Surface Trueness and Precision of Interim Restorations Fabricated by Digital Light Processing, Stereolithography, CAD-CAM Milling, and Conventional Chemical Polymerization: An In Vitro Comparative Study

Interim restorations are essential in fixed prosthodontics for maintaining pulpal protection, function, esthetics, periodontal health, and positional stability until definitive prosthesis delivery.¹˒² With the increasing use of digital workflows, the dimensional accuracy of restorations fabricated by additive and subtractive technologies has gained clinical relevance.³˒⁶˒¹¹ Purpose: To evaluate and compare the surface trueness and precision of interim crowns fabricated using digital light processing (DLP), stereolithography (SLA), CAD-CAM milling of PMMA, and conventional chemically polymerized temporary crown resin. Materials and methods: In this in vitro study, interim crowns fabricated by four different techniques were assessed for external and intaglio surface accuracy using three-dimensional deviation analysis. Surface accuracy was defined in accordance with trueness and precision concepts described by ISO standards.¹⁸ RMS deviation values were used for quantitative comparison. Four groups were evaluated: Group 1, DLP-printed resin; Group 2, SLA-printed resin; Group 3, milled PMMA; and Group 4, chemically polymerized temporary crown material. Mean RMS values and standard deviations were calculated, and intergroup comparison was performed using one-way ANOVA. Results: Group 1 demonstrated the lowest RMS values for external surface trueness (0.2539 ± 0.0812), intaglio surface trueness (0.1175 ± 0.0315), external surface precision (0.1932 ± 0.0964), and intaglio surface precision (0.0822 ± 0.0291). External surface trueness and precision did not differ significantly among groups (P = .102 and P = .507, respectively). Intaglio surface trueness and intaglio surface precision showed statistically significant differences among groups (P = .012 and P = .008, respectively), favoring additive manufacturing, particularly DLP. Conclusion: All tested techniques produced interim crowns with clinically acceptable surface accuracy. However, DLP-fabricated interim crowns demonstrated superior trueness and precision, especially on the intaglio surface. These findings support the growing role of digital additive manufacturing in fixed prosthodontics.³˒⁶˒¹¹