Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part III: marginal and internal fit

Abstract

STATEMENT OF PROBLEM Trials comparing the overall performance of digital with that of conventional workflows in restorative dentistry are needed. PURPOSE The purpose of the third part of a series of investigations was to test whether the marginal and internal fit of monolithic crowns fabricated with fully digital workflows differed from that of crowns fabricated with the conventional workflow. MATERIAL AND METHODS In each of 10 participants, 5 monolithic lithium disilicate crowns were fabricated for the same abutment tooth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 4 crowns using the Lava, iTero, Cerec inLab, and Cerec infinident systems. The conventional workflow included a polyvinyl siloxane impression, manual waxing, and heat-press technique. The discrepancy between the crown and the tooth was registered using the replica technique with polyvinyl siloxane material. The dimensions of the marginal discrepancy (Discrepancymarginal) and the internal discrepancy in 4 different regions of interest (Discrepancyshoulder, Discrepancyaxial, Discrepancycusp, and Discrepancyocclusal) were assessed using light microscopy. Post hoc Student t test with Bonferroni correction was applied to detect differences (=.05). RESULTS Discrepancymarginal was 83.6 ±51.1 m for the Cerec infinident, 90.4 ±66.1 m for the conventional, 94.3 ±58.3 m for the Lava, 127.8 ±58.3 m for the iTero, and 141.5 ±106.2 m for the Cerec inLab workflow. The differences between the treatment modalities were not statistically significant (P>.05). Discrepancyshoulder was 82.2 ±42.4 m for the Cerec infinident, 97.2 ±63.8 m for the conventional, 103.4 ±52.0 m for the Lava, 133.5 ±73.0 m for the iTero, and 140.0 ±86.6 m for the Cerec inLab workflow. Only the differences between the Cerec infinident and the Cerec inLab were statistically significant (P=.036). The conventionally fabricated crowns revealed significantly lower values in Discrepancycusp and Discrepancyocclusal than all the crowns fabricated with digital workflows (P<.05). CONCLUSIONS In terms of marginal crown fit, no significant differences were found between the conventional and digital workflows for the fabrication of monolithic lithium disilicate crowns. In the occlusal regions, the conventionally manufactured crowns revealed better fit than the digitally fabricated crowns. Chairside milling resulted in less favorable crown fit than centralized milling production. Purpose. The purpose of the fourth part of a series of investigations was to test whether the marginal and internal fit of monolithic crowns fabricated with fully digital workflows differed from that of crowns fabricated with the conventional workflow. Material and methods.In each of 10 participants, 5 monolithic lithium disilicate crowns were fabricated for the same abutment tooth according to a randomly generated sequence.Digital workflows were applied for the fabrication of 4 crowns with Lava, iTero, Cerec inLab, and Cerec infinident systems. The conventional workflow ...

Clinical performance of chairside monolithic lithium disilicate glass‐ceramic CAD‐CAM crowns

“…5,28 Nevertheless no statistically significant differences were found even when comparing marginal integrity based on models made using digital scanning or conventional impressions in vitro. 12,29 We did not observe other technical complications such as crown fracture, chipping, or loss of retention despite one patient having had a parafunctional habit (yet did not use a night-guard); this compares favorably with findings reported by others. [3][4][5] Even when it was determined that there was inadequate occlusal thickness in monolithic LDGC crowns; there was a relatively low rate of fracture.…”

“…The CEREC Omnicam scanner was used in our investigation, but at this time we do not know how this might have affected the marginal fit as compared to what might be expected with the scanning system (CEREC Bluecam) that was previously used in other studies . Nevertheless no statistically significant differences were found even when comparing marginal integrity based on models made using digital scanning or conventional impressions in vitro …”

Comparison of the Accuracy of Fit of Metal, Zirconia, and Lithium Disilicate Crowns Made from Different Manufacturing Techniques

“…Lithium disilicate ceramic is a glass‐ceramic with improved strength. Similar to reports on zirconia, reports on the marginal fit of lithium disilicate crowns made from conventional and CAD/CAM techniques were not consistent …”

“…While the superiority of the digital workflow was reported by some studies, another study indicated that conventional methods provided better marginal fit . Other authors, however, reported that digital and conventional impressions produced results with similar accuracy …”

The Conometric Concept: A Two‐Year Follow‐Up of Fixed Partial CEREC Restorations Supported By Cone‐In‐Cone Abutments

“…All the possible procedural mistakes inherent in the traditional chain of work based on impressions using individual trays and silicone impression material, impression of the antagonist using alginate, the creation of stone master casts, waxing, and fusion/pressing of the definitive restorations were eliminated. The possible occlusal misfit and marginal discrepancies produced by CAD/CAM systems were avoided secondary to the cementation procedure. A recent study concluded that the use of customized CAD/CAM abutments did not guarantee avoidance of subgingival cement residues after crown fixation .…”