Effect of Different Bonding Substrates on Fracture Resistance of Thin and Ultra-thin Occlusal Veneers constructed using Different CAD/CAM Materials

Abstract

Objectives:The aim of this study was to compare the fracture resistance of thin and ultra-thin occlusal veneers constructed from glass ceramics and hybrid ceramics bonded to different bonding substrates after thermomechanical aging. Materials and Methods:A total of 96 extracted maxillary first premolars were used. The teeth were divided into three equal groups according to the bonding substrate/protocol: EN, IDS Dentin, DDS Dentin. Each group was further subdivided into two equal subgroups according to the material of construction: E.max CAD, Vita Enamic. Each subgroup was further subdivided into two equal subdivisions according to the thickness of the occlusal veneer: Ultrathin, Thin. All the teeth were prepared to receive occlusal veneers. All the occlusal veneers were constructed using CAD/CAM technique. All occlusal veneers were cemented using adhesive resin cement. Thermomechanical aging was applied on all samples. Fracture resistance testing was performed.Results: There was statistically significant difference between bonding protocols where IDS Dentin showed the statistically significantly highest mean fracture resistance followed by Enamel then DDS Dentin. Vita Enamic showed statistical significant higher mean fracture resistance than E.max CAD. Ultra-thin occlusal veneers showed statistical significant lower mean fracture resistance than thin occlusal veneers.Conclusions: Ultrathin occlusal veneers must be cautiously used when glass ceramics is chosen. However, this minimal thickness could be a favorable option on using hybrid ceramics. Increasing the occlusal thickness to 0.5-0.8mm could be promising upon bonding with either enamel or dentin with both materials used. Ultra-thin occlusal veneers must be used carefully upon bonding to dentin (IDS must be applied).

Effect of Thickness and CAD/CAM Materials on the Fracture Resistance of Biomimetic Occlusal Veneers

“…Therefore, these results are within the clinically accepted limit. Our results come in with agreement with some studies 22,40 , and disagreement with other research studies 24,[41][42][43] whom reported significant difference between the ceramic groups. These differences might be attributed to different testing variables such as bonding protocol, aging, and different testing parameter.…”

“…The Celtra Duo group showed also no statistical significant difference with different thicknesses (1 mm, 1.5 mm), this came with agreement with Abbas et al (2020) 45 . Other studies reported also that increasing the thickness of the occlusal veneers did not impact the fracture resistance 19,46 , while other reported differently 42,47 .…”

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

“…Another factor which explains the difference could be the fluctuation in the bonding substrate. The fluctuation in the bonding substrate was evaluated by Elsayed [53] when comparing the compressive strength of thin and ultrathin occlusal veneers constructed from glass ceramics and hybrid ceramics, bonded to different bonding substrates. The author found that the immediate dentin sealing concept (immediate treatment of the freshly cut dentin after exposure by the bonding agent) showed the highest mean compressive strength followed by enamel and delayed dentin sealing.…”

Influence of Preparation Design on Fracture Resistance of Hybrid Ceramics Occlusal Veneer

“…This is in agreement with findings reported in the literature by Elsayed. (2021) (33) They examined the fracture resistance of hybrid ceramics attached to various bonding protocols and thin and ultra-thin occlusal veneers made of glass ceramics. Between bonding techniques, there was a statistically significant difference whereby immediate dentin sealing (IDS) exhibited the highest statistically significant mean fracture resistance, followed by enamel and finally delayed dentin sealing (DDS).…”