[Associations between indoor volatile organic compounds and nocturnal heart rate variability of young female adults: A panel study].

OBJECTIVE: To investigate the association between short-term exposure to indoor total volatile organic compounds (TVOC) and nocturnal heart rate variability (HRV) among young female adults. METHODS: This panel study recruited 50 young females from one university in Beijing, China from December 2021 to April 2022. All the participants underwent two sequential visits. During each visit, real time indoor TVOC concentration was monitored using an indoor air quality detector. The real time levels of indoor temperature, relative humidity, noise, carbon dioxide and fine particulate matter were monitored using a temperature and humidity meter, a noise meter, a carbon dioxide meter and a particulate counter, respectively. HRV parameters were measured using a 12-lead Holter. Mixed-effects models were used to evaluate the association between the TVOC and HRV parameters and establish the exposure-response relationships, and two-pollutant models were applied to examine the robustness of the results. RESULTS: The mean age of the 50 female subjects was (22.5±2.3) years, and the mean body mass index was (20.4±1.9) kg/m2. During this study, the median (interquartile range) of indoor TVOC concentrations was 0.069 (0.046) mg/m3, the median (interquartile range) of indoor temperature, relative humidity, carbon dioxide concentration, noise level and fine particulate matter concentration were 24.3 (2.7) ℃, 38.5% (15.0%), 0.1% (0.1%), 52.7 (5.8) dB(A) and 10.3 (21.5) µg/m3, respectively. Short-term exposure to indoor TVOC was associated with significant changes in time-domain and frequency-domain HRV parameters, and the exposure metric for most HRV parameters with the most significant changes was 1 h-moving average. Along with a 0.01 mg/m3 increment in 1 h-moving average concentration of indoor TVOC, this study observed decreases of 1.89% (95%CI: -2.28%, -1.50%) in standard deviation of all normal to normal intervals (SDNN), 1.92% (95%CI: -2.32%, -1.51%) in standard deviation of average normal to normal intervals (SDANN), 0.64% (95%CI: -1.13%, -0.14%) in percentage of adjacent NN intervals differing by more than 50 ms (pNN50), 3.52% (95%CI: -4.30%, -2.74%) in total power (TP), 5.01% (95%CI: -6.21%, -3.79%) in very low frequency (VLF) power, and 4.36% (95%CI: -5.16%, -3.55%) in low frequency (LF) power. The exposure-response curves showed that indoor TVOC was negatively correlated with SDNN, SDANN, TP, and VLF when the concentration exceeded 0.1 mg/m3. The two-pollutant models indicated that the results were generally robust after controlling indoor noise and fine particulate matter. CONCLUSION: Short-term exposure to indoor TVOC was associated with significant negative changes in nocturnal HRV of young women. This study provides an important scientific basis for relevant prevention and control measures.

Adeno-associated virus-mediated expression of myostatin propeptide improves the growth of skeletal muscle and attenuates hyperglycemia in db/db mice.

Inhibition of myostatin, a negative growth modulator for muscle, can functionally enhance muscle mass and improve glucose and fat metabolism in myostatin propeptide (MPRO) transgenic mice. This study was to investigate whether myostatin inhibition by adeno-associated virus (AAV)-mediated gene delivery of MPRO could improve muscle mass and achieve therapeutic effects on glucose regulation and lipid metabolism in the db/db mice and the mechanisms involved in that process. Eight-week-old male db/db mice were administered saline, AAV-GFP and AAV-MPRO/Fc vectors and monitored random blood glucose levels and body weight for 36 weeks. Body weight gain was not different during follow-up among the groups, but AAV-MPRO/Fc vectors resulted high level of MPRO in the blood companied by an increase in skeletal muscle mass and muscle hypertrophy. In addition, AAV-MPRO/Fc-treated db/db mice showed significantly lower blood glucose and insulin levels and significantly increased glucose tolerance and insulin sensitivity compared with the control groups (P<0.05). Moreover, these mice exhibited lower triglyceride (TG) and free fatty acid (FFA) content in the skeletal muscle, although no difference was observed in fat pad weights and serum TG and FFA levels. Finally, AAV-MPRO/Fc-treated mice had enhanced insulin signaling in the skeletal muscle. These data suggest that AAV-mediated MPRO therapy may provide an important clue for potential clinical applications to prevent type II diabetes, and these studies confirm that MPRO is a therapeutic target for type II diabetes.

[Development and application of digital technology in craniomaxillofacial surgery].

