Abstract: PURPOSE: To provide references for the selection of restoration types and materials for the first premolar with large defect in clinical practice. METHODS: A large area defect model of the maxillary first premolar was established and repaired with different types and materials, including group A (inlay group), group B (endocrown group), group C (fiber post core crown group), and group D (pure titanium post core crown group). And then, according to different repair materials, it was divided into 3 subgroups, namely group 1 (zirconia), group 2 (glass ceramic), and group 3 (resin based ceramic), totaling 12 groups. The stress distribution and magnitude were investigated using finite element analysis software. RESULTS: In the inlay group, the stress concentration area was large and tended to spread along the neck of tooth; in the post core crown group and endocrown group, the stress distribution was more uniform. In terms of restorative materials for endocrown, resin based ceramic materials had the lowest stress, followed by glass ceramic materials, and zirconia materials had the highest stress. CONCLUSIONS: Large defects of the first premolar can be repaired with endocrowns and post core crowns, and endocrowns have good applicability and advantages. Resin based ceramic materials are recommended for the selection of the endocrown materials for the least stress of the remaining tooth.

Key words: Maxillary first premolar, Large defects, Endocrown, Three-dimensional finite element analysis, Stress analysis