Rigid External Distraction System Research Articles

Does the Rigid External Distraction Device Alter Maxillary Pitch in Cleft Maxillary Distraction?

Statement of problemCorrection of cleft maxillary hypoplasia remains a controversial topic. Surgical correction can be accomplished through Le Fort I orthognathic correction, internal distraction osteogenesis, or external distraction osteogenesis.1 Proponents of rigid external distraction (RED) osteogenesis describe the ability of multi-vector directional distraction control as opposed to univector internal distraction. There are currently limited data on the ability of the RED system to alter the maxillary occlusal pitch.The purpose of this study is to address the following clinical question: “Among cleft patients presenting with severe maxillary hypoplasia and treated with rigid external distraction, does the rigid external distraction system result in alteration of the maxillary pitch?”The study hypothesis is: among cleft patients presenting with maxillary hypoplasia treated with RED, the investigators hypothesize that there is no change in maxillary pitch with distraction.The study's specific aims are to design a retrospective cohort study and enroll a sample composed of cleft patients with maxillary hypoplasia treated with RED: 1) identify a cohort of patients with cleft maxillary hypoplasia, 2) quantify the degree of pre-operative maxillary hyperplasia, 3) measure changes in maxillary position achieved through RED. Materials and methodsTo address the research objectives, the investigators designed a retrospective cohort study. The study sample was derived from the population of patients with cleft maxillary hypoplasia who underwent RED by the Department of Oral and Maxillofacial Surgery at the University of Alabama - Birmingham from June 2007 to August 2019. Subjects eligible for study inclusion had cleft maxillary hypoplasia and underwent RED. Subjects were excluded if there were incomplete data collection or their records were not available for review.Demographic and radiographic variables were recorded. Demographics included gender, age at date of surgery, and history of ULCP vs. BLCP. Radiographic variables included standard cephalometric data recorded prior to distraction (T1) and after completion of distraction (T2). Methods of data analysisDescriptive statistics were computed for all study variables. Due to the potential for both positive and negative occlusal pitch change, a paired 2-tailed T-test was used to compare T1 and T2. The level of statistical significance was set at P < .05. ResultsThe study sample was composed of 45 subjects with a mean age at surgery of 12.2+3.4 years. Twenty-two (49%) were BCLP and 27 (60.0%) were male. At T1, mean SNA was 76.35+/-6.4 degrees, and the maxillary occlusal plane to Frankfort horizontal plane was 8.18+/-6.9 degrees. The mean anterior-posterior distraction distance was 11.4+/-5.7 mm. At T2, the mean SNA was 86.0+/-7.5 degrees, and the occlusal plane to FH was 3.78+/-7.3 degrees. The average maxillary occlusal pitch change was -4.4+/-5.8 degrees (P = .005). ConclusionFor cleft lip and palate patients with maxillary hypoplasia, surgical advancement with RED results in counterclockwise rotation of the maxillary occlusal plane.

Skeletal Stability and Airway Changes After Maxillary Advancement Using a Rigid External Distraction System in Non-Growing Cleft Patients.

Distraction osteogenesis (DO) is a highly effective technique for correction of severe maxillary hypoplasia, especially in patients with orofacial clefts and craniofacial syndromes. The purpose of this retrospective, longitudinal study was to assess long-term airway alterations after maxillary advancement using a rigid external distraction system (RED) in non growing cleft patients. Fifteen cleft patients (8 males and 7 females) aged from 14 to 25 years were included in this study. All of them were treated with a rigid external distraction system for maxillary advancement after a high Le Fort I osteotomy. To analyse airway changes lateral cephalograms were obteined before distraction (T0), immediately after distraction (T1) and 1 to 3 years and 3 months after distraction (T2). All the measurements were describled by means of median, minimum and maximum. In order to evaluate differences between each time interval, a Wilcoxon test associated to a Delta Cliff test was used to evaluate the effect size (level of significance adopted was 5%). A significant maxillary advancement and increased upper airway antero-posterior dimensions were observed after the distraction osteogeness process, as demonstrated by the difference between T1 and T0. No significant relapse at T2 was found. Lower airway and the airway at tip of uvula region did not display significant alterations. A significant maxillary advancement and increased antero-posterior upper airway dimension was measured immediately after maxillary distraction with rigid external distraction in non growing cleft patients. The findings were stable three years after distraction.

