials and methods 2.1. Device description This internal maxillary distraction device was designed by one of the authors (PAD) and Selsy technologie SA (Paris, France). The device consists of a miniplate for fixation, an orthodontic double arch, and a vertical connecting bar (Fig. 1). The miniplate is fixed to the zygomatic buttress above the osteotomy line to secure the device. The miniplates (2 mm thick) are used for fixation to the zygoma. The miniplate is connected to a double dental arch applied to the maxillary teeth by an adjustable vertical bar, which can be orientated intraoperatively. Its caudal end is fixed to the double arch at the buccal aspect of, for example, the first maxillary molar. An activating horizontal screw emerges anteriorly from the double arch buccal to the maxillary teeth. The length of the vertical rod can be modified and the axis of orientation can also be adjusted, which ensures that it fits at both the zygomatic and the maxillary ends. The horizontal activating screw passes its force through the dental brackets soldered to the orthodontic arch to the maxillary teeth and thereby to the complete maxilla. The arch is the moveable part of the device and allows the forward pull movement of all the teeth and the complete maxilla. 2.2. Patients A retrospective review of all patients who had undergone DO with this RID at the French Center for Cleft Lip and Palate was
conducted. The institution ethics board approved the study protocol. Children with cleft lip and palate were included in the study. Syndromic patients were excluded. All patients who were eligible for DO were subject to a systematic investigation conducted by a psychologist, to evaluate their request and to prepare the patient psychologically for DO. From March 2004 until August 2008, 10 patients underwent DO. The group consisted of 10 males. The mean age at intervention in this group was 11.91 years (±3.41; range 9.28e20.51). Nine patients had developed maxillary hypoplasia resulting from unilateral complete cleft lip and palate (UCLP), whereas 1 patient had a bilateral complete cleft lip and palate (BCLP). All patients with cleft lip and palate had been operated on previously for their clefts; they were treated at our clinic according to the Malek protocol (Malek and Psaume, 1983) that was used at that time. This technique is comprised of primary closure of the soft palate at 3 months of age and subsequently a repair of the lip and hard palate at 6 months of age. In BCLP patients the latter operation was done as a two-stage procedure, at 6 months and 9 months of age. Other surgical interventions that had been performed included a velopharyngoplasty (3 patients) and one patient had undergone distraction 10 years prior to the operation using a Delaire facial mask (Table 1). 2.3. Surgical technique The surgical procedure was performed by the same senior authors (AP and PAD). It included a high Le Fort I osteotomy. To prevent damage to the dental roots and to create a projection of the cheek that will be aesthetically pleasing after distraction, the osteotomy line must be high enough (at the point of the zygomatic buttress). Down fracture and complete mobilization is done. Insertion of the device begins by fixing the miniplate to the zygomatic bone. The separation of the pterygomaxillary disjunction is cautiously completed so as to preserve the upper second molar. The maxilla is mobilized allowing for slight movement. The miniplate is fixed to the zygomatic buttress and connected to a double dental arch applied to the maxillary teeth by an adjustable vertical bar. Then, an activating horizontal screw is inserted anteriorly. The arch, the moveable part of this device, moves the maxilla forward. After a latency period of four days, active distraction was started at a rate of 1 mm/24 h. We aimed for over-correction of 3e5 mm. The mean retention period of the intraoral device was 4.21 months, ranging from 1.64 to 5.95 months. Lateral cephalometric radiographs,
Table 1 Patients' profile. N ¼ 10 Patients Male/female Mean age at DO (years) Cleft type Right/left/bilateral RID Maxillary advancement (mm) Retention period (months) Follow up (months) Primary treatment Velopharyngeoplasty Gingivoperioplasty External rigid devicea Relapse Horizontal (%)
Fig. 1. The rigid internal device Note the miniplate on the zygomatic bone, the orthodontic double arch, the vertical bar and the activating screw.
10/0 11.91 (±3.41) 6/3/1 8.25 (±3.17, range 4e15) 4.21 (±1.38, range 1.64e5.95) 15.42 (±3.94, range 10.62e23.06) 3 2 1 14.1
DO: distraction osteogenesis; RID: rigid intraoral device. a Patient used a Delaire facial mask.
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
325
which were used for the analysis, were taken preoperatively (T1), postdistraction (T2), and at the last follow up (T3). The mean follow-up from the moment of implementation of the RID (T3) was 15.42 months (±3.94; range 10.62e23.06).
demonstrated a small difference; it was however within the acceptable limit (1.0 mm).
2.4. Cephalometric analysis
Statistical analyses were performed using IBM SPSS version 20.0. A paired t-test was performed for all measurement data to compare treatment changes (T1 vs T2) and stability changes (T2 vs T3). A Pearson correlation coefficient was used to determine the correlation between the sagittal movement of soft and hard tissue.
