Effect of Different Restorative Materials on Primary Tooth Wear: A Quantitative Evaluation Using Microcomputed Tomography.

Purpose: The wear properties of restorative materials used in the primary dentition must be compatible with primary tooth wear. The purpose of this study was to investigate the wear rate of primary teeth opposing composite resin and different prefabricated crown materials. Methods: The study specimens were divided into four groups: (1) composite resin (CR) group; (2) stainless steel group (SS); (3) monolithic zirconia (MZ) group; and (4) fiberglass (FG) group. Ten specimens were prepared from each group, and primary canines were used as antagonist teeth. The wear test was conducted with a vertical load of 50 N and 240,000 cycles using a chewing simulator. The volume losses of antagonist teeth and the weight losses of restorative materials were calculated with microcomputed tomography and a digital scale, respectively. The worn surfaces of restorative materials were examined via scanning electron microscopy. Results: The amount of enamel wear was highest in the MZ group (1.551±0.859 [standard deviation] mm 3 ) group, followed by the FG group (1.028±0.854 mm 3 ), SS group (0.480±0.324 mm 3), and CR group (0.310±0.341 mm 3). The volume losses in the MZ group were significantly greater than those in the SS and CR groups (P<0.05). The weight loss amount of restorative materials was highest in the CR group (8±2 mg), followed by the FG (6±3 mg), SS (4±3 mg), and MZ (2±1 mg) groups. Conclusions: Prefabricated monolithic zirconia crowns caused greater wear on opposing primary teeth. The amount of weight loss in the composite resins was highest while causing minor primary tooth wear.

Correction to: Temporary materials: comparison of in vivo and in vitro performance.

A Correction to this paper has been published: https://doi.org/10.1007/s00784-021-04067-4.

Temporary materials: comparison of in vivo and in vitro performance.

OBJECTIVE: The aim of this investigation was to compare clinical performance and in vitro wear of temporary CAD/CAM and cartridge crowns. This study is an approach to estimate the influence of in vivo use and laboratory simulation on temporary crowns. MATERIALS AND METHODS: A total of 90 crowns were fabricated from each temporary CAD/CAM or cartridge material. Also, 10 crowns of each material were clinically applied for 14 days, and 80 identical duplicate restorations were investigated in the laboratory after storage in water (14 days; 37 °C) and subsequent thermal cycling and mechanical loading (TCML, 240.000 × 50N ML, 600 × 5°C/55 °C). After in vivo application or in vitro aging, facture force, superficial wear (mean and maximum), surface roughness (Ra, Rz), thermal weight loss (TGA), and heat of reaction (DSC) were determined for all crowns. STATISTICS: Bonferroni post hoc test; one-way analysis of variance (ANOVA); α = 0.05). RESULTS: The fracture resistance of the temporary materials varied between 1196.4 (CAD in vivo) and 1598.3 N (cartridge crown in vitro). Mean (maximum) wear data between 204.7 (386.7 µm; cartridge in vitro) and 353.0 µm (621.8 µm; CAD in vitro) were found. Ra values ranged between 4.4 and 4.9 µm and Rz values between 36.0 and 40.8 µm. DSC and TG analysis revealed small differences between the materials but a strong influence of the aging process. CONCLUSIONS: Comparison of in vivo and in vitro aging led to no significant differences in fracture force and wear but differences in roughness, DSC, and TGA. SEM evaluation confirmed comparability. Comparison of CAD/CAM and cartridge temporary materials partially showed significant differences. CLINICAL RELEVANCE: In vitro aging methods might be helpful to estimate materials' properties before principal clinical application. CAD/CAM and cartridge temporary materials provided comparable good clinical performance.