Comparative Evaluation of Marginal Fit in Monolithic Zirconia Crowns Fabricated Using Intraoral and Extraoral (Dental Laboratory) Scanners: An in vitro Study

Introduction: Precision in the marginal fit of dental restorations is critical for their long-term success. The introduction of computer-aided design and computer-aided manufacturing (CAD-CAM) technology and intraoral scanners has revolutionized digital prosthodontics, enabling the fabrication of high-strength, esthetic monolithic zirconia crowns. However, the effect of different scanning modalities on the marginal fit of crowns remains an area of ongoing investigation. Aims and Objectives: To evaluate and compare the marginal fit of CAD–CAM fabricated monolithic zirconia crowns using intraoral and dental laboratory (extraoral) scanners with the triple scan protocol. Methodology: This in vitro study was conducted on 40 standardized typodont mandibular first molars prepared for full-coverage monolithic zirconia crowns. Specimens were divided into two groups ( n = 20 each): Group 1 crowns were fabricated using intraoral scanning and Group 2 using dental laboratory scanning. All crowns were designed and milled under identical CAD–CAM protocols. The triple scan technique was employed to assess marginal fit. Statistical analysis was performed using one-way analysis of variance, independent t -tests, and Kruskal–Wallis tests. Results: Both scanning techniques produced crowns with clinically acceptable marginal gaps. However, crowns fabricated via intraoral scanning demonstrated significantly lower mean marginal discrepancies compared to those fabricated using dental laboratory scanners ( P < 0.05). The highest discrepancies were observed at the mesial surfaces in both groups. Conclusions: Intraoral scanning offers a superior marginal fit compared to dental laboratory scanning in the fabrication of CAD–CAM monolithic zirconia crowns. The use of the triple scan protocol provided accurate and reproducible three-dimensional marginal evaluations, supporting the clinical viability of intraoral scanners in digital prosthodontics workflows.