For cephalometric analysis, linear variables were measured ac€rk analysis (Bjo € rk, 1969). The cephalometric cording to the Bjo landmarks and reference lines are presented in Fig. 2. Hard and soft tissue landmarks were used to measure the distances moved. All lateral cephalometric radiographs were made at 100%. Acetate tracings were made on the first lateral cephalogram with a vertical reference line perpendicular to the line SN, through the midpoint of the sella turcica (Y-axis). To evaluate the distraction process and stability of the postoperative situation, the postoperative radiographs were superimposed on the preoperative lateral cephalogram (T1), using bony structures in the anterior cranial base as reference points. The sagittal distance from the line through the sella turcica, perpendicular to SN (Y-axis) towards point A, point B, Pr, Is, Id and Pog (SN⊥A, SN⊥B, SN⊥Is, SN⊥Id, SN⊥Pog, SN⊥distal molar) describe horizontal movements of the maxilla, mandible, bony chin and distal molar. Soft tissue measurements (SN⊥A0 , SN⊥B0 , SN⊥Pog0 , SN⊥Ls, SN⊥Li) were done identically. Vertical measurements were also made at different maxillary and mandibular landmarks to assess the downward movement (SNeMe, SNeGo left and right, SNeSp, SNePm). 2.5. Random error analysis Dahlberg's formula was used to determine the random error of the cephalometric readings (Houston, 1983). The cephalometric radiographs of five patients were retraced, superimposed, and digitalized by one examiner (CAT) for error determination. The random error analysis for skeletal and soft tissue measurements
2.6. Statistical analysis
3. Results Stability and treatment changes of all hard and soft tissue landmarks are shown in Table 2. In one patient the follow up (FU) cephalogram could not be retrieved from the medical records. There were no minor or major complications. 3.1. Hard tissue Cephalometry of the position of the maxilla at point A showed an improvement from pre-distraction (T1) to post-distraction (T2) of 8.25 mm (±3.1; P < 0.001). This was 8.30 mm at the prosthion (P < 0.001), 9.95 mm at the maxillary incisal edge (P < 0.001) and 7.00 mm at the distal molar (P < 0.001). The mandible showed a non-significant backward movement at point B of 2.20 mm (P ¼ 0.219). The other mandibular skeletal landmarks showed a 0.5 mm backward movement at the infradental point (P ¼ 0.69) and a 1.30 mm backward movement at the mandibular incisal edge (P ¼ 0.36). The pogonion retracted 4.20 mm (P ¼ 0.07). A slight horizontal relapse was noted in the skeletal and dental points of the maxilla 1 year after distraction (T2 vs T3). The relapse at maxillary point A was 1.17 mm (P < 0.05), hence a 14.1% regression of the maxilla towards its original position. The vertical
Fig. 2. Cephalometric landmarks A: deepest point in the curvature between the prosthion and the anterior nasal spine; A0 : soft tissue reflection of A; B: deepest point in the curvature between infradentale and the pogonion; B0 : soft tissue reflection of B; Go: gonion; Id: infradentale; Ii: tip of inferior central incisor crown; Is: tip of upper central incisor crown; Li: labrale inferior; Ls: labrale superior; Me: menton; N: nasion; N0 : soft tissue reflection of the nasion; Pm: pterygomaxillary point; Pog: pogonion; Pog0 : soft tissue reflection of Pog; Pr: prosthion; S: sella; Sp: anterior nasal spine.
326
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
Table 2 Clinical outcome of hard and soft tissue maxillary advancement. T1 Mean (mm) N ¼ 10 Hard tissue Horizontal A Pr Is Distal molar Ii Id B Pog Vertical Godx Gosx Sp Pm Chin Soft tissue Nose A0 Ls Li B0 Pog0
T2 Mean (mm) N ¼ 10
T3 Mean (mm) N¼9
DT2 T1
DT3 T2
1.16* 0.78 0.44 0.67 2.11* 1.67 2.11 4.11*
51.20 50.50 46.45 13.90 53.60 50.60 47.90 46.20
(±5.37) (±6.22) (±7.97) (±3.70) (±7.87) (±7.90) (±8.63) (±9.08)
59.45 58.80 56.40 20.90 52.30 50.10 45.78 42.00
(±6.86) (±7.13) (±7.43) (±4.98) (±7.27) (±7.20) (±7.50) (±8.84)
59.33 59.00 56.78 20.89 54.67 52.11 48.44 46.56
(±6.75) (±7.30) (±8.03) (±5.39) (±7.08) (±6.90) (±7.28) (±8.68)
8.25* 8.30* 9.95* 7.00* 1.30 0.50 2.20 4.20
68.80 68.90 48.20 38.30 108.90
(±7.52) (±7.09) (±3.79) (±3.27) (±3.47)
69.70 70.30 49.30 40.50 112.90
(±6.86) (±7.10) (±3.86) (±4.20) (±10.11)
72.38 70.89 50.50 41.67 114.88
(±7.56) (±7.62) (±5.37) (±4.18) (±9.05)
0.90 1.40 1.10 2.20* 4.00*
81.80 64.10 66.40 68.40 60.60 58.80
(±7.50) (±6.51) (±6.92) (±7.93) (±8.49) (±11.81)
85.40 71.20 71.60 68.30 59.70 56.00
(±6.54) (±6.78) (±6.95) (±8.10) (±8.51) (±10.72)
86.67 70.44 71.22 70.13 60.33 58.89
(±7.25) (±7.79) (±8.44) (±8.34) (±7.30) (±9.23)
3.60* 7.10* 5.20* 0.10 0.90 2.80
2.13 1.11 0.25 0.67 1.00 0.89 1.44 1.22 2.50* 0.11 1.89
A: deepest point in the curvature between the prosthion and the anterior nasal spine; A0 : soft tissue reflection of A; B: deepest point in the curvature between infradentale and the pogonion; B0 : soft tissue reflection of B; Godx: gonion dextra (right); Gosx: gonion sinistra (left); Id: infradentale; Ii: tip of inferior central incisor crown; Is: tip of upper central incisor crown; Li: labrale inferior; Ls: labrale superior; Me: menton; Pm: pterygomaxillary point; Pog: pogonion; Pog0 : soft tissue reflection of Pog; Pr: prosthion; Sp: anterior nasal spine. *P < 0.05.
