Fracture resistance force of primary molar crowns milled from Polymeric computer‑aided design/computer‑assisted manufactured resin blocks

Abstract

Purpose: To compare fracture resistance force (FRF) and failure types of crowns milled from resin nanoceramic (Lava Ultimate)‑, and modified polymethylmethacrylate (PMMA) (Vita computer‑aided design (CAD)‑Temp)‑, and PMMA (Telio CAD)‑based  CAD/computer‑assisted manufactured (CAM) blocks.

Materials and Methods: Three experimental groups of 10 milled crowns were arranged: Group‑1 (Lava Ultimate), Group‑2 (Vita CAD‑Temp), and Group‑3 (Telio CAD). Crowns were machined in sizes similar to a primary second molar stainless steel crown (SSC) and stored in water at 37°C for 30 days. The crowns were seated on Cr‑Co dies. Their FRFs were measured using a universal test machine until fracture. FRFs and failure types were recorded and statistically analyzed (P < 0.05).

Results: There were statistically significant differences among the groups for both FRFs and failure types. The sources of significant differences for FRFs and failure types were Group‑3 and Group‑1, respectively.

Conclusion: Crowns milled from different chemical structural CAD/CAM blocks may be used for restoration of primary molar teeth.

Keywords: Computer‑aided design/computer‑assisted manufactured resin, fracture resistance force, primary molar crowns