Distraction osteogenesis versus bilateral sagittal split osteotomy for advancement of the retrognathic mandible: a review of the literature

Skeletal stability of inter-molar mandibular distraction osteogenesis in growing patients

INTRODUCTION

The aim of this retrospective study was to firstly assess the stability of surgical advancement using inter-molar mandibular distraction osteogenesis (IMDO) and secondly to assess the impact of the surgical intervention on subsequent mandibular growth in patients with residual growth.

METHODS

The sample consisted of 17 (13F and 4M) consecutively treated patients who underwent IMDO and orthodontic treatment. Cephalometric analysis was performed at three time points: T0 prior to distraction; T1 post-distraction immediately prior to surgical removal of the distractors; and T2 following completion of orthodontic treatment when the final lateral cephalogram was taken (0.86-4.37 years after T1). Statistical comparison of lower facial height, mandibular length, growth, condylar position and anterior mandibular rotation was performed.

RESULTS

No association was found between changes in any of the cephalometric measurements and the length of the follow-up interval. The anterior mandibular segment underwent clockwise rotation during distraction and recovered to near its pre-distraction angulation during remodelling. An increase in the lower facial height of 1.88 ± 2.81mm also occurred during distraction (T0-T1) and was maintained during the follow-up period (T1-T2). Post-distraction (T1-T2) growth of lower facial height (p value 0.872) and mandibular length (p value 0.251) showed no association when compared to an untreated control group and an overall reduction in growth was reported.

CONCLUSIONS

IMDO was highly stable within a follow-up period of 2.3 ± 0.9 years; however, growth appears to have been inhibited.

Craniofacial Distraction Osteogenesis

Distraction osteogenesis (DO) of the craniofacial skeleton has become an effective technique for the treatment of both nonsyndromic and syndromic conditions. The advent of craniofacial DO has allowed for earlier intervention in pediatric patients with less complication risk and morbidity compared to traditional techniques. In this review, we will discuss current application and technique for craniofacial DO by anatomical region and explore future applications in craniofacial surgery.

Treatment of severe micrognathia in an adult with distraction osteogenesis: A case report

Key Clinical Message

Distraction osteogenesis (DO) of the mandible is often performed at a young age, and there are few reports after age 30, as in this case. The Hybrid MMF used in this case was useful in that it allowed correction of fine directionality.

Abstract

DO is often performed in young patients with a high capability of osteogenesis. We performed distraction surgery for a 35-year-old man who had severe micrognathia with serious sleep apnea syndrome. Four years postoperatively, suitable occlusion and improvement of apnea were observed.

Rehabilitation of Dentofacial Asymmetry Secondary to Unilateral Temporomandibular Joint Ankylosis with Dual Distraction and Fixed Orthodontics - Stability at Three-year Follow-up

Optimal rehabilitation of asymmetric dentofacial deformity secondary to unilateral temporomandibular joint (TMJ) ankylosis is often a challenge. The purpose of this case series is to present an insight into esthetic, occlusal and functional rehabilitation of two patients with varying degree of asymmetric Class II dentofacial deformities secondary to long-standing unilateral TMJ ankylosis. The patients were treated with one-stage surgical protocol employing simultaneous dual distraction technique along with interpositional arthroplasty. Dual distraction technique entailed the simultaneous use of two distractors which allowed for proper control of proximal condylar segment during the course of distraction and lowering the risk of ankylosis recurrence. Thereafter, comprehensive fixed orthodontic mechanotherapy involving the use of temporary anchorage devices was instituted to align and level the compensated dentition. Post-treatment records showed significant improvements in skeletal disharmony and functional stability with good functional occlusion. At the three-year follow-up, the morphological and functionally acceptable results were reasonably well-maintained, with no signs of relapse. Through the two cases reported here, we would like to highlight that one-stage concurrent arthroplasty and dual distraction technique is a safe, stable, and reliable approach for surgical and functional rehabilitation of an adult asymmetric dentofacial deformity secondary to unilateral TMJ ankylosis. Meticulously executed comprehensive orthodontic manipulations involving use of acrylic bite-blocks, elastic traction, and temporary skeletal anchorage device play a crucial role in enhancing the final occlusal outcomes.

