Kale Amit A, Jain Shashikala, Bhasin Navreet, Jaiswal Sneha B, Grover Ramanjeet K, Singh Balbir
Department of Prosthodontics, Maharaja Ganga Singh Dental College and Research Centre, Sri Ganganagar, IND.
Cureus. 2024 Oct 17;16(10):e71748. doi: 10.7759/cureus.71748. eCollection 2024 Oct.
The marginal fit of dental restorations is essential for longevity and effectiveness of fixed prostheses, particularly single-unit crowns. Direct digital scanning offers significant advantages over indirect methods, providing a non-invasive, accurate, and reproducible means to evaluate marginal fit. This study aimed to assess the marginal fit of single-unit copings fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia, direct metal laser sintering (DMLS), and porcelain-fused-to-metal (PFM) utilizing direct three-dimensional (3D) scanning.
The current in vitro investigation involved 60 right mandibular second premolar typodont teeth (Dentmark, Ambala, Haryana, India) designated for single-unit fixed dental prostheses. The specimens were categorized into three groups of 20 specimens each. Direct scanning for all groups was performed using the Helios 500 intraoral scanner (Orikam Healthcare India Pvt. Ltd., Haryana, India). Upon fabrication, all copings were directly scanned using a 3D scanner (Shining 3D EX Pro, California, USA). Marginal discrepancies were assessed using the Exocad software (CAD software, Darmstadt, Germany).
Mean marginal discrepancies of zirconia, DMLS, and PFM copings were evaluated and compared. Zirconia copings had the lowest mean discrepancy of 0.0172 mm whereas DMLS copings had a mean discrepancy of 0.0256 mm. The PFM copings had the highest mean discrepancy of 0.0375 mm. A one-way analysis of variance (ANOVA) indicated a significant difference in the marginal fit (p < 0.05). Post-hoc Tukey test comparisons revealed significant differences between the three groups (p < 0.05).
In conclusion, CAD/CAM-fabricated zirconia crowns exhibit superior marginal fit compared to DMLS and PFM copings, owing to precise digital design, milling, and material stability. DMLS copings, although less precise, still outperform PFM crowns, which display significant marginal gaps owing to the limitations of the lost-wax method.
牙齿修复体的边缘适合性对于固定修复体，尤其是单冠修复体的长期使用和有效性至关重要。直接数字扫描相较于间接方法具有显著优势，它提供了一种非侵入性、准确且可重复的手段来评估边缘适合性。本研究旨在利用直接三维（3D）扫描评估采用计算机辅助设计/计算机辅助制造（CAD/CAM）氧化锆、直接金属激光烧结（DMLS）和烤瓷熔附金属（PFM）制作的单冠修复体的边缘适合性。
当前的体外研究涉及60颗右侧下颌第二前磨牙模型牙（Dentmark，印度哈里亚纳邦安巴拉），用于制作单冠固定义齿。标本被分为三组，每组20个标本。所有组均使用Helios 500口腔内扫描仪（印度哈里亚纳邦Orikam Healthcare India Pvt. Ltd.）进行直接扫描。制作完成后，所有修复体均使用3D扫描仪（美国加利福尼亚州Shining 3D EX Pro）进行直接扫描。使用Exocad软件（德国达姆施塔特的CAD软件）评估边缘差异。
评估并比较了氧化锆、DMLS和PFM修复体的平均边缘差异。氧化锆修复体的平均差异最低，为0.0172毫米，而DMLS修复体的平均差异为0.0256毫米。PFM修复体的平均差异最高，为0.0375毫米。单因素方差分析（ANOVA）表明边缘适合性存在显著差异（p < 0.05）。事后Tukey检验比较显示三组之间存在显著差异（p < 0.05）。
总之，由于精确的数字设计、铣削和材料稳定性，CAD/CAM制作的氧化锆冠相比DMLS和PFM修复体表现出更好的边缘适合性。DMLS修复体虽然精度稍低，但仍优于PFM冠，PFM冠由于失蜡法的局限性显示出明显的边缘间隙。
