Oda Ken, Kanazawa Manabu, Takeshita Shin, Minakuchi Shunsuke
Graduate student, Gerodontology and Oral Rehabilitation, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo, Japan.
Assistant Professor, Gerodontology and Oral Rehabilitation, Tokyo Medical and Dental University, Tokyo, Japan.
J Prosthet Dent. 2017 Mar;117(3):380-385. doi: 10.1016/j.prosdent.2016.08.005. Epub 2016 Sep 24.
The rotational movement of an implant overdenture (IOD) has a negative effect on the perceived masticatory ability of the denture wearer. However, the influence of implant number on the movement of IODs has not been investigated.
The purpose of this in vitro study was to evaluate the denture movement of mandibular IODs anchored by different numbers of implants.
An edentulous mandibular test model with artificial mucosa and 5 experimental overdentures (N=5) was fabricated. The locator attachment system with blue nylon inserts was chosen for this study. Three implant positions were prepared: anterior midline (1-IOD), bilateral lateral incisor regions (2-IOD), and anterior midline and bilateral canine regions (3-IOD). Vertical loads of 50 N were applied to the mid-anterior region, the left canine region, the left premolar region, and the left first molar region. The vertical and horizontal displacements at the right distal edge and the vertical displacements at the loading point were measured. The displacement values were statistically analyzed using a 1-way analysis of variance and the post hoc Tukey honest significant difference test with the implant number as a factor. In addition, the values of the vertical and horizontal displacements at the distal edge of the overdenture were statistically compared using a paired t test, and the values of the vertical displacement at the distal edge of the overdenture were statistically analyzed by a repeated measures analysis of variance and the post hoc Tukey honest significance difference test with the loading point as a factor (a=.05).
Upon anterior loading, the 2-IOD showed significantly larger vertical displacements at the right distal edge than the 1-IOD or 3-IOD (P<.01). The horizontal displacements at the right distal edge were small compared with the vertical displacements at the same point, although the displacement of the 2-IOD was significantly larger than that of the 1-IOD upon anterior loading (P=.03). The magnitude of the vertical displacement at the loading point of the 2-IOD was significantly larger than that of the 3-IOD upon anterior loading (P<.01). No statistically significant differences were shown under the other conditions for each loading (P>.05).
Within the limitations of this in vitro study, the following conclusions were drawn: During mastication with the anterior teeth, the use of 2 implants for anchoring an IOD increased the rotation of the denture base more than the use of 1 or 3 implants. The horizontal movements of the IODs were small compared with the vertical movements. Denture movement under the occlusal force in the molar region was smaller than that in the anterior region.
种植覆盖义齿（IOD）的旋转运动会对义齿佩戴者的咀嚼能力产生负面影响。然而，种植体数量对IOD运动的影响尚未得到研究。
本体外研究的目的是评估由不同数量种植体固定的下颌IOD的义齿运动情况。
制作了一个带有人工黏膜的无牙下颌测试模型和5副实验性覆盖义齿（N = 5）。本研究选用了带有蓝色尼龙嵌体的定位附着系统。准备了三个种植体位置：前正中（1 - IOD）、双侧侧切牙区域（2 - IOD）以及前正中与双侧尖牙区域（3 - IOD）。在中前部区域、左侧尖牙区域、左侧前磨牙区域和左侧第一磨牙区域施加50 N的垂直载荷。测量右侧远端边缘的垂直和水平位移以及加载点处的垂直位移。使用单因素方差分析和以种植体数量为因素的事后Tukey诚实显著差异检验对位移值进行统计分析。此外，使用配对t检验对覆盖义齿远端边缘的垂直和水平位移值进行统计比较，并以加载点为因素通过重复测量方差分析和事后Tukey诚实显著性差异检验对覆盖义齿远端边缘的垂直位移值进行统计分析（α = 0.05）。
在前部加载时，2 - IOD在右侧远端边缘的垂直位移显著大于1 - IOD或3 - IOD（P < 0.01）。与同一点的垂直位移相比，右侧远端边缘的水平位移较小，尽管在前部加载时2 - IOD的位移显著大于1 - IOD（P = 0.03）。在前部加载时，2 - IOD加载点处的垂直位移幅度显著大于3 - IOD（P < 0.01）。在每种加载的其他条件下未显示出统计学显著差异（P > 0.05）。
在本体外研究的局限性内，得出以下结论：在前牙咀嚼过程中，使用2个种植体固定IOD比使用1个或3个种植体时义齿基托的旋转更多。与垂直运动相比，IOD的水平运动较小。磨牙区域在咬合力作用下的义齿运动比前部区域小。
