Nomogram prediction of vulnerable periodontal condition before orthodontic treatment in the anterior teeth of Chinese patients with skeletal Class III malocclusion.

OBJECTIVE: To establish and verify models predictive of thin periodontal phenotype and alveolar fenestration/dehiscence in the anterior teeth of patients with skeletal Class III malocclusion. MATERIAL AND METHODS: Retrospective data of 669 anterior teeth (305 in maxillae and 364 in mandibles) from 80 patients with skeletal Class III malocclusion before augmented corticotomy were collected. Distribution of thin periodontal phenotype and alveolar fenestration and dehiscence were evaluated and their associations with potential influencing factors were explored using univariate and multivariate analyses. The predictive models were visualized as nomograms, the accuracy of which was tested by receiver operating curve analyses. RESULTS: Thin phenotype was associated with Mazza bleeding index, sex, tooth type, probing depth and width of keratinized gingiva (WKG). Labial dehiscence was associated with age, jaw, labial bone thickness, mandibular plane angle, sagittal root position (SRP), sex, tooth type, and WKG. Labial fenestration was associated with sex, tooth type, SRP, and periodontal phenotype. The areas under the curves of nomogram prediction models for periodontal phenotype, alveolar dehiscence, and alveolar fenestration were 0.84, 0.81, and 0.73, respectively. CONCLUSIONS: Female sex, lateral incisor, and limited WKG may be risk factors for thin periodontal phenotype. Age, canine, male sex, mandible, thin labial bone thickness, and root positioned against the labial plate may be risk factors for labial dehiscence; and female sex, thick phenotype, root positioned against the labial plate, lateral incisor, and canine may be risk factors for labial fenestration. The predictive performance of the models was acceptable.

Prevalence of and risk factors for alveolar fenestration and dehiscence in the anterior teeth of Chinese patients with skeletal Class III malocclusion.

INTRODUCTION: This study investigated the prevalence of and risk factors for alveolar fenestration and dehiscence in the anterior teeth of Chinese patients with skeletal Class III malocclusion. METHODS: This study included clinical and radiographic examinations and intraoperative observations of 460 anterior teeth from 54 patients who underwent corticotomy and periodontal regenerative surgery before orthodontic treatment. Fenestration and dehiscence were detected and recorded during open-flap surgery. Univariate and multivariate analyses were performed to assess relationships between fenestration and dehiscence and age, sex, history of previous orthodontic treatment, mandibular plane angle, dentition, tooth position, sagittal root position, periodontal biotype, gingival recession, width of keratinized gingiva, and width of the basal bone. RESULTS: The prevalence of buccal alveolar bone defects was 16.1% (fenestration) and 20.7% (dehiscence) at the tooth level. Multivariate logistic regressions showed that fenestration was significantly associated with tooth position (canine vs central incisor, odds ratio [OR] = 3.324; P = 0.006; lateral incisor vs central incisor, OR = 5.588; P  <0.001), and sagittal root position (buccally positioned vs centrally positioned, OR = 5.865; P = 0.025). Dehiscence was significantly associated with dentition (mandible vs maxilla, OR = 11.685; P  <0.001), tooth position (canine vs central incisor, OR = 3.863; P = 0.007), age (OR = 1.227; P = 0.010), sex (male vs female, OR = 5.530; P = 0.026), and history of orthodontic treatment (yes vs no, OR = 4.773; P = 0.028). CONCLUSIONS: Buccally positioned teeth in the osseous housing, lateral incisors, and canines were more likely to exhibit alveolar fenestration. Mandibular teeth and canines, patients who were older, were male, and had a history of orthodontic treatment, were more likely to exhibit alveolar dehiscence.

[Three-dimensional measurement and facial symmetry analysis for the craniofacial structure of people in North China with normal occlusion].