Hybrid Distractor for Continuous Mandibular Distraction Osteogenesis

Distraction osteogenesis (DO) is a reconstruction method for repairing bone deficiencies in the oral and maxillofacial area. Manual DO techniques have shown the functionality of the DO method for bone tissue reconstruction. The DO method can improve treatment conditions, as well as the quality of the reconstructed bone, compared with conventional techniques. Recently, continuous DO devices have been proposed to enable an automatic DO process while using a continuous force for moving the bone segment (BS). Animal studies and clinical trials have shown the successful application of continuous distractors in terms of improving DO factors, including rate and rhythm. The continuous DO technique can shorten the treatment time and enhance the quality of the regenerated tissue. However, the developed continuous distractors are yet to be used in human applications. In this study, by combining motor-driven and hydraulic techniques, a hybrid distractor is proposed. The hybrid distractor is capable of generating a continuous distraction force while controlling the position of the BS in a linear vector, with a high positioning accuracy. Results of modelling and experimental study revealed that the proposed hybrid distractor met all required factors for enabling a continuous DO procedure in humans. The proposed distractor is capable of eliminating the drawbacks of exiting techniques in terms of generating and transferring a controlled distraction force to the BS. The wireless control, as well as the small size of the device, makes this device a suitable solution for use in the reconstruction of bone defects in the maxillofacial area in humans.

Three-dimensional surgical management of a patient with Pruzansky I hemifacial microsomia and severe facial asymmetry: A 4-year follow-up

Treatment of hemifacial microsomia is challenging and often requires multiple interventions to restore function and facial esthetics. In this article, the combined orthodontic-surgical treatment of a young patient exhibiting Pruzansky I hemifacial microsomia is reported. The patient was aged 15 years, but his bone age was determined to be 18 years. His facial asymmetry was severe, with the nose and a retrusive chin deviated to the left side and a canted smile. The presurgical phase was aimed at centering the mandibular midline to the center of the chin through the distal movement of the mandibular left buccal dentition. The surgery was planned with 3-dimensional computer-aided surgical simulation and included a LeFort I and unilateral sagittal split osteotomies combined with a genioplasty. This report illustrates the therapeutic stages and a 4-year follow-up of a unique and complex orthognathic surgical approach, chosen among other alternatives and leading to improved function and appearance and stable results.

Radiographic healing patterns after tooth-borne distraction in canine model

Background

The osteogenesis distraction technique applied to the craniofacial skeleton is an alternative treatment for dentofacial deformities. Despite the advantages of tooth-borne distractors, few studies have evaluated their clinical implementation in sagittal dentoskeletal deformities. This study aimed provide a radiographic assessment of the effect of two different activations of tooth-borne distraction in the lengthening of the mandible in canines.

Material and Methods

Ten male beagle dogs, approximately one year old, were used for this experimental study. Three remained as a control group and seven underwent a mandibular tooth-borne distraction protocol with single daily activation in one hemimandible and two daily activations in the other, during ten days. The consolidation period took 12 weeks. Occlusal radiographs were performed immediately pre- and postoperatively.

Results

After the distraction period, the host bone margins presented very well-defined outlines with regular contours. Concerning the consolidation period, between the second and fourth weeks, all hemimandibles showed small rectangular radiopaque regions with parallel orientation to the distraction axis. At the twelfth week, all hemimandibles presented an entire mineralization of the distraction gap with no axial deviations of the anterior and posterior host bone, nine of which with both margins showing corticalization.

Conclusions

Radiographic analysis showed bone regeneration in order to achieve the original bone architecture, especially in the group of multiple distraction. Tooth-borne distraction allowed successful sagittal lengthening of the mandible in a canine model.

Key words:Orthodontics, osteogenesis, distraction, mandibular advancement, orthodontic appliance design.

A systematic review on the outcome of distraction osteogenesis in TMJ ankylosis

Introduction

TMJ ankylosis (TMJa) management by arthroplasty alone fails to address the deformity and the compromised airway. Distraction osteogenesis (DO) can offer a pragmatic solution to TMJa. The aim of the study was to generate evidence towards the role of DO in TMJa, evaluate its efficiency and develop an algorithm for use of DO in TMJa.

Material and methods

The research question was formulated using the PICOS statement for reporting guidelines in systematic reviews, where the efficiency of DO was evaluated in terms of mouth opening, correction of facial deformity and asymmetry, airway correction, and its long term effects.

Results

1130 articles reported DO as a treatment modality for TMJ ankylosis, of which 32 prospective studies, 16 retrospective and 2 RCTs were included in the study. DO was used for mandibular distraction in 45 studies and for simultaneous maxillamandibular distraction in only five studies. An algorithm for use of DO in TMJa was developed.