Endoscopically assisted intraoral modified Le Fort II type midfacial advancement using piezoelectric surgery and an intraoperative red system

Background: The Le Fort II midfacial advancement appears to be an effective surgical method for the treatment of severe midfacial-nose hypoplasia with a skeletal class III malocclusion, which is usually combined with syndromic midfacial anomalies. However, the conventional surgical method requires the coronal approach, including a coronal incision, together with other surgical approaches, such as an intraoral incision. Therefore, surgeons often hesitate to propose this type of osteotomy, even for patients who develop severe nonsyndromic midfacial-nose hypoplasia. Objectives: This report presents a new surgical approach for performing a safe Le Fort II osteotomy for nasomaxillary, midfacial corrective advancement via a solely intraoral approach. Methods: Surgery was performed with endoscopically assisted piezoelectric surgery. The osteotomised nasomaxillary Le Fort II segment was successfully protracted without aggressive downfracture procedures with the sole intraoperative use of a rigid external distraction (RED) system, followed by internal rigid fixation, and the subsequent removal of the RED system. Seven patients (average age, 19.9 years) were included in this study. Findings: The degrees of midfacial advancement at the base of nasal bone (the top edge of the modified Le Fort II segment) that was osteotomised and at maxillary point A was 8.3 mm (range, 5.8–10.5 mm) and 8.5 mm (range, 5.9–9.8 mm), respectively. Conclusion: This new method less invasively facilitates safe, secure, and ideal nasomaxillary midfacial protraction to yield a satisfactory resultant facial profile and favourable occlusion in patients with severe midfacial-nose hypoplasia and skeletal class III malocclusions.

Maxillary Distraction Osteogenesis in Unilateral Cleft Lip and Palate Patients with Rigid External Distraction System.

Aim:Distraction osteogenesis (DO) is a treatment option for patients with maxillary hypoplasia secondary to cleft lip and palate (CLP).Purpose:The aim of this study is to present a technique for maxillary DO using Le Fort I osteotomy with rigid external distraction (RED) system.Subjects and Methods:The patient presented in this paper was an Asian female with CLP aged 13 years and 6 months. She presented with severe midfacial deficiency with a Class III dental malocclusion with a negative overjet and concave facial profile. Cone-beam computed tomography images were recorded preoperatively and the operation performed involved a high Le Fort I osteotomy. The appliance fabricated was banded to upper first molars used for anchorage of the RED system. Distraction of the maxilla was initiated after 7-day latency period.Results:Postoperative cephalometric analysis showed maxillary advancement anteriorly and superiorly, the total distraction treatment period was 10 days. The maxillary advancement was 10.5 mm and the SNA angle increased from 67.5° to 77.9°. Furthermore, the ANB angle changed from −9.8° to 1.6° and the occlusion changed from Class III to Class I. The profile of the face changed from concave to convex and a much better esthetic result was achieved.Conclusion:The study suggests RED system to be a reliable alternative procedure for the treatment of midfacial hypoplasia with or without cleft. Furthermore, it minimizes the risk of the surgical procedure and shortens the operating time.

