Haline Drumond Nagem

Surface roughness of composite resins after finishing and polishing

This study evaluated the effect of surface finishing methods on the average surface roughness of resin composites. Seven composites and two polishing systems were used. One hundred and twenty-six conical specimens of each material were prepared in stainless steel molds against a polyester strip. Forty-two of them remained intact and were used as controls. Each half of the remaining samples was polished with either diamond burs or diamond burs + aluminum oxide discs. The results showed no statistical difference in average surface roughness (Ra, microm) between the polyester strip and aluminum oxide discs (p > 0.05). However, finishing with diamond burs showed a statistically higher average roughness for all composites (p < 0.05). Statistical differences were detected among materials (p < 0.05) in the use of diamond burs.

VOLUMETRIC POLYMERIZATION SHRINKAGE OF CONTEMPORARY COMPOSITE RESINS

The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (á=0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01) and Definite (1.89±0.01) shrank significantly less than the other composite resins. SureFil (2.01±0.06), Filtek Z250 (1.99±0.03), and Fill Magic (2.02±0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

Propriedades do paramonoclorofenol canforado e paramonoclorofenol canforado associado ao hidróxido de cálcio

Resumen pt: Objetivo: Avaliar a biocompatibilidade do paramonoclorofenol canforado na proporcao 3,5:6,5 (PMCC) e do paramonoclorofenol canforado associado ao hidro...