Accuracy of Intra-Oral Scanners for Full Crown Tooth Preparations with Subgingival Margins: A Systematic Review.

INTRODUCTION: The accuracy of intra-oral scanners (IOS) has not been thoroughly evaluated across all clinical scenarios, particularly in crown preparations with subgingival margins. OBJECTIVES: This systematic review aims to assess the accuracy of IOS in tooth preparations with subgingival margins and identify factors influencing their performance in these situations. METHODS: A comprehensive literature search was conducted in databases including PubMed, Scopus, Embase, Medline, Google Scholar, and Web of Science for studies published in the last five years. Quality Assessment Tool for In-Vitro Studies (QUIN) was used to evaluate study quality. RESULTS: Out of 605 studies, seven met the inclusion and exclusion criteria. The review found that the trueness of IOS is significantly compromised in subgingival margins, often failing to achieve clinically acceptable results. Influencing factors included gingival retraction and saliva contamination. Specifically, cord retraction enhanced IOS accuracy, while saliva contamination reduced it. CONCLUSIONS: The accuracy of IOS in crown preparations with subgingival margins is severely affected by saliva contamination and visibility issues. Clinically acceptable results are achieved with proper gingival retraction and a dry field. CLINICAL RELEVANCE: To ensure accurate scanning for tooth preparations with subgingival margins, achieving proper gingival retraction and dryness is crucial.