Endoscopically Assisted Intraoral Modified Le Fort II Type Midfacial Advancement Using Piezoelectric Surgery and an Intraoperative RED System

The Le Fort II midfacial advancement appears to be an effective surgical method for the treatment of severe midfacial-nose hypoplasia with a skeletal class III malocclusion, which is usually combined with syndromic midfacial anomalies. However, the conventional surgical method requires the coronal approach, including a coronal incision, together with other surgical approaches, such as an intraoral incision. Therefore, surgeons often hesitate to propose this type of osteotomy, even for patients who develop severe nonsyndromic midfacial-nose hypoplasia. This report presents a new surgical approach for performing a safe Le Fort II osteotomy for nasomaxillary, midfacial corrective advancement via a solely intraoral approach. Surgery was performed with endoscopically assisted piezoelectric surgery. The osteotomized nasomaxillary Le Fort II segment was successfully protracted without aggressive down-fracture procedures with the sole intraoperative use of a rigid external distraction (RED) system, followed by internal rigid fixation, and the subsequent removal of the RED system. Seven patients (all patients were nonsyndromic, but 2 had cleft lip and palate, and an average age of 19.9 years) were included in this study. The degrees of midfacial advancement at the base of nasal bone (the top edge of the modified Le Fort II segment) that was osteotomized and at maxillary point A was 8.3 mm (range 5.8 mm to 10.5mm) and 8.5 mm (range 5.9 mm to 9.8 mm), respectively. This new method less invasively facilitates safe, secure, and ideal nasomaxillary midfacial protraction to yield a satisfactory resultant facial profile and favorable occlusion in patients with severe midfacial-nose hypoplasia and skeletal class III malocclusions.

Orthodontic Treatment in Combination with Le Fort II Bone Distraction in Patient with Apert Syndrome

We report a case of an 11-year-old girl presenting with Apert syndrome characterized by midface concavity, protrusion of the eyeballs, and ocular hypertelorism. She had class III anterior crossbite, narrow upper and lower arches, and marked crowding. Based on cephalometric analysis, anterior crossbite associated with marked midfacial hypoplasia was diagnosed. Orthodontic treatment in combination with Le Fort II maxillary distraction was scheduled. The dentition was laterally extended using a Rapid palatal expander in the upper jaw and a Bihelix in the lower jaw. Multi-bracket appliances were simultaneously applied for leveling. Next, Le Fort II maxillary osteotomy was performed to distract the midface bone 16 mm anteroinferiorly using a rigid external distraction system. Orthodontic treatment was completed at 3.8 years after initiation. Bone distraction moved the upper jaw anteriorly downward, and the lower jaw subsequently rotated posteriorly downward, leading to a marked improvement in facial appearance and occlusion. Elongation of the dorsum of the nose, in particular, allowed esthetic improvement of the saddle nose. These improvements remain stable at 2 years after orthodontic treatment.

Segmental distraction osteogenesis with modified LeFort II osteotomy for a patient with craniosynostosis

In this article, we report successful orthodontic treatment combined with segmental distraction osteogenesis after a modified LeFort II osteotomy in a patient with craniosynostosis. An 8-year-old boy diagnosed with craniosynostosis had a dished-in face, an anterior crossbite, and a skeletal Class III jaw relationship because of midfacial hypoplasia. At the age of 13 years 6 months, the maxillary second and mandibular first premolars were extracted, and leveling and alignment of both arches was started with preadjusted edgewise appliances. At age 14 years 11 months, the patient had a modified LeFort II osteotomy, and the maxillary segment was advanced 7 mm and fixed to the zygomatic bone. At thesame time, segmental distraction osteogenesis was started with a rigid external distraction system, and the nasal segment was advanced for 20 days at a rate of 1.0 mm per day. The total active treatment period was 40 months. As a result of the modified segmental distraction osteogenesis, significant improvement of his severe midfacial hypoplasia was achieved without excessive advancement of the maxillary dentition. Both the facial profile and the occlusion were stable after 1 year of retention. However, the nasal segment relapsed 1.4 mm during the 1.5 years after the segmental distraction osteogenesis. Evaluation of the stability and retention suggests that some overcorrection in midfacial advancement is recommended.

