Abstract
Objective: Studies demonstrated that as one of the newly developed restorative materials, monolithic zirconia resolved several issues of zirconia restoration. Therefore, marginal accuracy and internal fit are necessary for clinical success and quality of restorations, and cement space may influence the marginal fit. Thus, the present research aimed to investigate the effects of the cement thickness and kind of restoration on the marginal discrepancy. Material and methods: In this study, 20 maxillary left first molars, prepared by DRSK Co., were used to fabricate a full crown. Two types of material included monolithic zirconia (Zolid) and Sintron were used to make a full crown. Samples from each group were scanned by dental laboratory 3D scanner and designed and processed using CAD-CAM. The samples were divided into four groups of five with 30- and 50- µm cement spaces. In order to assess the vertical marginal discrepancy, the crowns were fitted on their respective teeth without using any mediator and examined by a micro-CT scanner. Data were analyzed by SPSS software. Results: It has been found that marginal discrepancy in Sintron is higher than the discrepancy of monolithic zirconia. In fact, monolithic zirconia with 50-micron cement space exhibited the least marginal discrepancy and the cement space in Sintron did not significantly influence the marginal discrepancy. Conclusion: It has been concluded that the material kinds and cement space influence the restoration marginal discrepancy constructed by digital workflow. KEYWORDSDental cements; Dental marginal adaptation; X-Raymicrotomography.
Highlights
All ceramic metal-free restorations attracted further attention of patients increasingly due to increased awareness of beauty and biocompatibility [1]
Two points were considered for vertical marginal discrepancy, so 20 sizes for vertical marginal discrepancy were obtained for each sample, whose mean was considered as marginal discrepancy of each sample (Figure 4)
20 samples consisted of 5 monolithic zirconia crowns with 50-micron cement space, 5 monolithic zirconia crowns with 30-micron cement space, 5 Sintron crowns with 50-micron cement space and 5 Sintron crowns with 30-micron cement space (Table 1)
Summary
All ceramic metal-free restorations attracted further attention of patients increasingly due to increased awareness of beauty and biocompatibility [1]. The use of monolithic zirconia is expanding as a new restorative material due to its easier and cheaper fabrication [3,4] These restorations have an acceptable beauty, and have high fracture resistance and could even withstand the fracture forces above the maximal mean occlusal forces incurred on the posterior regions [5,6]. In vitro studies have cited a minimum thickness of 0.7 mm for implant-supported monolithic zirconia restorations and 0.5 mm for tooth-supported restorations to the long-term resistance of restoration against chewing forces [11] This restoration can be a treatment candidate for people with limited interocclusal space, an inadequate clinical crown length and requiring maintaining a dental structure [5]. This study was conducted to investigate the marginal fit of monolithic zirconia and Sintron crowns and the effect of cement space on them before cementation
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