points moved 0.90 mm downward at the right gonion (P ¼ 0.15), 1.40 mm at the left gonion (P ¼ 0.07), 1.10 mm at the anterior nasal spine (P ¼ 0.75), 2.20 mm at pterygomaxillare (P ¼ 0.02). The chin point moved 4.00 mm downwards after distraction (P ¼ 0.01). The maxilla moved (Sp and Pm points) slightly downward at T3, but changes were not significant. 3.2. Soft tissue After distraction the soft tissue points A0 and the labrale superius advanced 7.10 mm (P < 0.001) and 5.20 mm (P < 0.001), respectively. The labrale inferius regressed 0.10 mm (P ¼ 0.92). The backward movement of the mandible was 0.90 mm at the B0 point (P < 0.57), and 2.80 mm at the Pog0 point on the chin (P ¼ 0.19). The maxillary soft tissue, A0 and labrale superius, retracted 1.44 mm and 1.22 mm respectively, at FU. This finding was not significant. The mandibular soft tissue landmarks moved forward slightly. 3.3. Hard and soft tissue ratio For horizontal movement at the level of soft/hard tissue point A, after DO (DT1T2) and the post-DO period (DT2T3), a ratio of 0.86: 1 (R2 ¼ 0.629, P ¼ 0.05) respectively 1.23:1 (R2 ¼ 0.823, P < 0.001) was seen. This indicates a ratio of less than 1:1 between soft and hard tissue forward movement during active distraction and backward movement during the post-DO period, with good correlation. 4. Discussion Treatment of cleft-related severe maxillary hypoplasia with the RID showed stable results after 1 year post-distraction. An average advancement of 8.25 mm at point A was achieved. Even though this study did not include angular measurements, we found that facial concavity improved greatly in all patients. It showed a great
aesthetic improvement, as the ‘dish-face like’ appearance was reduced (Fig. 3A,B). At the last FU the negative overjet was inverted and a class 1 central incisor relationship was retained (Fig. 4A,B). Soft tissue movements occurring in conjunction with the underlying skeletal tissue movement renders a great functional and aesthetic outcome in patients with midface hypoplasia related to cleft lip and palate. Soft-to-hard-tissue ratio after distraction with the RID at hard tissue point A was 0.86: 1 with high correlation. This is partially in line with the findings observed in an extensive soft tissue profile analysis after distraction of the maxilla with a RED device by Ko et al. (2000). They reported an almost one-to-one relationship of soft tissue versus hard tissue change during active distraction (0.96:1) and concluded that the soft tissue response was better during DO than with conventional orthognathic surgery. Maxillary relapse in this study was 1.17 mm (14.1%) at point A. The facial profile (Fig. 3B) however remained fairly stable, despite the partial reversion towards the original position of hard tissue point A and the tendency of mandibular advancement at the last FU. Relapses in other studies that have used intraoral devices varied from 1.8% in a study performed by Kumar (Kumar et al., 2006) with the KLS Martin Zurich to 30% in a study performed by Gateno (Gateno et al., 2005). The rigid external device had a relapse of 13.3% (Ko et al., 2000). The psychological sequelae of an external halo and distractor are not negligible and patient acceptance is low in our experience. Furthermore various authors have reported pin loosening and frame migration as frequent device-related complications (Baker et al., 2007; Nout et al., 2006). Consequently, this could diminish the effectiveness of the distraction osteogenesis and alter the distraction vector (Rachmiel et al., 2006). The main obstacle faced by intraoral distractors that are anchored on the maxillary bone and zygomatic buttress, is attaining the correct vector orientation and movement of the maxilla, since the two vectors should not be allowed to converge. The limited advancement due to this convergence is not found with this
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
327
Fig. 3. A: Lateral view of the patient before distraction; B: Lateral view of patient; correction of the midface hypoplasia (1 year postdistraction).
Fig. 4. A: Frontolateral occlusion before treatment; B: Frontolateral occlusion 1 year after distraction.
RID. This explains why some intraoral devices require the use of expensive preoperative (vector) planning with stereolithographic models or scans. Other intraoral devices require the fixation of two miniplates; one for the zygomatic bone and one for the maxilla. Fixation of the miniplate within the narrow maxillary vestibule is surgically challenging, especially in younger patients and entails a risk of damaging the dental roots and limiting the force of distraction. One of the advantages of the RID over conventional orthognathic surgery or external devices is that the RID offers better rigid fixation. The zygomatic buttress is a secure anchor for intraoral devices (Cheung et al., 2003). The RID can be maintained longer than the RED, therefore increasing the period of consolidation of the maxilla and hence creating a more favorable environment for osteogenesis. A shortcoming of the RID and tooth-borne devices in general, is that it they may induce mesial movement of the anchorage teeth and distort their position within the maxillary arch (Kuroda et al., 2005). Although no dental compensations occurred in these patients, Block et al. (Block et al., 1995) reported that during DO the distraction forces applied to the teeth due to tooth-borne fixation may diminish the necessary force for the advancement of the maxilla. The RID therefore requires adequate dentition for the attachment of the dental anchor. The RID would, however, still need a secondary operation under general anesthesia for removal of the zygomatic miniplate, albeit just one miniplate. An option would be designing the RID with a bioresorbable miniplate (Cohen and Holmes, 2001).