Conclusion

Although DO has proven its application in TMJ ankylosis cases, its best use is for correction of obstructive sleep apnoea. Relapse causing loss of posterior ramal height is a concern after transport DO. Prearthroplastic DO appears to best correct mandibular deformity. A maxillomandibular deformity requires simultaneous maxillomandibular distraction. However, a metanalysis is still awaited for effectiveness of DO in TMJ ankylosis.

Three-dimensional evaluation of distal and proximal segment skeletal relapse following isolated mandibular advancement surgery in 100 consecutive patients: A one-year follow-up study

The aim of this study was to perform a three-dimensional evaluation of the skeletal relapse of the proximal and distal mandibular segments following isolated bilateral sagittal split osteotomy advancement surgery. One hundred consecutive patients (mean age 25.8±11.7 years), comprising 65 female patients (mean age 26.4±12.1 years) and 35 male patients (mean age 24.6±11.0 years) requiring mandibular advancement without genioplasty, were enrolled prospectively in the study. Cone beam computed tomography scans were acquired for each patient at three time-points: preoperatively, immediately (1-6 weeks) after surgery, and 1 year after surgery. A validated tool was utilized to assess the surgical movement and relapse. Based on percentage, the majority of the distal and proximal translational and rotational movements relapsed within the range of ≤2mm and ≤2°. The distal segment revealed a significant relapse in a posterior, inferior, and clockwise pitch direction. Both left and right proximal segments showed a significant translational relapse in the medial, posterior, and superior direction. Amongst the rotational parameters, proximal segments relapsed significantly in clockwise pitch, clockwise roll, and counterclockwise yaw direction. Overall, both distal and proximal bone segments showed a clinically acceptable translational and rotational stability. The proximal segments torqued towards their original position with a reduction of flaring.

Biomechanical evaluation of a novel mandibular distraction osteogenesis protocol: an in-vitro validation and the practical use of the method

The aim of this study was to optimize and experimentally validate the certain parameters affecting the operation success of Mandibular Distraction Osteogenesis (MDO). According to FEA results, the displacement of the samples showed 28.5% reduction as only the osteotomy line was separately optimized, and 64.2% less displacement was determined when the osteotomy line and the screw configuration were optimized together. In consistent with the FEA results, the samples showed 62% and 84.5% fewer displacement values, respectively. As a result, the MDO protocol suggested, which is validated by both numerical and experimental studies, offers promising outcomes for operation success.

Evaluation of use of distraction osteogenesis in mandibular retrognathia and its effect on soft and hard tissues and airway

Objectives:

Bone distraction is the process of new bone formation between the surfaces of bone segments gradually separated by incremental traction of soft tissues. These adaptive changes in the soft tissues allow for greater skeletal movements while minimizing the potential relapse. In this study, we are reporting our clinical experience with mandibular distraction used to achieve simultaneous skeletal and soft-tissue correction with distraction osteogenesis (DO).

Methodology:

A total of five patients who reported to the department for the treatment of mandibular deficiencies were selected. Cephalometric studies were done preoperatively and postoperatively for hard tissue assessment. Predefined reference points were used for the clinical evaluation for the evaluation of soft tissues. Results were compared between preoperative and 1^st-, 3^rd-, 6^th-, and 12^th-month postoperatively.

Results:

The clinical observations in our study showed that there is a remarkable improvement in the facial esthetics. Cephalometric analysis has shown lengthening of the mandibular corpus and increase in the height of the vertical ramus. Certain minimal complications have also been noted.

Conclusion:

Despite the few complications, DO has become a popular surgical modality due to its many advantages.

Transverse Changes in Mandible Following Bilateral Sagittal Split Ramus Osteotomy Advancement

Background

BSSRO is the most frequently performed surgical procedure for mandibular advancement. However, the effect of advancement on proximal segment is not clearly understood.

Aim and Objectives

The aim of the study was to evaluate the radiographic transverse changes in mandible following BSSRO advancement and to compare the amount of transverse displacement of the proximal segment with the amount of surgical advancement.

Materials and Methods

Twelve cases of skeletal class II deformity undergoing fixed orthodontic mechanotherapy and requiring mandibular advancement were selected for the study. Pre-operative (T0) PA ceph and OPG were used to measure the linear distances from right to left Co-Go, Go-Me, Go-Go, Co-Co, Rp-Rp and Co-Me points. The cases were operated for BSSRO mandibular advancement. Post-operative (T1) PA ceph and OPG were used to compare the changes in linear measurements.