Maxillary Distraction Osteogenesis in the Adolescent Cleft Patient: Three-Dimensional Computed Tomography Analysis of Linear and Volumetric Changes over Five Years

To assess the results of maxillary distraction osteogenesis with the Rigid External Distraction System using three-dimensional computed tomography scan volume-rendered images with respect to stability and facial growth at three time frames: preoperative (T0), 1-year postoperative (T1), and 5-years postoperative (T2). Retrospective analysis. Tertiary. A total of 12 patients with severe cleft maxillary hypoplasia were treated between June 30, 1997, and July 15, 1998. The mean age at surgery was 11 years 1 month. Le Fort I maxillary distraction osteogenesis. Distraction was started 2 to 5 days postsurgery at a rate of 1 mm per day. The consolidation period was 3 months. No face mask was used. A paired t test was used for statistical analysis. Overjet, ANB, and SNA and maxillary, pterygoid, and mandibular volumes. From T0 to T1, there were statistically significant increments of overjet, ANB, and SNA and maxillary, pterygoid, and mandibular volumes. The T1 to T2 period demonstrated a reduction of overjet (30.07%) and ANB (54.42%). The maxilla showed a stable SNA and a small but statistically significant advancement of the ANS point. There was a significant increase in the mandibular volume. However, there was no significant change in the maxillary and pterygoid volumes. Maxillary distraction osteogenesis demonstrated linear and volumetric maxillary growth during the distraction phase without clinically significant continued growth thereafter. Overcorrection is required to take into account recurrence of midface retrusion over the long term.

Outcome of Early Rigid Fixation and Removal of Rigid External Distraction System After Distraction Osteogenesis of the Midface

After distraction osteogenesis of the midface using a rigid external distraction (RED) system, there is a high possibility that a relapse might occur due to an incomplete fixation during the consolidation period, and it is uncomfortable for the patients to wear a head frame for 2 to 3 months. There are also risks of trauma that are developing. To overcome these problems, we suggest the protocol of early rigid fixation, with excellent treatment outcomes and a review of literatures. Of 9 patients, Le Fort III osteotomy was completed in 2 patients with Crouzon disease, and a Le Fort I osteotomy was completed in 7 patients with a cleft lip and palate. Immediately after the distraction with RED was completed, the fixation was done using a miniplate. This was followed by the early removal of the RED system. In patients who underwent the current procedure, an analysis was performed for the degree and the duration of distraction and the period of use of the RED system. Then, the presence of relapse was examined. The mean degree of bone distraction was found to be 18.05 mm (range, 9-31.5 mm). The mean period of wearing RED system was 29.78 days (range, 21-43 days). Thereafter, the mean follow-up period was 13 months (range, 6 months to 3 years). The degree of accumulated relapse was found to be 1.7 mm (10%) on postoperative year 1, 2.4 mm (13.3%) on postoperative year 2, and 2.3 mm (14.6%) on postoperative year 3. With the concept of early rigid fixation, we were able to eliminate the disadvantages of distraction osteogenesis such as the long period of wearing a head frame, the delay of returning to society, and the inconvenience of patients. Moreover, early rigid fixation could decrease the need of overcorrection and the amount of relapses.

Application of Orthodontic Mini-Implants and Ligation for Absolute Skeletal Anchorage to the Intraoral Labiolingual Appliance

Patients with cleft and several craniofacial syndromes usually show skeletal class III malocclusion with midface hypoplasia. Although the Rigid External Distraction (RED) System (KLS Martin, LP, Jacksonville, FL) has been used widely, bowing of the external traction hooks (ETHs) and tooth-borne anchorage for the intraoral labiolingual appliance (ILA) can result in inappropriate change of force application level and vector control, eventually improper rotation of the osteotomized bony segment and unwanted dentoalveolar effect. Instead of the ETH and ILA, direct fixation of the skeletal plate on the maxilla can be another option. However, it also has some disadvantages including inflammation, fixation failure, and the need for a second surgery to remove the plates. These phenomena could be minimized by the addition of rigidity to the ETHs and fortification of absolute skeletal anchorage to the ILA. Therefore, the purpose of this article was to introduce application orthodontic mini-implants on the buccal attached gingiva and palate areas and ligation for absolute skeletal anchorage to the ILA in midface distraction osteogenesis cases treated with the RED System. In cases that need a large amount of advancement and bodily translation or clockwise rotation of the midface and that have oligodontia or anchorage problem for the ILA, application of the orthodontic mini-implants and ligation for absolute skeletal anchorage to the ILA can be a highly effective fixation approach to obtain more accurate vector control.