5. Conclusion We reported excellent results with this RID. This device provides both treatment and stability effectiveness in maxillary advancement in patients with severe cleft maxillary hypoplasia. Likewise, the soft tissue and aesthetic profile improved greatly. We reported no complications. It is well accepted by our patients and has not been associated with psychosocial stigmata. Additionally, this device is less expensive than those currently in use. We believe that this distractor, due to the limited amount of material to be implanted, its affordability and simple design, possesses several advantages over the current armamentarium of external devices and intraoral designs. Conflict of interest statement None of the authors had financial or personal relationships with other people, organizations or any financial interest to declare. References Ayliffe PR, Banks P, Martin IC: Stability of the Le Fort I osteotomy in patients with cleft lip and palate. Int J Oral Maxillofac Surg 24: 201e207, 1995 Baker SB, Reid RR, Burkey B, Bartlett SP: Rapid maxillary distraction protocol utilizing the halo distraction system and rigid internal fixation. Cleft Palate Craniofac J 44: 476e481, 2007 €rk A: Prediction of mandibular growth rotation. Am J Orthod 55: 585e599, 1969 Bjo Block MS, Cervini D, Chang A, Gottsegen GB: Anterior maxillary advancement using tooth-supported distraction osteogenesis. J Oral Maxillofac Surg 53: 561e565, 1995
328
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
Chua HD, Cheung LK: Soft tissue changes from maxillary distraction osteogenesis versus orthognathic surgery in patients with cleft lip and palateea randomized controlled clinical trial. J Oral Maxillofac Surg 70: 1648e1658, 2012 Cheung LK, Chua HD: A meta-analysis of cleft maxillary osteotomy and distraction osteogenesis. Int J Oral Maxillofac Surg 35: 14e24, 2006 Cheung LK, Chua HD, Hagg MB: Cleft maxillary distraction versus orthognathic surgery: clinical morbidities and surgical relapse. Plast Reconstr Surg 118: 996e1008, 2006 Cheung LK, Zhang Q, Wong MC, Wong LL: Stability consideration for internal maxillary distractors. J Craniomaxillofac Surg 31: 142e148, 2003 Cohen SR, Holmes RE: Internal Le Fort Ⅲ distraction with biodegradable devices. J Craniofac Surg 12: 264e272, 2001 Gateno J, Engel ER, Teichgraeber JF, Yamaji KE, Xia JJ: A new Le Fort I internal distraction device in the treatment of severe maxillary hypoplasia. J Oral Maxillofac Surg 63: 148e154, 2005 Hochban W, Gauss C, Austermann KH: Long term results after maxillary advancement in patients with clefts. Cleft Palate Craniofac J 30: 237e243, 1993 Houston WJB: The analysis of errors in orthodontic measurement. Am J Orthod 83: 382e390, 1983 Ko EW, Figueroa AA, Polley JW: Soft tissue profile changes after maxillary advancement with distraction osteogenesis by use of a rigid external distraction device: a 1-year follow-up. J Oral Maxillofac Surg 58: 959e969, 2000 Kumar A, Gabbay JS, Nikjoo R, Heller JB, O'Hara CM, Sisodia M, et al: Improved outcomes in cleft patients with severe maxillary deficiency after Le Fort I internal distraction. Plast Reconstr Surg 117: 1499e1509, 2006 Kuroda S, Araki Y, Oya S, Mishima K, Sugahara T, Takano-Yamamoto T: Maxillary distraction osteogenesis to treat maxillary hypoplasia: comparison of an
internal and an external system. Am J Orthod Dentofacial Orthop 127: 493e498, 2005 Kusnoto B, Figueroa AA, Polley JW: Radiographic evaluation of bone formation in the pterygoid region after maxillary distraction with a rigid external distraction (RED) device. J Craniofac Surg 12: 109e118, 2001 Malek R, Psaume J: New concept of the chronology and surgical technique in the treatment of cleft lip and palate. Ann Chir Plast Esthet 28: 237e247, 1983 Molina F, Ortiz Monasterio F, de la Paz Aguilar M, Barrera J: Maxillary distractions: aesthetic and functional benefits in cleft lip palate and prognathic patients during mixed dentition. Plast Reconstr Surg 101: 951e963, 1998 Nout E, Wolvius EB, van Adrichem LN, Ongkosuwito EM, van der Wal KG: Complications in maxillary distraction using the RED II device: a retrospective analysis of 21 patients. Int J Oral Maxillofac Surg 35: 897e902, 2006 Picard A, Diner PA, Galliani E, Tomat C, Vazquez MP, Carls FP: Five years' experience with a new intraoral maxillary distraction device (RID). Br J Oral Maxillofac Surg 49: 546e551, 2011 Polley JW, Figueroa AA: Management of severe maxillary deficiency in childhood and adolescence through distraction osteogenesis with an external, adjustable, rigid distraction device. J Craniofac Surg 8: 181e185, 1997 Rachmiel A, Aizenbud D, Peled M: Distraction osteogenesis in maxillary deficiency using a rigid external distraction device. Plast Reconstr Surg 117: 2399e2406, 2006 Swennen G, Schliephake H, Dempf R, Schierle H, Malevez C: Craniofacial distraction osteogenesis: a review of the literature. Part I: clinical studies. Int J Oral Maxillofac Surg 30: 89e103, 2001
Contents lists available at ScienceDirect
Journal of Cranio-Maxillo-Facial Surgery journal homepage: www.jcmfs.com
Skeletal and soft tissue changes and stability in cleft lip and palate patients after distraction osteogenesis using a new intraoral maxillary device Edward Ansari a, *, Catherine Tomat a, Natacha Kadlub a, b, Patrick A. Diner a, Thomas Bellocq a, Marie-Paule Vazquez a, b, Arnaud Picard a, b a b
Department of Maxillofacial and Plastic Surgery, Necker Children's Hospital, AP-HP, Universit e Paris 5, Paris, France Centre de Recherche des Cordeliers, INSERM, UMRS872, equipe 5, 75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history: Paper received 2 November 2014 Accepted 9 December 2014 Available online 17 December 2014
Background: The authors have recently reported on the use of an internal maxillary distraction device. In this study, we report on the hard and soft tissue movements achieved with this intraoral distraction device, and the stability changes after distraction osteogenesis for maxillary hypoplasia in patients with cleft lip and palate. Methods: Ten male patients with severe hypoplasia of the maxilla, with complete uni- or bilateral cleft lip and palate were included. The mean age of the patients at the time of operation was 11.91 years (±3.41). To evaluate the distraction process and stability, superimpositions on the preoperative lateral cephalograms were performed. The mean follow-up (FU) was 15.42 months (±3.94). Results: Cephalometric measurements at all of the maxillary hard and soft tissue points improved significantly. Maxillary point A was advanced by 8.25 mm (±3.17; P < 0.001). After distraction soft tissue point A0 had advanced 7.10 mm (±2.69; P < 0.001). The soft tissue to hard tissue ratio at point A was 0.86:1 after distraction. Maxillary horizontal relapse at point A was 14.1% at FU. Vertical relapse was not significant. Conclusion: This rigid intraoral distraction device can be successfully used in the correction of severe maxillary hypoplasia. The marked aesthetic improvement and low psychological encumbrance make this device viable for the treatment of cleft-related hypoplasia of the maxilla. © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Keywords: Hard tissue Intraoral device Maxillary distraction Soft tissue Stability
1. Introduction Traditionally, maxillary hypoplasia has been corrected with orthognathic surgery. This type of surgery encounters technical difficulties. This is especially seen in the treatment of patients with cleft lip and palate, who often have scarring from previous operations and concurrent hypoplasia of the maxilla, which requires large maxillary advancement. Various reports have noted a relapse or partial regression towards the pre-operative state in Le Fort I maxillary advancements (Hochban et al., 1993, Ayliffe et al., 1995). In conventional orthognathic surgery, autogenous bone grafting is often essential to fill a significant osteotomy gap for bone healing * Corresponding author. The French Center for Cleft Lip and Palate, Department of ^pital Necker e Enfants Malades, 149 Rue de Plastic and Maxillofacial Surgery, The Ho Sevres, 75015 Paris, France. Tel.: þ33 1 44736935; fax: þ33 1 44736936. E-mail address: [email protected] (E. Ansari).
