Three-Dimensional Evaluation of Marginal Gap in Prefabricated Zirconia and 3D-Printed Pediatric Crowns

Objective: This study aimed to compare the marginal gap values of prefabricated zirconia and resin crowns fabricated using different three-dimensional (3D) printing technologies for primary molars using a 3D digital analysis method. Materials and Methods: Forty crowns (n = 10/group) were evaluated, including prefabricated zirconia crowns (NuSmile) and three resin crown systems fabricated using different additive manufacturing technologies: Crowntec (Saremco, DLP), Permanent Crown Resin (Formlabs, SLA), and Graphy TC-80DP (MSLA). All restorations were cemented with self-adhesive resin cement. The specimens were scanned before and after cementation, and the obtained STL datasets were superimposed using the Geomagic Control X software. Marginal gap values were calculated using three-dimensional (3D) digital analysis. Data were analyzed using one-way ANOVA and Games-Howell post hoc tests (α = 0.05). Results: The mean marginal gap values differed among the groups. The lowest marginal gap value was observed in the Formlabs group (113.22 ± 1.94 µm), followed by that of the Saremco group (118.54 ± 1.58 µm). Higher marginal gap values were recorded in the Graphy group (134.23 ± 2.16 µm), whereas the highest value was observed in the prefabricated zirconia crown group (163.14 ± 3.95 µm). Statistically significant differences were observed among all groups (p < 0.001), with all 3D-printed resin crown systems exhibiting lower marginal gap values than the prefabricated zirconia crowns. Conclusions: Within the limitations of this in vitro study, 3D-printed resin crowns exhibited superior marginal adaptation compared to prefabricated zirconia crowns. Among the evaluated materials, the SLA-fabricated Formlabs crowns exhibited the lowest marginal gap values. All tested resin crown systems demonstrated marginal gap values within clinically acceptable limits.