17 - Mechanical and optical properties of composites containing calcium orthophosphate particles

• Published in: Dental materials Vol. 39; p. e15
• Main Authors: Trinca, RB, Almeida Oliveira, B, dos Santos Vilela, H, Braga, RR
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 2023
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/j.dental.2023.08.032

The aim of the study is to evaluate the flexural strength and modulus, and color change/transmittance of experimental resin composites containing different dicalcium phosphate dihydrate (DCPD)-to-barium glass ratio and two different DCPD particle sizes. The null hypotheses were (1) the DCPD: glass ratio and (2) DCPD particle size do not change the mechanical and optical behavior of the composites. A series of ten resin-based composites were prepared. The organic matrix was constituted by an equimolar mixture of BisGMA and TEGDMA. The inorganic phase consisted of both silanated barium glass (median: 0.4 μm) and DCPD particles (pristine: 12 μm, milled: 3 μm or a mixture of both in equal parts) at a fixed volume fraction of 50% and different DCPD:glass ratios (3:1, 1:1 and 1:3). A composite without DCPD was used as a control. Degree of conversion (DC, n=3) was determined using near-infrared spectroscopy, biaxial flexural strength and modulus were measured for disc-shaped specimens (12 ×1.2mm², n=10). Color change (ΔE) and transmittance at 468nm were evaluated using a spectrophotometer (n=3). Data were analyzed by ANOVA/Tukey test (a:0.05) The DC of the composites ranged from 74.3% to 77.1% (p>0.05). Biaxial flexural strength was not affected by the size of the DCPD particles but was strongly dependent on the DCPD:glass ratio (in MPa, 3:1: 71-74, 1:1: 35-99, 1:3: 111-115 and control: 123, p<0.001). DCPD:glass ratio is a significant factor on the flexural strength of resin composites, while DCPD particle size affected the flexural modulus and the optical behavior. The null hypotheses were rejected (FAPESP 2019/04737-4 and 2020/13983-6).