OBJECTIVE: To investigate the internal regularities and symmetry of craniofacial structures from adults with normal occlusion in North China. METHODS: The study consisted of 60 volunteers who were examined with spiral 3D computed tomography (CT). The axial images of craniofacial structure were reconstructed into 3D models and analyzed by using Proplan 1.2 software to measure the internal regularities and symmetry of craniofacial structures. RESULTS: All the linear measurement's value of the males were bigger than those of the females (P<0.05). There were no significant differences in the ratio measurements between the males and the females(P>0.05). Facial asymmetry was less than 10% in all the images. CONCLUSION: CT is an effective method for three-dimensional analyses of craniofacial structure and symmetry. There are certain and harmonious regularities in normal 3D craniofacial structures. The 3D craniofacial structure database of people with normal occlusion can provide standards and references for diagnosis and treatment planning of craniofacial deformities.

[Effect of segmental Le Fort I osteotomy and bilateral sagittal split ramus osteotomy on the condyle position in skeletal class III malocclusion patients].

OBJECTIVE: To investigate the effect of segmental Le Fort I osteotomy and bilateral sagittal split ramus osteotomy (BSSRO) on the condyle position in skeletal class III malocclusion patients. METHODS: In this retrospective study, 19 patients with skeletal class III malocclusion who met the inclusion criteria were enrolled. All the patients underwent the segmental Le Fort I osteotomy and BSSRO. Cone beam computed tomography (CBCT) scans were performed in the following phases: T1: within one week before the surgeries; T2: within one week post-surgery;T3:three months post-surgery; T4: 6 to 14 months post-surgery. The posterior spaces, anterior spaces and the superior spaces of the bilateral temporomandibular joints were measured according to the Kamelchuk method respectively. The fossa ratios of the condyle and the distribution of the condyle positions related to the glenoid fossa (anterior, concentric and posterior position)were calculated. The results were analyzed statistically. RESULTS: The posterior space, the anterior space and the superior space of bilateral temporomandibular joints in T2 phase[right: (2.78±1.23) mm, (2.47±0.89) mm, (3.07±0.85) mm; left: (2.93±0.83) mm, (2.69±1.14) mm, (3.44±1.16) mm] showed significantly larger spaces than those in T1 phase [right: (1.81±0.95) mm, (1.65±0.55) mm, (2.13±0.52) mm; left: (2.12± 1.05) mm, (1.79±0.59) mm, (2.15±0.93) mm],in T3 phase [right: (2.08±1.25) mm, (1.79±0.68) mm, (1.80±0.76) mm; left: (2.05±0.75) mm, (1.99±0.94) mm, (2.14±0.71) mm] and in T4 phase [right: (1.94±0.77) mm, (1.81±0.69) mm, (2.05±0.69) mm; left: (1.89±0.69) mm, (1.80±0.61) mm, (2.19±0.75) mm], P<0.05. No significant differences were observed among T1,T3 and T4 phases in the terms of the joint spaces of both sides(P>0.05).The fossa ratio and the condyle position related to the glenoid fossa had no significant difference in all the four phases (P>0.05).The results suggested that the condyle moved downward in T2 phase and changed to the original pre-surgery position in T3 phase, then keot stable in T4 phase. CONCLUSION: Segmental Le Fort I osteotomy and BSSRO caused significant and transient changes of the condyle position in skeletal class III malocclusion patients. However, the condyle tended to move back to the original pre-surgery position and might keep stable.

[Three-dimensional evaluation of condylar morphology remodeling after orthognathic surgery in mandibular retrognathism by cone-beam computed tomography].

OBJECTIVE: To evaluate the effect of orthognathic surgery on condylar morphology changes by comparing three-dimension surface reconstructions of condyles using cone-beam computed tomography (CBCT) data. METHODS: In the study, 18 patients with mandible retrognathism deformities were included and CBCT data of 36 temporomandibular joints were collected before surgery and 12 months after surgery. Condyles were reconstructed and superimposed pre- and post-operatively to compare the changes of condylar surfaces. One-sample t test and χ2 test were performed for the analysis of three-dimension metric measurement and condylar head remodeling signs. P<0.05 was considered significant. RESULTS: The root-mean-square (RMS) of condylar surface changes before and after the surgery was (0.37±0.11) mm, which was significant statistically (P<0.05). The distribution of condylar remodeling signs showed significant difference (P<0.05). Bone resorption occurred predominantly in the posterior area of condylar head and bone formation occurred mainly in the anterior area. CONCLUSION: Three-dimension superimposition method based on CBCT data showed that condylar morphology had undergone remodeling after mandibular advancement.

