Fracture Resistance and Failure Mode of Mandibular Molar Restored by Occlusal Veneer: Effect of Material Type and Dental Bonding Surface

Abstract

This study assesses the effect of the material type (lithium disilicate, zirconia, and polymer-infiltrated ceramic) and dental bonding substrates (dentin, dentin with intra-coronal cavity, and dentin with composite filling) on the fracture resistance and failure mode of molars restored by occlusal veneers. Methods: Ninety occlusal veneers, fabricated from either lithium disilicate, zirconia, or polymer-infiltrated ceramic, were adhesively bonded to teeth prepared with either dentin, dentin with intra-coronal cavity, or dentin with composite filling. All specimens were thermally aged (5000 cycles), then load cycled (120,000 cycles). Each specimen was subjected to a compressive load through fracture, then was examined (×20) to identify the fracture type. Data were statistically analyzed. Results: Material type and dental substrate had no significant effect on the fracture resistance of adhesively retained occlusal veneer restorations. For each material, no significant differences were found between veneers bonded to dentin, dentin with intra-coronal cavity, and dentin with composite filling. Additionally, within each bonding substrate, there were no significant differences between lithium disilicate, zirconia, and polymer-infiltrated ceramic veneers. The adhesive failure was recorded mainly with zirconia occlusal veneer restorations. Conclusions: Considering the fracture results, lithium disilicate, zirconia, and polymer-infiltrated ceramic occlusal veneers perform well whatever the type of dental bonding surface. When the dental bonding surface varies, different occlusal veneer materials should be considered. Occlusal veneers bonded to dentin, dentin with composite filling, or dentin with an intra-coronal cavity exhibited a fracture resistance exceeding the average human masticatory forces in the molar area.

Effect of preparation design on marginal adaptation and fracture strength of ceramic occlusal veneers: A systematic review

“…They proposed that the recent study's higher fracture strength in dentin could be due to the improvement of a newly developed so‐called universal bonding system. On the other hand, the study by Walid Al‐Zordk et al ( 2021 ) has shown that the fracture resistance within veneers bonded to dentin, dentin with intra‐coronal cavity, and dentin with the composite filling was not significantly different. However, their fracture resistance is above human regular masticatory forces in molars.…”

“…However, their fracture resistance is above human regular masticatory forces in molars. Also, by varying dental bonding surfaces, different overlays' materials have to be considered (Al‐Zordk et al, 2021 ).…”

“…In another study byAbu-Izze et al (2018), 1-mm hybrid ceramics achieved better results in the fatigue test compared with 0.5-mm Zirconium-reinforced lithium silicate restorations, the rise in the thickness of the restorations significantly decreased the concentrations of stresses on different internal and external surfaces, and the stress concentration of Zirconium-reinforced lithium silicate at the adhesive interface was higher in comparison to hybrid ceramics. In Baldissara's study(Al-Zordk et al, 2021), comparing different groups, 0.8 mm may be considered an acceptable compromise between fracture resistance and tooth reduction as a threshold value. Also, Ioannidis et al (2019) indicated both 0.5 and 1.0 mm thicknesses as suitable for minimally invasive lithium-disilicate ceramic (IPS e.max Press), zirconia (Vita YZ H.T.…”

The Effect of Surface Treatments on Zirconia Bond Strength and Durability

“…Furthermore, the adhesion of resin cements to zirconia is still questionable due to its chemically inert surface and lack of micro-mechanical interlocking [ 7 ]. A resin-bonded fixed dental prosthesis made from zirconia exhibits more adhesive failure than that made from lithium disilicate [ 8 , 9 ]. Appropriate resin bonding protocols are crucial for the clinical success of zirconia restorations.…”

Wear behavior of bonded occlusal veneers constructed from machine milled glass and polymer infiltrated ceramics in contact with enamel: An in vitro study

“…They have high quantity of glass in their structure, which makes them among the most naturallooking materials [22] . The proven competence of lithium disilicate material has been acknowledged which encourages its use in restoring worn teeth through a more conservative approach [4] . These days, the CAD/CAM hybrid ceramics have been presented with rapid restoration manufacturing with no need for firing after milling and uncomplicated intraoral mending of the restoration using direct composite material [22] .…”