Comparative evaluation of fracture resistance of endodontically treated premolars restored with additively manufactured inlays and self-cure bulk-fill composites.

OBJECTIVE

This study aimed to evaluate and compare the fracture resistance of endodontically treated maxillary premolars restored with various direct and indirect restorative approaches, focusing on new self-cure composites and 3D-printed resin inlays.

MATERIALS AND METHODS

Sixty extracted human maxillary first premolars were divided into six groups (n = 10): (1) positive control (intact), (2) negative control (unrestored endodontically treated), (3) EverX Posterior + G-ænial Posterior (4) Stela Capsule (self-cure bulkfill composite), (5) Stela Automix (self-cure bulkfill composite), and (6) Saremco CrownTec (3D-printed inlays). All teeth, except Group 1, underwent root canal treatment and standardized MOD cavity preparation. Restored specimens were thermocycled (5000 cycles, 5-55 °C) and subjected to oblique compressive loading at 30°. One-way ANOVA and post hoc tests assessed statistical significance (p < 0.05).

RESULTS

The intact group showed the highest fracture resistance. Among restorations, 3D-printed inlays and Stela Automix performed significantly better than EverX Posterior + G-ænial Posterior and Stela Capsule. The negative control had the lowest resistance. Differences among groups were statistically significant (p < 0.001).

CONCLUSIONS

Both 3D-printed inlays and Stela Automix self-cure composite significantly improved fracture resistance in endodontically treated premolars, indicating their clinical potential as alternatives to conventional direct restorations.

CLINICAL RELEVANCE

These findings support the use of high-performance 3D-printed inlays and automix self-cure composites for reinforcing structurally compromised premolars, offering viable restorative options in cases of extensive MOD cavities.