Midfacial Changes Through Distraction Osteogenesis Using a Rigid External Distraction System With Retention Plates in Cleft Lip and Palate Patients

The purpose of this study was to investigate the changes in and stability of the maxilla and soft tissue profile achieved after the application of distraction osteogenesis (DO) by use of rigid external distraction (RED) with a retention plate system in unilateral cleft lip and palate (UCLP) adult patients. We compared 2 treatment methods in the management of maxillary hypoplasia: Le Fort I osteotomy and DO. Six UCLP adult patients who underwent treatment with the RED retention plate system were examined (DO group). Changes in the positions of soft and hard tissue landmarks were calculated from lateral cephalograms taken before distraction, at the removal of the halo, and 1 year after surgery and were compared with those in 7 other UCLP patients who underwent Le Fort I osteotomy (LF1 group). The mean maxillary advancement was significantly larger in the DO group than in the LF1 group after distraction. During the follow-up period, the relapse rate of the maxilla was significantly smaller in the DO group. An undesirable labial inclination of the upper incisors was found in the LF1 group, which may have been due to relapse. The DO group tended to have a higher soft tissue-to-hard tissue anterior movement ratio from the time of distraction to follow-up. The RED retention plate system improved the midfacial profile by advancement of soft and hard tissue and minimized the risk of injury to the upper lip. Using the RED system with retention plates prevented the undesirable labial inclination of upper incisors that was found in the LF1 group.

Comparison of the efficiency of two types of intraoral splints in the RED system for maxillary distraction osteogenesis

Purpose This study was conducted to compare the ratio of maxillary advancement to the amount of activation achieved by distraction osteogenesis (DOG) using a rigid external distraction system with two different types of intraoral splints and to evaluate the applicability of a new type of splint. Materials and methods The mechanical deformation and the distraction efficiency of two types of intraoral splints, Type 1 and Type 2, were evaluated. The Type 1 was a conventionally used intraoral splint. Type 2 was a reinforced, custom-made splint composed of twin-labial arches made of 0.060-in. orthodontic wires. In this study, 11 cleft lip and palate patients were analyzed; 5 patients were treated using Type 1 splint and the other 6 using Type 2. Lateral cephalograms taken at 4 stages—the onset, the end of activation, immediately after the removal of distraction device, and 1 year after distraction—were superimposed and measured to estimate the advancement and relapse at point A. Results Type 2 splint demonstrated significantly higher strength than Type 1 in a tensile test. Distraction efficiency for Type 1 and Type 2 was 31.6% and 51.0%, respectively, demonstrating significantly higher efficiency for Type 2. On the other hand, the amount of relapse during the 1-year follow-up period did not show significant difference between two groups. Conclusion The distraction efficiency was affected by the types of intraoral splints used and maxillary distraction could be effectively performed using the reinforced intraoral splint without impairing the stability after DOG.