(Cheung et al., 2006), however donor site morbidities, resorption and infection can occur and potentiate a relapse. Moreover conventional surgery is not recommended in growing patients due to the tooth buds and the need for tremendous mobilization. Distraction osteogenesis (DO), a method of gradual bone distraction, has been advocated as a viable alternative for large maxillary advancements. Various studies have reported improved results with the use of DO over conventional orthognathic surgery (Chua and Cheung, 2012; Molina et al., 1998) and have demonstrated a decreased relapse (Chua and Cheung, 2012; Cheung and Chua, 2006), especially with large maxillary advancements. Furthermore, it has been demonstrated that DO induces gradual bone formation (Kusnoto et al., 2001; Swennen et al., 2001) and improves the surrounding soft tissue profile (Chua and Cheung, 2012). In this manner, it contributes to more stable and aesthetically refined results, thereby offering possibilities conventional osteotomy cannot.
http://dx.doi.org/10.1016/j.jcms.2014.12.006 1010-5182/© 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
324
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
The use of external distraction devices has been studied extensively (Molina et al., 1998; Polley and Figueroa, 1997). Although rigid external distractors (RED) still have a place in certain applications, a wide variety of intraoral distractors are now available; these distractors are small and compact, with augmented patient comfort and acceptance. In 2011 we described our experience with a new intraoral maxillary distraction device (Picard et al., 2011) which has been the preferred treatment at our institution since 2004 to correct severe maxillary hypoplasia. This rigid intraoral device (RID) has the advantage of being easy to surgically implement due to its single miniplate fixation. Another major advantage, which is absent for other intraoral devices, is to have an unlimited distraction capacity. This characteristic allows it to always achieve the desired advancement, despite the lack of correlation between real bone advancement and the advancement measured on the device. In this cephalometric study we evaluate the skeletal and soft tissue changes and stability in patients with cleft lip and palate after DO with this RID. 2. Materials and methods 2.1. Device description This internal maxillary distraction device was designed by one of the authors (PAD) and Selsy technologie SA (Paris, France). The device consists of a miniplate for fixation, an orthodontic double arch, and a vertical connecting bar (Fig. 1). The miniplate is fixed to the zygomatic buttress above the osteotomy line to secure the device. The miniplates (2 mm thick) are used for fixation to the zygoma. The miniplate is connected to a double dental arch applied to the maxillary teeth by an adjustable vertical bar, which can be orientated intraoperatively. Its caudal end is fixed to the double arch at the buccal aspect of, for example, the first maxillary molar. An activating horizontal screw emerges anteriorly from the double arch buccal to the maxillary teeth. The length of the vertical rod can be modified and the axis of orientation can also be adjusted, which ensures that it fits at both the zygomatic and the maxillary ends. The horizontal activating screw passes its force through the dental brackets soldered to the orthodontic arch to the maxillary teeth and thereby to the complete maxilla. The arch is the moveable part of the device and allows the forward pull movement of all the teeth and the complete maxilla. 2.2. Patients A retrospective review of all patients who had undergone DO with this RID at the French Center for Cleft Lip and Palate was
conducted. The institution ethics board approved the study protocol. Children with cleft lip and palate were included in the study. Syndromic patients were excluded. All patients who were eligible for DO were subject to a systematic investigation conducted by a psychologist, to evaluate their request and to prepare the patient psychologically for DO. From March 2004 until August 2008, 10 patients underwent DO. The group consisted of 10 males. The mean age at intervention in this group was 11.91 years (±3.41; range 9.28e20.51). Nine patients had developed maxillary hypoplasia resulting from unilateral complete cleft lip and palate (UCLP), whereas 1 patient had a bilateral complete cleft lip and palate (BCLP). All patients with cleft lip and palate had been operated on previously for their clefts; they were treated at our clinic according to the Malek protocol (Malek and Psaume, 1983) that was used at that time. This technique is comprised of primary closure of the soft palate at 3 months of age and subsequently a repair of the lip and hard palate at 6 months of age. In BCLP patients the latter operation was done as a two-stage procedure, at 6 months and 9 months of age. Other surgical interventions that had been performed included a velopharyngoplasty (3 patients) and one patient had undergone distraction 10 years prior to the operation using a Delaire facial mask (Table 1). 2.3. Surgical technique The surgical procedure was performed by the same senior authors (AP and PAD). It included a high Le Fort I osteotomy. To prevent damage to the dental roots and to create a projection of the cheek that will be aesthetically pleasing after distraction, the osteotomy line must be high enough (at the point of the zygomatic buttress). Down fracture and complete mobilization is done. Insertion of the device begins by fixing the miniplate to the zygomatic bone. The separation of the pterygomaxillary disjunction is cautiously completed so as to preserve the upper second molar. The maxilla is mobilized allowing for slight movement. The miniplate is fixed to the zygomatic buttress and connected to a double dental arch applied to the maxillary teeth by an adjustable vertical bar. Then, an activating horizontal screw is inserted anteriorly. The arch, the moveable part of this device, moves the maxilla forward. After a latency period of four days, active distraction was started at a rate of 1 mm/24 h. We aimed for over-correction of 3e5 mm. The mean retention period of the intraoral device was 4.21 months, ranging from 1.64 to 5.95 months. Lateral cephalometric radiographs,
Table 1 Patients' profile. N ¼ 10 Patients Male/female Mean age at DO (years) Cleft type Right/left/bilateral RID Maxillary advancement (mm) Retention period (months) Follow up (months) Primary treatment Velopharyngeoplasty Gingivoperioplasty External rigid devicea Relapse Horizontal (%)
Fig. 1. The rigid internal device Note the miniplate on the zygomatic bone, the orthodontic double arch, the vertical bar and the activating screw.
