Bhering Cláudia Lopes Brilhante, Marques Isabella da Silva Vieira, Takahashi Jessica Mie Ferreira Koyama, Barão Valentim Adelino Ricardo, Consani Rafael Leonardo Xediek, Mesquita Marcelo Ferraz
Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas, Piracicaba, Brazil.
Department of Prosthodontics, Health Sciences Graduate School, Amazonas State University, Manaus, Brazil.
J Prosthodont. 2016 Aug;25(6):459-65. doi: 10.1111/jopr.12349. Epub 2015 Oct 14.
The aim of the study was to evaluate the effect of a prosthetic cylinder and casting on the misfit and loosening torque of screw-retained multiple-unit implant-supported dental prostheses under masticatory simulation.
Screw-retained, three-unit fixed dental prostheses (FDP) and screw-retained full-arch FDP frameworks were waxed using calcinable (plastic cylinders) or overcasted (premachined cast-on cylinders) on the dental implant abutments. The cylinders were cast in Co-Cr alloy to obtain four groups according to cylinder type and prosthesis type (n = 10). The screws were tightened with 20 N/cm (abutment) and 10 N/cm (prosthetic) torque according to the manufacturer's recommendation. After 24 hours, the initial loosening torque was analyzed. The initial misfit measurements were performed according to the Schiffleger test. The screws were retightened, and the specimens were submitted to 10(6) mechanical cycles (2 Hz/280 N). Loosening torque and misfit were reevaluated (final measurements), and data were submitted to ANOVA, Tukey's HSD, and Pearson's correlation tests (α = 0.05).
The calcinable three-unit FDP demonstrated greater misfit (initial: 107.53 ± 40.36 μm; final: 99.00 ± 40.85 μm) than did the overcasted three-unit FDP frameworks (initial: 51.50 ± 22.98 μm; final: 44.33 ± 14.14 μm) (initial: p = 0.0005; final: p = 0.0007). No difference was noted between the calcinable and overcasted full-arch FDP frameworks (p > 0.05). Masticatory simulation did not affect the misfit (p > 0.05). The overcasted full-arch FDP presented a lower abutment screw loosening torque (12.05 ± 1.80 N/cm) than did the calcinable ones (14.75 ± 1.72 N/cm) in the final measurement (p = 0.0024). The calcinable groups presented a lower prosthetic screw loosening torque than did the overcasted groups in the final evaluation (p < 0.05). After masticatory simulation, the prosthetic screw loosening torque of the calcinable three-unit FDP decreased (initial: 5.49 ± 1.07 N/cm; final: 3.73 ± 1.15 N/cm; p = 0.0044). Correlation between misfit and loosening was observed only for the prosthetic screws (p < 0.05).
The overcasted components provided a better fit in three-unit FDPs but did not influence the fit of full-arch FDPs. Prosthetic screws of overcasted frameworks presented higher stability, whereas masticatory simulation did not influence misfit but did reduce the prosthetic screw loosening torque of calcinable three-unit FDP frameworks.
本研究旨在评估在咀嚼模拟条件下，修复体圆柱体和铸造工艺对螺丝固位的多单位种植体支持式牙修复体的不匹配度和松动扭矩的影响。
在牙种植体基台上，使用可煅烧的（塑料圆柱体）或包铸的（预加工铸造圆柱体）方法为螺丝固位的三单位固定义齿（FDP）和螺丝固位的全牙弓FDP框架制作蜡型。根据圆柱体类型和修复体类型将圆柱体铸造成钴铬合金，分为四组（n = 10）。按照制造商的建议，用20 N/cm（基台）和10 N/cm（修复体）的扭矩拧紧螺丝。24小时后，分析初始松动扭矩。根据Schiffleger试验进行初始不匹配度测量。重新拧紧螺丝，将标本进行10(6)次机械循环（2 Hz/280 N）。重新评估松动扭矩和不匹配度（最终测量），数据进行方差分析、Tukey's HSD检验和Pearson相关性检验（α = 0.05）。
可煅烧的三单位FDP显示出比包铸的三单位FDP框架更大的不匹配度（初始：107.53 ± 40.36 μm；最终：99.00 ± 40.85 μm）（包铸的初始：51.50 ± 22.98 μm；最终：44.33 ± 14.14 μm）（初始：p = 0.0005；最终：p = 0.0007）。可煅烧的和包铸的全牙弓FDP框架之间未观察到差异（p > 0.05）。咀嚼模拟未影响不匹配度（p > 0.05）。在最终测量中，包铸的全牙弓FDP的基台螺丝松动扭矩（12.05 ± 1.80 N/cm）低于可煅烧的（14.75 ± 1.72 N/cm）（p = 0.0024）。在最终评估中，可煅烧组的修复体螺丝松动扭矩低于包铸组（p < 0.05）。咀嚼模拟后，可煅烧的三单位FDP的修复体螺丝松动扭矩降低（初始：5.49 ± 1.07 N/cm；最终：3.73 ± 1.15 N/cm；p = 0.0044）。仅在修复体螺丝中观察到不匹配度与松动之间的相关性（p < 0.05）。
包铸部件在三单位FDP中提供了更好的适配性，但不影响全牙弓FDP的适配性。包铸框架的修复体螺丝具有更高的稳定性，而咀嚼模拟不影响不匹配度，但确实降低了可煅烧的三单位FDP框架的修复体螺丝松动扭矩。
