Marginal Gap Distance and Dynamic Fatigue Performance of Esthetic Crowns for Primary Teeth.

Background: The growing demand for esthetic restorative materials highlights the need to evaluate their marginal accuracy and fracture resistance to ensure optimal clinical outcomes for primary molars.

Aim: The aim was to assess the vertical marginal gap distance and fracture resistance of esthetic restorative materials after cyclic loading.

Design: Forty extracted primary molars were randomly divided into four groups: Group I, stainless steel veneered crowns with tooth-colored material; Group II, prefabricated monolithic zirconia crowns; Group III, yttria-partially stabilized zirconia computer-aided design/computer-aided manufacturing (CAD/CAM) crowns; and Group IV, hybrid ceramic CAD/CAM crowns. A stereomicroscope was used to measure the vertical marginal gap distance. The fracture resistance was then evaluated by applying cyclic loading.

Results: Group I (1710 μm) exhibited the highest total median vertical marginal gap distance, followed by Groups II, III, and IV (418.3, 341.7, and 86.7 μm, respectively; with an overall statistically significant difference, p < 0.001). Regarding fracture resistance, Group III exhibited the best performance (2018.5 ± 236.0 N), followed by Groups II, IV, and I (1185.4 ± 326.1, 782.8 ± 278.5, and 728.3 ± 247.4 N, respectively). The CAD/CAM crowns exhibited better marginal gap distances than the prefabricated crowns. The CAD/CAM hybrid ceramic crowns exhibited better marginal accuracy than the CAD/CAM zirconia crowns.

Conclusions: Zirconia crowns showed promising results regarding marginal adaptation, whereas hybrid ceramics showed promising results regarding fracture resistance.