Result

There were six male and six female patients with an average age of 19.5 years. The average mandibular advancement was 6.5 mm. Post-operative radiographic changes in transverse measurements of Go-Me, Go-Go, Co-Co, Rp-Rp and Co-Me were statistical significant. The changes in Co-Go measurements were statistically not significant. We could not establish any correlation between mandibular advancement and amount of transverse changes.

Conclusion

Significant changes were noticed in transverse dimensions of mandible following BSSRO advancement in both PA ceph and OPG. The transverse changes had no clinical implication during the post-operative follow-up.

Micrognathia with temporomandibular joint ankylosis and obstructive sleep apnea treated with mandibular distraction osteogenesis using skeletal anchorage: a case report

Background

We describe the case of a 16-year-old female patient with micrognathia, temporomandibular joint (TMJ) ankylosis, and obstructive sleep apnea, who was treated with mandibular distraction osteogenesis (DO) combined with sliding genioplasty, using skeletal anchorage.

Case presentation

We first performed interpositional arthroplasty, in which an interposition of fascia temporalis and surrounding fat tissue was inserted into the defect after bilateral condylectomy, increasing the maximum mouth opening from 5.0 to 32.0 mm. Subsequently, orthodontic treatment and advancement of the mandible were carried out by mandibular DO, using miniscrews and miniplates. Finally, sliding genioplasty was performed to bring the tip of the mandible forward. The total amount of mandibular advancement at the menton was 16.0 mm. An improved facial appearance and good occlusion were eventually achieved, and the apnea-hypopnea index decreased from 37.1 to 8.7. There was no obvious bone resorption or pain in the temporomandibular region, limited mouth opening (maximum mouth opening: 33.0 mm), myofascial pain or headache, downward rotation of the mandible, or lateral shift of mandibular position evident at 5 years and 6 months after mandibular DO.

Conclusion

Mandibular DO using skeletal anchorage with intermaxillary elastics is useful for preventing extrusion of the upper and lower anterior teeth, thereby preventing rotation of the mandible. In addition, mandibular DO combined with sliding genioplasty is effective at improving both dentofacial deformities and impaired respiratory function.

Treatment outcomes of archwise distraction osteogenesis in mandibular dentoalveolar retrognathia cases

The aim of this study was to describe the treatment of class II malocclusion by sagittal advancement of the alveolar bone in the symphyseal area using an intraoral archwise distractor device and to determine the effects of this method on the dentoalveolar complex. Fifteen patients (10 female, five male) aged 16-20 years with a class II division 2 malocclusion, characterized by mandibular dentoalveolar retrusion and a prominent chin, underwent archwise alveolar distraction in the anterior mandible. Lateral cephalometric radiographs were obtained before distraction (T0), after 6 weeks of consolidation (T1), and after debonding (T2). Linear and angular skeletal, dental, and soft tissue measurements were performed. Forty-seven parameters were measured for each of the 15 subjects on pre- and postoperative lateral cephalometric radiographs (T0, T1, and T2). The distraction protocol was successful in all patients. Skeletally, the mandible showed a clockwise rotation. B-point moved forward significantly (P<0.05). Overjet decreased significantly (P<0.001). The total profile angle was unaffected, and the improvement in the submental fold was highly significant (P<0.001). The intraoral archwise distraction force that is applied through brackets and archwires is sufficiently effective for alveolar advancement. This procedure is simple and effective in the treatment of specific adult patients with a class II division 2 malocclusion, characterized by a prominent chin and severe mandibular dentoalveolar retrusion.

Orthodontic and surgical management of a patient with severe skeletal Class II deformity and facial asymmetry: A case report with a 5-year follow-up

In this case report, we present the orthodontic and surgical management of an 18-year-old girl who had a severe craniofacial deformity, including maxillary prognathism, vertical maxillary excess (gummy smile), mandibular retrognathism, receding chin, and facial asymmetry caused by unilateral temporomandibular joint ankylosis. For correction of the facial asymmetry, the patient's right mandibular ramus and body were lengthened via distraction osteogenesis after 5 months of preoperative orthodontic therapy. Subsequently, extraction of 4 first premolars, bimaxillary anterior segmental osteotomy, and genioplasty were simultaneously performed in the second-stage operation to correct the skeletal deformities in the sagittal and vertical planes. Postoperative orthodontic treatment completed the final occlusal adjustment. The total active treatment period lasted approximately 30 months. The clinical results show that the patient's facial esthetics were significantly improved with minimal surgical invasion and distress, and a desirable occlusion was achieved. These pleasing results were maintained during the 5-year follow-up.

