[Clinical research on curative effect of complete denture with two kinds of occlusion for temporomandibular joint disorders of aged edentulous patients].

OBJECTIVE: To compare curative effect between complete denture with lingualized occlusion and anatomic occlusion on temporomandibular joint disorders (TMD) of aged edentulous patients with severe residual alveolar ridge resorption. METHODS: Seventy aged edentulous patients with severe residual alveolar ridge resorption were recruited in this study and randomly assigned into two groups, thirty-five each. In Group A, patients received complete denture with lingualized occlusion, and in Group B, patients received complete denture with anatomic occlusion. The condition of TMD was examined and recorded by the same TMD specialist at baseline, 3 months and 6 months following denture delivery. The recovery effect of TMD was evaluated according to Fricton Index. Related data were analyzed statistically with t-test and rank sum test. RESULTS: Three months following denture delivery, the craniomandibular index (CMI) decrease value was (0.064 ± 0.022) in group A, and was significantly higher than that in group B (0.043 ± 0.018) (P < 0.01). Six months following denture delivery, the CMI decrease value was (0.084 ± 0.020) in group A, and was significantly higher than that in group B (0.070 ± 0.021) (P = 0.011<0.05). CONCLUSIONS: Complete denture with lingualized occlusion may be more conducive to the remission of TMD for aged edentulous patients with severe residual alveolar ridge resorption.

[Nicotine affects biological properties of the human osteosarcoma cell line MG63].

OBJECTIVE: To evaluate the effect of nicotine on cell proliferation. METHODS: The cells were cultured with DMEM medium containing 10% fetal bovine serum with 0, 1 x 10(-4) mol x L(-1), and 1 x 10(-3) mol x L(-1) nicotine for up to 3, 5, 7, 10, 14 days. The cell proliferation was evaluated by MTT. The alkaline phosphatase (ALP) activity was estimated by PNPP. The expression of collagen type I (COL1) and osteocalcin (OCN) were estimated by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Nicotine suppressed the cell proliferation. ALP activity increased to peak on 10 days in control and 1 x 10(-4) mol x L(-1) nicotine. COL1 expression increased to peak on 10 days in control and 1 x 10(-4) mol x L(-1) nicotine, but there was decreased to the minimum on 10 days and increased on 14 days in 1 x 10(-3) mol x L(-1) nicotine. OCN expression increased to peak on 10 days in control, and increased in 1 x 10(-4) mol x L(-1) nicontine from 3 days to 14 days, but there wasn't significant change in 1 x 10(-3) mol x L(-1) nicontine. CONCLUSION: Nicotine suppresses osteogenesis through a decrease in ALP and COL1 production by osteoblasts.

[The effect of mold temperature on the accuracy of titanium castings].

PURPOSE: To study the effect of mold temperature on the accuracy of titanium castings invested in the ZrP99 investment. METHODS: 30 artificial stone dies simulated the post-tooth and their corresponding complete crown wax patterns were made with a truncated cone-shape standard brass model with round sleeves. They were divided randomly into five groups and each group had six samples. Four group wax patterns were invested in ZrP99 investment as test groups and one group was invested in Titavest-CB investment as control. The test group moulds were cast at the mould temperature 600 degrees centigrade, 450 degrees centigrade, 300 degrees centigrade, 150 degrees centigrade, respectively. Measure the distance separating the gingival margin of the crown and the shoulder of the die in the same way as for the wax pattern. The casting accuracy was represented by the discrepancies derived from the space distance measurements made with wax patterns and cast crowns. t test and one-way ANOVA were used for statistical analysis. RESULTS: Measurement of the casting accuracy indicated that the casting accuracy of the control group was higher than all the test groups. When the mold temperature was lower than 450 degrees centigrade, the accuracy of the castings invested in ZrP99 investment was improved significantly with the mold temperature raised. CONCLUSION: To satisfy the requirement of the clinical practice in the point of the casting accuracy, the mold temperature of ZrP99 investment must be chosen higher than 300 degrees centigrade.