Compressive strength evaluation of thin occlusal veneers from different CAD/CAM materials, before and after acidic saliva exposure

Abstract

In the present study are depicted valuable observations for practitioners, obtained from an in vitro study which aims to evaluate the compressive strength of occlusal veneers fabricated from 3 type of restorative materials, before and after 1 month of acidic artificial saliva exposure (pH = 2.939). In this context, 90 extracted human molars were prepared to receive computer-aided design/computer-aided manufacturing (CAD/CAM) occlusal veneers. The restorative materials considered in this study were: Cerasmart; Straumann Nice and Tetric CAD. The occlusal veneers were designed, milled and cemented with an adhesive dual-cure resin cement. From all the extracted human molars, only sixty specimens were immersed in acidic artificial saliva, for 1 month, at 37 °C ± 1 °C and part of this specimens were also thermo-cycled, between 5 and 55 °C ± 2 °C, before compressive strength test. The results showed a lower compressive strength for both the samples exposed to acidic artificial saliva as well as for the samples exposed to acidic artificial saliva and thermo-cycled. Scanning electron microscopy (SEM) showed that after compressive strength, all the specimens non-exposed to acidic artificial saliva, present extensive cracks formation at the surface of the restorations, and after exposure to acidic artificial saliva for 1 month, the surface damage was characterized by longitudinal and profound fractures of the restoration, as well as the fracture of the tooth structure. Between CAD/CAM materials tested, nanoceramic resin shows more favorable fracture patterns, both before and after acidic artificial saliva exposure.

Influence of Storing Composite Filling Materials in a Low-pH Artificial Saliva on Their Mechanical Properties—An In Vitro Study

“…Some authors have observed lower crush resistance values when samples are stored in a low-pH artificial saliva. This type of test can also help determine changes inside composite materials subjected to the action of various factors [ 33 ].…”

The Biological Activity of Fragmented Computer-Aided Design/Manufacturing Dental Materials before and after Exposure to Acidic Environment

“…The protocol used for the preparation of acidic artificial saliva was extensively described in the previous study published by our research group [ 43 ]. Briefly, the artificial saliva was obtained by weighing NaCl, KCl, CaCl 2 ·2H 2 O, and CO(NH 2 ) 2 in a mass ratio of 1:1:2:2.5 and dissolved in 1 L of distilled water, until a clear solution was obtained.…”

Chairside CAD/CAM Restorations

“…The findings of various investigations on the partial coverage of ceramic restorations are inconclusive. Even though most manufacturers advise posterior ceramic restorations to have a minimum thickness of 1.5 mm, several research studies have examined ceramic restorations with a thickness of 1.0 mm or even less that have excellent long-term clinical results [68][69][70][71][72][73][74].…”