The treatment of craniomaxillofacial (CMF) defects and deformities is highly challenging due to the complex anatomical structures, significant individual variations and high demands for personalized reconstruction. In recent decades, the integration of cutting-edge technologies from fields such as computer science, mechanical engineering, and material science into medicine has greatly facilitated the transformation of CMF surgery from traditional, experience-based approaches to digitalized and intelligent methods. This review thoroughly analyzes the development and application areas of digital technology in CMF surgery including virtual surgical planning and facial prediction, three-dimensional printing, computer-assisted navigation and robotic surgery, virtual and mixed reality, as well as big data and artificial intelligence technologies. The aim is to offer comprehensive and in-depth reference information for the clinical practice in digital CMF surgery.

Association between hepatitis C infection during pregnancy with maternal and neonatal outcomes: a systematic review and meta-analysis.

OBJECTIVE: Studies of possible implications of the maternal hepatitis C virus (HCV) infection in terms of intrauterine fetal growth restriction (IUGR), preterm birth (PTB), low birth weight (LBW) infants, premature rupture of membranes (PROM), maternal and neonatal mortality are limited and inconclusive. Our study aims to assess the impact of HCV on maternal and neonatal outcomes. MATERIALS AND METHODS: Systematic literature search was done in PubMed, Scopus, and Google Scholar, Cochrane Library, and TRIP databases for all observational studies published from 1st January 1950 to 15th October 2022. The pooled odds ratio (OR) or risk ratio (RR) with a 95% confidence interval (CI) was estimated. STATA version 12.0 software was used for analysis. Heterogeneity among the included articles was evaluated by sensitivity, meta-regression, and publication bias analyses. RESULTS: A total of 14 studies involving 12,451 HCV (+) and 56,42,910 HCV (-) pregnant women were included in our meta-analysis. Maternal HCV during pregnancy was significantly associated with the increased risk of PTB (OR=1.66, 95% CI: 1.59-1.74), IUGR (OR=2.09, 95% CI: 2.04-2.14) and LBW (OR=1.96, 95% CI: 1.63-2.36) as compared to healthy pregnant women. Subgroup analysis based on ethnicity also suggested a strong association between maternal HCV infection and a higher risk of PTB in Asian and Caucasian populations. Maternal (RR=3.44, 95% CI: 1.85-6.41), as well as neonatal (RR=1.54, 95% CI: 1.18-2.02) mortality was significantly higher in HCV (+) cases. CONCLUSIONS: Mothers with HCV infection had a markedly increased probability of PTB and/or IUGR and/or LBW. In clinical practice, standard care of treatment and proper monitoring are needed for the pregnant population with HCV infection. Our findings may provide useful information for selecting appropriate therapy methods for HCV-positive pregnant women.

[Expert consensus on the treatment of oral and maxillofacial space infections].

Oral and maxillofacial space infections (OMSI) are common diseases of the facial region involving fascial spaces. Recently, OMSI shows trends of multi drug-resistance, severe symptoms, and increased mortality. OMSI treatment principles need to be updated to improve the cure rate. Based on the clinical experiences of Chinese experts and with the incorporation of international counterparts' expertise, the principles of preoperative checklist, interpretation of examination results, empirical medication principles, surgical treatment principles, postoperative drainage principles, prevention strategies of wisdom teeth pericoronitis-related OMSI, blood glucose management, physiotherapy principles, Ludwig's angina treatment and perioperative care were systematically summarized and an expert consensus on the diagnosis and treatment of OMSI was reached. The consensus aims to provide criteria for the diagnosis and treatment of OMSI in China so as to improve the level of OMSI treatment.

Effect of cryopreservation on the immunogenicity of osteoblasts.

BACKGROUND: Tissue-engineered bone is the most perspective and ideal prosthesis for bone defects. But the immunological reaction in allograft is unavoidable. To date there has not been an analysis of the effect of cryopreservation on osteoblast immunogenicity. In this study, we investigated the effects of fluid nitrogen cryopreservation on immunogenicity of osteoblasts. MATERIALS AND METHODS: The osteoblasts were harvested and cultured from the tibial periosteum of New Zealand rabbits, examined by alkaline phosphatase (ALP) and alizarin red S stains, and then cryopreserved for 90 days. Cryopreserved (group C) and fresh (group F) osteoblasts were labeled by the immunofluorescene technique, and the MHC class I antigen was examined by flow cytometric (FC) assay. At the same time, by establishing an osteoblast and lymphocyte mixed culture model (OLMC), the immunogenicity of osteoblasts was examined. RESULTS: The positive rate of MHC class I antigen in group F was 46.36%+/-3.15%, while in group C it was 26.43%+/-2.57%. The MHC I antigen expression was significantly stronger in fresh cells than that in cryopreserved ones (P<.01). In the OLMC assay, the stimulation index (SI) of group F was 3.55+/-0.78, which was significantly higher than that of group C (1.83+/-0.41; P<.01). CONCLUSIONS: The FC assay and OLMC experiments showed that osteoblasts surface antigen expression and allostimulatory function were greatly reduced by cryopreservation. Fluid nitrogen cryopreservation is an ideal method to reduce the immunogenicity in allograft.

