Eman Albelasy1, Hamdi H Hamama2, James K H Tsoi3, Salah H Mahmoud1. 1. Operative Dentistry Department, Faculty of Dentistry, Mansoura University, Egypt. 2. Operative Dentistry Department, Faculty of Dentistry, Mansoura University, Egypt. Electronic address: hamdy@connect.hku.hk. 3. Dental Material Science, Division of Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
Abstract
OBJECTIVES: The present study aimed to evaluate the effect of restoration thickness, CAD/CAM material, and 6 months of artificial saliva storage on the fracture resistance of occlusal veneers. MATERIALS AND METHODS: A total of 84 intact maxillary molars were sectioned 4.0 mm occlusal to the cementoenamel junction to expose the dentine. The teeth were assigned into 3 main groups according to the type of restorative material (e.max CAD, Vita Enamic, and Lava Ultimate). In each group, the teeth were allocated into 2 subgroups (n = 14) according to restoration thickness (1.0 and 1.5 mm). The veneers were adhesively bonded using dual-cure self-adhesive luting agent. A total of 42 specimens comprising half the tested subgroups were stored in distilled water for 24-h before the test. The remaining half was stored in artificial saliva at 37 ± 1 °C in an incubator for 6 months. All specimens (n = 84) were subjected to 5000 thermal cycles between 5 and 55 °C ± 2 before the fracture resistance test. The maximum force at fracture was recorded in Newton. Failure mode was analyzed using a stereomicroscope. The results were analyzed using a parametric Three-way ANOVA test. RESULTS: The results of the Three-way ANOVA test revealed that material type and restoration thickness significantly affected fracture resistance values (p < 0.5), while 6 months of storage in artificial saliva had no significant effect on mean fracture resistance values (p˃0.5). The most common failure patterns in CAD/CAM resin composite and polymer-infiltrated ceramics were scores I and score II. For glass ceramic groups, score IV and III were more dominant. CONCLUSIONS: All the tested CAD/CAM restorations in both thicknesses exhibited fracture resistance values exceeding normal and parafunctional bite forces. Polymer-infiltrated ceramics and CAD/CAM resin composite veneers showed more favorable fracture patterns.
OBJECTIVES: The present study aimed to evaluate the effect of restoration thickness, CAD/CAM material, and 6 months of artificial saliva storage on the fracture resistance of occlusal veneers. MATERIALS AND METHODS: A total of 84 intact maxillary molars were sectioned 4.0 mm occlusal to the cementoenamel junction to expose the dentine. The teeth were assigned into 3 main groups according to the type of restorative material (e.max CAD, Vita Enamic, and Lava Ultimate). In each group, the teeth were allocated into 2 subgroups (n = 14) according to restoration thickness (1.0 and 1.5 mm). The veneers were adhesively bonded using dual-cure self-adhesive luting agent. A total of 42 specimens comprising half the tested subgroups were stored in distilled water for 24-h before the test. The remaining half was stored in artificial saliva at 37 ± 1 °C in an incubator for 6 months. All specimens (n = 84) were subjected to 5000 thermal cycles between 5 and 55 °C ± 2 before the fracture resistance test. The maximum force at fracture was recorded in Newton. Failure mode was analyzed using a stereomicroscope. The results were analyzed using a parametric Three-way ANOVA test. RESULTS: The results of the Three-way ANOVA test revealed that material type and restoration thickness significantly affected fracture resistance values (p < 0.5), while 6 months of storage in artificial saliva had no significant effect on mean fracture resistance values (p˃0.5). The most common failure patterns in CAD/CAM resin composite and polymer-infiltrated ceramics were scores I and score II. For glass ceramic groups, score IV and III were more dominant. CONCLUSIONS: All the tested CAD/CAM restorations in both thicknesses exhibited fracture resistance values exceeding normal and parafunctional bite forces. Polymer-infiltrated ceramics and CAD/CAM resin composite veneers showed more favorable fracture patterns.