Liu Wei, Zhang Xin, Qing Hai, Wang Jian
Postgraduate student, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
Doctoral student, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.
J Prosthet Dent. 2020 Aug;124(2):224-229. doi: 10.1016/j.prosdent.2019.09.005. Epub 2019 Nov 25.
The LOCATOR system has been widely used for 2-implant-retained mandibular overdentures (2-MOs), but the influence of different LOCATOR attachments on the stability of 2-MOs has not been assessed.
The purpose of this in vitro study was to investigate the stability of 2-MOs anchored by LOCATOR attachments with different retentive forces.
An edentulous mandibular test cast with 2 bone-level implants inserted in the left and right mandibular canine regions was used. Twelve overdentures were then fabricated and anchored on the cast, following the instructions of the LOCATOR system. By replacing inserts of the 12 overdentures, the stability of 3 groups of LOCATOR inserts with different retentive forces was evaluated: blue group, pink group, and transparent group. With artificial saliva used on the cast and overdentures, vertical forces of 40 N, 55 N, and 100 N were loaded on the occlusal surface of the left incisor, left canine, and left molar, respectively. Under each loading condition, the vertical displacements at the loading point and the vertical and horizontal displacements of overdentures at the right distal edge were measured at the same time. One-way ANOVA and the post hoc Tukey honestly significant difference (HSD) test were used to compare the stability of 2-MOs with different LOCATOR attachments (α=.05 for all tests).
When a force of 40 N was applied to the incisor, the largest vertical movement of the incisor loading point appeared in the blue group (P<.05), and the displacements of the pink group showed significant difference from those of the transparent group (P>.05). When 55 N was loaded on the canine, the blue group showed the largest vertical displacements of both the loading point and the right distal edge of the overdentures (P<.05). No significant difference was found in the vertical displacements between the pink group and the transparent group (P>.05). When a force of 100 N was loaded on the molar point, the transparent group indicated a smaller movement in the vertical direction at the edge of the overdentures than the blue group (P<.05) or the pink group (P<.05).
LOCATOR attachments with different retentive forces had a significant effect on the denture stability of 2-MOs. Compared with the blue inserts, the pink and transparent inserts can offer greater stability for 2-MOs and could therefore be suggested for clinical situations.
定位器系统已广泛应用于双种植体支持的下颌覆盖义齿（2-MOs），但不同定位器附着体对2-MOs稳定性的影响尚未得到评估。
本体外研究的目的是调查由具有不同固位力的定位器附着体固定的2-MOs的稳定性。
使用一个无牙下颌试验模型，在左右下颌尖牙区植入2枚骨水平种植体。然后按照定位器系统的说明制作12副覆盖义齿并固定在模型上。通过更换12副覆盖义齿的嵌体，评估3组具有不同固位力的定位器嵌体的稳定性：蓝色组、粉色组和透明组。在模型和覆盖义齿上使用人工唾液，分别在左中切牙、左尖牙和左磨牙的咬合面上施加40 N、55 N和100 N的垂直力。在每种加载条件下，同时测量加载点处的垂直位移以及覆盖义齿右远端边缘处的垂直和水平位移。采用单因素方差分析和事后Tukey真实显著性差异（HSD）检验来比较不同定位器附着体的2-MOs的稳定性（所有检验的α = 0.05）。
当在中切牙上施加40 N的力时，蓝色组中切牙加载点的垂直移动最大（P < 0.05），粉色组的位移与透明组的位移有显著差异（P > 0.05）。当在尖牙上施加55 N的力时，蓝色组在覆盖义齿加载点和右远端边缘处的垂直位移均最大（P < 0.05）。粉色组和透明组之间的垂直位移无显著差异（P > 0.05）。当在磨牙上施加100 N的力时，透明组在覆盖义齿边缘处的垂直方向移动比蓝色组（P < 0.05）或粉色组（P < 0.05）小。
具有不同固位力的定位器附着体对2-MOs的义齿稳定性有显著影响。与蓝色嵌体相比，粉色和透明嵌体可为2-MOs提供更高的稳定性，因此可推荐用于临床情况。
