Abstract
Objectives The aim of this study was to investigate the internal fit (IF) of glass-infiltrated alumina (ICA - In-Ceram Alumina), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD), and metal-ceramic (MC - Ni-Cr alloy) crowns. Material and Methods Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each) according to the core material used (metal, ICA or Y-TZP). The IF of the crowns was measured using the replica technique, which employs a light body polyvinyl siloxane impression material to simulate the cement layer thickness. The data were analyzed according to the surfaces obtained for the occlusal space (OS), axial space (AS) and total mean (TM) using two-way ANOVA with Tukey's multiple comparison test (p<0.05). Results No differences among the different areas were detected in the MC group. For the Y-TZP and ICA groups, AS was statistically lower than both OS and TM. No differences in AS were observed among the groups. However, OS and TM showed significantly higher values for ICA and Y-TZP groups than MC group. Comparisons of ICA and Y-TZP revealed that OS was significantly lower for Y-TZP group, whereas no differences were observed for TM. Conclusions The total mean achieved by all groups was within the range of clinical acceptability. However, the metal-ceramic group demonstrated significantly lower values than the all-ceramic groups, especially in OS.
Highlights
The metal-ceramic system is still ZLGHO\ XVHG WR IDEULFDWH FURZQV DQG ¿[HG SDUWLDO dentures (FPDs)14 and is considered as the standard treatment in dentistry7, aesthetic concerns have stimulated the development of new dental ceramic systems33
Measurements were obtained for two regions of interest to better evaluate the results in addition to the total mean (TM)
WKHVH VSDFHV 1R VLJQL¿FDQW GLIIHUHQFHV LQ $6 ZHUH observed among the groups, but occlusal surface (OS) and TM showed VWDWLVWLFDOO\ VLJQL¿FDQW GLIIHUHQFHV 5HPDUNDEO\ the ICA and Y-TZP groups displayed high values for OS, as compared to the values obtained for the MC group
Summary
The metal-ceramic system is still ZLGHO\ XVHG WR IDEULFDWH FURZQV DQG ¿[HG SDUWLDO dentures (FPDs) and is considered as the standard treatment in dentistry, aesthetic concerns have stimulated the development of new dental ceramic systems. In addition to the development of ceramic materials, new processing technologies have been introduced for the production of all-ceramic cores. In contrast to the conventional technique (lost wax) employed to produce the metal core, all-ceramic cores are fabricated from heat-pressed, slip-cast, CAD/CAM (computer-assisted design/computerassisted machining), and CAM technologies, which employ many ceramic-based materials. The slip-cast (e.g., alumina ceramic-based) is a hand-building technique that requires a duplication of the stone die to the stone refractory prior to fabrication of the alumina core. The CAD/CAM technique employs sophisticated technologies, and the core can be fabricated from densely sintered or partially-sintered ceramic blocks. A scanner digitalizes the prepared tooth, and the framework or a restoration is fabricated according to the
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