Objective:To investigate the levels of parathyroid hormo ne -related protein(PTHrP) in mandibular condylar cartilage during mandible forwar d positioning in different seasons. Methods:64 SD rats were rand omly divided into four groups according to seasons. Orthodontic appliance was us ed in 32 rats for 12 hours each day in daytime for mandibular protrusion. 8 rats were sacrificed at each season time point.Condyle samples were processed for PT HrP detection by a two-site immunoradiometric assay (IRMA) method.Another 32 ra ts without treatment were used as the controls.Macroscopic and microscopic appro ach were applied to analyze the results. Results:The level of P THrP in mandibular condylar cartilage(MCC) in the group of orthodontic treatmen t was higher than that in the control group(P

Objective:To observe the response and changes of cranial suture to the distraction forces in growing goats.Methods:A custom-made distractor was used for expanding coronal suture of 11 growing goats at the rate of 0.4 mm/day for 8 days.The animals were killed 0,2 and 4 weeks respectively after completion of suture distraction application. X-ray examination was taken and the distracted suture samples were harvested and processed for scanning electron microscopic observation and immunohistochemistry examination of BMP and TGF-? expression. The coronal sutures taken from other undistracted animals were used as the controls. Results:The coronal sutures were separated successfully in distracted goats. 0 and 2 weeks after application of suture distraction, the collagen fiber bundles were strengthened and aligned in the direction of the distraction. Strong expression of BMP and TGF-? were detected in the fibroblast-like cells and the active osteoblasts. 4 weeks after suture distraction, signs of intramembranous ossification were found in the edge areas of the distracted suture, and the positive staining of BMP and TGF-? was still noted in the osteoblasts around the newly formed bone trabeculae. Conclusion:BMP and TGF-? may play important roles in the process of bone formation and remodeling during suture distraction osteogenesis.

objective: To study the development of available space of lower posterior arch. Methods: The sample consisted of 188 randomly selected subjects aged from 11 to 18 years, 76 males and 112 females. The distance from the distal surface of mandibular first molar to the anterior border of the ramus was measured on orthopantomography. All the data were analyzed statistically. Results: 1) The distance(mm) in female and in male was 14.45?3.54 and 13.29?4.17 respectively( P

Objective:To introduce the clinical application of the coil-spring utility arch for orthodontic treatment. Methods:A 35-year-old male patient with mild skeletal anterior crossbite was treated by fixed appliance combined with coil-spring utility arch for 16 months. Cephalometric analysis was conducted before and after treatment.Results:After treatment, the patient's appearance was improved,and the cephalometric analysis showed that SNA increased by 2?,SNB decreased by 1?,ANB increased by 3?,U1-NA increased by 1?,L1-NB increased by 3?.Conclusion:Coil-spring utility arch can expand anterior dental arch continuously and stably.

Objective To evaluate the functional and aesthetic disturbance of patients treated with lingual orthodontic surgery and to investigate the key points of laboratory procedure and clinical treatment of lingual orthodontic deformity. Methods A total of 30 cases of Angle class Ⅰ with moder-ate crowding were selected. They were equally divided into two groups: one group was treated using lingual brackets, and the other using conventional labial brackets. Each patient completed a four-part survey right after the bracket placing and 7, 28, 56 days after the treatment. The differences of tongue-lip-cheek soreness, eating and speech difficulties and aesthetic problems were evaluated be-tween two groups. Lateral cephalograms were analyzed at the start of the treatment and the end of the overall treatment. Results Speech difficulties of lingual orthodontics were significantly greater (P<0.01) than that in the labial orthodontics group in the first week of the treatment. Eating difficulties were greater (P<0.01) in the lingual orthodontics group by 28 days, whereas aesthetic problems were greater in group using labial appliance than group lingual appliance. Conclusions In the first two months of the orthodontic treatment, eating and speech difficulties are the most severe problems for the lingual group. Lingual orthodontics offers important aesthetic advantages over labial orthodontics, and it will be one of the development directions of current orthodontics.