Pathologic features of initial adenomas as predictors for metachronous adenomas of the rectum.

BACKGROUND: Colorectal cancer is the third most common cancer in the world, arising mostly from pre-existing adenomatous polyps (adenomas) of the large bowel. Patients with colorectal adenomas are at increased risk of colorectal cancer because of a high recurrence rate for adenomas. We followed a cohort of 1490 patients with rectal adenomas to determine whether recurrence might be related to pathologic characteristics of the initial adenomas. METHODS: The patients were identified in Haining County, China, from 1977 through 1978 by means of examination with a 15-cm rigid sigmoidoscope. They were followed by endoscopic examination at years 2, 4, 6, 11, and 16 after their initial polypectomy. New adenomas in the rectum were identified in 280 patients in these follow-up examinations. RESULTS: Statistically significant twofold to threefold elevated risks of metachronous (recurrent) adenomas were observed for patients who had more than two initial adenomas or whose most advanced initial adenoma was more than 1.0 cm in size, was of villous/tubulovillous type, or showed moderate to severe dysplasia. Much stronger associations were observed for advanced metachronous neoplasms, which are defined as cancers or adenomas with severe dysplasia, with multivariate adjusted relative risks (95% confidence interval) of 4.2 (1.8-9.9) for a large initial adenoma (>1.0 cm), 8.1 (4.2-15.6) for villous/tubulovillous architecture, and 14.4 (5.0-41.3) for severe dysplasia. In particular, patients who had a large (>1.0 cm) adenoma with severe dysplasia at baseline had a relative risk of 37 (7.8-174.7) of developing advanced metachronous neoplasms compared with patients who had small adenoma(s) with mild dysplasia. CONCLUSIONS: The risk of metachronous adenomas is closely related to the pathology of initial adenomas, thus allowing identification of a high-risk group of adenoma patients for close surveillance after their initial polypectomy.

[Clinical application and accuracy of the genioplasty surgical templates system for osseous genioplasty].

Objective: To develop and validate a new genioplasty templates system for monoblock osseous genioplasty. Methods: Thirty-six patients with chin deformities were enrolled in this study. The chin template system included a cutting guide and a repositioning guide for a genioplasty. Chin templates were designed in a computer and fabricated using a three-dimensional printing technique. The accuracy of the genioplasty templates were assessed by comparing the actual postoperative outcomes with the virtual plan. Results: All genioplasty was successfully completed by the template system. The largest linear root-mean-square deviation(RMSD) between the planned and the postoperative chin segments was 1.16 mm and the largest angular RMSD was 3.06°. Conclusions: The results showed that the chin template system provides a reliable method for transfer of genioplasty planning. The operation precision of the genioplasty can be improved by using the surgical templates system.

[Establishment and application of a digital workflow in the treatment of condylar osteochondroma and secondary dentofacial deformities using image-guided endoscopic navigation combined with orthognathic surgery].

