Effect of Different Computer-aided Design/Computer-aided Manufacturing (CAD/CAM) Materials and Thicknesses on the Fracture Resistance of Occlusal Veneers

Abstract

The aim was to evaluate, in vitro, the influence of different computer-aided design/computer-aided manufacturing (CAD/CAM) materials (IPS e.max CAD, Vita Enamic, and Lava Ultimate) and thicknesses (0.6 mm and 1.5 mm) on the fracture resistance of occlusal veneers. Sixty human third molars were prepared to simulate advanced erosion of the occlusal surface, and the teeth were randomly divided into six experimental groups (n=10) according to the material and thickness used to build the veneers. Ten sound teeth formed the control group. The veneers were adhesively luted and submitted to mechanical cyclic loading (1 million cycles at 200-N load). The fracture resistance test was performed in a universal testing machine. The failures were classified as "reparable" and "irreparable." According to two-way analysis of variance and the Tukey test, the interaction (material × thickness) was significant ( p=0.013). The highest fracture resistance was obtained for IPS e.max CAD at a 1.5-mm thickness (4995 N) and was significantly higher compared to the other experimental groups ( p<0.05). The lowest fracture resistance was obtained for Vita Enamic at 0.6 mm (2973 N), although this resistance was not significantly different from those for IPS e.max CAD at 0.6 mm (3067 N), Lava Ultimate at 0.6 mm (3384 N), Vita Enamic at 1.5 mm (3540 N), and Lava Ultimate at 1.5 mm (3584 N) ( p>0.05). The experimental groups did not differ significantly from the sound teeth (3991 N) ( p>0.05). The failures were predominantly repairable. The occlusal veneers of IPS e.max CAD, Vita Enamic, and Lava Ultimate, with thicknesses of 0.6 mm and 1.5 mm, obtained fracture resistances similar to those associated with sound teeth.

Influence of preparation designs on marginal adaptation and failure load of full‐coverage occlusal veneers after thermomechanical aging simulation

“…Bonded occlusal veneers made of e.max CAD were found to resist to forces of up to 800 N and 1000 N, when their thickness was 0.6‐1.0 mm or 1.2‐1.8 mm, respectively; these values are only slightly inferior to those of monolithic full crowns of comparable thickness . The use of ultrathin LDG occlusal veneers (0.6 mm) has been reported to be a promising and viable restorative procedure . Further, Guess et al reported no significant effect on the fracture resistance of pressable LDG ceramic onlay restorations on premolars reducing the preparation depth to 1.00 and 0.5 mm.…”

“…22 The use of ultrathin LDG occlusal veneers (0.6 mm) has been reported to be a promising and viable restorative procedure. 23,24 Further, Guess et al 25 reported no significant effect on the fracture resistance of pressable LDG ceramic onlay restorations on premolars reducing the preparation depth to 1.00 and 0.5 mm.…”

Brittleness index and its relationship with materials mechanical properties: Influence on the machinability of CAD/CAM materials

“…The developments of CAD/ CAM technology combined with the new ceramic materials specifically designed for this technology are attracting the curiosity of many researchers. 5,9,10,[29][30][31] The principles of chair-side CAD/CAM are becoming increasingly accepted among clinicians and universities, changing the common way of learning indirect restorations and providing access to their application by more professionals in their practices. 10,32,33,34 A new skill is becoming of major importance for future dentists, improving their competence and ability to do digital restorations.…”

“…This technology reduces the distortions caused by standard methods and eliminates numerous laboratorial phases that could be complicating factors during the manufacturing process. 8,9,10 Dental ceramics and polymer-based materials can be easily fabricated with CAD/CAM technology, with desirable properties due to adequate environment where it is produced. 10,11,12 CAD/CAM technology provides powerful restoration and conservative preparation; however, for best performance the materials should be chosen during the treatment planning.…”

“…8,9,10 Dental ceramics and polymer-based materials can be easily fabricated with CAD/CAM technology, with desirable properties due to adequate environment where it is produced. 10,11,12 CAD/CAM technology provides powerful restoration and conservative preparation; however, for best performance the materials should be chosen during the treatment planning. 5,11,12,13 The digital system allows preparations that are less complex and also less invasive; in addition, it provides the same strength of other treatment options.…”