RESUMEN
BACKGROUND: Repairs in composite resin restorations are common procedures in clinical practice. Many surface treatment options have been proposed to improve the adhesion between the old and new composite. The objective of this study was to evaluate the microtensile bond strength of repairs performed on aged bulk fill and conventional composites after different adhesion protocols. MATERIAL AND METHODS: First, 84 specimens (8x8x4 mm3) of a microhybrid composite and a high-viscosity bulk fill composite were prepared and aged. Afterward, they received a mechanical surface treatment by means of abrasion with a diamond bur, followed by division into six groups according to the adhesion protocol employed: PSA - etching with 35% phosphoric acid + silane + etch-and-rinse adhesive; SA - silane + etch-and-rinse adhesive; PA - etching with 35% phosphoric acid + etch-and-rinse adhesive; A - etch-and-rinse adhesive; PU - 35% phosphoric acid + universal adhesive; and U - universal adhesive. The repairs were performed with a microhybrid composite. Repaired resin blocks were cut into sticks (8x1x1 mm3) and submitted to a microtensile test. Fractured specimens were evaluated to determine the failure pattern (adhesive or cohesive). Data were analyzed by two-way ANOVA. RESULTS: No statistically significant differences were found in bond strength values among different adhesion protocols and composite types. CONCLUSIONS: The repair bond strength of a bulk fill composite was similar to that found in a conventional composite, with no distinction among adhesion protocols. Key words:Dental restoration repair, composite resins, adhesiveness.
RESUMEN
INTRODUCTION: This study was an ex vivo evaluation of the accuracy and repeatability of 3 electronic apex locators (EALs) in locating simulated root canal perforations. METHODS: Thirty-five human teeth were used. Perforations were placed 5 mm from the apex of each specimen. A #15 K-file was attached to a micrometer, and the specimens were fixed in a mounting model. The EALs were connected to the files, and electronic measurements of the simulated perforations were obtained. This procedure was repeated, the files were cemented in place, and x-rays were obtained to evaluate the distances between the measurement files and the simulated perforations. The obtained results were compared with the corresponding control lengths. Three investigators evaluated the distance of the file position in relation to the perforation for each specimen. The 3 investigators reached consensus regarding these measurements. RESULTS: Statistical analyses of the results revealed that the EAL reliabilities in the exact detections of the root canal perforations were 97.1% for the Mini Apex Locator, 100% for the Root SW, and 91.4% for the Root ZX II. Analysis of variance revealed that the accuracies of the 3 devices were not different (P > .05). The results also indicated high levels of repeatability for each of the 3 EALs (intraclass correlation coefficients: 0998, 0.999, and 0.999 for the Mini Apex Locator, Root SW, and Root ZX II, respectively). CONCLUSIONS: It was concluded that each of these 3 EALs provided excellent ex vivo accuracy in locating root perforations and that all tested devices possess excellent ex vivo repeatability.