Objective: To establish a digital workflow in the treatment of mandibular condylar osteochondroma with secondary dentofacial deformities using navigation and endoscope combined with orthognathic surgery. Methods: Thirty-six patients with unilateral condylar osteochondroma were analyzed retrospectively. Preoperative planning and simulation were carried out on the digital three-dimansional (3D) model in all patients. With the aid of image-guided endoscopic navigation, osteochondroma resection and condylectomy were accurately performed. Secondary dentofacial deformities were simultaneously corrected using orthognathic surgery. All patients were followed up regularly and received postoperative CT scans. The preoperative simulated model and the postoperative actual model were matched using ProPlan CMF 2.0 software. Four corresponding points were marked in the virtual and actual ostectomy plane, respectively. The intersections of mandibular sigmoid notch and posterior ramusrim with condylectomy plane were marked as the anterior point and the posterior point, respectively. The perpendicular bisector of the line from the anterior point to the posterior point was intersected with the lateral and medial margin of condylectomy plane to form the lateral point and the medial point, respectively. The straight-line distances between the corresponding points in the virtual and actual ostectomy plane were respectively measured to analyze the ostectomy discrepancy. Results: All of 36 patients obtained satisfactory clinical effects. Facial symmetry and morphology were greatly improved. Postoperative CT showed that condylar tumors were completely removed. The preoperative simulated model and the postoperative actual model were matched. The average discrepancy between the planned and actual surgical resection was minimal on the anterior points ([0.24 ± 0.17] mm) and the mean error was maximal on the posterior points ([3.86±1.03] mm). The patients showed no signs of tumor recurrence in the 6 to 12 months of follow-up. Conclusions: Endoscope-assisted and navigation-guided tumor resection and condylectomy combined with simultaneous orthognathic surgery has satisfactory clinical effects in the treatment of condylar osteochondroma and secondary dentofacial deformities. The digital management workflow reported in this paper provides us a valuable option for this potentially complicated procedure.

[Comparison between computer aided simulation and dental model orthognathic surgery for the treatment of patients with mandibular excess and facial asymmetries].

Objective: To evaluate the results of the orthognathic surgery with computer aided simulation-three-dimensional(3D) printed surgical guide and dental model surgery in the treatmemt of patients with mandibular excess and facial asymmetries. Methods: The coordinate system was built in ProPlan CMF 2.0 software, and the horizontal plane consisted of PoL, PoR, OrL, middle sagittal plane through nasion point and basion point and the plane perpendicular to the horizontal plane, coronoid plane through nasion point and the plane perpendicular to the horizontal plane and middle sagittal plane. The orientation of maxilla and mandibular distal segment was calculated by each triangle(U1-U6L-U6R, L1-L6L-L6R, Me-M5L-M5R) before and after orthognathic surgery. A total of 60 mandibular excess patients with facial asymmetries were enrolled in this retrospective study. They were divided into two groups, group Ⅰ with computer aided simulation, group Ⅱ with dental model surgery. The difference of maxillary occlusal plane roll and yaw angle, mandibular occlusal plane roll and yaw angle, and mandibular body plane roll and yaw angle were calculated. Statistical analysis was performed with SPSS 17.0 software. Results: The yaw angle of mandibular occlusal plane of the dental model surgery and computer aided simulation was 0.36°± 0.48° and 0.84° ± 0.36° (P=0.043), respectively. The roll angle of mandibular occlusal plane of the dental model surgery and computer aided simulation was 0.26°±0.79° and 0.54°±0.40°(P=0.032), respectively. The yaw angle of mandibular body plane of the dental model surgery and computer aided simulation was 0.60°± 1.04° and 0.23°±0.52°(P=0.008), respectively. The roll angle of mandibular body plane of the dental model surgery and computer aided simulation was 0.82° ± 0.72° and 0.53° ± 0.37° (P=0.028), respectively. The changes in computer aided simulation group were more obvious than that in the dental model surgery group, but the difference was not significant in the yaw angle of maxillary occlusal plane and the roll angle of maxillary occlusal plane between the two groups(P >0.05). Conclusions: It was more effective to correct mandibular asymmetry by computer aided simulation than dental model surgery.

Cephalometric studies on the upper airway space in normal Chinese.

A detailed cephalometric analysis of the soft and hard tissues of the upper airway was conducted with lateral cephalographs from 116 normal Chinese, aged between 18 and 25 years. Normal values and deviation range were preliminarily established for the size of the tongue, soft palate, nasopharynx, oropharynx, and hypopharynx, and for the relative position of the hyoid bone and vallecula in both sexes. Statistical findings showed that there were significant differences between the sexes. Significant relationships (P < 0.001) were observed 1) between the hypopharyngeal depth and the position of the hyoid bone and the vallecula, in which the horizontal position of vallecula appears to be the best predictor of the hypopharyngeal depth, as confirmed by the multiple regression equation; 2) between the upper airway depths at four different levels; and 3) between the naso-oropharyngeal area and tongue, soft palate, and oral area. The present data can be used to investigate further the upper airway in abnormal states.

[Expression of Bacillus thuringiensis (Bt) crystal toxin gene in the chloroplast of tobacco].