[Comparison of three surgical techniques for controlling nasal width after Le Fort I osteotomy].

OBJECTIVE: To identify nasal width changes occurring after Le Fort I osteotomy and to compare prospectively the effect of three surgical techniques for controlling postoperative nasal width. METHODS: In the study, 79 patients (22 male and 57 female, mean age 23.2 ± 3.4 years), who received Le Fort I osteotomy at Peking University Hospital of Stomatology from 2011 to 2014, were randomly divided into three groups. Group 1 was treated with traditional intraoral alar base cinch suture (ABCS); Group 2 with extraoral ABCS, and Group 3 with traditional ABCS plus an extra intraoral suture at points G.lat. All the patients had taken 3D photos using 3dMD camera before operation, and 3, and 6 months after operation. The nasal widths, which were indicated as distances between Sbal-Sbal, G.lat-G.lat and Al-Al, were measured by two examiners in the 3D photos three times with a time-interval of one week. SPSS 13.0 was used to do the statistic analysis. RESULTS: At the end of the postoperative 6 months, the nasal widths lessened as compared with the postoperative 3 months. No significant differences were found between the three groups 6 months after the operation. The degree of the postoperative nasal width widening had positive correlation with that of the intraoperative nasal width widening, and had negative correlation with the initial nasal width and the amount of post-suture narrowing. CONCLUSION: There is no difference between three suturing techniques for controlling nasal width widening after Le Fort I osteotomy. The postoperative nasal width-widening can't be totally avoided, and the alteration might last at least 6 months after the operation. For patients with narrow nasal width and need to move maxilla forward, more overcorrection of ABCS is needed to control the postoperative nasal base widening.

[Subjective outcomes after modified maxillomandibular advancement for the treatment of obstructive sleep apnea syndrome].

OBJECTIVE: To evaluate subjective outcomes after modified maxillomandibular advancement(MMMA) for the treatment of obstructive sleep apnea-hypopnea syndrome (OSAHS). METHODS: In the study, 15 patients underwent MMMA for the treatment of OSAHS and received presurgical and postsurgical polysomnography. A questionnaire was done pre- and postoperatively. The questionnaire included the Epworth sleepiness scale (ESS), snoring, witnessed apneas, CPAP use, and satisfaction of the treatment. RESULTS: The preoperative polysomnography results of the patients were as follows: apnea-hypopnea index, 40.5±12.8 per hour; lowest oxygen saturation, 73.0%±7.4%; the postoperative polysomnography results were as follows: apnea-hypopnea index, 6.5±3.5 per hour; lowest oxygen saturation, 90.8%±2.1%.Preoperatively, the mean ESS score of the patients was 17.6. Postoperatively, the mean ESS score decreased to 4.3. CPAP was in nine patients before surgery and postoperatively no patients continued. All the patients were satisfied with the treatment and wanted to recommend the treatment to other patients with OSAHS. CONCLUSION: The review demonstrated that AHI,LSAT,EDS,snoring and witnessed apneas were improved greatly after MMMA technique for the treatment of OSAHS.

[Clinical application of transport distraction osteogenesis arthroplasty in the treatment of temporomandibular joint bony ankylosis].

