Influence of thickness and restorative system on the mechanical behavior of CAD/CAM minimally invasive occlusal veneers: an in vitro study.

Abstract

Aim: The aim of the present study was to evaluate the physical-mechanical behavior of occlusal veneers when subjected to thermomechanical cycling.

Materials and methods: Sixty specimens were divided into four groups (n = 15) according to different restorative materials and thicknesses: lithium disilicate (IPS e.max CAD) and nano-ceramic resin (Lava Ultimate) materials at thicknesses of 0.6 and 1.2 mm. The occlusal veneers were bonded over human freshly extracted flattened molars with dual-polymerizing luting agent (Variolink N and RelyX Ultimate) using the respective adhesive systems following the selective-etch technique (self-etch in dentin and total-etch in enamel). The resin cement was light cured for 40 s on each face using light-emitting diode (LED) light-cure equipment (Blue Star 2; 1100 mW/cm2). The response variables were veneer survival rates (crack formation, catastrophic cracks, and debonding) when subjected to thermal cycling from 5°C to 55°C and simultaneous mechanical cycling performed at load intensities of 100, 200, 300, 400, and 450 N for 20,000 cycles each.

Results: Data were submitted to the Kruskal-Wallis test and pairwise comparison, adopting a significance level of 5%. The occlusal veneers made of nano-ceramic resin presented a lower incidence of failures (P 0.05) than those made of lithium disilicate. According to the thickness factor, 1.2-mm-thick occlusal veneers withstood higher cycling loads.

Conclusion: The occlusal veneers made of nano-ceramic resin with a 1.2-mm thickness presented superior physical-mechanical behavior than those made of lithium disilicate with a 0.6-mm thickness. (Int J Comput Dent 2025;28(3):275-0; doi: 10.3290/j.ijcd.b5290647).