Mandibular Body Osteotomy Research Articles

Esthetic management of extraction sites delayed to immediate loading protocols

will continue to undergo modifications and change in an effort to improve the quality of patient care and outcome. This program will present newer treatment approaches and technical modifications, as well as the clinical and research results substantiating the efficacy of these surgical methods. The following modifications will be discussed: 1. Genioplasty A. Porous block HA and HTR augmentations B. Tenon and mortise osseous genioplasty 2. Anterior mandibular subapical osteotomy 3. Mandibular body osteotomy A. Anterior B. Posterior 4. Mandibular ramus sagittal split modifications A. Ramus and inferior border osteotomy B. Rigid fixation 5. Maxillary osteotomy modification A. Maxillary step osteotomy and rigid fixation B. Porous block HA grafting 6. Double jaw surgery A. Selective alteration of the occlusal plane B. Surgical sequencing of the maxilla and mandible C. Model surgery modifications 7. Simultaneous orthognathic surgery and rhinoplasty A. Surgical sequencing B. Rhinoplasty techniques Implementation of these techniques by the experienced, skilled surgeon, coupled with accurate diagnosis and treatment planning, should provide optimal functional and esthetic outcomes for our patients.

Mandibular Lengthening by Distraction Osteogenesis: Role of Periosteum and Endosteum

Objective: To study the role of the periosteum and endosteum in new bone formation by distraction osteogenesis.Materials and Methods: Twenty four rabbits were divided into 3 groups of perieosteum destruction (group P), endosteum destruction (group E), and a control group (group C). After right mandibular body osteotomy followed by distractor placement, the buccal periosteum in the segment between the second and third screws was removed by scalpel in group P. In group E, the endosteum was scraped out from both bone ends between the second and third screws. In group C both periosteum and endosteum were preserved during the surgical operation. After a latency period of 3 days, bone lengthening was started at a rate of I mm per day for 10 days, after which the newly formed bone was allowed to consolidate for 6 weeks with the device serving as an external fixator Radiographs were taken at the following time intervals: 2 weeks, 4 weeks, and 6 weeks after completion of distraction and 6 months after consolidation. The animals were sacrificed 6 weeks after completion of distraction and 6 months after consolidation for the gross macroscopic, histological, and radiological examinations and stability measurement of the distracted segment.Results: New bone was generated in all animal groups. The buccal cortex was incompletely formed in groups P and E but was completely formed and indistinguishable in the control group after 6 months. Histologically, the newly formed bone in the control group had a more mature appearance and better organised bone spicules than in groups P and E. In addition the remodelling process occurred more rapidly in the control group. However, quantitative analysis of the newly formed bone by densitometry revealed no statistically significant differences at each time interval among the 3 groups except for a decline in density in the control group after 6 months due to the bone remodelling process. The stability of the regenerated bone of the lengthened segment was best in the control group, with groups P and E showing marked changes in the length of the distracted distance.Conclusion: Although groups P and E exhibited slower new bone maturation, the amount of newly formed bone was equal in all groups. It could be stated that the periosteum and endosteum are probably not indispensable or particularly important for adequate callus formation. This may be due to the rich blood supply of the craniofacial skeleton. However the instability of the segment caused by the slow maturation and remodelling of the newly formed bone in groups P and E should be noted, and a longer consolidation period is recommended to avoid instability of the regenerated segment in such cases.

