Marginal quality of cervical restorations, made with materials of different modulus of elasticity, in premolars subject to eccentric occlusal loading

Abstract

Restorative materials used in the cervical region of teeth may be subjected to resultants of eccentric occlusal loads, which may have already contributed to the formation of the lesion, and should be capable of withstanding the stresses. There is no consensus, however, about the role of the modulus of elasticity of such materials in the success of the respective restorations. This in vitro study aims to evaluate the influence of the use of materials with different elastic moduli, and of the association between them, on marginal quality of cervical restorations in premolars subjected to eccentric occlusal loading. Cervical wedge-shaped standardized cavities, prepared in 60 human upper single-rooted premolars, healthy and extracted, will be restored with a composite resin (Z250 XT®; groups RCt-test and RCc-control); with the resin in combination with a resin-modified liner ionomer (Vitrebond®; Mt and Mc), and with a resin-modified restorative ionomer (Vitremer®; CIVt groups and CIVc). Embedded in acrylic resin, with their roots wrapped by an artificial ligament, test teeth will be subjected to an eccentric occlusal loading (Biocycle Pneumatic Mechanical Cycler - Biopdi, dynamic load by the action of a torpedo-shaped metal tip, 150 N, 1000000 cycles, 2.5 Hz). Control teeth will be only stored in deionized water at 37°C. A fluorescein-marked adhesive system will be used for delimitation of possible formed defects, which will be evaluated by means of laser scanning confocal microscopy. For qualitative variables (presence/absence and location of marginal gaps) the chi-square test will be applied; for quantitative variables (width and depth of the gaps), if sampling distribution is normal and homogeneous, one-way ANOVA and, if necessary, Tukey tests (p<0.05) will be applied. (AU)