Micro tensile strength and surface appearance of a CAD/CAM nanoceramic resin treated by different etching methods

Abstract

Introduction: CAD/CAM polymer infiltrated ceramic materials need micromechanical and chemical treatments that modify their surface and favor adhesion to dentin of indirect restorations. Objective: To evaluate in vitro the micro tensile strength caused by the combination of micro-sandblasting (MS) plus hydrofluoric acid (HF10%) applying a universal adhesive (UA) on LavaTM Ultimate (LVU) specimens. Materials and methods: LVU resin nanoceramics (3M ESPE, St. Paul, MN, USA) were used. The samples were divided into 4 groups: Group 1: Control (No treatment), Group 2: MS with50 μm Al2O3 (Zeta Sand Zhermarck Dental SpA, Italy) + UA (All-®Bond Universal Bisco Inc. Schaumburg, IL). Group 3: Etching with 10% FA Angelus® (Solucoes Odontologicas, Londrina, Brazil) + UA, group 4: MS + FA + UA. Specimens were cemented with Duo-LinkTM dual resin (Bisco Inc. Schaumburg, IL) in the middle dentin of extracted third molars. After 24 h, micro tensile testing was performed. The failure mode of the samples was recorded under a stereomicroscope at 20X. Surface roughness and appearance were evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Results: surface treatment of LVU with MS +FA + UA showed significant differences in microtractional strength (p < 0.011). The predominant failure mode in the groups was adhesive. A significant correlation was identified by observing that the higher the roughness of the treated surface the higher the micro-tractional resistance (r = 0.88). Conclusions: LVU nanoceramic resin etched with MS and FA creates a surface roughness that combined with a UA increases the adhesive strength resistance in dentin.