顎関節症を伴った下顎後退症に対しＰｒｏｇｒｅｓｓｉｖｅ ｃｏｎｄｙｌａｒ ｒｅｓｏｒｐｔｉｏｎの発現を制御すべく骨延長術を行った１例

Progressive condylar resorption (PCR) has been identified as a major problems in the outcome of orthognathic surgery. In order to prevent postoperative PCR, a patient with severe retromandible underwent mandibular lengthening using distraction osteogenesis with intraoral devices. An occlusal splint was simultaneously used during the distraction and consolidation period for the management.The patient was a 27-year-old female. Mandibular body osteotomy was performed in the angle region. The vector of distraction was parallel to the occlusal plane. The latency period was 7 days. The distraction rate was 0.8mm/day (0.4mm twice daily) for 18 days and the mandible was lengthened approximately 14mm in total. After 30 days of stabilization, the intraoral devices were removed. Enough osteogenesis was confirmed, and Le fort I type osteotomy and genioplasty were performed. Post-operative PCR has not manifested so far. Clinical and radiographic examination revealed no marked changes in the occlusion and profile at 14 months after distraction.

Effect of electrical stimulation on mandibular distraction osteogenesis

This study was designed to examine whether the use of electrical stimulation during mandibular lengthening accelerates new bone formation.Twenty adult female rabbits weighing between 2800 g and 3200 g underwent left mandibular body osteotomy. After a 3 day latency period, an external fixation device was activated at a rate of 0.7 mm per day for 10 days. Direct current electrical stimulation of 10 μA was applied to 10 rabbit mandibles. Two of the screws were used as electrodes during the distraction phase. The other 10 rabbits (control group) were not stimulated. The device was then stabilized for periods of 10, 20, 30 and 60 days in both groups. The distraction segment was evaluated radiographically by assessing the proportion of bone mineral density using a dichroma scan. The amount of new bone formation was studied histologically with an image analyzer to evaluate the bone formation in the distraction gap.Histological examination showed that the new bone formation 10 and 20 days after distraction was greater in the electrical stimulation group than in the control group. Ten and 20 days after distraction, image analysis and analysis of bone mineral density in areas of newly formed bone indicated that there was a greater amount of new bone formation in the stimulation group than in the control group. The radiographic evaluation, however, did not demonstrate significantly different images between the stimulation group and the control group. Thirty and 60 days after distraction, no difference in the amount of new bone formation was noted in either the experimental or the control groups. These results indicate that electrical stimulation during gradual distraction promotes new bone formation in the early retention period in a rabbit model.

Condylar changes after contralateral mandibular osteotomy in the rabbit

Following orthognathic surgery undesirable changes in the temporomandibular joints (TMJs) are noted sometimes. Altered stress on the condyle and surrounding tissue frequently causes morphological changes in the TMJ. The purpose of the present study was to assess these morphologic changes in a rabbit following mandibular osteotomy and the resulting mandibular body rotation. Adult male Japanese white rabbits (3 kg, 12–16 weeks old) were applied in this study. An experimental mandibular osteotomy was performed on the right side of the body of the mandible. The surgery includes vertical mandibular body osteotomy 5 mm in width after masseter muscle reflection. Then the anterior and posterior osseous segments were fixed with wire at previously made holes. As a result, the condylar medio-lateral width on the contralateral (left) side was significantly larger than that of the ipsilateral side 2 weeks postoperatively (p<0;0.05). There were significant differences in the angle between the right and the left condylar heads 4 weeks postoperatively (p<0.05). The present experimental study demonstrated morphological changes in the contralateral TMJ caused by unilateral mandibular osteotomy. Postoperative morphological changes implied that there is a process of biological adaptation in the rabbit TMJ.

Fixation of mandibular body osteotomies using biodegradable amorphous self-reinforced (70L:30DL) polylactide or metal lag screws: an experimental study in sheep

Mandibular body osteotomies were fixed in nine sheep using new totally amorphous (70L:30DL), self-reinforced, polylactide (SR-PLA) lag screws and in nine sheep using standard stainless steel lag screws. No intermaxillary fixation was used. During follow-up, radiological, histological and microradiological studies were undertaken at 3, 6, 12 and 24 weeks. In both groups, all osteotomies consolidated at similar rates and no adverse reaction to the screws was seen. However, displacements of the fixed osteotomy fragments were common in both groups during the first 3 weeks. The biocompatibility of SR-PLA during the follow-up period was found to be good. Only initial signs of biodegradation were seen. The results of this study indicate that (70L:30DL) SR-PLA has potential for use as a fixation screw material in oral and maxillofacial surgery, and that further studies using this material are justified.

