Comparison of Resin Cement Insertion Techniques for Luting Fiberglass Posts

Objective: To evaluate the effect of two insertion techniques of self-adhesive dual resin cement on the bond strength of fiberglass posts in different portions of the root. The homogeneity of the cement layer along the root canal was also evaluated. Material and Methods: The root canals of 28 bovine teeth were instrumented, filled, and 14mm-space was prepared for luting fiberglass posts (Reforpost #3, Angelus), maintaining 4mm of apical sealing. The roots were randomly allocated into two groups according to the cement insertion technique (n=14): Lentulo Drill (Dentsply/Maillefer) or Centrix syringe (Dentsply). The posts were fixed with self-adhesive resin cement (RelyX U200, 3M ESPE). After 7 days, the roots were cross-sectioned to obtain three 1.0-mm-thick samples of each third of the space prepared for the post. Two samples of each third were subjected to push-out test (0.5 mm/min; 200N) and the third specimen was used for the analysis of cementation layer homogeneity. Images of specimens (40x magnification) were assessed and classified by two calibrated examiners (Kappa = 0.87) according to the presence or absence of voids and misfit. Data were analyzed by two-way ANOVA and Pearson Chi-Square test. Results: There was no statistically significant effect of insertion technique (p=0.278) or post-space thirds (p = 0.521) on bond strength of fiberglass posts. Chi-Square test showed that cement insertion with the Lentulo drill produced more cement voids than Centrix syringe (p = 0.023). Conclusion: The cement insertion technique did not influence bond strength of fiberglass posts in bovine root dentin. The use of Centrix syringe for cement insertion is preferred since it produced more homogenous cement layer.

Facetas indiretas unitárias: previsibilidade na obtenção de cor / Unitary indirect veneers: previsibility in the color obtaining

A previsibilidade de trabalhos restauradores estéticos, sejam eles diretos ou indiretos, é reconhecidamente um dos maiores desafios ao cirurgião-dentista, principalmente em casos de facetas indiretas ou coroas unitárias. Atualmente, estão disponíveis no mercado odontológico cimentos de resina com grande diversidade quanto a tipo de presa e cores. Com respeito à diversidade de cores, podem ser utilizados cimentos de diferentes matizes, opacidade e viscosidade, a fim de realizar pequenas correções em função do substrato a ser mascarado ou da própria restauração. Para decidir a cor mais adequada a ser utilizada em cada caso, utilizamse as chamadas pastas simuladoras ou tryin. Essa opção consiste em pastas matizadas não polimerizáveis, hidrossolúveis, cujas cores correspondem a seu respectivo cimento, permitindo que haja previsão do resultado estético final.