Βei Maria, Kamalakidis Savvas N, Pissiotis Argirios L, Michalakis Konstantinos, Naka Olga
Postgraduate student, Department of Prosthodontics, Faculty of Health Sciences, School of Dentistry, Aristotle University, Thessaloniki, Greece.
Researcher, Department of Prosthodontics, Faculty of Health Sciences, School of Dentistry, Aristotle University, Thessaloniki, Greece; Adjunct Assistant Professor, Division of Post-graduate Prosthodontics, School of Dental Medicine, Tufts University, Boston, Mass.
J Prosthet Dent. 2025 Mar;133(3):838-843. doi: 10.1016/j.prosdent.2023.04.019. Epub 2023 May 25.
The loss in the retentive capability of implant-supported overdenture attachments has been related to the wear of the retentive inserts. Wear of the abutment coating material when following the replacement period for the retentive inserts requires investigation.
The purpose of this in vitro study was to compare the changes in retentive force of 3 polyamide and a polyetheretherketone denture attachments under repeated insertion and removal cycles in wet conditions while following their manufacturers' replacement time recommendations.
Four different denture attachments (LOCKiT, OT-Equator, Ball attachment, and Novaloc) with their retentive inserts were tested. Four implants were embedded into individual acrylic resin blocks, and 10 abutments for each attachment were used. Forty metal housings with their retentive inserts were attached to polyamide screws with autopolymerizing acrylic resin. A customized universal testing machine was used to simulate insertion and removal cycles. The specimens were mounted on a second universal testing machine at 0, 540, 2700, and 5400 cycles, and the maximum retentive force was recorded. The retentive inserts for LOCKiT (light retention), OT-Equator (soft retention), and Ball attachment (soft retention) were replaced every 540 cycles, while the Novaloc (medium retention) attachments were never replaced. All the abutments were weighed with a precision scale at 0, 2700, and 5400 cycles. The surface of every abutment was examined under a stereomicroscope at ×10 magnification. Data were analyzed with descriptive statistics. Two-way repeated measures ANOVA was used to compare the mean retentive force and mean abutment mass of all groups and time evaluation points. Bonferroni corrections were made to adjust for multiple tests (α=.05).
The mean retention loss for LOCKiT was 12.6% after 6 months and 45.0% after 5 years of simulated use. The mean retention loss for OT-Equator was 16.0% after 6 months and 50.1% after 5 years of simulated use. The mean retention loss for Ball attachment was 15.3% after 6 months and 39.1% after 5 years of simulated use. The mean retention loss for Novaloc was 31.0% after 6 months and 59.1% after 5 years of simulated use. The mean abutment mass difference was statistically significant (P<.05) for LOCKiT and Ball attachment but not statistically significant (P>.05) for OT-Equator and Novaloc at baseline, 2.5 years, and 5 years.
All tested attachments recorded retention loss under the experimental conditions, even when their manufacturers' recommendations for replacement time for the retentive inserts were followed. Patients should be aware that implant abutments should be replaced after a recommended period since their surfaces also change over time.
种植体支持的覆盖义齿附着体固位能力的丧失与固位嵌体的磨损有关。在固位嵌体更换期后，基台涂层材料的磨损情况需要进行研究。
本体外研究的目的是比较3种聚酰胺和1种聚醚醚酮义齿附着体在潮湿条件下按照制造商的更换时间建议进行反复插入和取出循环时固位力的变化。
对4种不同的义齿附着体（LOCKiT、OT-Equator、球帽附着体和Novaloc）及其固位嵌体进行测试。将4枚种植体植入单独的丙烯酸树脂块中，每种附着体使用10个基台。40个带有固位嵌体的金属外壳用自凝丙烯酸树脂固定在聚酰胺螺钉上。使用定制的万能试验机模拟插入和取出循环。在0、540、2700和5400个循环时，将标本安装在另一台万能试验机上，记录最大固位力。LOCKiT（轻度固位）、OT-Equator（软质固位）和球帽附着体（软质固位）的固位嵌体每540个循环更换一次，而Novaloc（中度固位）附着体从不更换。在0、2700和5400个循环时，用精密天平对所有基台进行称重。在体视显微镜下以×10放大倍数检查每个基台的表面。数据采用描述性统计进行分析。采用双向重复测量方差分析比较所有组和时间评估点的平均固位力和平均基台质量。采用Bonferroni校正进行多重检验调整（α = 0.05）。
模拟使用6个月后，LOCKiT的平均固位损失为12.6%，5年后为45.0%。模拟使用6个月后，OT-Equator的平均固位损失为16.0%，5年后为50.1%。模拟使用6个月后，球帽附着体的平均固位损失为15.3%，5年后为39.1%。模拟使用6个月后，Novaloc的平均固位损失为31.0%，5年后为59.1%。LOCKiT和球帽附着体的平均基台质量差异具有统计学意义（P < 0.05），而OT-Equator和Novaloc在基线、2.5年和5年时的平均基台质量差异无统计学意义（P > 0.05）。
在实验条件下，所有测试的附着体均出现固位损失，即使遵循了制造商对固位嵌体更换时间的建议。患者应意识到，种植基台在建议期后应进行更换，因为其表面也会随时间变化。
