The correlation analysis between environmental factors, bone morphogenetic protein-4 and transforming growth factor beta-3 polymorphisms in nonsyndromic cleft lip with or without cleft palate / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of interactions among environmental factors, bone morphogenetic protein-4 (BMP4) and transforming growth factor beta-3 (TGF-β(3)) polymorphisms on nonsyndromic cleft lip and cleft palate (NSCLP).</p><p><b>METHODS</b>The data of environmental exposures were collected with questionnaires. Genotypes were determined with techniques of polymerase chain reaction-restriction fragment length polymorphism. Interactions between genes, environmental factors and NSCLP were analyzed using multifactor dimensionality reduction (MDR) method. The interactions were validated by logistic regression analysis.</p><p><b>RESULTS</b>There was no correlation between three single nucleotide polymorphism (SNP) associated with NSCLP. The developmental accident of NSCLP had higher risk in the interaction between BMP4 T538C, maternal passive smoking and infection in first trimester pregnancy, as well as in the interaction of six factors between TGF-β(3) G15572-, maternal passive smoking, infections, multivitamin supplement in the first trimester pregnancy, paternal smoking and high risk drinking before realizing pregnancy than in other interactions of environmental factors. The results could be validated by logistic regression analysis.</p><p><b>CONCLUSIONS</b>The NSCLP is induced by the interactions between genes and environmental risk factors.</p>

Effect of simvastatin on bone morphogenetic protein-2 expression in the periodontal tissue after rat tooth movement / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of systematic administration of simvastatin on the bone morphogenetic protein-2 (BMP-2) expression in the periodontal tissue after rat tooth movement and on the relapse of tooth movement.</p><p><b>METHODS</b>Orthodontic tooth movement of upper first molar was performed in 32 rats with coil spring for 21 days. The 32 rats were randomly allocated into 4 groups: negative control group (isotonic saline) and three experimental groups (2.5 mg x kg(-1), 5.0 mg x kg(-1) and 10.0 mg x kg(-1)). The simvastatin started to be administered to the experimental groups 1 day before appliances were removed, and once a day there after for 4 weeks. The negative control group received the isotonic saline only. The interdental distance between the first and second maxillary molars were measured, when appliances were removed, and 1 week and 4 weeks after that. After the rats were sacrificed, sections of first maxillary molar and periodontal tissue were studied by immunohistochemistry.</p><p><b>RESULTS</b>The number and percentage of relapse was lower in the three experimental groups than in the negative control group (P < 0.05, P < 0.01). The lower dose was given, the less relapse there was, with the lowerest dose resulting in lowest percentage of relapse (26.81% and 53.38%). BMP-2 expression in experimental groups was higher than in the negative control group, with the lowerest dose group showing the highest expression (P < 0.001). The BMP-2 expression on the tension side was slightly stronger than that on the compression side (P > 0.05).</p><p><b>CONCLUSIONS</b>Systemic administration of simvastatin could decrease the extent of relapse of the orthodontic-moved tooth in rat, and the lower-dose of simvastatin seemed more effective. The possible mechanism for this may be that simvastatin functions by increasing the expression of BMP-2 in the periodontal tissue, accelerating the osteoblast activity and promoting bone formation.</p>

Biomechanical study of open bite treatment with tip forward bend / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To verify whether it is effective to treat open bite cases with tip-forward bend.</p><p><b>METHODS</b>Three-dimensional finite element (TDFE) models of the lower left central incisor and first molar were set up by means of CT. Stress distribution in root, PDL and alveolar bone, and the tendency of the tooth movement were obtained by calculation under different orthodontic forces.</p><p><b>RESULTS</b>(1) The molar model revealed that the tensile stress concentration was at the distal cervix and the compressive stress concentration at mesial cervix. (2) The incisor model showed that the tensile stress was concentrated at apical tip and the compressive stress concentration was at the lingual side of the cervix. (3) The incisor had the tendency to elongate and move lingually. The molar tended to tip mesially and buccally.</p><p><b>CONCLUSIONS</b>Arch wire with tip forward bend depends on the elongation and lingual movement of anterior teeth to treat open bite, but the anchorage molar will incline mesially further, which is not consistent with the mechanism to treat open bite.</p>