Skeletal and Dental Stability After Maxillary Distraction With a Rigid External Device in Adult Cleft Lip and Palate Patients

To evaluate skeletal and dental stability in adult cleft lip and palate patients treated with a rigid external distraction system at the end of distraction and during the postdistraction period. Lateral cephalograms of 7 patients were obtained before distraction, at the end of distraction, and during the postdistraction period. The mean age before distraction was 21.56 +/- 4.73 years. The mean follow-up was 37.3 +/- 12.4 months. The assessment of findings showed that skeletal maxillary sagittal movement was achieved in a superoanterior direction. The maxillary depth angle and effective maxillary length increased significantly (2 degrees and 9 mm, respectively) after distraction, whereas the palatal plane angle increased by 8 degrees , resulting in an anterior movement of the maxilla with a counterclockwise rotation. The lower facial height showed no significant changes after distraction. The sagittal movement of the upper incisors and the angulation of the upper first molars increased significantly (4.5 mm and 5.5 degrees , respectively). During the postdistraction period, the maxilla showed a slight relapse (22%). The effective maxillary length decreased by 2 mm. The palatal plane angle almost returned to its original position, showing 7 degrees of clockwise rotation. The lower facial height remained stable. The upper incisors moved anteriorly and the upper first molars showed a significant mesioangular change during follow-up. After distraction, significant maxillary advancement was achieved with a counterclockwise rotation. The upper incisors moved labially, and the upper first molars angulated mesially. After 3 years, a 22% relapse rate was seen in the maxilla. The counterclockwise rotation of the maxilla was returned to its original position. The upper incisors moved more anteriorly.

Distraction assisted treatment of a unilateral complex facial cleft

Unilateral maxillary hypoplasia is a characteristic feature of an oblique facial cleft. This three-dimensional shortage of osseous structures and soft tissue becomes more prominent over the years and is difficult to correct. The authors describe a 17-year-old boy born with a unilateral nasomaxillary dysplasia and nasal dysplasia (Tessier type 1, 2, 3) who underwent a hemi-Le Fort III distraction with a rigid external distraction (RED) system. This distraction, in combination with initial peroperative advancement and retained with elastic traction with a facial mask, achieved a substantial horizontal improvement of the hemi-midface; this resulted in a better projection of the left cheek, infra-orbital rim, nasal ala, and improved occlusion. Owing to the underdevelopment of the maxilla and zygoma in all three dimensions, contour deformities remain. Creating several bone segments for multidirectional distraction would jeopardize vascularization of the bone. Good long-term planning is essential in these complicated cases, and more long-term results need to be assessed. The major reconstructive challenge for this complex pathology continues.

Midface Distraction Osteogenesis Complication: Intracranial Penetration of a Rigid External Distraction System Pin

Midface Distraction Osteogenesis Complication: Intracranial Penetration of a Rigid External Distraction System Pin

Distraction Osteogenesis of the Hypoplastic Midface using a Rigid External Distraction System: The Results of a One- to Six-Year Follow-Up

Distraction Osteogenesis of the Hypoplastic Midface using a Rigid External Distraction System: The Results of a One- to Six-Year Follow-Up

Removable splint with locking attachments for maxillary distraction osteogenesis with the RED system

The external traction hooks of the intraoral splint used to control traction forces applied to the maxilla with the rigid external distraction system represent a major barrier to surgical procedures. The purpose of this article is to introduce a removable intraoral splint with locking attachments that can be placed post-surgically immediately before distraction, facilitating surgery and consequently reducing the operative time. Fifteen cleft lip and palate patients underwent maxillary distraction osteogenesis using a rigid external distraction device in combination with the proposed removable splint that was fixed onto the maxillary teeth to provide anchorage. Initial records showed severe maxillary hypoplasia and negative overjet. The removable splint was fabricated using 1.5-mm diameter stainless-steel rigid orthodontic wires soldered to the locking attachments (Y&B Products LP, Chiang Mai, Thailand), making possible its placement post-surgically. Stable splint fixation was achieved prior to the distraction procedure and the desired treatment goals were reached. No complications inserting or removing the splint post-surgically, including pain or discomfort, were observed. The use of the removable splint with locking attachments has proved to be a highly effective fixation approach to manage the severely hypoplastic maxilla, eliminating lip constraints resulting from scarring, and allowing for easier, more deliberate and careful dissection.