大阪歯科大学口腔外科学第２講座における１１年間の顎矯正手術の臨床統計的観察

Orthognathic surgery was performed on 362 patients from 1987 to 1997 at the Second Department of Oral and Maxillofacial Surgery, Osaka Dental University.The results were as follows: 1. The male-female ratio was 1: 2.4.2. The mean age was 22.4 years old.3. The diagnosis of mandibular prognathism was made for most of the patients (89.2%).4. Sagittal splitting ramus osteotomy (SSRO) was performed on 274 cases (75.7%).5. The mean time of operation for SSRO was 3hr. 7 min±57min, and for mandibular body osteotomy was 3hr. 15min±60.7min.6. The mean blood loss during operation for SSRO was 275.8±221.4ml and for mandibular body osteotomy was 171.8±147.5ml.7. Paresthesia of the lip and mental area was observed in 404 sides after opration. 80.7% of patients treated for SSRO recovered within a year.8. TMJ were examined in 202 cases for 1 year after SSRO. The symptom of TMJ was recognized in 5 cases.

Mandibular osteotomy fixed with biodegradable plates and screws: an animal study

The objective of the study was to evaluate the use of a totally biodegradable fixation device in the fixation of mandibular osteotomy in sheep. Mandibular unilateral body osteotomies were fixed with biodegradable self-reinforced poly-L-lactide (SR-PLLA) multi-layer plates and screws in nine sheep. The unoperated sides acted as control. The follow-up times were 6, 12 and 24 weeks, after which radiological, mechanical and histological studies were carried out. An analysis of the implanted material was also carried out. The results showed that the SR-PLLA plates and screws were strong enough to fix the osteotomy and that the osteotomies healed mainly with callus formation. Therefore we conclude that SR-PLLA multi-layer plates and screws can be used together successfully in the fixation of mandibular osteotomies without maxillomandibular fixation. However, before they can be used in humans, the size of the plate and screws should be decreased.

Comparison of absorbable self-reinforced multilayer poly-1-lactide and metallic plates for the fixation of mandibular body osteotomies: An experimental study in sheep

Eighteen unfavorable transverse osteotomies were created in the mandibular body of sheep. Nine were fixed with self-reinforced poly-1-lactide and nine with metallic dynamic compression plates. Both plates were fixed with similar titanium screws. The follow-up times for radiographic, histologic, and microradiographic studies were 6, 12, and 24 weeks. With both methods, bony union with callus formation was accomplished by 6 weeks in all but one osteotomy in the metallic fixation group. There were no signs of plate failure.

The Application and Problems of the Mandibular Body Osteotomy

The mandibular body osteotomy operation has become unpopular recently with the development of the mandibular ramus osteotomy. However, there were several cases which seemed to be an indication of this operation.In this paper, a successful surgical-orthodontic case with the mandibular body osteotomy was reported and its associated problems were discussed.A twenty year and five month old man showed mandibular prognathism with anterior open bite due to a large and clockwise rotated mandibular body. The body osteotomy was performed in the space of the first molar extraction. The mandibular arch width was adjusted in pre-surgical orthodontic treatment by the lingual arch appliance. It took two years and three months for the total active treatment and one year for retention. The treatment was finished successfully and followed up for eight months after retention.Through this case, we reconfirmed the usefulness of the body osteotomy in the case of mandibular prognathism with the poor molar condition. By careful maintenance of the excision space, prevention of injurying adjacent teeth and the neurovascular bundle and also comprehensive periodontal care after surgery, we had a stable result with the mandibular body osteotomy.

