Wear behavior of CAD-CAM zirconia, ceramic, and 3D printed nano-hybrid resin crowns for the restoration of primary and permanent molars: An in vitro study.

Abstract

Statement of problem: Early childhood caries is one the world's most common problems in infants and treatment of posterior teeth with esthetic crowns in a low rate of wear on opposite dentition is a challenge for pediatric dentists.

Purpose: The purpose of this in vitro study was to evaluate the wear behavior of the tooth colored crown materials and the opposing teeth in using different esthetic crown materials in the mixed dentition period.

Material and methods: The following tooth type and crown materials were considered in the experiment. Primary molars consist of first and second molars that were close to exfoliation or needed to be extracted because of orthodontic treatment and were caries free and with no restorations. Permanent teeth consisted of third molars that were caries free and with no restorations. Three different types of crown materials were used: nano-hybrid resin (VarseoSmile Crown ^plus; Bego GmbH), tetragonal zirconia polycrystalline stabilized with 3 mol% yttria (G-CERAM; Atlas Enta), and lithium disilicate glass-ceramic (IPS e.max CAD; Ivoclar AG). The wear test was performed in an artificial saliva environment (pH=6.7), based on the pin-on-plate technique, for a 2-mm stroke, under a compressive force of 30-N, at a frequency of 2-Hz and with 10 000, 20 000, and 30 000 cycles. A multi-way ANOVA statistical method was used (α=.05).

Results: Wear of the opposing teeth by the glass-ceramic was greater than by the nano-hybrid resin or zirconia materials (P<.05). All 3 crown materials wore primary teeth more than permanent teeth (P<.05). Compared with nano-hybrid resin, zirconia led to more wear of the opposing tooth (P<.05). The wear behavior of the nano-hybrid resin was more predictable compared with the other 2 materials.

Conclusions: Zirconia and lithium disilicate-based glass-ceramic materials caused more wear on both primary and permanent teeth compared with nano-hybrid materials, yet exhibited less wear themselves when opposed by primary or permanent teeth.