The effect of micro-mechanical signatures of constituent phases in modern dental restorative materials on their macro-mechanical property: A statistical nanoindentation approach.

This study utilized a statistical nanoindentation analysis technique (SNT) to measure the amount of organic and inorganic constituents of twenty different brands of dental resin-based composites (RBCs) and tested whether their macro-property such as flexural modulus could be approximated by the proportions of constituents' micromechanical signatures using various rules of mixtures. The probability density function (PDF) of constitutive moduli per RBC brand were measured for three groups, comprised of different indent arrays and inter-indent spacings. SNT was then applied to deconvolute each PDF, from which the effective filler (μ) and matrix (μ) moduli and filler (V) and matrix (V) volume fractions per RBC brand were computed.

Effect of high-intensity curing lights on the polymerization of bulk-fill composites.

Objectives: The purpose of this study was to investigate the effect of high-irradiance light-curing-units (LCUs) on the depth-of-cure (DoC) and degree-of-polymerization (DoP) of bulk-fill composites (BFCs).

Methods: The DoC of composites (Beautifil-Bulk, SHOFU; Filtek-Bulk-Fill, 3M ESPE; Tetric-EvoCeram-Bulk-Fill, Ivoclar; Sonic-Fill-2, Kerr; Venus-Bulk-Fill, Heraeus; Z250, 3M-ESPE) were measured according to ISO-4049 using high-irradiance LCUs (FlashMax-P3, CMS-Dental; SPEC3, Coltene) and conventional LCU (Paradigm, 3M-ESPE) for exposure times: 3/9-s, 3/20-s, and 10/20-s respectively. Using FTIR, the DoP per composite was measured at the bottom surface as a function of post-curing times for the LCUs at the same exposure times.