OBJECTIVE: To explore the clinical application of transport distraction osteogenesis arthroplasty (TDOAP) in the treatment of temporomandibular joint (TMJ) bony ankylosis. METHODS: From December 1999 to December 2011, a total of 73 patients (89 sides of TMJ) underwent TDOAP were included. There were 39 males and 34 females with a mean age of 19.6 years (range: 3 - 60). Among them, 27 patients were recurrence cases and 30 cases were accompanied with micrognathia and obstructive sleep apnea-hypopnea syndrome (OSAHS). The mean preoperative degree of mouth opening was 6.6 mm (range: 1 - 20). After a release of ankylosis, a transport disc was performed and fixed to ramus with a distractor. Distraction began at Days 4 - 8 postoperation. The distraction rhythm and rate were 0.25 mm four times daily. Distraction stopped when planning distance was achieved. And a distractor was maintained in place for 3-6 months after completion of distraction and then removed. Active postoperative training of mouth opening was implemented. RESULTS: The mean distance of distraction was 15.3 mm (range: 12 - 23). The range of mouth opening of 65 patients increased to normal and bone formation in gaps were perfect. The mean follow-up period was 44.8 months (range: 18 - 102). Eight cases were recurrent. And 1/37 over 15 years old and 7/36 under 15 years old had recurrence. CONCLUSIONS: TDOAP is an effective treatment for TMJ ankylosis. A pediatric patient, especially recurrent, should be operated after adolescence to decrease recurrence. Micrognathia and OSAHS should be also considered during the treatment of ankylosis.

Effect of augmented corticotomy-assisted presurgical orthodontic treatment on alveolar bone fenestration and dehiscence in skeletal class III patients.

Background/purpose: Alveolar bone fenestration and dehiscence is common in untreated patients and potentially harmful. This study was to evaluate the effect of augmented corticotomy (AC) on the prevention and treatment of alveolar bone defects in skeletal class III high-angle patients during presurgical orthodontic treatment (POT). Materials and methods: Fifty patients with skeletal Class III high-angle malocclusion were enrolled, of whom 25 patients (G1) underwent traditional POT and 25 patients (G2) received AC during POT. The alveolar bone fenestration and dehiscence around the upper and lower anterior teeth were measured by CBCT. The incidence and transition of fenestration and dehiscence in the two groups were compared by the chisquare and Mann‒Whitney rank-sum tests. Results: Before treatment (T0), the incidence of fenestration and dehiscence around the anterior teeth of all patients was 39.24% and 24.10%, respectively. After POT (T1), the incidence of fenestration in G1 and G2 was 49.83% and 25.86%, respectively, and the incidence of dehiscence in G1 and G2 was 58.08% and 32.07%, respectively. For teeth without fenestration and dehiscence at T0, more anterior teeth in G1 exhibited fenestration and dehiscence at T1 than in G2. For teeth with fenestration and dehiscence at T0, most transitions in G1 were maintained or worsened, but "cure" cases were observed in G2. After POT, the cure rates of fenestration and dehiscence in G2 were 80.95% and 91.07%, respectively. Conclusion: During the POT of skeletal Class III high-angle patients, augmented corticotomy can significantly treat and prevent alveolar bone fenestration and dehiscence around anterior teeth.

[Clinical study on modified maxillomandibular advancement for the treatment of obstructive sleep apnea syndrome].

OBJECTIVE: To evaluate the modified maxillomandibular advancement (MMMA) technique for the treatment of obstructive sleep apnea syndrome (OSAS) in yellow race of convex profile. METHODS: Eight patients underwent MMMA for the treatment of OSAHS. All the patients underwent pre-surgical and postsurgical polysomnography, cephalometric analysis and objective results assessment. RESULTS: The preoperative polysomnography results of the patients were as follows: apnea-hypopnea index, (40.1±16.1) per hour; lowest oxygen saturation, (72.4±7.2)%. The postoperative polysomnography results were as follows: apnea-hypopnea index, (5.4±3.8) per hour; lowest oxygen saturation, (90.6±2.1)%. The mean preoperative SNA was (80.9± 1.7)°, and the mean postoperative SNA was (82.9±1.5)°. The mean preoperative SNB was (72.5±2.6)°, and the mean postoperative SNB was (81.5±1.7)°. The mean preoperative PAS was (5.3 ±1.6) mm, and the mean postoperative PAS was (10.8 ±1.8) mm. CONCLUSION: The preliminary review has demonstrated that the modified MMA technique for the treatment of OSAS is highly effective in the treatment of severe OSAS without the significant facial profile change commonly associated with the traditional MMA technique. With the introduction of this modified MMA technique for the treatment of OSAS, skeletal surgery may be less perceived as an unattractive treatment modality due to the markedly reduced anticipated facial changes after surgery.

