Effect of the Superficial Treatments to Porcelain Repair: SEM Evaluation

About 16% of the failures in FPD are associated with fracture of the porcelain. However, the whole replacement is not always feasible considering the economic, esthetic and biologic point of view. So, different surface treatments are used to improve bond strengths between porcelain and composite resin making the repair feasible. Objectives: the aim of this study was to analyze the ceramic surface etched with 37% phosphoric acid and 9.5% hydrofluoric acid with the scanning electron microscope. Methods: forty ceramic samples (VITA Zahnfabrik, Germany) were made by using a circular metallic mold with a diameter of 10mm and a high of 3mm. The samples were randomly divided in the following groups, I) control – the samples were not etched; II) the samples were etched with 9.5% hydrofluoric acid for 1 minutes; III) etching with hydrofluoric acid for 2 minutes; IV) etching with phosphoric acid for 1 minute; V) etching with phosphoric acid for 2 minutes. After the respective treatments, the samples were gold-coated (20Kv, 15mA, 2 minutes), using the Denton Vaccum Desk II machine, and then were put on a support for the analysis on the SEM (JEOL – JSM 5410). Results: the surfaces etched with 37% phosphoric acid for 1 and 2 minutes (Groups IV and V) didn't show any morphologic changes, while the ceramic surface etched with 9.5% hydrofluoric acid for 1 minute (Group I) showed morphologic changes and this fact was more evident when the ceramic surface were etched with hydrofluoric acid. Conclusions: clinically, this study suggests a repair more efficient when the ceramic surface is etched with hydrofluoric acid.