Bilateral sagittal split mandibular osteotomies for enhanced exposure of the anterior cervical spine in children: technical note

The bilateral sagittal split mandibular osteotomy (BSSMO), a common maxillofacial technique for expanding the oropharynx during treatment of micrognathia, is a rarely employed but useful adjunct to improve surgical access to the ventral cervical spine in children. Specifically, it provides enhanced exposure of the craniocervical junction in the context of midface hypoplasia, and of the subaxial cervical spine in children with severe kyphosis. The authors describe their technique for BSSMO and evaluate long-term outcomes in patients. The pediatric neurosurgical database at a single center was queried to identify children who underwent BSSMO as an adjunct to cervical spine surgery over a 22-year study period (1993-2015). The authors retrospectively reviewed clinical and radiographic data in all patients. The authors identified 5 children (mean age 5.3 ± 3.1 years, range 2.1-10.0 years) who underwent BSSMO during cervical spine surgery. The mean clinical follow-up was 3.0 ± 1.9 years. In 4 children, BSSMO was used to increase the size of the oropharynx and facilitate transoral resection of the odontoid and anterior decompression of the craniocervical junction. In 1 patient with subaxial kyphosis and chin-on-chest deformity, BSSMO was used to elevate the chin, improve anterior exposure of the subaxial cervical spine, and facilitate cervical corpectomy. Careful attention to neurovascular structures, including the inferior alveolar nerve, lingual nerve, and mental branch of the inferior alveolar artery, as well as minimizing tongue manipulation and compression, are critical to complication avoidance. The BSSMO is a rarely used but extremely versatile technique that significantly enhances anterior exposure of the craniocervical junction and subaxial cervical spine in children in whom adequate visualization of critical structures is not otherwise possible.

A case of severe mandibular retrognathism with bilateral condylar deformities treated with Le Fort I osteotomy and two advancement genioplasty procedures

We report a case involving a young female patient with severe mandibular retrognathism accompanied by mandibular condylar deformity that was effectively treated with Le Fort I osteotomy and two genioplasty procedures. At 9 years and 9 months of age, she was diagnosed with Angle Class III malocclusion, a skeletal Class II jaw relationship, an anterior crossbite, congenital absence of some teeth, and a left-sided cleft lip and palate. Although the anterior crossbite and narrow maxillary arch were corrected by interceptive orthodontic treatment, severe mandibular hypogrowth resulted in unexpectedly severe mandibular retrognathism after growth completion. Moreover, bilateral condylar deformities were observed, and we suspected progressive condylar resorption (PCR). There was a high risk of further condylar resorption with mandibular advancement surgery; therefore, Le Fort I osteotomy with two genioplasty procedures was performed to achieve counterclockwise rotation of the mandible and avoid ingravescence of the condylar deformities. The total duration of active treatment was 42 months. The maxilla was impacted by 7.0 mm and 5.0 mm in the incisor and molar regions, respectively, while the pogonion was advanced by 18.0 mm. This significantly resolved both skeletal disharmony and malocclusion. Furthermore, the hyoid bone was advanced, the pharyngeal airway space was increased, and the morphology of the mandibular condyle was maintained. At the 30-month follow-up examination, the patient exhibited a satisfactory facial profile. The findings from our case suggest that severe mandibular retrognathism with condylar deformities can be effectively treated without surgical mandibular advancement, thus decreasing the risk of PCR.

Skeletal Stability after Large Mandibular Advancement (> 10 mm) with Bilateral Sagittal Split Osteotomy and Skeletal Elastic Intermaxillary Fixation

OBJECTIVES

The aim of the present study was to assess the skeletal stability after large mandibular advancement (> 10 mm) with bilateral sagittal split osteotomy and skeletal elastic intermaxillary fixation and to correlate the skeletal stability with the vertical facial type.

MATERIAL AND METHODS

A total of 33 consecutive patients underwent bimaxillary surgery to correct skeletal Class II malocclusion with a mandibular advancement (> 10 mm) measured at B-point and postoperative skeletal elastic intermaxillary fixation for 16 weeks. Skeletal stability was evaluated using lateral cephalometric radiographs obtained preoperative (T1), 8 weeks postoperatively (T2), and 18 month postoperatively (T3). B-point and pogonion (Pog) was used to measure the skeletal relapse and the mandibular plane angle (MP-angle) was used to determine the vertical facial type.