Periodontal soft- and hard-tissue changes after augmented corticotomy in Chinese adult patients with skeletal Angle Class III malocclusion: A non-randomized controlled trial.

BACKGROUND: To investigate soft- and hard-tissue changes after augmented corticotomy in Chinese adult patients with skeletal Angle Class III malocclusion. METHODS: This non-randomized controlled trial included 357 anterior teeth from 30 Chinese adult patients with skeletal Angle Class III malocclusion for whom the proposed treatment was augmented corticotomy. Jaws receiving surgery were allocated to a test group (S, surgical group, n = 47) and jaws not receiving surgery were allocated to a control group (NS, non-surgical group, n = 13). Changes in the periodontal biotype, width of the keratinized gingiva (WKG), and labial and lingual horizontal bone thicknesses (BTs) were compared 6 months after surgery by univariate and multivariate analyses. RESULTS: After adjustment for confounding variables, average gains of 0.473 mm in the WKG and 0.649 mm in the labial BT were found in the S group relative to the NS group (P <0.05). The odds of transition from a thin periodontal biotype to a thick biotype in the S group were about 230 times those in the NS group, and the odds of the reverse biotype transition in the NS group were about 83 times those in the S group (P <0.05). CONCLUSIONS: Within the limitations of the present study, augmented corticotomy is a promising approach to improve insufficient periodontal soft and hard tissues in Chinese adult patients with skeletal Angle Class III malocclusion.

[Surgical correction of severe maxillary hypoplasia secondary to the repairment of congenital cleft palate].

OBJECTIVE: To evaluate the surgical corrective results of severe maxillary hypoplasia in cleft lip and palate patients using distraction osteogenesis (DO) and orthognathic surgical procedures. METHODS: High step Le Fort I osteotomy was performed in 17 cases. Le Fort I segments were moved forward with DO (11 cases with internal distraction device, 6 cases with rigid external distraction device). Maxillary anterior segmental osteotomy was performed in another 6 cases, the maxillary anterior segments were advanced with DO (3 cases with internal distraction device, 3 cases with rigid external distraction device). Bilateral sagittal split ramus osteotomy and genioplasty were performed in 13 cases. Before surgery, when DO was completed and 12 months after DO was completed, oriented lateral cephalograms at rest position of each patient were taken, the position of point A on horizontal direction and SNA angle were collected and analyzed. RESULTS: All patients had successfully accomplished maxillary segment DO. Point A had been moved forward 7.9 mm on average in horizontal direction when DO was completed, and maintained 7.1 mm when DO was completed 12 months. The average of SNA angle was 70.8 degree pre-surgery, but 81.6 degree when DO was completed, and maintained 80.9 degree at 12 months after DO was completed. CONCLUSION: The severe maxillary hypoplasia in cleft lip and palate patients can be successfully corrected with DO and orthognathic surgical procedures. The long-term skeletal stability was satisfactory.

Triangeliphthalides A-D: bioactive phthalide trimers with new skeletons from Angelica sinensis and their production mechanism.

Triangeliphthalides A-D (1-4), four novel phthalide trimers with two new linkage styles, were isolated from Angelica sinensis, together with two related phthalide dimers (5-6). Their structures including absolute configurations were determined. The production mechanism of phthalide polymers was proposed, and their bioactivities were also evaluated.

[Evaluation of Yunnan Baiyao capsules for reducing postoperative swelling after orthognathic surgery].

