Fracture resistance and survival rates of chairside, milled, and 3D-printed provisional three-unit FDPs with two cements before and after masticatory simulation.

PURPOSE: The aim of this study was to compare in-vitro changes and properties of conventional chairside-dispensed, 3D-printed and milled interim fixed dental protheses using two different cements.

MATERIALS AND

METHODS

Identical three-unit fixed dental prostheses (FDP) were fabricated from conventional dispensed (1x), milled (1x) and 3D-printed (2x) materials and cemented onto standardized Co-Cr-Mo alloy molars using either conventional or resin cement. Ten FDPs of each group were stored in distilled water and artificially aged for a simulated wear period of 5 years (1.2 × 106 cycles, 50 N force) through thermocycling (TCML). An additional ten FDPs of each group served as the control group, stored in distilled water without aging. Fracture resistance was analyzed before and after TCML (α = 0.05).

RESULTS

Survival rates: All FDPs made from conventional and subtractive materials survived TCML, while those made from additive materials did not. Fracture resistance: The median of the fracture resistance values for conventional material was 1096 N (24 h water storage, conventional cementation), 1117 N (TCML, conventional cementation), 1762 N (24 h water storage, adhesive cementation) and 1400 N (TCML adhesive cementation). Significant differences were observed between conventional and additive materials, but not for the subtractive material. The median of the fracture resistance values for subtractive material was 988 N (24 h water storage, conventional cementation), 1065 N (TCML, conventional cementation), 1486 N (24 h water storage, adhesive cementation) and 1204 N (TCML adhesive cementation). Significant differences were found between subtractive and additive materials. The median of the fracture resistance values of the additive materials was 953 N and 754 N (24 h water storage, conventional cementation), 1090 N and 876 N (24 h water storage, adhesive cementation) and 706 N and 373 N (TCML adhesive cementation), showing significant differences both among them and compared to the other materials.

CONCLUSION

Conventionally and subtractively fabricated temporaries do not show significant differences in fracture resistance, although they do outperform additively fabricated temporaries, which exhibit significantly lower fracture resistance. Since none of the tested additively manufactured specimens survived TCML when cemented with Temp Bond NE, premature failure of these materials can be expected in clinical use.

CLINICAL RELEVANCE: This study informs clinicians on the fracture resistance of chairside, milled, and 3D-printed provisional FDPs with different cements, aiding material selection to improve durability and predictability of provisional restorations in clinical practice.