10/0 11.91 (±3.41) 6/3/1 8.25 (±3.17, range 4e15) 4.21 (±1.38, range 1.64e5.95) 15.42 (±3.94, range 10.62e23.06) 3 2 1 14.1
DO: distraction osteogenesis; RID: rigid intraoral device. a Patient used a Delaire facial mask.
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
325
which were used for the analysis, were taken preoperatively (T1), postdistraction (T2), and at the last follow up (T3). The mean follow-up from the moment of implementation of the RID (T3) was 15.42 months (±3.94; range 10.62e23.06).
demonstrated a small difference; it was however within the acceptable limit (1.0 mm).
2.4. Cephalometric analysis
Statistical analyses were performed using IBM SPSS version 20.0. A paired t-test was performed for all measurement data to compare treatment changes (T1 vs T2) and stability changes (T2 vs T3). A Pearson correlation coefficient was used to determine the correlation between the sagittal movement of soft and hard tissue.
For cephalometric analysis, linear variables were measured ac€rk analysis (Bjo € rk, 1969). The cephalometric cording to the Bjo landmarks and reference lines are presented in Fig. 2. Hard and soft tissue landmarks were used to measure the distances moved. All lateral cephalometric radiographs were made at 100%. Acetate tracings were made on the first lateral cephalogram with a vertical reference line perpendicular to the line SN, through the midpoint of the sella turcica (Y-axis). To evaluate the distraction process and stability of the postoperative situation, the postoperative radiographs were superimposed on the preoperative lateral cephalogram (T1), using bony structures in the anterior cranial base as reference points. The sagittal distance from the line through the sella turcica, perpendicular to SN (Y-axis) towards point A, point B, Pr, Is, Id and Pog (SN⊥A, SN⊥B, SN⊥Is, SN⊥Id, SN⊥Pog, SN⊥distal molar) describe horizontal movements of the maxilla, mandible, bony chin and distal molar. Soft tissue measurements (SN⊥A0 , SN⊥B0 , SN⊥Pog0 , SN⊥Ls, SN⊥Li) were done identically. Vertical measurements were also made at different maxillary and mandibular landmarks to assess the downward movement (SNeMe, SNeGo left and right, SNeSp, SNePm). 2.5. Random error analysis Dahlberg's formula was used to determine the random error of the cephalometric readings (Houston, 1983). The cephalometric radiographs of five patients were retraced, superimposed, and digitalized by one examiner (CAT) for error determination. The random error analysis for skeletal and soft tissue measurements
2.6. Statistical analysis
3. Results Stability and treatment changes of all hard and soft tissue landmarks are shown in Table 2. In one patient the follow up (FU) cephalogram could not be retrieved from the medical records. There were no minor or major complications. 3.1. Hard tissue Cephalometry of the position of the maxilla at point A showed an improvement from pre-distraction (T1) to post-distraction (T2) of 8.25 mm (±3.1; P < 0.001). This was 8.30 mm at the prosthion (P < 0.001), 9.95 mm at the maxillary incisal edge (P < 0.001) and 7.00 mm at the distal molar (P < 0.001). The mandible showed a non-significant backward movement at point B of 2.20 mm (P ¼ 0.219). The other mandibular skeletal landmarks showed a 0.5 mm backward movement at the infradental point (P ¼ 0.69) and a 1.30 mm backward movement at the mandibular incisal edge (P ¼ 0.36). The pogonion retracted 4.20 mm (P ¼ 0.07). A slight horizontal relapse was noted in the skeletal and dental points of the maxilla 1 year after distraction (T2 vs T3). The relapse at maxillary point A was 1.17 mm (P < 0.05), hence a 14.1% regression of the maxilla towards its original position. The vertical
Fig. 2. Cephalometric landmarks A: deepest point in the curvature between the prosthion and the anterior nasal spine; A0 : soft tissue reflection of A; B: deepest point in the curvature between infradentale and the pogonion; B0 : soft tissue reflection of B; Go: gonion; Id: infradentale; Ii: tip of inferior central incisor crown; Is: tip of upper central incisor crown; Li: labrale inferior; Ls: labrale superior; Me: menton; N: nasion; N0 : soft tissue reflection of the nasion; Pm: pterygomaxillary point; Pog: pogonion; Pog0 : soft tissue reflection of Pog; Pr: prosthion; S: sella; Sp: anterior nasal spine.
