ABSTRACT
Objective@#To evaluate the influence of fracture resistance of endodontically treated teeth with different thickness of ferrule by mechanical fatigue test and static loading test, and so as to provide a reference for the clinical treatment planning.@*Methods@#Fifty bovine incisors were divided into 5 groups by random number table method (n=10). Group A was the control group in which the incisors were prepared without a ferrule design (0 mm). The other four groups (B, C, D, E) were experimental groups, and the thickness of the dentin ferrule prepared for specimens in each group was 0.5, 1.0, 1.5, and 2.0 mm. The height of ferrules in all the specimens was 2 mm. Cyclic fatigue loading (2.33 Hz, 50 N) was applied on each specimen until either the specimen was dislodged/fractured or the 300 000 cycles were finished. After fatigue loading, the mode of failure was observed. Those intact specimen after fatigue loading were tested under a gradually increasing force using a universal testing machine (0.05 mm/min) until fracture occurred. The forces required to fracture and failure model was recorded.@*Results@#The results of cyclic loading tests showed that: all specimens survived the 300 000 cycles of intermittent loading. The results of static loading tests showed that: the fracture force of A, B, C, D and E groups respectively were (226.4±67.7), (369.7±34.5), (400.7±48.2), (528.1±56.3), and (555.4±98.5) N (F=15.227, P=0.000). There was a significant difference in fracture resistance between group A and the other four groups, and between group B, C and group D, E (P<0.05). No statistical difference were found in fracture resistance among the other groups (P>0.05). There was strong correlation between the thickness of ferrule and the fracture force by Pearson correlation analysis (r=0.973, P=0.002).@*Conclusions@#Within the limitations of this study, the following conclusions can be drawn: The different thickness of ferrule can influence the fracture resistance of the teeth, and when the height of the ferrule is 2.0 mm, the fracture force increased significantly with an increasing ferrule thickness.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of fushenkeli on the expression of TAK1 in the proliferation of the renal tubular epithelial cells induced by TGF-beta1 and its possible mechanism.</p><p><b>METHOD</b>Human renal tubular epithelial (HK-2) cells were divided into five groups:blank control group, TGF-beta1 group (5 microg x L(-1)), intervention group 1 (5 microg x L(-1) of TGF-beta1 + 100 mg x L(-1) of fushenkeli), intervention group 2 (5 microg x L(-1) of TGF-beta1 + 500 mg x L(-1) of fushenkeli) and intervention group 3 (5 microg x L(-1) of TGF-beta1 + 1 g x L(-1) of fushenkeli). HK-2 proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay. Type IV collagen in the supernatants of the cultured HK-2 was detected by ELISA at 12, 24, 48 hours respectively. The protein and mRNA expressions of TAK1 was measured by Western blot and real-time quantitative PCR.</p><p><b>RESULT</b>1) The cell proliferation and the expression of type IV collagen were increased compared with the control group (P<0.05, P<0.01), but they were decreased in intervention group. 2) The expressions of protein and mRNA of TAK1 in TGF-beta1 group were upregulating significantly compared with control group (P<0.01), but they were downregulating in intervention group, especially in intervention group 3.</p><p><b>CONCLUSION</b>Fushenkeli could inhibits TAK1 expression induced by TGF-beta1 in the proliferation of HK-2 cell.</p>