Self-etching Primers vs Acid Conditioning: Impact on Bond Strength Between Ceramics and Resin Cement

Abstract

This study tested whether a self-etching surface agent and the conventional hydrofluoric acid (HF) would provide the same bonding capacity between resin cement and feldspathic (Fd) and lithium disilicate (Ld) ceramics. Ceramic blocks were cut with a low-speed diamond saw with water cooling (Isomet 1000, Buehler, Lake Bluff, IL, USA) into 20 blocks of 5 × 7 × 4 mm, which were ground flat in a polishing machine (EcoMet/AutoMet 250, Buehler) under water cooling. The blocks were randomly divided into eight groups (n=5), according to ceramic type (Ld or Fd), surface conditioning (HF + Monobond Plus or Etch and Prime), and aging by thermocycling (TC or absence-baseline). After 24 hours in 37°C distilled water, blocks were embedded into acrylic resin and 1-mm cross-section beams composed of ceramic/cement/composite were obtained. The microtensile test was performed in a universal testing machine (DL-1000, EMIC, São José dos Campos, Brazil; 0.5 mm.min, 50 kgf load cell). Bond strength (MPa) was calculated by dividing the load at failure (in N) by the bonded area (mm). The fractured specimens were examined under stereomicroscopy, and one representative sample of each group was randomly selected before the cementation and was further used for analysis using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). The self-etching agent showed the highest bond strength for Fd (24.66±4.5) and Ld (24.73±6.9) ceramics and a decrease in surface wettability. SEM and EDS showed the presence of similar components in the tested materials with different topographies for both. Therefore, the self-etching primer was able to deliver even higher bonding than HF+silane to a resin cement.

Effect of hydrofluoric acid concentration and etching time on resin-bond strength to different glass ceramics

“…The failure modes were classified as: a) adhesive at the ceramic / cement interface (ADHES cer / cem); b) cohesive in ceramic (COHES cer); c) cohesive in cement (COHES cem); and D) mixed adhesive/cohesive failure (adhesive failure at the ceramic/cement interface + predominantly cohesive failure in cement or in ceramic). 23…”

Influence of Shear Bonding Strength of Lithium Disilicate to Enamel under Different Surface Treatments

“…This could be related to the intimate contact of enamel to light cure resin cement, consequently, to improve the overall bond strength. Tribst et al 11 have presented both ceramics for HF-treated surfaces based on contact angles and wettability. The study has indicated that the exposure of chemical ligands and removal of the glass matrix is likewise in both tested ceramics.…”

“…However, the surface wettability should be influenced by any overtreatment for increasing the number of pores. Tribst et al 11 have further assessed and compared the ceramic-resin cement adhesion strength after undertaking one-step and two-step conditioning systems. Acid etching and primer application was independently carried out in the conventional two-step conditioning system.…”

“…In particular, a milder acidity is observed in ammonium polyfluoride as compared to hydrofluoric acid, resulting in weaker etching pattern. 11 Several prior studies have been conducted to compare the efficiency of the protocol using 2step surface treatments and silane followed by concentration and application times. [12][13][14] Comparative outcomes are provided by these studies on field-emission scanning electron microscopic analysis, micromorphological analysis, tensile bond strength, shear bond strength, and contact angle.…”

“…Hydrofluoric acid and primer/silane coupling agents were used for the ceramic side as they create a porous surface on the ceramic that allow a good interaction with silane coupling agent. 11 Despite of the advantages of the HF acid etching followed by silane application, the protocol of etching ceramics is still not clear. 10 In this regard, the study aims to evaluate the changes in surface treatment protocols on the tensile bonding strength between enamel and ceramic restorations (lithium disilicate).…”