Marginal adaptation of CAD-CAM and heat-pressed lithium disilicate crowns: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Lithium disilicate crowns can be manufactured by computer-aided design and computer-aided manufacturing (CAD-CAM) or with the heat-pressed technique. The outcome of studies comparing the effect of the manufacturing method on the marginal adaptation of these crowns is not clear. PURPOSE: The purpose of this systematic review and meta-analysis was to investigate the effect of the CAD-CAM system and pressing technique on the marginal adaptation of lithium disilicate crowns. MATERIAL AND METHODS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A literature research was conducted in MEDLINE via PubMed and Scopus databases, relevant journal sites, and the authors' collected references, from January 2009 to April 2019. RESULTS: The electronic and manual searches that could be read in full totaled 24 studies; of which, 9 were included in the systematic review and meta-analysis, 7 of which were in vitro and 2 in vivo. Statistical analyses were conducted by using Review Manager software program. Meta-analyses were performed with the random effects model (α=.05). In vitro studies showed no difference in the manufacturing (P>.001; 95% confidence interval -0.687 to 0.632), and no significant difference was found for in vivo studies (P=.7, 95% confidence interval 0.00 to 54.77). In the joint analysis of the in vivo and in vitro articles, there was a significant difference between the manufacturing methods (P<.001). CONCLUSIONS: Differences were detected between the marginal adaptation of lithium disilicate crowns fabricated with the CAD-CAM system and the pressing technique, but the accuracy values were clinically acceptable.

Analysis of the marginal adaptation of different crowns fabricated with computer-aided technology using an intraoral digital scanner

Aim: The aim of this study was to evaluate the marginal adaptation of ceramic and composite resin crowns fabricated with computer-aided design and computer-aided manufacturing (CAD/CAM) technology using an intraoral digital scanner. Methods: A human mandibular right second molar was prepared for a ceramic crown. The impressions were made using intraoral scanning device and crowns were milled. Tem crowns were fabricated for each group (n=10): GF ­ Feldspathic Ceramic (Cerec Blocs, Sirona), GL - Lithium Disilicate Ceramic (IPS e.max CAD, Ivoclar), GG - composite resin (Grandio Blocs, VOCO) and GB - composite resin (Brava Block, FGM). The marginal gap was measured for each specimen at 4 points under magnification with a stereomicroscope. All data were statistically analyzed using one-way ANOVA followed by the Tukey's test (α=.05). Results: The lowest marginal discrepancy value was observed in GB (60.95 ± 13.64 µm), which was statistically different from the GL (84.22 ± 20.86 µm). However, there was no statistically significant difference between these groups when compared with the other groups, GF (73.26 ±8.19 µm) and GG (68.42 ± 11.31 µm). Conclusion: It can be concluded that the composite resin presented the lowest variance compared to the lithium disilicate glass ceramic, although the marginal gap of all materials tested was within the acceptable clinical limit (120 µm)