OBJECTIVE: To evaluate the effects of Yunnan Baiyao capsules on facial swelling and anti-inflammatory response after orthognathic surgery. METHODS: 87 patients scheduled for Le Fort I osteotomy and bilateral sagittal split ramus osteotomy (BSSRO) and genioplasty were randomly divided into 2 groups: experiment roup (n = 43) given with Yunnan Baiyao capsules orally 4 days before operation once daily and then via nasal feeding tube after operation once a day for 5 days, and placebo group given with placebo capsules. Antibiotic was routinely given to both groups. Serum levels of C-reactive protein (CRP), interleukin 6 (IL-6), and IL-1 were quantified on postoperative days 1, 2, 3, and 5. Degrees of facial swelling were evaluated on postoperative days 3, 5, and 7. RESULTS: Peak CRP and cytokines levels were reached on the first postoperative day in both groups, and the the variables decreased. The serum concentrations of CRP and IL-6 in the Yunan Baiyao group were lower than those in the control group. The CRP levels on the postoperative day 2, 3 and 5 of the experiment group were all significantly lower than those of the placebo group, and the IL-6 level on the second postoperative day of the experiment group was significantly lower than that of the placebo group. CONCLUSION: Perioperative administration of Yunnan Baiyao capsules can reduce the magnitude of inflammatory response and facial swelling after orthognathic surgery. Yunnan Baiyao capsule has efficacy of anti-inflammatory response.

Temporal and spatial expression of osteoprotegerin and receptor activator of nuclear factor -kappaB ligand during mandibular distraction in rats.

PURPOSE: The expression profiles of osteoprotegerin and receptor activator of nuclear factor-kappaB ligand (RANKL) were investigated in the distraction region to reveal bone remodelling characters during mandibular distraction osteogenesis. MATERIAL AND METHODS: Osteotomies were performed and external distractors were used on the mandibles of 42 adult male SD rats. After a 5-day latency period, the distractors were activated at a rate of 0.4mm/day for 6 days, followed by a 4-week consolidation period. Radiographs were taken, and specimens were harvested at the end of the latency period, when distraction was completed, and at the end of 1, 2, 3 and 4 weeks of the consolidation period. Tartrate-resistant acid phosphatase staining was used to detect activated osteoclasts. Temporospatial expression of osteoprotegerin and RANKL was investigated by using immunohistochemistry, in situ hybridization and reverse transcription polymerase chain reaction. Semi-quantitative analysis was used to characterize osteoprotegerin (OPG). RANKL and RANKL/OPG ratio. RESULTS: In all time points, osteoprotegerin and RANKL were co-localized in bone marrow lining cells, osteoblasts and newly embedded osteocytes. Osteoprotegerin mRNA expression increased to a peak when distraction was completed and maintained this level until the end of week 2 of the consolidation period. RANKL mRNA expression increased steadily until the end of week 1 of the consolidation period and maintained a peak level until the end of week 3, with a slight decrease at the end of week 2. The RANKL/OPG ratio increased continuously and reached its highest level at the end of weeks 3 and 4 of the consolidation period. Tartrate-resistant acid phosphatase staining positive osteoclasts were mainly detected at weeks 2, 3 and 4 of the consolidation period in bone marrow cavities and bone surfaces. CONCLUSIONS: The temporospatial expression patterns of osteoprotegerin and RANKL suggest that the osteoblast lineage cell network orchestrates bone remodelling during distraction osteogenesis and most activated bone resorption takes place during weeks 3 and 4 of the consolidation phase.

[Clinical study of simultaneous correction of unilateral temporomandibular joint ankylosis and mandibular micrognathia with internal distraction osteogenesis].

OBJECTIVE: To observe the clinical results in correction of unilateral temporomandibular joint(TMJ) ankylosis accompanying with mandibular micrognathia using internal distraction osteogenesis simultaneously. METHODS: Seven adult patients of unilateral TMJ ankylosis accompanying with mandibular micrognathia (13 sides of mandibular body) were treated simultaneously with internal distraction osteogenesis. Obstructive sleep apnea and hypopnea syndrome(OSAHS) was diagnosed in all patients preoperatively. The treatment includes distraction osteogenesis of mandibular body and transport distraction osteogenesis for TMJ arthroplasty at the same time. Distraction was started on the 6th to 8th day after operation. The distraction rhythm and rate was one mm a day operated in 4 separate times. The patients underwent active mouth opening postoperatively. Distractors were kept in place for 3-5 months after completion of distraction and then removed. Mean distraction distance of the 13 sides of mandibular body was 17.1mm(ranged from 14 to 20 mm) and that of the 7 sides of TMJ was 16.4mm(ranged from 15 to 20mm). RESULTS: After treatment, micrognathia of the 7 patients was corrected. OSAHS was cured in 6 patients. The mean range of mouth opening was increased from 8.1 mm to 39.9 mm and bone formation in the distraction gaps was observed. The mean following-up period was 34.3 months(ranged from 18 to 51 months). No recurrence of TMJ ankylosis or micrognathia was occurred. CONCLUSION: Unilateral TMJ ankylosis accompanying with micrognathia and OSAHS can be treated effectively by distraction osteogenesis simultaneously. The operation is simple with low risk. The course of treatment can be simplified and the operation times can be reduced.

