Evaluation of Fracture Resistance Force in Three Types of Primary Molar Crowns: Milled by CAD\CAM, 3D Dental Printed, and Composite Celluloid Crowns

Abstract

Abstract Objective This study compares three types of esthetic crowns in fracture resistance force (FRF) and failure type: (1) polymethylmethacrylate (PMMA) milled by computer-aided design/computer-assisted manufacture (CAD\CAM), (2) resin-based material via three-dimensional (3D) dental printer, and (3) direct composite celluloid crowns technique in primary molars. Material and Methods Thirty lower second primary molar were randomized into three experimental groups consisting of ten molars for each: group A:CAD\CAM crowns using PMMA blocks; group B: 3D dental printer to fabricate crowns using glycidyl carbamate photopolymer resin; group C: Selected teeth crowned using direct resin composite celluloid crowns. The three groups (A, B, and C) were stored in water at 37°C for 30 days. The FRFs for the experimental crowned teeth were measured using a universal test machine (Testometric) until fracture and the values compared with the mean maximum bite force of children in the primary dentition. FRFs and failure types were recorded and statistically analyzed. Results One-way analysis of variance (ANOVA) revealed significant differences among the groups in FRF testing. Bonferroni test was used for multiple-correction comparison in comparing force needed to fracture the specimens in the three groups. A significant difference was noticed between groups B-C (p = 0.000) and groups A-C (p = 0.000). No significant statistical differences were noted between groups A-B (p = 0.325) in FRF scores. In failure type, no statistical differences were noted when comparing groups, A and B, groups B and C, but comparing groups A and C showed statistical differences in chi-square statistical test. Conclusion The three tested esthetic crowns exceeded the mean maximum bite force of children in the primary dentition; thus, they can be expected to perform well clinically. Even though using an indirect technique (CAD\CAM milling and 3D printer) showed a higher score in FRF, direct composite celluloid crowns technique can be beneficial since it is easier to repair and still is a useful modality.