National University of Singapore, Faculty of Dentistry, Singapore.
J Prosthet Dent. 2013 Jan;109(1):37-43. doi: 10.1016/S0022-3913(13)60008-6.
The fabrication of an accurately fitting implant-supported fixed prosthesis requires multiple steps, the first of which is assembling the impression coping on the implant. An imprecise fit of the impression coping on the implant will cause errors that will be magnified in subsequent steps of prosthesis fabrication.
The purpose of this study was to characterize the 3-dimensional (3D) precision of fit between impression coping and implant replica pairs for 3 implant systems. The selected implant systems represent the 3 main joint types used in implant dentistry: external hexagonal, internal trilobe, and internal conical.
Ten impression copings and 10 implant replicas from each of the 3 systems, B (Brånemark System), R (NobelReplace Select), and A (NobelActive) were paired. A standardized aluminum test body was luted to each impression coping, and the corresponding implant replica was embedded in a stone base. A coordinate measuring machine was used to quantify the maximum range of displacement in a vertical direction as a function of the tightening force applied to the guide pin. Maximum angular displacement in a horizontal plane was measured as a function of manual clockwise or counterclockwise rotation. Vertical and rotational positioning was analyzed by using 1-way analysis of variance (ANOVA). The Fisher protected least significant difference (PLSD) multiple comparisons test of the means was applied when the F-test in the ANOVA was significant (α=.05).
The mean and standard deviation for change in the vertical positioning of impression copings was 4.3 ±2.1 μm for implant system B, 2.8 ±4.2 μm for implant system R, and 20.6 ±8.8 μm for implant system A. The mean and standard deviation for rotational positioning was 3.21 ±0.98 degrees for system B, 2.58 ±1.03 degrees for system R, and 5.30 ±0.79 degrees for system A. The P-value for vertical positioning between groups A and B and between groups A and R was <.001. No significant differences were found for vertical positioning between groups B and R. The P-value for rotational positioning between groups A and B and between groups A and R was <.001. No significant differences were found for rotational positioning between groups B and R.
The results of the study confirmed that implant systems differ in precision of fit. Vertical precision between paired implant components is a function of joint type and the tightening force applied to the guide pin. The magnitude of vertical displacement with applied torque is greater for conical connections than for butt joint connections. The rotational freedom between paired components is unique to the implant system and is presumably related to the machining tolerances specified by the manufacturer.
制作精确适配的种植体支持固定修复体需要多个步骤，其中第一步是将印模帽组装到种植体上。印模帽与种植体之间不精确的适配会导致误差，这些误差将在修复体制作的后续步骤中放大。
本研究的目的是为了研究 3 种种植体系统的印模帽和种植体复制件之间的三维（3D）精度。所选的种植体系统代表了种植牙科中使用的 3 种主要连接类型：外六角形、内三叶形和内锥形。
将每个系统的 10 个印模帽和 10 个种植体复制件配对，分别为 B（Brånemark 系统）、R（NobelReplace Select）和 A（NobelActive）。将标准化的铝测试体粘接到每个印模帽上，将相应的种植体复制件嵌入到石材底座中。使用坐标测量机来量化在垂直方向上的最大位移范围作为施加到导向销上的紧固力的函数。在水平平面上的最大角位移作为手动顺时针或逆时针旋转的函数进行测量。通过单向方差分析（ANOVA）分析垂直和旋转定位。当方差分析中的 F 检验显著时（α=.05），应用 Fisher 保护最小显著差异（PLSD）均值多重比较检验。
印模帽垂直定位变化的平均值和标准差分别为种植体系统 B 的 4.3±2.1μm，种植体系统 R 的 2.8±4.2μm，种植体系统 A 的 20.6±8.8μm。旋转定位的平均值和标准差分别为系统 B 的 3.21±0.98 度，系统 R 的 2.58±1.03 度，系统 A 的 5.30±0.79 度。组 A 和 B 以及组 A 和 R 之间的垂直定位 P 值均<.001。组 B 和 R 之间的垂直定位无显著差异。组 A 和 B 以及组 A 和 R 之间的旋转定位 P 值均<.001。组 B 和 R 之间的旋转定位无显著差异。
研究结果证实，种植体系统的精度存在差异。配对种植体部件之间的垂直精度是接头类型和施加到导向销上的紧固力的函数。施加扭矩时的垂直位移量与锥形连接大于对接连接。配对部件之间的旋转自由度是种植体系统特有的，可能与制造商规定的加工公差有关。
