Characteristics of mandible and mandibular dentition according to vertical facial skeletal features of adolescents / 华西口腔医学杂志

OBJECTIVE@#We aim to examine teenagers with varying vertical facial skeletal types with near-normal occlusion. We further aim to identify and study mandibular morphology and dentition characteristics to establish normal ranges and variations for future clinical reference.@*METHODS@#According to the results of the case studies, 42 adolescents with near-normal occlusion were divided into three groups, namely, low- (7 cases), average- (23 cases) and high-angle (12 cases) groups. We used Invivo 5 software for Digital Imaging and Communications in Medicine (DICOM) data to calculate the cant of occlusal plane, axis corner of L6, ∠L1/MP, ∠L6/MP, Balkwill angle and Bonwill triangle of each group.@*RESULTS@#Markedly, the finding shows that the cant of occlusal plane and axis corner of L6 in the low-angle group were smaller than those of the other two groups. In the average-angle group, ∠L1/MP was larger than that of the high-angle group. Lastly, in the high-angle group, ∠L6/MP was smaller than those of the two other groups. On the one hand, these differences were considered statistically significant (P0.05).@*CONCLUSIONS@#In the low-angle group, the parallelisation of the occlusal plane tends to be more obvious compared with the two other groups. In the coronal section of the low-angle group, the axis of the mandibular first molar is up-right, whereas it is distally tilted in the sagittal section of the high-angle group. Furthermore, a number of differences are noted in the adult groups. Factors, such as aging and development in the craniofacial region, lead to changes in functional occlusion.

Expressions of RANK, RANKL, and osteoprotegerin in male rats at different ages / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the expression of receptor activator of nuclear factor-κB (RANK), its ligand RANKL, and osteoprotegerin, and observe the effects of αD3 on their expressions in male rats at different ages.</p><p><b>METHODS</b>Wistar rats at 6 weeks, 6 months, and 24 months (n=15) were examined for mRNA expressions of RANK/RANKL and osteoprotegerin in the left proximal femur using RT-PCR and for their protein expressions in the right femur using immunohistochemistry. RANK/RANKL and osteoprotegerin expressions were also detected in another 15 rats aged 24 months following intragastric administration of 0.05 µg/kg αD3 (3 times a week for 10 weeks).</p><p><b>RESULTS</b>Compared with 6-week-old rats, 6-month- and 24-month-old rats showed a 6.2-fold and 7.3-fold increase of RANKL mRNA expression, respectively (P<0.05), and osteoprotegerin mRNA levels increased slightly with age. αD3 treatment resulted in significantly increased expression of RANK in 24-month-old rats with a lowered RANKL/osteoprotegerin ratio. RANKL and osteoprotegerin were co-localized in the osteoblasts and chondrocytes. αD3 treatment also caused an increased expression of osteoprotegerin mRNA in 24-month-old rats.</p><p><b>CONCLUSION</b>The age-related increase of the ratio of RANKL/osteoprotegerin mRNA promotes osteoclast activity and bone turnover. αD3 has favorable effect on osteogenesis and suppress bone absorption in the femur possibly by reducing RANK expression and lowering RANKL/osteoprotegerin ratio.</p>

Three-dimensional finite element model of maxillary protraction of the maxilla in patients with cleft lip and palate / 中南大学学报(医学版)

OBJECTIVE@#To determine the effective rule of protraction in different directions,strains, and shifts of maxillary bone,and to supply the scientific data for treatment of the maxilla in patients with cleft lip and palate.@*METHODS@#" Based on the establishment of 3-dimensional finite element model of maxilla with cleft lip and palate,ANSYS 10.0 software was used to simulate protraction,and then we analyzed the change of maxillary stress and shift in the same force of traction in different directions.@*RESULTS@#With 500 g per lateral protraction and the protraction angle from 20 degree to 45 degree,the maxillary shifted upward, forward, and outward, and the shape of maxillary plate bow showed internal shrinkage. There was a close relation between the internal shrinkage and the direction of protraction. The smaller the angle between the direction of protraction and the functional occlusion plane,the larger the internal shrinkage of tooth bow. The larger the angle between the direction of protraction and the functional occlusion plane,the smaller the internal shrinkage of tooth bow.@*CONCLUSION@#With protraction,the maxilla grows upward, forward, and outward, and the maxillary palate shinks internally. There is a close relation between the direction of protraction and the range of internal shrinkage.

MBT straight wire for Class II division I malocclusion cases / 中南大学学报(医学版)

OBJECTIVE@#To evaluate the therapeutic effects of MBT straight wire on extraction case of Class II division I.@*METHODS@#Thirty-six class II division I malocclusion patients were treated with MBT straight wire by extracting 4 bicuspid premolars or 2 maxillary bicuspid premolars. The X-ray cephalograms were analyzed before and after the treatment of MBT straight wire.@*RESULTS@#After the treatment, the overjet was reduced by 6.04 mm (P < 0.01); U1-NA was reduced by 15.43 degrees (P <0.01); and U1-NA (mm) was reduced by 4.71 mm (P <0.01). ANB was significantly reduced (P < 0.05).@*CONCLUSION@#MBT straight wire not only shortens the operation but also shows superior effect for Class II division I malocclusion cases.