Statement of the problem: Thin, posterior occlusal veneers establish a conservative approach to conventional complete coverage restorations. Information about the proper material and its effect upon fracture resistance, which may affect the durability of the restoration, is still unknown.Objective: This in-vitro study was carried out to assess the effect of variable materials and preparation designs on marginal fit and fracture resistance of CAD/CAM fabricated occlusal veneers. Materials and Methods:A total number of sixty freshly extracted maxillary first premolars were collected. The selected teeth were inspected for being intact, non-restored and free from caries, cracks and severe occlusal erosive lesions. The teeth were chosen to be of comparable bucco-lingual and mesio-distal dimensions. All teeth were mounted along their long axis in epoxy resin templates. A standardized occlusal preparation (simulating advanced occlusal erosion) including enamel removal, dentin exposure and immediate dentin sealing were made. Teeth were randomly assigned equally to three test groups (n=20) according to the material of the CAD/CAM blocks used for fabrication of the occlusal veneers, group (I): Lithium di-silicate glass ceramics (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein), group (II): Hybrid all-ceramic material (VITA ENAMIC, VITA Zahnfabrik, Germa ny) and group (III): Nano ceramic reinforced resin composite (BRILLIANT Crios, Coltène/Whaledent AG, Switzerland). Each group was then sub-divided into two equal sub groups (n=10) according the preparation design used for occlusal veneer, where subgroup (1): represented the minimally invasive occlusal veneer preparation resembling occlusal erosion. Subgroup (2): represented occlusal veneer preparation with marginal chamfer. Teeth were restored with 1.0 mm thickness occlusal veneers. Vertical marginal gap distance for all occlusal veneers was measured using stereomicroscope. Following Vertical marginal gap distance measurements, the samples were subjected to cyclic fatigue loading for 60000 cycles which is equivalent to six months clinical service. Then vertical marginal gap distance for all samples was recalculated after fatigue loading testing. Fracture resistance test was done using universal testing machine. The load to fracture for all samples was recorded in Newton. Data were collected, tabulated and statistically analyzed.
Background:The diagnosis of hidden caries extending deeply into dentine with intact enamel is based on digital radiograph (RVG) and is considered a difficult procedure, which needs more analysis of the affected teeth. Aim:The purpose of the present study was to determine the accuracy of laser fluorescence (DIAGNOdent) and the conventional method (bitewing radiograph) in identifying the depth of the proximal carious lesions in posterior teeth in vivo.Materials and methods: Forty proximal lesions were identified in 26 patients aged between 20-45 years old, who were recruited from the out clinic of Umm Al-Qura Dental Teaching Hospital. Following initial clinical examination, the patients were subjected to two diagnostic methods: The first one is a bitewing digital radiograph using GXS -700 Gendex with exposure time of 0.32 second and patients with scores from 1 to 3 were selected. The second method was carried out using the DIAGNOdent device to take the reading of demineralization existing in proximal surfaces. Only teeth with readings representing actual cavitation were included. Cavity preparations were performed to the selected carious lesions according to the extension of the caries, then axial cavity depths were measured, and teeth were restored using bonded resin composite restorations.Results: Statistical analysis revealed a significant positive correlation between DIAGNOdent and RVG (R= 0.868; p< 0.05). Also, there were positive correlation between cavity depth and DIAGNOdent (R= 0.998; p< 0.01) as well as between cavity depth and RVG (R= 0.798; p< 0.05). The strongest correlation was detected between cavity depths with DIAGNOdent compared to RVG. Conclusion:The current study suggests that the score of DIAGNOdent has higher correlation with the cavity depth and it could present a better sensitive and specific tool for the diagnosis of proximal caries. Further studies are needed to measure the sensitivity and specificity of laser florescence.
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