Evaluation of the marginal and internal fit of crowns fabricated by additive manufacturing using different CAD/CAM software according to various preparation type

ABSTRACT EVALUATION OF THE MARGINAL AND INTERNAL FIT OF CROWNS FABRICATED BY ADDITIVE MANUFACTURING USING DIFFERENT CAD-CAM SOFTWARE ACCORDING TO VARIOUS PREPARATION TYPES MÜMTAZ, Görkem PhD., Department of Prosthodontics, Altınbaş University Supervisor: Asst. Prof. Dr. Beril KOYUNCU Date: 06/2025 Pages: 98 Purpose: The aim of this in vitro study is to investigate the effect of different design software programs and various tooth preparation techniques on the marginal and internal fit of crowns fabricated using different resin nanohybrid materials Materials and Method: Teeth were prepared with three different finish line designs (knife-edge, chamfer, and shoulder). Crowns were fabricated on the prepared teeth using two different brands of resin nanohybrid materials (Saremco, Crowntec, Saremco Dental AG, Rebstein, Switzerland ve VarseoSmile Triniq, Bego, Bremen, Almanya)and two different CAD software programs (Exocad DentalCAD; Exocad GmbH ve 3Shape dental designer, 3Shape A/S, Copenhagen, Denmark) The restorations were fabricated using the Asiga Max UV device. Marginal and internal gap values were measured using the silicone replica technique under a light microscope at ×40 magnification. Three-way ANOVA and Post Hoc Tukey tests were performed in order to analyze the obtained data using IBM SPSS version 22. Results: As a result of the measurements, it was found that the type of tooth preparation had a significant effect on both marginal and internal fit (p = 0.001; p <0.05). The CAD software used had no significant effect on marginal fit (p> 0.05). However, the type of material used significantly affected the marginal fit (p = 0.007; p <0.05). The infrastructure software was found to affect internal fit only in the occlusal region (p = 0.008; p < 0.05). Additionally, the materials used also had a significant impact on marginal fit (p = 0.007; p <0.05). As a result, the marginal gap value of crowns designed using the 3Shape CAD software, fabricated with Saremco Crowntec material, and prepared with the shoulder finish line was measured as 120 µm, whereas the marginal gap value of crowns fabricated using Bego TriniQ material, designed with the Exo-CAD software, and prepared with a knife-edge finish line was measured as 80.97 µm. On models prepared with the shoulder finish line, the internal gap at the axial walls of crowns designed using the 3Shape software and fabricated with Saremco Crowntec material was measured as 151.59 µm. For crowns designed with the 3Shape software, prepared with the knife-edge technique, and fabricated using Bego TriniQ material, the internal gap at the axial walls was measured as 107.2 µm. The occlusal marginal gap of models prepared with the knife-edge finish line, designed using 3Shape, and fabricated with Bego TriniQ material was recorded as 145.38 µm. Lastly, the occlusal internal gap of models prepared with the shoulder finish line, designed using Exo-CAD, and fabricated with Bego TriniQ material was measured as 188.83 µm. Conclusion: Marginal and internal fit values vary depending on the measured region. CAD software systems should provide material options for the fabrication of permanent resin crowns. Additionally, permanent resin crowns require further development and improvement. Keywords: Resin Crown, Internal Gap, Marginal Gap, DLP, Exo-CAD.