Does Post-etching Cleaning Influence Bond Strength of Lithium Disilicate Laminate Veneers?

This paper aims to present a clinical case of laminate veneers in lithium disilicate (LD) reinforced ceramic, complemented with scanning electron microscopy and energy dispersive x-ray spectroscopy analysis of this ceramic's surfaces submitted to some of the different post-etching cleaning protocols proposed by literature. Many dentists are applying all-ceramic restorations, especially veneers, with the most applied material being LD, due to its good mechanical properties, esthetics, and ability to adhere to tooth substrate. The cementation process is critical to clinical success of indirect restorations. Combination of hydrofluoric acid and silane application on the inner surface of ceramic has been the most recommended method to increase bond strength between ceramic and tooth substrate. As a result of surface corrosion, residual subproducts are formed and precipitate on the ceramic surface, affecting the bonding process to the resin cement. Elimination of residue is recommended in the literature and can be done via 3 common techniques: thorough washing with air/water spray for 30 seconds, 37% phosphoric acid for 60 seconds, or ultrasonic bath for 4 to 10 minutes. Little information on LD ceramics post-etching cleaning methods is available in the literature. For this ceramic, the thorough washing with air/water spray for 30 seconds appeared to remove most of the residue without damaging the material. Being also the most practical and easiest of the reviewed procedures, it was, therefore, the protocol of choice for the clinical cases presented in this paper with success after 18 months.