Faculty, Department of Prosthetic Dental Sciences, King Khalid University College of Dentistry, Abha, Saudi Arabia; Fellow in Advanced Digital Prosthodontics and Implant Dentistry, Department of Prosthodontics, Loma Linda University School of Dentistry, Loma Linda, Calif.
Private practice, Bellevue, Wash; Affiliate Assistant Professor, Department of Restorative Dentistry, University of Washington School of Dentistry, Seattle, Wash.
J Prosthet Dent. 2024 Mar;131(3):476.e1-476.e7. doi: 10.1016/j.prosdent.2022.09.006. Epub 2022 Nov 17.
Screw loosening is the most common mechanical complication with implant prostheses. How the alteration of implant-to-abutment connection surfaces that occurs during laboratory procedures affects screw loosening is unclear.
The purpose of this in vitro study was to compare the reverse tightening value (RTV) differences between custom castable abutments before casting, after casting in a conventional manner, and after casting with custom protector caps and pegs.
Thirty implants with a standard-diameter conical connection (NobelReplace Conical Connection 4.3×13 mm; Nobel Biocare AG) and 30 premachined 4.3-mm GoldAdapt abutments (GoldAdapt; Nobel Biocare AG) were selected for this study. Specimens were divided into 3 groups (n=10): the uncast custom castable abutment group (UCCA) in which abutments were new and not cast; the unprotected custom castable abutment group (UPCCA) in which abutments were cast and devested with airborne-particle abrasion; and the protected custom castable abutment group (PCCA) in which abutments were cast by using protector caps and pegs made by milling zirconia and then devested with airborne-particle abrasion. All abutments in each group were tightened to 35 Ncm with a calibrated digital tightening device. After 10 minutes, all screws were retightened to 35 Ncm. At 3 hours, each screw was loosened, and the value at which the initial loosening occurred was documented as the RTV. The results were statistically analyzed with 1-way ANOVA to explore differences, and post hoc tests with Tukey adjustment were used for multiple comparisons.
Among the tested groups, the mean RTV ranged from 19.89 Ncm to 27.19 Ncm: UCCA 27.19 Ncm, UPCCA 19.89 Ncm, and PCCA 24.24 Ncm. A significant difference was found among the tested groups (P<.05).
Casting procedures, especially devestment with airborne-particle abrasion, affected implant-abutment connections and the seat site of the screw. Protecting the implant connection site and the seat site of the abutment screw with protector caps and pegs prevented a significant loss of the RTV.
螺丝松动是植入物修复体最常见的机械并发症。在实验室过程中，连接界面发生的改变如何影响螺丝松动尚不清楚。
本体外研究的目的是比较铸造前、常规铸造后和使用定制保护帽和销钉铸造后的定制可铸造基台的反向拧紧值（RTV）差异。
选择 30 个具有标准直径锥形连接（NobelReplace 锥形连接 4.3×13mm；Nobel Biocare AG）的种植体和 30 个预加工的 4.3mm GoldAdapt 基台（GoldAdapt；Nobel Biocare AG）进行本研究。标本分为 3 组（n=10）：未铸造的定制可铸造基台组（UCCA），其中基台为新的且未铸造；无保护的定制可铸造基台组（UPCCA），其中基台经过喷射磨料喷砂处理后铸造；使用铣削氧化锆制成的保护帽和销钉铸造并经过喷射磨料喷砂处理后的定制可铸造基台组（PCCA）。每组中的所有基台均使用校准的数字拧紧装置拧紧至 35 Ncm。10 分钟后，所有螺丝均重新拧紧至 35 Ncm。3 小时后，每个螺丝均松动，并记录初始松动时的数值作为 RTV。使用单因素方差分析对结果进行统计学分析，以探索差异，并使用 Tukey 调整进行多重比较。
在所测试的组中，平均 RTV 范围为 19.89 Ncm 至 27.19 Ncm：UCCA 27.19 Ncm、UPCCA 19.89 Ncm 和 PCCA 24.24 Ncm。在所测试的组之间存在显著差异（P<.05）。
铸造过程，特别是喷射磨料喷砂处理，影响了种植体-基台连接和螺丝的就位部位。使用保护帽和销钉保护种植体连接部位和基台螺丝的就位部位可防止 RTV 显著损失。
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