Investigation of digital and conventional methods for verifying the fitness of CAD/CAM crowns on abutments with different shapes

Abstract

Purpose

To evaluate the marginal and internal compatibility of computer-aided design and computer-aided manufacturing crowns produced via a digital workflow using an intraoral scanner, and to compare this digital-detection technique with the conventional fit test using silicone rubber (silicone-compatibility technique) on various abutments.

Methods

Implant bodies were placed in the maxillary right central incisor and mandibular right first molar of reference models. Digital scans were acquired using an intraoral scanner, and abutments were prepared. Twenty-four crowns with a cement space of 70 μm were fabricated from the digital file of the abutment. The crown’s inner surface, abutment, and occlusal surface were scanned. The gaps between the crown and abutment were measured using stereoscopic image analysis software based on standard triangulated language data, and the accuracy of the fit was verified using silicone rubber.

Results

Significant differences (P < 0.05) were observed between the silicone-compatibility and digital-detection techniques for the maxillary central incisor at the incisal edge and the palatal lower region, and for the mandibular first molar at the occlusal surface and the center of lingual axis. The digital-detection technique yielded values closer to 70 μm for the cement space. The values measured using the silicone-compatibility technique exhibited greater variation than those measured using the digital-detection technique.

Conclusions

The novel digital-detection technique had superior or equivalent performance compared to the silicone-compatibility technique and could be beneficial for verifying crown fitness accuracy.