Effect of thermo-mechanical load cycling on silorane-based composite restorations

Abstract

The aim of this study was to compare the formation of marginal gaps after thermo-mechanical load cycling, between siloranebased and methacrylate-based restorations. Standardized class II cavities were made in 10 permanent human third molars that were restored with the adhesive system Clearfil SE Bond+composite Filtek Z-350 (Methacrylates) and with the composite bonding Filtek P90+P90 (Siloranes), respectively. After 24 h of storage in 100% humidity at 37°C, the restoration margins were stained, photographed, and evaluated. The gap length was calculated as the percentage of the total length of the margins. Thereafter, the specimens were tested by a thermo-mechanical machine and the marginal gap formation of the specimens was re-evaluated. The results were expressed as percentages of gaps and were submitted to a Mann Whitney test at 5% level of significance. Methacrylates showed a statistically significant higher percentage of gaps than Siloranes, both before and after cycling.

Surface Properties and Color Stability of Resin-Infiltrated Enamel Lesions

“…Repeated temperature fluctuations in the oral cavity may induce degradation of resin-hydoxyapatite bonds due to differences in thermal expansion coefficients between enamel hydroxyapatite and the infiltration resin. 38,39 Thermal stress may also affect the surface integrity of resin-infiltrated enamel lesions as indicated by the presence of surface microcracks and microfissures after thermocycling challenges (Figure 3). These changes in surface properties may contribute to staining and discoloration of resin-infiltrated surfaces.…”

Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

“…These stresses are expected to increase the width of existent gaps or develop other gaps. Increased gaps have been demonstrated after mechanical and/or thermal cycling 4,8,22 . Contradictorily, this was not observed in the present study.…”

Surface Properties of Resin-Infiltrated Incipient Enamel Lesions After Aging Under Thermal Stresses

“…Alternating temperature fluctuations in the oral environment may enhance bond degradation between the infiltrating resin and enamel hydoxyapatite because of differences in coefficients of thermal expansion between them. 28,29 Regarding surface roughness, our results indicated that resin infiltration could provide smoother enamel surface, as compared to untreated lesions. On exposure to thermal challenge, Icontreated specimens could maintain smoother surface, both at 5000 and 10,000 cycles.…”