Marginal Adaptation of BIS-GMA-based Composites Containing Various Diluents

Abstract

The aim of this study was to determine how otherwise acceptable diluent monomers affect the marginal adaptation of BIS-GMA-based composites. Based on the results of the investigation, the following conclusions can be drawn: 1. Addition to dimethacrylate diluents containing (CH2) recurring units generally yields composites having better marginal adaptation than do those containing (CH2 CH2 O) groups. Best marginal adaptation for a single diluent is obtained for compositions using 1, 4 and 1, 10-polymethylene glycol dimethacrylate as diluent. 2. Marginal adaptation is improved on lowering the diluent concentration. Optimum adaptation will be obtained for a formulation containing a minimum percentage of diluent with clinically acceptable working properties. 3. Volume changes on temperature cycling resulting from differences in thermal expansion coefficients of composites do not effect the marginal integrity as much as does curing shrinkage.

Degree of conversion of seven visible light‐cured posterior composites

“…The type and concentration of diluent used will affect the molecular weight, cross-linked density and residual tnonomer of the cured resin (Brauer et al, 1981). The advantages of using the bulky difunctional monomer Bis-GMA rather than a smaller tnonofunctional monomer, such as methyl methacrylate, were reported as better clinical performance in terms of better marginal adaptability and lower order of toxicity because of reduced volatility and tissue penetration (Antonucci, 1981).…”

Properties and interactions of oral structures and restorative materials

“…The stresses resulting from the contraction of the organic phase of composites can result in microcracks, filler debonding and marginal gap formation. [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] Elaborate layering methods for composite placement [55,56] and time consuming multi-step bonding protocols [52] have failed to provide a composite-dentin interface which can reliably withstand the contractile forces and remain intact. The resulting gap formation at either the surface margin or the cavity base can promote staining and/or secondary caries formation, both of which can necessitate replacement of the restoration.…”