Maxillary Distraction Osteogenesis Using the Intraoral Distractors and the Full-Covered Tooth-Supported Maxillary Splint

p w 1 c 2 fl a t t m d t s m u m ecent numerous clinical reports described well the enefit of distraction osteogenesis for facial bone deormities. For cases of severe midfacial retrusion, it ay be said that distraction osteogenesis in combinaion with Le Fort osteotomy is now one of the stanard procedures. Distraction osteogenesis for the axilla can be divided into 2 groups according to its nchorage: the external distractor, such as the RED ystem (Rigid External Distraction system: KLS-Martin P, Tuttlingen, Germany), and the intraoral distracor. In the latter group, many intraoral devices are nvolved, and the cylindrical distractor, such as Zurich ediatric Maxillary Distractor (KLS-Martin LP) is one f the well-known intraoral distractors for maxillary dvancement. Indeed, although these distractors have ome benefit, quite a smaller number of cases using nternal distractors has been reported in comparson with cases treated by the RED system. One of

Maxillary Distraction Osteogenesis in Cleft Lip and Palate Patients with Skeletal Anchorage

Maxillary distraction osteogenesis with the rigid external distraction (RED) system has been used to treat cleft lip and palate (CLP) patients with severe maxillary hypoplasia. We introduce maxillary distraction osteogenesis for CLP patients with skeletal anchorage adapted on a stereolithographic model. Six maxillary deficiency CLP patients treated according to our CLP treatment protocol had undergone maxillary distraction osteogenesis. In all patients, computed tomography (CT) images were recorded preoperatively, and the data were transferred to a workstation. Three-dimensional skeletal structures were reconstructed with CT data sets, and a stereolithographic model was produced. On the stereolithographic model, miniplates were adapted to the surface of maxilla beside aperture piriforms. The operation performed involved a high Le Fort I osteotomy with pterygomaxillary disjunction. Miniplates were fixed to the maxillary segment with three or four screws and used for anchorage of the RED system. Retraction of the maxillary segment was initiated after 1 week. The accuracy of the stereolithographic models was enough to adapt the miniplates so that there was no need to readjust the plates during surgery. Postoperative cephalometric analysis showed that the direction of the retraction was almost parallel to the palatal plane, and dental compensation did not occur. We performed maxillary distraction osteogenesis with skeletal anchorage adapted on the stereolithographic models. Excellent esthetic outcome and skeletal advancement were achieved without dentoalveolar compensations.

Distraction Osteogenesis of the Hypoplastic Midface using a Rigid External Distraction System: The Results of a One- to Six-Year Follow-Up

The purpose of this study was to evaluate the long-term stability of maxillary distraction osteogenesis by use of a rigid external distraction device, based on a 7-year experience. Nine patients with severe cleft maxillary hypoplasia were treated between January of 1998 and August of 2003. Their ages at the time of surgery ranged from 13 to 19 years. Distraction was started at 5 days after a Le Fort I osteotomy at a rate of 1 mm per day for 10 to 15 days. All patients used the Rigid External Distraction I system. After distraction was completed, the device was left in place for another 5 to 6 weeks for bony consolidation. When this was completed, an orthodontic face mask was used with elastic traction for 5 to 6 weeks. The follow-up period ranged from 1 to 6 years. The mean distraction length was 13.6 mm immediately after distraction, 10.8 mm at 6 months after distraction, and 10.4 mm between the 1- and 6-year follow-up period, resulting in relapse rate of 23.0 percent. In three children with mixed dentition, the ANB angle ranged from 7.1 to 8.5 degrees immediately after distraction, from 2.8 to 4.0 degrees 6 months postoperatively, and from 0.4 to 1 degree 5 years postoperatively. Therefore, the growth rate of the distracted maxilla was lower than that of the mandible in those three children. The results suggest that greater anterior overcorrection of the hypoplastic maxilla is needed in the growing child than in adults to compensate for a partial relapse and growth deficit.