Objective:To investigate the hyoid bone position on the cephalometric radiographs of patients with early permenant dentitions and Class I or Class Ⅲ malocclusion.Methods:The cephalometric radiographs were taken in centric occlusion and 16 measures were performed on tracing in 30 cases of Class I malocclusion and 30 of Class Ⅲ, the data were statistically analysed.Results:At-APH and S-APH in Class I malocclusion were shorter than those in Class Ⅲ(P

Objective:To evaluate the influence of minimally invasive corticotomy on the treatment time and molar anchorage of adult orthodontic extraction cases.Methods:60 adult cases of Angle Class Ⅰ crowding malocclusion were devided into 3 groups (n =20) and treated by orthodontic treatment wtih minimally invasive corticotomy(group A),orthodontic treatment with classic modified corticotomy(group B) and routine orthodontic treatment (group C) respectively.Time needed for leveling and alignment,space closure,delicate adjustment,total treatment time and mesial sagittal antedisplacement of first molar anchorage were compared among the 3 groups.Results:Time needed for leveling and alignment of orthodontic treatment of group A,B and C was (5.64 ± 2.57),(4.91 ± 3.31) and (8.87 ± 3.75) months respectively(C vs A or B,P ＜ 0.01).Time needed for space closure of group A,B and C was (6.84 ± 2.69),(6.64 ± 3.87) and (8.63 ± 3.29) months respectively(C vs A or B,P ＜0.01).Time needed for delicate adjustment showed no significant difference among the 3 groups(P ＞ 0.05).Total treatment time of group A,B and C was (16.07 ± 6.21),(15.77 ± 5.11)and (21.94 ± 5.74) months respectively (C vs A or B,P ＜ 0.01).There was on statistical difference of mesial sagittal antedisplacement of first molar anchorage among the 3 groups.Conclusion:Minimally invasive corticotomy can shorten the orthodontic treatment time,but can not decrease the retraction resistance of the anterior teeth.

UNLABELLEDTo evaluate the effects of preadjusted bracket base shape, the morphology of tooth surface where bracket locates, and the suitability relevant to location of bracket on the preadjusted edgewise appliance technique. 1 vertical curve and 3 horizontal curves of the clinical crown surface of anterior teeth and bicuspid teeth were measured with the precise contour instrument on the 60 plaster models of the subjects who have normal occlusion in Sichuan province. It was found that variation of identical curve exists at the different heights between the teeth and between the individuals; the surface of the central zone of tooth-crown gradually protrudes from incisors to bicuspid teeth in the vertical direction, and the mesial contour of cuspid is more prominent than the distal in the horizontal direction.

CONCLUSIONThe 4 mm X 3 mm contour of the vestibular central zone of identical tooth-crown in different individuals is fairly stable; it is suitable for the location of preadjusted brackets. The vertical shifts of brackets could change the preadjusted torque value and the design of cuspid bracket should have the distinction between mesial and distal shape.

Bicuspid ; anatomy & histology ; Dental Occlusion ; Humans ; Incisor ; anatomy & histology ; Tooth Crown ; anatomy & histology ; Torque

OBJECTIVEThe characteristics of lip-mouth region including the soft and hard tissues in smiling position with frontal fixed position photographic computer-aided analysis were studied.

METHODSThe subjects were 80 persons (40 male and 40 females, age range: 17 to approximately 25 years) with acceptable faces and individual normal occlusions. The subjects were asked to take maximum smiling position to accept photographic measurement with computer-aided analysis.

RESULTSThe maximum smile line could be divided into 3 categories: low smile line (16.25%), average smile line (68.75%), and high smile line (15%).

CONCLUSIONThe method adopting maximum smiling position to study the lip-month region is reproducible and comparable. This study would be helpful to provide a quantitative reference for clinical investigation, diagnosis, treatment and efficacy appraisal.

Adolescent ; Adult ; Anthropometry ; Dental Occlusion ; Female ; Humans ; Lip ; anatomy & histology ; Male ; Mouth ; anatomy & histology ; Smiling ; Tooth ; anatomy & histology

OBJECTIVEThe aim of this study was to analyse the stress distribution in the periodontium of the maxillary first molar and to search optimal loads pattern when distal movement to provide biomechanical basis for the clinical practice.

METHODSBy spiral CT scanning, a three-dimensional finite element model of the maxillary first molar was established, and then four different load patterns were added to the molar to obtain the optimal load partern for molar bodily distal movement.

RESULTSDifferent loads lead to different stress distributions when distal movement.

CONCLUSIONA distalizing force combined with a countertipping moment (Mt/F = 10) and a counterrotation moment(Mr/F = 6) can lead to a lower and uniform stress on the distal side of the periodontal ligament, it implys a tendency of translation of the maxillary first molar.

Biomechanical Phenomena ; Dental Stress Analysis ; Finite Element Analysis ; Humans ; Maxilla ; Molar ; Periodontium ; Tooth Movement Techniques