Influence of thermomechanical fatigue loading on the fracture resistance of all-ceramic posterior crowns.

This study evaluated the fracture resistance and the survival rate of different all-ceramic crowns in-vitro after thermomechanical fatigue loading in comparison to porcelain-fused-to-metal posterior crowns. Sixteen crowns for human mandibular first molars were made of each of the following: Cercon, IPS-Empress 2 In-Ceram Zirconia, Procera AllZircon and porcelain-fused-to-metal. Half of the specimens of each group was thermocycled and dynamically loaded using a chewing simulator All samples were thereafter tested for the maximum fracture resistance.

Cure width potential for MOD resin composite molar restorations.

Objectives: To investigate the capability of modern light-curing units exhibiting differences in emission spectra and light source exit window dimensions, for "one-shot" full-width curing of extensive (molar MOD) resin composite restorations.

Method: Specimens of Tetric (TT), Tetric Ceram HB (TC), Tetric Evoceram (TE) and Tetric Ceram Bleach (TB) resin composites containing varying ratios of Lucirin (TPO) and/or camphorquinone (CQ) photoinitiators were packed into a bar-shaped mould (12 mm length x 2 mm width x 2 mm thickness). Each product was irradiated using a halogen (Optilux 401; QTH), a conventional LED (LEDemetron; LED) and two so-called "third generation" oval-footprint LED light-curing units (LCUs) of the same model.