326
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
Table 2 Clinical outcome of hard and soft tissue maxillary advancement. T1 Mean (mm) N ¼ 10 Hard tissue Horizontal A Pr Is Distal molar Ii Id B Pog Vertical Godx Gosx Sp Pm Chin Soft tissue Nose A0 Ls Li B0 Pog0
T2 Mean (mm) N ¼ 10
T3 Mean (mm) N¼9
DT2 T1
DT3 T2
1.16* 0.78 0.44 0.67 2.11* 1.67 2.11 4.11*
51.20 50.50 46.45 13.90 53.60 50.60 47.90 46.20
(±5.37) (±6.22) (±7.97) (±3.70) (±7.87) (±7.90) (±8.63) (±9.08)
59.45 58.80 56.40 20.90 52.30 50.10 45.78 42.00
(±6.86) (±7.13) (±7.43) (±4.98) (±7.27) (±7.20) (±7.50) (±8.84)
59.33 59.00 56.78 20.89 54.67 52.11 48.44 46.56
(±6.75) (±7.30) (±8.03) (±5.39) (±7.08) (±6.90) (±7.28) (±8.68)
8.25* 8.30* 9.95* 7.00* 1.30 0.50 2.20 4.20
68.80 68.90 48.20 38.30 108.90
(±7.52) (±7.09) (±3.79) (±3.27) (±3.47)
69.70 70.30 49.30 40.50 112.90
(±6.86) (±7.10) (±3.86) (±4.20) (±10.11)
72.38 70.89 50.50 41.67 114.88
(±7.56) (±7.62) (±5.37) (±4.18) (±9.05)
0.90 1.40 1.10 2.20* 4.00*
81.80 64.10 66.40 68.40 60.60 58.80
(±7.50) (±6.51) (±6.92) (±7.93) (±8.49) (±11.81)
85.40 71.20 71.60 68.30 59.70 56.00
(±6.54) (±6.78) (±6.95) (±8.10) (±8.51) (±10.72)
86.67 70.44 71.22 70.13 60.33 58.89
(±7.25) (±7.79) (±8.44) (±8.34) (±7.30) (±9.23)
3.60* 7.10* 5.20* 0.10 0.90 2.80
2.13 1.11 0.25 0.67 1.00 0.89 1.44 1.22 2.50* 0.11 1.89
A: deepest point in the curvature between the prosthion and the anterior nasal spine; A0 : soft tissue reflection of A; B: deepest point in the curvature between infradentale and the pogonion; B0 : soft tissue reflection of B; Godx: gonion dextra (right); Gosx: gonion sinistra (left); Id: infradentale; Ii: tip of inferior central incisor crown; Is: tip of upper central incisor crown; Li: labrale inferior; Ls: labrale superior; Me: menton; Pm: pterygomaxillary point; Pog: pogonion; Pog0 : soft tissue reflection of Pog; Pr: prosthion; Sp: anterior nasal spine. *P < 0.05.
points moved 0.90 mm downward at the right gonion (P ¼ 0.15), 1.40 mm at the left gonion (P ¼ 0.07), 1.10 mm at the anterior nasal spine (P ¼ 0.75), 2.20 mm at pterygomaxillare (P ¼ 0.02). The chin point moved 4.00 mm downwards after distraction (P ¼ 0.01). The maxilla moved (Sp and Pm points) slightly downward at T3, but changes were not significant. 3.2. Soft tissue After distraction the soft tissue points A0 and the labrale superius advanced 7.10 mm (P < 0.001) and 5.20 mm (P < 0.001), respectively. The labrale inferius regressed 0.10 mm (P ¼ 0.92). The backward movement of the mandible was 0.90 mm at the B0 point (P < 0.57), and 2.80 mm at the Pog0 point on the chin (P ¼ 0.19). The maxillary soft tissue, A0 and labrale superius, retracted 1.44 mm and 1.22 mm respectively, at FU. This finding was not significant. The mandibular soft tissue landmarks moved forward slightly. 3.3. Hard and soft tissue ratio For horizontal movement at the level of soft/hard tissue point A, after DO (DT1T2) and the post-DO period (DT2T3), a ratio of 0.86: 1 (R2 ¼ 0.629, P ¼ 0.05) respectively 1.23:1 (R2 ¼ 0.823, P < 0.001) was seen. This indicates a ratio of less than 1:1 between soft and hard tissue forward movement during active distraction and backward movement during the post-DO period, with good correlation. 4. Discussion Treatment of cleft-related severe maxillary hypoplasia with the RID showed stable results after 1 year post-distraction. An average advancement of 8.25 mm at point A was achieved. Even though this study did not include angular measurements, we found that facial concavity improved greatly in all patients. It showed a great
aesthetic improvement, as the ‘dish-face like’ appearance was reduced (Fig. 3A,B). At the last FU the negative overjet was inverted and a class 1 central incisor relationship was retained (Fig. 4A,B). Soft tissue movements occurring in conjunction with the underlying skeletal tissue movement renders a great functional and aesthetic outcome in patients with midface hypoplasia related to cleft lip and palate. Soft-to-hard-tissue ratio after distraction with the RID at hard tissue point A was 0.86: 1 with high correlation. This is partially in line with the findings observed in an extensive soft tissue profile analysis after distraction of the maxilla with a RED device by Ko et al. (2000). They reported an almost one-to-one relationship of soft tissue versus hard tissue change during active distraction (0.96:1) and concluded that the soft tissue response was better during DO than with conventional orthognathic surgery. Maxillary relapse in this study was 1.17 mm (14.1%) at point A. The facial profile (Fig. 3B) however remained fairly stable, despite the partial reversion towards the original position of hard tissue point A and the tendency of mandibular advancement at the last FU. Relapses in other studies that have used intraoral devices varied from 1.8% in a study performed by Kumar (Kumar et al., 2006) with the KLS Martin Zurich to 30% in a study performed by Gateno (Gateno et al., 2005). The rigid external device had a relapse of 13.3% (Ko et al., 2000). The psychological sequelae of an external halo and distractor are not negligible and patient acceptance is low in our experience. Furthermore various authors have reported pin loosening and frame migration as frequent device-related complications (Baker et al., 2007; Nout et al., 2006). Consequently, this could diminish the effectiveness of the distraction osteogenesis and alter the distraction vector (Rachmiel et al., 2006). The main obstacle faced by intraoral distractors that are anchored on the maxillary bone and zygomatic buttress, is attaining the correct vector orientation and movement of the maxilla, since the two vectors should not be allowed to converge. The limited advancement due to this convergence is not found with this
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
327
Fig. 3. A: Lateral view of the patient before distraction; B: Lateral view of patient; correction of the midface hypoplasia (1 year postdistraction).
Fig. 4. A: Frontolateral occlusion before treatment; B: Frontolateral occlusion 1 year after distraction.