Stability following superior repositioning of the maxilla by LeFort I osteotomy

Cephalornetric data from 61 patients who had undergone superior repositioning of the maxilla via LeFort I osteotomy by means of the downfracture technique were analyzed to evaluate stability of skeletal and dental landmarks at various time intervals up to 1 year. None of these patients had concurrent mandibular ramus or body osteotomy except genioplasty and all had at least 2 mm intrusion at the maxillary incisor or molar. In approximately 20% of the patients, there was 2 mm (critical value) or more postsurgical movement of skeletal or dental landmarks. During the first 6 weeks postoperatively, the maxilla showed a strong tendency to move farther upward in the patients in whom it was not stable. The posterior maxilla was vertically stable in 90% of the patients, the anterior maxilla in 80%. Horizontally, skeletal landmarks were stable in 80%, but when changes occurred, there was a tendency for the anterior maxilla to move back when it had been advanced. After the first 6 weeks, the posterior maxilla was stable vertically in all patients, but in 20% anterior maxillary landmarks moved downward, opposite to the direction of movement during fixation. In 11 of the 15 patients who demonstrated vertical changes postsurgery, the movement from fixation release to 1 year follow-up was opposite and approximately equal to the initial change, so that the net movement after 1 year was less than 2 mm. Only 6.5% (four patients) demonstrated 2 mm or greater net vertical movement for any of the variables studied 1 year after surgical treatment. There was no indication that the amount of presurgical orthodontic movement of incisors, the presence of multiple segments at surgery, the age of the patient, the presence or absence of genioplasty, or the presence or absence of suspension wires was a risk factor for instability.

Treatment of Class II deep bite by orthodontic and surgical means

Conventional orthodontic correction of the Class II deep-bite deformity with a decreased lower anterior facial height tendency can be mechanically difficult, inefficient and, in many instances, impossible. Orthodontic treatment alone of either adults or adolescents with such deformities frequently can neither increase lower anterior facial height sufficiently to achieve ideal facial proportions nor achieve long-term occlusal stability. Despite the need for surgical intervention to achieve satisfactory occlusal and esthetic results, many patients with such deformities are still being treated in clinical practice by traditional orthodontic procedures, with less than ideal esthetic and/or occlusal results. The challenge to achieve efficient and stable treatment of this deformity has been met by the use of various surgical techniques in combination with orthodontic treatment. This combined surgical-orthodontic approach can provide increased treatment efficiency, long-term stability, and optimal esthetic results. The proper sequencing and correct selection of orthodontic mechanotherapy are essential to ensure the desired results. This article purposes to detail basic problems involved in diagnosis and treatment planning for the combined surgical-orthodontic approach to patients exhibiting Class II deep bite and decreased lower facial height. Orthodontic and surgical treatment objectives are explained, and representative case reports are presented and discussed to illustrate this method of treatment. Extraction patterns, control of the transverse dimension, arch wire selection, auxiliary wires, elastics, and extraoral appliance use are described. Surgically, the dentofacial disharmony associated with this deformity may defy treatment by surgical advancement of the mandible only. Genioplasty, Le Fort I osteotomy, symphyseal osteotomy, anterior or total mandibular subapical osteotomy, body osteotomy, submental lipectomy, and rhinoplasty are adjunctive procedures that are described and may be used in concert with mandibular advancement surgery.

An idea on mandibular body osteotomy in case of prognathism

An idea on mandibular body osteotomy in case of prognathism

Surgical correction of bimaxillary protrusion and mandibular retrusion

A 16-year-old boy with known emotional and psychologic problems also had a severe maxillary protrusion and a mandibular retrusion. The malocclusion was accentuated as a result of wearing a Milwaukee type of back brace with chin rest for 2 years. The orthodontist thought that a satisfactory result could not be achieved by orthodontic treatment. By means of a maxillary anterior reduction osteotomy and a mandibular body osteotomy with iliac bone graft, an esthetic and functional result was achieved. The patient's emotional outlook improved, and his relationship with his friends and with members of the opposite sex was enhanced.