Assessment of accuracy and reproducibility of intra-oral scanners as impression taking method for post and core / Gita Deepak Buxani

Gita Deepak , Buxani (2024) Assessment of accuracy and reproducibility of intra-oral scanners as impression taking method for post and core / Gita Deepak Buxani. Masters thesis, Universiti Malaya.

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Abstract

Digital workflows have significantly transformed restorative dental practices by enabling the creation of customized fibre-reinforced posts and zirconia cores (P+C) through CAD/CAM technology. Despite the reduced necessity for posts due to advancements in adhesive dentistry, they remain essential for restoring extensively damaged teeth. Prefabricated fibre posts often fail to conform accurately to post-space shapes, raising questions about the precision of intraoral scanners (IOS) in fabricating custom posts compared to traditional silicone impressions. This study aims to compare the accuracy and reproducibility of two intraoral scanners (IOS) namely Trios 5 and Primescan as well as the combination technique of the traditional silicone impression and digital scanner against traditional silicone impression techniques in recording post-space depths in extracted teeth. The significance of the study is to understand the precision of IOS versus traditional methods is crucial for ensuring optimal fit and function of custom posts, thereby improving clinical outcomes and patient satisfaction in restorative dentistry. A total of 42 extracted teeth were categorized into seven groups based on tooth type: mandibular lateral incisors, maxillary central incisors, maxillary canines, maxillary first premolars, mandibular second premolars, maxillary first molars, and mandibular first molars. For each tooth, five impressions were taken using different techniques: traditional polyvinyl siloxane (PVS), Trios 5 intraoral scanner (IOS), Primescan IOS, and combination techniques where PVS impressions were scanned with both Trios 5 and Primescan. Post-space depths were measured with a K-file and compared to measurements obtained from the three methods (PVS, Trios 5, and Primescan). Traditional impressions were measured with digital calipers, and Standard Tessellation iv Language (STL) files from IOS were analysed using Exoviewer3D 2.4 software. Reproducibility was assessed by superimposing digital impressions (Trios 5 and Primescan) and the combination technique impressions (PVS-Trios 5 and PVS-Primescan). Data were analysed using pairwise comparison, Kruskal Wallis and Mann-Whitney U tests. The study revealed significant differences in the accuracy of post-space depth recordings among the different methods. Traditional silicone impressions demonstrated higher accuracy and reproducibility than digital impressions obtained directly from IOS. The combination technique, which involved scanning traditional silicone impressions with IOS, showed improved performance over direct digital impressions, particularly in recording the full depth of the post spaces and reproducibility of the impressions. While digital impressions via intraoral scanners offer advancements in speed and convenience, traditional silicone impressions remain the gold standard for accuracy in post-space depth recording. The combination of traditional and digital techniques provides a viable alternative, enhancing the precision of custom post fabrication. These findings underscore the need for further refinement in IOS technology to match the reliability of traditional methods, ensuring better clinical outcomes in restorative dentistry.

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