RID. This explains why some intraoral devices require the use of expensive preoperative (vector) planning with stereolithographic models or scans. Other intraoral devices require the fixation of two miniplates; one for the zygomatic bone and one for the maxilla. Fixation of the miniplate within the narrow maxillary vestibule is surgically challenging, especially in younger patients and entails a risk of damaging the dental roots and limiting the force of distraction. One of the advantages of the RID over conventional orthognathic surgery or external devices is that the RID offers better rigid fixation. The zygomatic buttress is a secure anchor for intraoral devices (Cheung et al., 2003). The RID can be maintained longer than the RED, therefore increasing the period of consolidation of the maxilla and hence creating a more favorable environment for osteogenesis. A shortcoming of the RID and tooth-borne devices in general, is that it they may induce mesial movement of the anchorage teeth and distort their position within the maxillary arch (Kuroda et al., 2005). Although no dental compensations occurred in these patients, Block et al. (Block et al., 1995) reported that during DO the distraction forces applied to the teeth due to tooth-borne fixation may diminish the necessary force for the advancement of the maxilla. The RID therefore requires adequate dentition for the attachment of the dental anchor. The RID would, however, still need a secondary operation under general anesthesia for removal of the zygomatic miniplate, albeit just one miniplate. An option would be designing the RID with a bioresorbable miniplate (Cohen and Holmes, 2001).
5. Conclusion We reported excellent results with this RID. This device provides both treatment and stability effectiveness in maxillary advancement in patients with severe cleft maxillary hypoplasia. Likewise, the soft tissue and aesthetic profile improved greatly. We reported no complications. It is well accepted by our patients and has not been associated with psychosocial stigmata. Additionally, this device is less expensive than those currently in use. We believe that this distractor, due to the limited amount of material to be implanted, its affordability and simple design, possesses several advantages over the current armamentarium of external devices and intraoral designs. Conflict of interest statement None of the authors had financial or personal relationships with other people, organizations or any financial interest to declare. References Ayliffe PR, Banks P, Martin IC: Stability of the Le Fort I osteotomy in patients with cleft lip and palate. Int J Oral Maxillofac Surg 24: 201e207, 1995 Baker SB, Reid RR, Burkey B, Bartlett SP: Rapid maxillary distraction protocol utilizing the halo distraction system and rigid internal fixation. Cleft Palate Craniofac J 44: 476e481, 2007 €rk A: Prediction of mandibular growth rotation. Am J Orthod 55: 585e599, 1969 Bjo Block MS, Cervini D, Chang A, Gottsegen GB: Anterior maxillary advancement using tooth-supported distraction osteogenesis. J Oral Maxillofac Surg 53: 561e565, 1995
328
E. Ansari et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 323e328
Chua HD, Cheung LK: Soft tissue changes from maxillary distraction osteogenesis versus orthognathic surgery in patients with cleft lip and palateea randomized controlled clinical trial. J Oral Maxillofac Surg 70: 1648e1658, 2012 Cheung LK, Chua HD: A meta-analysis of cleft maxillary osteotomy and distraction osteogenesis. Int J Oral Maxillofac Surg 35: 14e24, 2006 Cheung LK, Chua HD, Hagg MB: Cleft maxillary distraction versus orthognathic surgery: clinical morbidities and surgical relapse. Plast Reconstr Surg 118: 996e1008, 2006 Cheung LK, Zhang Q, Wong MC, Wong LL: Stability consideration for internal maxillary distractors. J Craniomaxillofac Surg 31: 142e148, 2003 Cohen SR, Holmes RE: Internal Le Fort Ⅲ distraction with biodegradable devices. J Craniofac Surg 12: 264e272, 2001 Gateno J, Engel ER, Teichgraeber JF, Yamaji KE, Xia JJ: A new Le Fort I internal distraction device in the treatment of severe maxillary hypoplasia. J Oral Maxillofac Surg 63: 148e154, 2005 Hochban W, Gauss C, Austermann KH: Long term results after maxillary advancement in patients with clefts. Cleft Palate Craniofac J 30: 237e243, 1993 Houston WJB: The analysis of errors in orthodontic measurement. Am J Orthod 83: 382e390, 1983 Ko EW, Figueroa AA, Polley JW: Soft tissue profile changes after maxillary advancement with distraction osteogenesis by use of a rigid external distraction device: a 1-year follow-up. J Oral Maxillofac Surg 58: 959e969, 2000 Kumar A, Gabbay JS, Nikjoo R, Heller JB, O'Hara CM, Sisodia M, et al: Improved outcomes in cleft patients with severe maxillary deficiency after Le Fort I internal distraction. Plast Reconstr Surg 117: 1499e1509, 2006 Kuroda S, Araki Y, Oya S, Mishima K, Sugahara T, Takano-Yamamoto T: Maxillary distraction osteogenesis to treat maxillary hypoplasia: comparison of an
internal and an external system. Am J Orthod Dentofacial Orthop 127: 493e498, 2005 Kusnoto B, Figueroa AA, Polley JW: Radiographic evaluation of bone formation in the pterygoid region after maxillary distraction with a rigid external distraction (RED) device. J Craniofac Surg 12: 109e118, 2001 Malek R, Psaume J: New concept of the chronology and surgical technique in the treatment of cleft lip and palate. Ann Chir Plast Esthet 28: 237e247, 1983 Molina F, Ortiz Monasterio F, de la Paz Aguilar M, Barrera J: Maxillary distractions: aesthetic and functional benefits in cleft lip palate and prognathic patients during mixed dentition. Plast Reconstr Surg 101: 951e963, 1998 Nout E, Wolvius EB, van Adrichem LN, Ongkosuwito EM, van der Wal KG: Complications in maxillary distraction using the RED II device: a retrospective analysis of 21 patients. Int J Oral Maxillofac Surg 35: 897e902, 2006 Picard A, Diner PA, Galliani E, Tomat C, Vazquez MP, Carls FP: Five years' experience with a new intraoral maxillary distraction device (RID). Br J Oral Maxillofac Surg 49: 546e551, 2011 Polley JW, Figueroa AA: Management of severe maxillary deficiency in childhood and adolescence through distraction osteogenesis with an external, adjustable, rigid distraction device. J Craniofac Surg 8: 181e185, 1997 Rachmiel A, Aizenbud D, Peled M: Distraction osteogenesis in maxillary deficiency using a rigid external distraction device. Plast Reconstr Surg 117: 2399e2406, 2006 Swennen G, Schliephake H, Dempf R, Schierle H, Malevez C: Craniofacial distraction osteogenesis: a review of the literature. Part I: clinical studies. Int J Oral Maxillofac Surg 30: 89e103, 2001
