Comparison of marginal and internal fit of zirconia crowns fabricated by three-dimensional printing with different offset parameters: A preliminary pilot study

Abstract

Purpose: This study aimed to evaluate the marginal and internal fit of zirconia crowns fabricated using 3-dimen- sional (3D) printing technology with different offset parameters. Materials and Methods: A maxillary right first molar of a standard typodont (D85DP-500B.1; Nissin Dental, Kyoto, Japan) was prepared for a zirconia crown with a 1.0 mm margin. Virtual casts were obtained using an intraoral scanner (i700; MEDIT, Seoul, Republic of Korea). Crown designs were created with CAD software (Dentbird; IMAGOWORKS, Seoul, Republic of Korea) using specific parameters: cement space (50 µm), adaptive extra gap (0 µm), height for minimal gap (50 µm), and margin width (100 µm). Zirconia crowns were fabricated using a vat photopolymerization DLP 3D printer (TD6+; 3D Controls, Busan, Republic of Korea). Two offset groups were de- fined: the Offset -70 µm group (outermost XY-direction pixels reduced by one unit) and the Offset 0 µm group (no adjustment). All crowns were printed with a 50 µm Z-layer thickness. Eighteen crowns were fabricated (N = 9 per group). Marginal and internal fit measurements were conducted using the triple-scan method. The measured marginal and internal gaps were statistically compared using an independent t-test (α = 0.05). Results: The offset -70 µm group demonstrated significantly smaller marginal gaps (P<0.05) and internal gaps (P>0.05) compared to the offset 0 µm group. Conclusion: These findings suggest that adjusting the XY-direction offset may help minimize manufacturing er- rors, enhancing the overall accuracy of zirconia crown fabrication