Accuracy of trial restorations from virtual planning: A comparison of two fabrication techniques.

Statement Of Problem: Different technologies have been used to fabricate trial restorations. However, studies investigating the accuracy of trial restorations fabricated with different techniques in comparison with the initial 3-dimensional virtual design are lacking.

Purpose: The purpose of this clinical study was to evaluate completely digital workflows for managing the esthetic outcome through the production of trial restorations with 2 different technologies: stereolithography apparatus (SLA 3D) and computer-aided design and computer-aided manufacturing (CAD-CAM). The aim was to determine which of them provided trial restorations more similar to those of the 3D virtual design.

Material And Methods: Thirty participants who did not meet ideal esthetic proportions for the anterior maxillary teeth were enrolled. For each, 2 intraoral and extraoral frontal photographs and intraoral digital scans were made. The digital images were processed by using the Digital Smile System (DSS) software program to have a smile preview after the treatment. Virtual designs were matched with the surface tessellation language (STL) files from the intraoral scans and edited by exocad DentalCAD to create custom trial restorations using SLA 3D and CAD-CAM technologies. Two independent examiners measured the virtual restorations by using virtual calipers in the software program and then the trial restorations by using digital calipers. The measurements were carried out from the incisal edge to the gingival margin, mesial-distal widths of the central incisors, and the distance from the distal margins of maxillary right and left canines. The trial restorations were evaluated intraorally for fit. The participants approved the definitive treatment outcome after the evaluation. The normality of data was verified with the Shapiro-Wilk test, and the Friedman test for matched groups with the Bonferroni and Dunn tests for multiple comparisons were used (α=.05).

Results: Comparing the 3D designs with the printed trial restorations, a significant increase was only found in the mesial-distal width of central incisors (P<.05), while the milled trial restorations showed a significant increase (P<.05) of all measurements except for the maxillary right and left canines. Comparing printed trial restorations with the milled ones, the only significant difference was found in height measures of maxillary right central incisor, with the milled trial restorations exhibiting higher values than the printed ones (P<.05). The printed trial restorations showed good clinical fit, and the milled restorations had poor clinical adaptation.

Conclusions: The accuracy of printed trial restorations was higher than that of milled trial restorations, except for the canine to canine width of maxillary anterior teeth. However, this difference did not compromise the fit of the printed trial restorations. The milled trial restorations had increased dimensions in comparison with the measurements made in 3D designs, and consequently, their clinical fit was compromised. SLA 3D- printing technology provided the best fit.