The 3.5 kb wild-type Bt Cry I A(c) gene and its 3' truncated forms (2.1 kb, 1.8 kb) were placed under the control of plastid expression signals consisting of the strong light-induced psbA promoter and its 3' untranslated region with the aadA cassette (Prrn, aadA and psbA3') as a selectable marker. The resulting vectors pBT3, pBT8 and pBT22 also contain flanking tobacco plastid DNA homology regions to direct insertion of the Bt transgene into the tobacco plastid genome between psbA and trnK by homologous recombination. Transformed plastid genomes were selectively amplified by growing the cells on spectinomycin medium. Several independently transformed lines were obtained at last. The results of Southern and Western blot demonstrated that these three kinds of Bt genes had been introduced into tobacco plants, and their filial generations are resistant to spectinomycin. Insecticidal activity assay with transgenic tobacco leaves indicate that some plants have strong toxicity to cotton bollworm. This is the first report in China that Bt gene has been introduced and successfully expressed in the chloroplast of higher plants.

Emergency removal of a grinding wheel embedded in the midface via modified Le Fort I osteotomy.

Le Fort I osteotomy is commonly used to rectify craniofacial deformity in orthognathic surgery and it can be used in approaching a cranial base lesion. This technique has not been well documented in craniofacial penetrating trauma. This article describes a case of midface penetrating injury caused by a grinding wheel. A modified Le Fort I osteotomy was used to remove the foreign object. This surgical approach can be safe and effective when removing foreign bodies in the midface. Good access and adequate exposure can be achieved, which facilitate precise foreign body extraction and achieve reasonable cosmetic results.

Changes in condylar and joint disc positions after bilateral sagittal split ramus osteotomy for correction of mandibular prognathism.

The effect of combined orthodontic and orthognathic treatment was studied retrospectively in 24 patients with skeletal class III malocclusions with mandibular hyperplasia, particularly the effect on temporomandibular joint (TMJ) disc position. The patients underwent preoperative orthodontic treatment, orthognathic surgery, and postoperative orthodontic treatment. The patients were studied clinically, radiographically with lateral cephalometric radiograph and MRI to locate the position of the TMJ disc in relation to the glenoid fossa. One patient had less pain after treatment, one lost abnormal joint clicking sounds after treatment. There were no TMJ symptoms in 20 of the 24 preoperatively and postoperatively. 48 sagittal MRI images showed that the disc length before treatment was 3.040-12.928 (mean 8.289+/-2.028) and after treatment was 3.699-11.589 (mean 8.097+/-1.966); results were not significant (p>0.05). Maximum disc displacement before treatment was 6.090 (mean 1.383), after treatment it was 11.931 (mean 2.193); results were not significant (p>0.05). The results suggest that combined orthodontic and orthognathic treatment (including bilateral SSRO and rigid internal fixation) can be used safely to correct skeletal class III malocclusion with mandibular hyperplasia without causing additional TMJ symptoms.

Navigation-guided gap arthroplasty in the treatment of temporomandibular joint ankylosis.

Gap arthroplasty, used in the treatment of temporomandibular joint (TMJ) ankylosis, is challenging, requiring resecting of massive abnormal bone formation at the skull base with complex and distorted anatomy. This study evaluated the application of image-guided navigation to gap arthroplasty. Four gap arthroplasties were performed on patients with unilateral TMJ ankylosis under computer-assisted navigation guidance. After preoperative planning and 3-dimensional simulation, the normal anatomic structures of the TMJ were created by superimposing and comparing the unaffected and affected sides. The amount and range of ankylotic bone to be resected was determined and displayed. Registration achieved an accurate match between the intra-operative anatomy and the CT virtual images. Anatomic structures and the position of surgical instruments were shown real time on the screen. In all cases the accuracy of the system measured by the computer did not exceed 1mm. No complications occurred and the mean minimal thickness of the skull base between middle cranial fossa and reconstructed glenoid fossa was 1.97 mm. Using image-guided navigation resulted in safe surgical excision of the bony ankylosis from the skull base. Navigation-guided resection of the ankylotic bone in the TMJ gap arthroplasty was a valuable and safe technique in this potentially complicated procedure.

Nicotiana chloroplast genome III. Chloroplast DNA evolution.