RESULTS

The mean advancement from T1 to T2 were 11.6 mm and 13.5 mm at B-point and Pog, respectively. The mean skeletal relapse from T2 to T3 was -1.3 mm at B-point and -1.6 mm at Pog. The nineteen patients characterized as long facial types, showed the highest amount of skeletal relapse (-1.5 mm at B-point and -1.9 mm at Pog).

CONCLUSIONS

The present study showed a limited amount of skeletal relapse in large mandibular advancement (> 10 mm) with bilateral sagittal split osteotomy and skeletal elastic intermaxillary fixation. Bilateral sagittal split osteotomy in combination with skeletal intermaxillary fixation can therefore be an alternative to distraction osteogenesis in large mandibular advancements.

Changes in posterior airway space and mandibular plane hyoid distance following mandibular advancement DO

Aim:

To study the changes in posterior airway space (PAS) and mandibular plane hyoid (MPH) distance following mandibular advancement using distraction osteogenesis (DO).

Subjects and Methods:

A prospective study was conducted at a tertiary care dental center from May 2009 to May 2014. Twenty-five consecutively operated patients of mandibular hypoplasia who underwent mandibular advancement using distraction with at least 12 months follow-up were included in the study. The study group comprised 15 males and 10 females with an age range of 15–30 years (mean 22 years). Presurgical and postsurgical cephalometric changes were compared to determine the changes in PAS and MPH distance.

Results:

The mean distraction achieved was 14.50 mm. The mean preoperative MPH was 18.88 mm and mean postoperative MPH was 13.16 mm with a resultant reduction by 32%. Mean preoperative PAS was 6.48 mm and mean postoperative PAS was 11.08 mm. Mean increase in PAS was 75%. Mean preoperative and postoperative SNB values were 75.4° and 79.52°, respectively. The results were statistically analyzed using paired “Student's t-test.”

Conclusion:

From this study, it is concluded that statistically significant changes were achieved in MPH and SNB. Although change in PAS was statistically insignificant, it may have clinical applications, especially in the field of Phase II surgical management of obstructive sleep apnea.

Skeletal stability after bilateral sagittal split osteotomy or distraction osteogenesis of the mandible: a randomized clinical trial

A randomized clinical trial was carried out to evaluate postoperative stability after mandibular advancements in non-syndromal class II patients with a bilateral sagittal split osteotomy (BSSO) or distraction osteogenesis (DO). In total 32 patients could be included in the BSSO group and 34 patients in the DO group. The BSSO was converted to a unilateral procedure for one patient, and two patients in the BSSO group were lost during follow-up. A total 63 patients could be evaluated, 29 in the BSSO group and 34 in the DO group. Advancement was comparable in the two groups (mean 7.2mm). The mean follow-up period was 23.8 months (range 11-50 months). Lateral cephalograms were hand-traced. Horizontal relapse was measured in Y-B (mm) and SNB (°). For DO this was -0.324 mm and -0.250°, and for BSSO this was -0.448 mm and -0.259°, respectively (both not significant; NS). Vertical relapse measured in X-B was -0.074 mm for DO and -0.034 mm for BSSO (NS). The magnitude of advancement, a high mandibular plane angle, age and gender were not identified as independent risk factors for relapse. In conclusion, a BSSO and DO gave both similar stable results in advancements of the mandible up to 10mm.

The modifications of the sagittal ramus split osteotomy: a literature review

BACKGROUND

In 1953, the sagittal ramus split osteotomy was introduced by Obwegeser. For many years, and in some countries still, this technique has defined the term oral and maxillofacial surgery.

METHODS

The basic design of the sagittal ramus split surgical procedure evolved very quickly. The original operation technique by Obwegeser was shortly after improved by Dal Pont's modification. The second major improvement of the basic technique was added by Hunsuck in 1967. Since then, the technical and biological procedure has been well defined. Resolution of the problems many surgeons encountered has, however, taken longer. Some of these problems, such as the unfavorable split or the damage of the inferior alveolar nerve, have not been satisfactorily resolved.

