RESUMO
The purpose was to evaluate the effect of tris(trimethylsilyl)silane (TTMSS) associated with diphenyl iodonium hexafluorophosphate (DPIHP) on the polymerization shrinkage stress (PSS), mechanical properties, color change (CC), and degree of conversion (DC) of resin-based composites (RBCs). Experimental RBCs containing 35 wt% of organic matrix (10.2 wt% BisGMA, 11.1 wt% BisEMA10 and UDMA and 2.1 wt% TEGDMA) and 65 wt% filler (13 wt% fumed silica and 52 wt% BaBSiO2) were assigned to six groups: control (0.2 wt% CQ, 0.5 wt% DMAEMA); TD05 (0.2 wt% CQ, 0.5 wt% TTMSS, 0.5 wt% DPIHP); TD10 (0.2 wt% CQ, 1 wt% TTMSS, 0.5 wt% DPIHP); DTD (0.2 wt% CQ, 0.25 wt% of DMAEMA, 0.25 wt% TTMSS, 0.5 wt% DPIHP); DT (0.2 wt% CQ, 0.25 wt% DMAEMA, 0.25 wt% TTMSS); and T05 (0.2 wt% CQ, 0.25 wt% TTMSS). The experimental formulations were submitted to the following tests: DC; PSS; CC; rate of polymerization (Rp); depth of cure by Knoop hardness; flexural strength; and flexural modulus. TTMSS showed no effect on the DC, Rp, and mechanical properties of the RBCs. DMAEMA reacted with TTMSS and reduced the Rp; the RBCs containing no DMAEMA showed no reduction in CC. DT showed the lowest PSS mean value among the groups. TTMSS differed from DMAEMA only when used in combination with DPIHP, which significantly improved the DC, maximum Rp, and mechanical properties of the RBCs tested. Based on the artificial ageing results, TTMSS was ineffective in reducing CC in the RBCs tested.