[Effects of maxillary distraction osteogenesis on the velopharyngeal configuration of cleft palate patients].

OBJECTIVE: To study the effects of internal maxillary distraction osteogenesis(DO) on the velopharyngeal configuration of cleft palate patients. METHODS: Ten patients with severe maxillary hypoplasia secondary to cleft lip and palate patients (7 males and 3 females, average age 20.1 years old) had undertaken high step LeFort I osteotomy, and internal maxillary distraction devices were applied to advance the maxilla. Before surgery, when DO was completed and 6 months after DO was completed, oriented lateral cephalograms at rest position of each patient were taken, and 6 measure indexes of velopharyngeal configuration were collected and analyzed. RESULTS: All patients had successfully accomplished maxillary DO and the maxilla had been averagely advanced 11.3 mm. PNS-PhW, C-PhW, UL and ANS-PNS-T had all significantly increased, and UD had significantly decreased when DO was completed and 6 months after DO was completed as compared with pre-surgery. No significant linear correlation was found between maxilla advancement distance and velopharyngeal configuration changes. CONCLUSION: Correction of maxillary hypoplasia secondary to cleft palate surgery by using internal maxillary DO can increase the velopharyngeal cavity depth, and may impair velopharyngeal competence, but the compensatory changes of velopharyngeal soft tissue can alleviate this impairment to certain extent.

Effects of mandibular distraction osteogenesis on the inferior alveolar nerve: an experimental study in monkeys.

A series of experimental studies were performed in monkeys to study the effect of mandibular distraction osteogenesis on the inferior alveolar nerve at different times before and after distraction. A mandible osteotomy was performed and distraction was carried out unilaterally in 10 young rhesus monkeys and bilaterally in six. The intact nerves on the contralateral side of the 10 monkeys were used for the control. Care was taken to avoid destroying the integrity of the inferior alveolar nerve during the surgical procedure. After a 5-day latency period, the distraction device was activated at a rate of 0.5 mm twice each day for 15 days. Sensory nerve action potential testing was applied before and 1 day after the operation, at completion of distraction, and at 2, 4, 6, 9, and 12 weeks of fixation. Necropsy was performed at the completion of distraction and 2, 4, 6, and 12 weeks of fixation. The mental nerves were taken, sectioned, and stained with lead citrate and uranyl acetate, and examined with a transmission electron microscope. The inferior alveolar nerves in the distraction gap were obtained, and paraffin slides were made and stained with hematoxylin and eosin, Luxol fast blue, and Bodian methods. The authors found that immediately after the mandible osteotomy, most nerves showed signs of slight acute injury; the latency was increased by 5.553 percent, and the amplitude was decreased to 1808 microV. This might be caused by the surgical procedure or by compressions produced by swelling tissues around the nerves. When distraction was completed, the latency was prolonged for an average of 22.18 percent, and the amplitude average had attenuated to 28.54 percent (804 microV) of the preoperative value on the distracted side. Most nerve fibers exhibited signs of degeneration, such as myelin disruption, swelling of cell organs greatly increased in axoplasm, axon tearing, and myelin fragments engulfed by macrophages. These were nerve reactions to the tensions produced by mandible lengthening. As time elapsed, the nerve's action potential recovered gradually because of its repairing ability, the latency shortened, amplitude increased, Schwann cells proliferated and formed new myelin sheaths, and the tearing axons reconnected. After 12 weeks of consolidation, there was still a latency of 12.384 percent prolongation because of the prolonged conduction distance, and the average amplitude was restored to 2786 microV, the approximate preoperative value. The nerve seemed to be repaired completely; its myelin thickness, axon diameter, and ultrastructure were all similar to those of the control. It was concluded that mandibular distraction osteogenesis can produce some degree of harmful effects on the function and structure of inferior alveolar nerves, but it is reversible and relatively slight. Along with the regeneration of the nerve's myelin and axon, the nerve function can gradually rehabilitate to a normal level.

