Evaluation of the fracture strength of different CAD/CAM inlay restorations after accelerated aging

Abstract

Background: The purpose of this study was to compare thefracture resistance of inlay restorations manufactured by computeraided design/computer aided manufacturing (CAD/CAM) usingdifferent materials after accelerated artificial aging. Materials and Methods: Class I inlay preparations were made for40 mandibular molar teeth. The teeth were allocated into fourgroups (n=10) according to the type of manufacturing materialused: feldspathic-ceramic (CEREC blocks); leucite-based glassceramic (IPS Empress CAD); resin nano-ceramic (Lava Ultimate);and a control (intact teeth). After obtaining digital impressions,restorations were designed and milled with CAD/CAM. Inlayrestorations were cemented to the inlay cavities using a dualpolymerizing resin cement (Rely X Ultimate) and stored in distilledwater at 37°C for a week. All the samples were then exposed toaccelerated ultraviolet aging for 300 hours. Finally, a compressiveload was applied to the samples until fracture. Statistical analysiswas conducted using One-Way ANOVA and the Tukey HSD test(?=0.05).Results: The mean fracture strength values of the groups were;Control (1555.3±412.2 N)> Lava Ultimate (1525±394N)>IPSEmpress CAD (1364.3±545.6N) > CEREC(1231.9±412.2N),respectively. However, there was no statistically significantdifference in mean fracture strength among different inlayrestoration groups (P>0.05). Fifty percent of the both CEREC andIPS Empress CAD groups and 60% of the Lava Ultimate groupshowed reparable fractures.Conclusion: The type of material used did not influence thefracture strength of inlay-restored molar teeth and inlay restorationsdid not weaken the strength of the restored teeth. Therefore, all ofthe tested materials are suitable for use in the posterior reg