Accuracy of lithium disilicate and polymer-infiltrated ceramic-network (PICN) ceramic restorations fabricated from subtractive manufacturing: A systematic review of in vitro studies.

OBJECTIVE

To systematically review studies that investigated the accuracy of dental ceramic restorations after subtractive manufacturing.

DATA/SOURCES: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines according to PRISMA, electronic searches were performed via OVID MEDLINE(R), Scopus and PubMed for articles between 2003 and 2023. The search strategy was limited to in vitro peer-reviewed publications in the English language. Studies evaluating lithium disilicate (LD) or polymer-infiltrated ceramic network (PICN) material were selected. Exclusion criteria were articles that did not assess the accuracy of subtractively-manufactured ceramic restorations.

STUDY SELECTION

A total of 1824 studies were initially identified. After screening titles and abstracts and assessing full-text, 53 in vitro studies satisfied the inclusion criteria and were selected for analysis. The risk of bias was assessed according to a modified Consolidated Standards of Reporting Trials (CONSORT) checklist.

RESULTS

Forty-five studies measured marginal and internal gaps. For LD ceramics, the marginal and internal discrepancies ranged from 12.7 μm to 200 μm and 11.41 μm to 391 μm, respectively. Manufactured PICN restorations had a marginal gap between 29.48 μm and 163.1 μm but an internal gap between 50.27 μm and 181.83 μm. Nine studies investigated accuracy. The mean trueness of LD restorations ranged from 26.5 μm to 146 μm, and PICN restorations had mean values between 32.69 μm and 83.04 μm.

CONCLUSIONS

The accuracy of subtractively-manufactured restorations is influenced by the type of ceramics, tooth preparation, impression digitization, digital design, machining strategy (axis number and instrument tool wear), and post-processing. Heat treatment and adjustment alter the crown fit, and crystallization enlarges the marginal gap but reduces the internal gap of LD restorations.

CLINICAL SIGNIFICANCE

Multiple factors influence the quality of subtractively-manufactured ceramic restorations. This review highlights the factors that dental practitioners should consider when milling ceramic restorations for the best clinical performance.