ABSTRACT
OBJECTIVE@#To investigate the influence of cuspal-coverage thickness on the stress distribution of all-ceramic onlay-restored premolars by using 3D finite element (FE) analysis and to provide references for the design of all-ceramic onlays for clinical application.@*METHODS@#3D FE models of all-ceramic onlays with three cuspal-coverage thicknesses (2, 3, and 4 mm) of endodontically treated maxillary premolar were constructed based on micro-CT images. Stress distributions in the onlay, adhesive resin cement layer, and dentin of models were analyzed under vertical load (600 N) and oblique load (200 N).@*RESULTS@#When the cuspal-coverage thickness increased, the peak maximum principal stress value decreased inside the onlay but increased in the margin of the adhesive resin cement layer. In addition, stress concentration areas increased in the coronal residual dentin on the palatal side under oblique load.@*CONCLUSIONS@#An increase in the cuspal-coverage thickness of all-ceramic onlays may reduce the risk of rupture of the restoration but may deteriorate the restoration and cause palatal dentin fracture.
Subject(s)
Bicuspid , Ceramics , Composite Resins , Dental Porcelain , Dental Stress Analysis , Finite Element Analysis , InlaysABSTRACT
<p><b>UNLABELLED</b>OBJECTIVE To investigate the effect of Guanxinkang (GXK) on ATP-sensitive potassium channel in myocardial cells of rat with ischemic/reperfusion injury and its possible mechanism for cardiac vascular protection and anti-myocardial ischemia.</p><p><b>METHODS</b>Wistar rats were established into I/R injured models by 10 min perfusion--30 min no-flow ischemia--45 min reperfusion, and divided into 5 groups: the I/R model group and 4 treatment groups treated respectively with glibenclamide, pinacidil, GXK and GXK+glibenclamide. Rats' heart were isolated for detecting Ca(2+)-Mg(2+)-ATPase, Na(+)-K(+)-ATPase activity in myocardial cells, and the changes of current in ATP-sensive potassium channel (K(ATP)) was recorded by whole patch clamp technique. Data were controlled by those taken from normal rats in a control group.</p><p><b>RESULTS</b>K(ATP) in the GXK treated group were higher than that in the I/R model group; and similar to that in the pinacidil treated group (P > 0.05). As compared with the model group, activities of Ca(2+)-Mg(2+)-ATPase and Na(+)-K(+)-ATPase in the GXK treated group were increased significantly (P < 0.05).</p><p><b>CONCLUSION</b>GXK shows definite intervention effect on myocardial I/R injury; which is possibly by way of furthering the opening of K(ATP) channel, decreasing Ca2+ influx, and inhibiting Ca2+ overload.</p>