RESULTS

Further modifications, with or without the application of new instruments, have been introduced by Epker and Wolford, whose modification was recently elaborated by Böckmann. The addition of a fourth osteotomy at the inferior mandibular border in an in vitro experiment led to a significant reduction of the torque forces required for the mandibular split.

CONCLUSIONS

The literature was reviewed, and the last modifications of the successful traditional splitting procedure are presented narrowly. It indicates the better the split is preformatted by osteotomies, the less torque force is needed while splitting, giving more controle, a better predictability of the lingual fracture and maybe less neurosensory disturbances of the inferior alveolar nerve.

Influence of osteotomy procedure and surgical experience on early complications after orthognathic surgery in the mandible

INTRODUCTION

This study evaluated the influence of osteotomy procedure and surgical experience on early complication rates following orthognathic surgery in the mandible.

MATERIALS AND METHODS

In a retrospective study, patients who underwent a mandibular osteotomy (Obwegeser-Dal Pont (ODP) and Hunsuk-Epker (HE)) were included. Incidence of "bad splits", "bleeding episodes", "delayed wound healing", "failed osteosynthesis" and "nerve lesions" at 2 months post-operatively were recorded. Surgical experience was classified as: beginner (<10), intermediate (10-40) and expert (>40). Complications were correlated to the surgical approach and the experience level of the surgeon.

RESULTS

400 patients were included. 200 underwent a bimaxillary approach. 186 patients were operated using the ODP technique, 214 according to HE. Multivariate analysis confirmed significantly more unwanted fractures and bleeding events for ODP when compared to HE (p = 0.28, p = 0.003). Experienced surgeons had more osteosynthesis failures (0.047) and significantly more nerve lesions than the other groups (p = 0.01).

DISCUSSION

The HE osteotomy showed a more reliable fracture mechanism with less relevant bleeding episodes. Differences between the surgeons of varying training status were marginal with exception of a higher rate of osteosynthesis failure and temporary hypoesthesia in the experienced group.

Effects of intermittent parathyroid hormone treatment on new bone formation during distraction osteogenesis in the rat mandible

OBJECTIVE

The effect of intermittent parathyroid hormone (PTH[1-34]) treatment on bone regeneration in a rat model of mandibular distraction was evaluated using microcomputed tomography.

STUDY DESIGN

After a 5-day latency period, mandibles of 18 rats were distracted at 0.2 mm/12 hours for 10 days, and rats in the PTH and control groups received subcutaneous injections of PTH(1-34) at a dosage of 60 μg/kg body weight or a vehicle only, respectively, 3 times a week. The animals were humanely killed after 10 days of distraction and after 1 week and 3 weeks of consolidation.

RESULTS

In reconstructed 3-dimensional images of the distracted mandible, mean bone volumes of the desired region of interest in the PTH group were significantly larger than those in the control group at all time points.

CONCLUSIONS

Intermittent PTH(1-34) treatment enhances new bone formation during mandibular distraction in a rat model, and it may be effective for shortening the consolidation period.

BMP4 localization and PCNA expression during distraction osteogenesis of the porcine mandible

This study characterized sequential molecular and cellular events in the porcine mandibular distraction osteogenesis (DO) wound. Nineteen Yucatan minipigs were divided into three treatment groups: Group A, unilateral mandibular distraction with 0 day latency, 1mm/day rate for 12 days, 24 days fixation (n=16); Group B, acute lengthening 12 mm (n=2); Group C, sham control (n=1). Group A was further divided by death date: mid-DO (n=5), end-DO (n=4), mid-fixation (n=5) and end-fixation (n=2). Groups B and C were killed on postoperative day 36, corresponding to end-fixation. Specimens were stained for proliferating cell nuclear antigen (PCNA) and bone morphogenetic protein-4 (BMP4). Cellular proliferation (PCNA) was assessed quantitatively and BMP4 staining was assessed on a semi-quantitative scale. Progenitor cell proliferation was greatest during mid-DO and decreased from end-DO through end-fixation. Proliferation in the acute lengthening group was elevated relative to sham control and comparable to end-DO. BMP4 staining intensity (localized to the periosteal cambium layer) was greatest during mid- and end-DO, decreased at mid-fixation and was undetectable at end-fixation. Progenitor cell proliferation and BMP4 expression are greatest during mid-DO and decrease progressively thereafter. At the time of death of the acute lengthening group, only increased cell proliferation was demonstrated.