Nicotiana chloroplast genomes exhibit a high degree of diversity and a general similarity as revealed by restriction enzyme analysis. This property can be measured accurately by restriction enzymes which generate over 20 fragments. However, the restriction enzymes which generate a small number (about 10) of fragments are extremely useful not only in constructing the restriction maps but also in establishing the sequence of ct-DNA evolution. By using a single enzyme, Sma I, a elimination and sequential gain of its recognition sites during the course of ct-DNA evolution is clearly demonstrated. Thus, a sequence of ct-DNA evolution for many Nicotiana species is formulated. The observed changes are all clustered in one region to form a "hot spot" in the circular molecule of ct-DNA. The mechanisms involved for such alterations are mostly point mutations but inversion and deficiency are also indicated. Since there is a close correlation between the ct-DNA evolution and speciation in Nicotiana a high degree of cooperation and coordination betwen organellar and nuclear genomes is evident.

[A preliminary cephalometric study on characters of facial soft tissue in mandibular asymmetry cases]

OBJECTIVE: To study the alterations of facial soft tissue in mandibular asymmetry cases.METHODS:The asymmetric rates of the bone were compared with that of soft tissue by cephalometric analysis in 20 mandibular asymmetry cases by study on the thickness of the soft tissue in special position.RESULTS:It showed that the soft tissue is more symmetric than the bones.CONCLUSION:It can be concluded that the facial soft tissue is not as asymmetric as the bone.This suggests that the reconstrction of the bony deformities and the soft tissue deformities should not be performed at same time.

[Presurgical infant orthopedics in complete bilateral cleft lip and palate reconstruction]

OBJECTIVE:This study want to effects on using intraoral-appliance treatment of complete bilateral left lip and Palate in clinic.METHODS:Using Lisson's method preliminary evaluated to effect of presurgical infant orthopedics complete bilateral cleft lip and palate.A sample of 4 cases of 18 weeks infant complete bilateral cleft lip and palate.2 of they are males, others are females.All of they had received presurgical infant orthopedics,Using intraoral appliance. comparison of before and after cast analysis.Evaluate anteiro posteior I, tranverse,oblique degree of the lateral segment, pretrusion premaxilla position change.RESULTS:Every patients after orthopedics treatment had retracted premaxilla come back,corrected of oblique of premaxilla,had lateral segments growth equally on both side,their inclination should be similar.CONCLUSION:Intraoral-appliance can successfully improved malarrangement maxilla of bilateral cleft lip and palate.

[Mandibular reconstruction using "chain flap" of iliac crest free flap and forearm free flap]

OBJECTIVE:Following ablation of oromandibular malignant neoplasms,3 patients underwent immediate mandibular reconstruction using "chain flap".It was composed of iliac crest composite free flap(ICCFF). seven flaps of 3 cases survived completely,follow-up ranged and donor sites were generally satisfactry.Consecutive X-ray films showed that the grafting bone produed a more rapid processes of incorporation and bone remodling,and experienced minimal bony resorption.The results suggested that FFF could remedy defects of soft-tissue compoment of ICCFF.It was an useful method that mandibular reconstructin of large composite defects using "chain flaps" of ICCFF and FFF.

Evaluation of the treatment for micromandibular deformity by distraction osteogenesis with submerged intraoral device.

OBJECTIVE: To evaluate the results of distraction osteogenesis for correcting the micromandible with an intraoral device. MATERIALS AND METHODS: Eight cases of micromandible resulting from temporomandibular joint (TMJ) ankylosis and first and second branchial arch syndrome received treatment by distraction osteogenesis. Subjects included 5 females and 3 males, ranging in age from 10 to 43 years (avg 20.25). Five micromandibles were associated with obvious mandibular asymmetry. An osteotomy was performed on bilateral mandibular bodies by intraoral approach. Elongation was started on the 5th or 6th day postoperation at a rate of 0.8 to 1 mm per day. The distractors were removed after a consolidation period from 71 to 139 days. RESULTS: The distractions were fulfilled with a range of 8.5 to 24.4 mm. Pain appeared in osteotomy region when the 1 mm distraction was carried out once a day and disappeared when it was divided into twice a day. Mandibular lengthening was successful. Micromandible and facial asymmetries were corrected satisfactorily. The follow-up period ranged from a minimum of 1 month to a maximum of 10 months. There was no recurrence. One case of soft tissue infection and one case of lower lip numbness were reported. There were no cases of infection or other disturbance of wound healing or pseudarthrosis. CONCLUSIONS: Because of its advantage in little injury, avoiding bone grafting, and few complications, intraoral distraction osteogenesis is a valuable approach to correct mandibular agenesis. However, in the management of mandibular deformities, distraction osteogenesis achieves better results when combined with other orthognathic operations. How to control the direction of distraction is a problem that needs further study.