Germana Coeli de Farias Sales

In vitro biological response to a self-adhesive resin cement under different curing strategies

Self-adhesive resin cements represents a new approach in indirect restorative dentistry, although little is known about its biological properties. The influence of the curing strategy on the biological response of a self-adhesive resin cement (Rely-X Unicem/3M ESPE) was evaluated through methyltetrazolium (MTT) and nitric oxide (NOx) assays. Cylindrical specimens (n = 48) were prepared and cured according to the following strategies: photoactivation with halogen light-curing unit (LCU) Demetron/Kerr, LED LCU Radii/SDI, and chemical activation. A control group with culture medium and a group with lipopolysaccharide, employed for cells stimulation, were used for comparisons (n = 8). After 24 h of direct contact between specimens and rat alveolar macrophages, the biological response was evaluated. Statistical evaluation of the data was performed with Kruskal-Wallis and Dunns test (p = 0.05). The MTT test showed that the specimens cured by halogen light and chemical activation provided higher alterations on cell metabolism. For LED-cured specimens, cell viability was compatible to the results observed in the control group. For the NOx assay, all curing methods were cytotoxic to rat macrophages. Rely-X Unicem demonstrated different cytotoxic effects according to the curing strategy employed.

INFLUÊNCIA DA PRESENÇA DO CÁLCIO EM AGENTES CLAREADORES E SUA RELAÇÃO COM A MICRODUREZA DO ESMALTE DENTAL HUMANO

Objective: This study examined the microhardness of tooth enamel exposed to the bleaching agent hydrogen peroxide 35%, with or without calcium in its composition in order to ascertain whether the addition of this substance influences the change in microhardness. Material and methods: The samples were composed of ten intact human third molars, of which three fragments were obtained, so that each fragment from the same tooth was part of a different group. Group B consisted of ten samples, bleached with hydrogen peroxide 35% containing calcium. Group M consisted of ten samples, bleached with hydrogen peroxide at 35% without calcium, and group C (control) consisted of ten samples immersed in artificial saliva. The microhardness was evaluated before the treatment and after three sessions with an interval of seven days between them. Results: In Group B there was an increase of 5.47% in microhardness, considered significant, assigned to the presence of calcium in the bleaching agent. There was a reduction of 2.59% and 0.64% in groups M and C respectively, both considered nonsignificant. Conclusion: It was concluded that the presence of calcium in the whitening gel increases the microhardness of the bleached enamel, providing a remineralization of this substrate.

Effect of periodontal disease on the bond strength of fiber post cemented with different adhesive systems and resin luting agents

The objective of the present study was to determine the effect periodontal disease on the bond strength of fiberglass posts, different adhesive systems and resin cements. Ninety human maxillary central incisors roots extracted due to periodontal disease or prosthetic reasons were endodontically treated and divided into six experimental groups: NPD-ARC – no periodontal disease/RelyX ARC and Adper Single Bond 2; NPD-PF – no periodontal disease/Panavia F and ED Primer; NPD-U – no periodontal disease/RelyX U100; PD-ARC – periodontal disease/RelyX ARC and Adper Single Bond 2; PD-PF – periodontal disease/Panavia F and ED Primer; and PD-U – periodontal disease/RelyX U100. Specimens were subjected to push-out test and data were analyzed by two-way ANOVA and Tukey’s test (p = 0.05). The periodontal disease groups showed that the Panavia F/ED Primer group presented no significantly higher mean values compared with RelyX U100, and that both presented significantly higher mean values when compared with RelyX ARC/Single Bond 2 group. These results were also observed in roots with no periodontal disease. There were no differences in bond strength mean values of roots related or not to periodontal disease.

INFLUÊNCIA DO POLIMENTO SUPERFICIAL NA RETENÇÃO DE PLACA BACTERIANA EM RESTAURAÇÕES ESTÉTICAS

Objective: The aim of this study was to evaluate the influence of superficial finishing and polishing procedures on bacterial plaque retention of composite resin restorations. Material and Methods: Twenty patients participated in the study presenting forty restored surfaces in various classifications of cavities, cervical edges and types of teeth. The finishing and polishing procedures were performed with polishing discs (TDV), silicone points (Optimize – TDV) and strips polishing (3M). To verify plaque retention was used Index Retention and Extension Plaque in Restoration – IRPR, applied before polishing and after 7 and 14 days. Results: The results showed that, before polishing, most of surfaces presented plaque retention on highest levels of IRPR, and after polishing there was reduction and also absence of plaque retention, demonstrated by the lowest levels of IRPR. Conclusion: It was concluded that the polishing materials and the technique used were effective in reducing bacterial plaque retention over restored surfaces, and that IRPR is an efficient method to demonstrate the plaque retention on esthetic restoration.