Distraction osteogenesis in correction of micrognathia accompanying obstructive sleep apnea syndrome.

To evaluate the effect of distraction osteogenesis in correction of micrognathia accompanying obstructive sleep apnea syndrome, a total of 28 patients with different severities of obstructive sleep apnea syndrome underwent mandibular distraction osteogenesis. A total of 51 distraction devices were placed for bilateral distraction in 23 patients and for unilateral distraction in five patients. The mean age of patients was 21.2 years (range, 3 to 60 years). Eleven patients had micrognathia accompanying obstructive sleep apnea syndrome secondary to bilateral temporomandibular joint ankylosis, and 10 patients had micrognathia accompanying obstructive sleep apnea syndrome secondary to unilateral temporomandibular joint ankylosis. Three patients had developmental micrognathia accompanying obstructive sleep apnea syndrome. The other four patients had micrognathia and concomitant obstructive sleep apnea syndrome induced by trauma, infection, or tumor resection. Each patient had been evaluated preoperatively and postoperatively with cephalometry and polysomnography. Mandible advancement ranged from 9 to 30 mm (average, 20.4 mm) and was successfully achieved after distraction. Fine new bone formed in the distraction gap when the distraction devices were removed 3 to 4 months after distraction was completed. No infection or other complications occurred in any patients. Complete curative effects were achieved in nine severe, six moderate, and eight mild obstructive sleep apnea syndrome patients after distraction, and the other five patients had been improved to the mild level. After distraction was completed, the posterior airway space was increased on average from 4.6 mm to 12.5 mm and the sella-nasion-point B angle was increased on average from 66 degrees to 75 degrees on cephalometric studies. The polysomnographic examination showed that the apnea hypopnea index was lowered on average from 58.0 to 3.15, and the lowest oxygen saturation was increased on average from 77 percent to 90.3 percent after distraction was completed. The follow-up period was 3 to 61 months (average, 18.1 months). The curative effect was stable and no relapse occurred. Therefore, the authors conclude that mandibular distraction osteogenesis is an effective method for correcting micrognathia accompanying obstructive sleep apnea syndrome. Compared with other current routine surgical procedures, it has many advantages, such as low risk, simple manipulation, high curative rate, low relapse rate, and stable result. It is presently the most effective method for the treatment of this difficult and complicated disorder.

[Clinical application of condylectomy via intraoral approach under computer assisted surgical navigation].

OBJECTIVE: To assess the application of computer assisted surgical navigation in condylectomy via intraoral approach and its clinical results. METHODS: Eight patients aged from 16 to 56 were treated by condylectomy via intraoral approach under computer assisted surgical navigation. There were 6 female and 2 male. The lesions were condyle osteoma in 3 patients, hemimandibular hyperplasia and condylar hyperplasia in 5 patients. Most patients had concomitant LeFortIosteotomy (6 cases), bilateral sagittal split ramus osteotomy (BSSRO) (5 cases),contralateral sagittal split ramus osteotomy (SSRO) (1 cases), genioplasty (4 cases) and mandible contouring (6 cases) to recover the facial symmetry. RESULTS: All patients had good occlusion, oral function and facial symmetry after the operation. The average mouth opening was 38 mm before operation, and 41 mm one month after operation. The temporomandibular joint(TMJ) dysfunction syndrome alleviated or disappeared. The follow-up period was 3-12 months, and results were stable. CONCLUSIONS: Computer assisted surgical navigation can precisely accomplish the condylectomy via intraoral approach.It causes less trauma to the patient than traditional condylectomy, and can better preserve the TMJ structure and function.