Long term stability of mandibular advancement procedures: bilateral sagittal split osteotomy versus distraction osteogenesis

The aim of this study was to compare the postoperative stability of the mandible after a bilateral lengthening procedure, either by bilateral sagittal split osteotomy (BSSO) or distraction osteogenesis (DO). All patients who underwent mandibular advancement surgery between March 2001 and June 2004 were evaluated. There were 17 patients in the BSSO group and 18 patients in the DO group. The decision to use intra-oral distraction or BSSO for mandibular advancement primarily depended on the choice of the patient and their parents. In both groups, standardized cephalometric radiographs were taken preoperatively, postoperatively (BSSO group) or directly post-distraction (DO group) and during the last study measurement in May 2008. Cephalometric analysis was performed using the following measurements: sella/nasion-mandibular point B and sella/nasion-mandibular plane. Point B was used to estimate relapse. This study showed no significant difference in relapse between the BSSO and the DO groups measured 46-95 months after advancement of the mandible (P>.05). It can be concluded from this study that there is no postoperative difference in the stability between BSSO and DO after mandibular advancement after 4 years.

Treatment of maxillomandibular deformities with internal curvilinear distraction

Internal curvilinear distraction is successful in achieving clinically significant distraction with stable occlusion in our patient population of infants, adolescents, and adults. When distracting the mandible, the curve of the distractor, the position of the distractor, and the osteotomy site are accountable for the final result. The curved distractor can mimic part of the natural logarithmic growth of the maxillomandibular complex. In addition, the result is predictable based on this design and the internal nature of the distractor, which can be left in place longer than other distractor types. Distraction can be combined with orthognathic surgery in certain cases resulting in increased benefit. This new procedure is called distraction orthognathics.

Dental or skeletal relapse after sagittal split osteotomy advancement surgery? Long-term follow-up

PURPOSE

To evaluate the short- and long-term stability of mandibular advancement surgery with sagittal split osteotomy (SSO), and to investigate when relapse occurs and identify variables contributing to relapse.

PATIENTS AND METHODS

Thirty-six patients with Class II anomalies were included; the mean age at surgery was 33.0 years. All underwent SSO surgery and clinical and radiologic follow-up at 8 weeks, 1 year, and 13 years. Model analysis, cephalometric analysis, and clinical examinations were performed at each control.

RESULTS

Mean overjet relapse from 8 weeks to 13 years was 2.3 mm (range, 0 to 7.0 mm). Between 8 weeks and 1 year, mean overjet relapse was 0.6 mm (range, -1.0 to 4.0 mm), and it was 1.7 mm (range, -1.0 to 6.0 mm) between 1 year and 13 years. Overjet relapse greater than 4 mm was found in 13.9% of the patients. Mean overjet 1 year after surgery was 2.6 mm and was significantly increased compared with 8 weeks (P = .006). Mean overjet 13 years after surgery was 4.3 mm and was significantly increased compared with 1 year (P < .001). Inferior incisor line to nasion-B-point was 29.0° at 8 weeks after surgery and 25.4° at 13 years (P = .001). Insignificant changes in the other cephalometric variables were found at follow-up.

CONCLUSION

SSO advancement surgery is a relatively stable technique over time. Mean overjet relapse was found to be 2.3 mm after 13 years, following a continuous pattern over time. The cephalometric variables showed insignificant changes during follow-up, indicating that relapses are mainly of dental and not skeletal origin.

Current practice of distraction osteogenesis for craniofacial anomalies in Europe: a web based survey

Aim of the study was to get more insight into the opinion of European surgeons and orthodontists on the use of distraction osteogenesis (DO) for patients with different diagnoses and treatment protocols. A web based survey was set up, showing records of four patients with different conditions: hemifacial microsomia (case 1), bilateral mandibular deficiency (case 2), cleft lip and palate (case 3) and Crouzon syndrome (case 4). Respondents from 181 Eurocleft centres were asked to fill out a questionnaire for each patient. Most of the respondents considered case 1 (80%), case 3 (81%) and case 4 (86%) suitable for DO, while only 31% were considering case 2 for DO. There was lack of consensus among the respondents about many aspects of DO. Out of six different treatment parameters, an acceptable degree of agreement was only seen in two: a latency period of 3-7 days and a distraction rate of 1mm per day. Furthermore, there was noticeable disagreement on the ideal age for treatment, surgical technique, distraction device, and retention period. Our results showed that there is a wide variety in treatment approaches for craniofacial anomalies in Europe. There is disagreement on essential steps in the distraction procedures.