[Effect of bleaching on microhardness of two nanofilled and one microhybrid composite resins]

Discolored teeth can be treated by various techniques, including direct composite resin veneers, indirect porcelain veneers, ceramic crowns and bleaching agents. The aim of this study was to evaluate the effect of at-home and in-office bleaching agents on the surface microhardness of one microhybrid [Point 4] and two nanofilled [Filtek Supreme and Premise] composite resins. Opalescence PF with 20% carbamide peroxide and Opalescence Quick with 35% carbamide peroxide were used as at-home and in-office bleaching agents, respectively. Fifty samples from each composite resin, including Point 4 microhybrid, Premise and Filtek Supreme nanofilled composites resins were prepared and exposed to bleaching agents. For each composite resin the samples were randomly divided into five groups of 10 and designated as: control, two-week at-home, four-week at-home, one-time in-office and two-times in-office bleaching groups with two-week intervals. After the appropriate bleaching procedures on samples of each group, microhardness measurements were carried out on each sample. Data was analyzed using ANOVA and post hoc Tukey HSD test [p value < 0.05]. There were significant differences in mean surface microhardness values of each composite resin type. No significant differences were observed in mean microhardness values of Point 4 between four-week at-home and one-time office, Filtek Supreme between two-week at-home and four-week at-home, and Premise between one-time in-office and two-time in-office bleaching groups. Under the limitations of the present study, it was concluded that the microhardness of three composite resins tested in the present study were affected by bleaching agents

[Diastema closure with composite resin using a new direct technique: a case report]

One of the main problems in esthetic dentistry is closing diastema between teeth with a direct technique without creating the black triangle [gingival embrasure lacking papilla]. Black triangle will ruin the patients' smile and is not desirable. Composite resin used to close diastema should have adequate convexity from gingivo-incisal direction to avoid this problem. Various techniques have been introduced to close diastema, some of which are time-consuming or cannot provide proper contour. This article describes a case in which diastema between two teeth was closed with direct composite resin with minimum amount of time. Although closing diastema with direct composite depends on operator skill in most part, this technique is probably less dependent on operator skill compared to other techniques. Closing diastema between anterior teeth with composite resin with direct technique is conservative and timesaving, and the presented technique which provides adequate contour can be carried out very easily by many dental practitioners