Takahashi Toshihito, Gonda Tomoya, Tomita Akiko, Maeda Yoshinobu
Int J Oral Maxillofac Implants. 2018 Mar/Apr;33(2):357-364. doi: 10.11607/jomi.6157.
Palateless maxillary implant overdentures are often used for patients experiencing problems with a full-palate denture. However, palateless overdentures are reported to be a risk factor for implant complications. The purpose of this study was to examine the strain on implants beneath palateless overdentures with unsplinted attachments under various implant distributions.
A maxillary edentulous model with implants and an experimental palateless overdenture were fabricated. Four strain gauges were attached to each implant, positioned in the anterior, premolar, and molar areas. Three types of unsplinted attachments (ball, locator, and magnet) were set on the implants under various implant distributions. A vertical occlusal load of 98 N was applied through the mandibular complete denture, and the bending strain on the implants was compared using the Kruskal-Wallis test (P = .05).
When comparing the strain among different attachments, those using a magnet attachment were the smallest and those using a ball attachment were the greatest, and this difference was significant in most situations (P < .05). When comparing the strain among different implant distributions, the strain on a four-implant distribution was significantly smaller than that on a two-implant distribution in most situations (P < .05), and those using premolar and molar implants recorded the smallest strain. The strain on implants using a locator attachment tended to be midway between those using ball and magnet attachments, regardless of the implant distribution.
In most implant distributions, magnet attachments decrease the strain on implants more than ball and locator attachments. The most favorable unsplinted attachments for use beneath palateless overdentures to decrease the implant strain are magnet attachments and four implants placed in the premolar and molar areas.
无腭上颌种植覆盖义齿常用于全腭义齿出现问题的患者。然而，据报道无腭覆盖义齿是种植体并发症的一个风险因素。本研究的目的是在不同种植体分布情况下，检查采用非夹板式附着体的无腭覆盖义齿下方种植体的应变情况。
制作一个带有种植体的上颌无牙颌模型和一个实验性无腭覆盖义齿。在每个种植体上附着四个应变片，分别位于前部、前磨牙区和磨牙区。在不同种植体分布情况下，在种植体上设置三种类型的非夹板式附着体（球帽、Locator附着体和磁性附着体）。通过下颌全口义齿施加98 N的垂直咬合负荷，并使用Kruskal-Wallis检验比较种植体上的弯曲应变（P = 0.05）。
比较不同附着体之间的应变时，使用磁性附着体的应变最小，使用球帽附着体的应变最大，并且在大多数情况下这种差异具有统计学意义（P < 0.05）。比较不同种植体分布之间的应变时，在大多数情况下，四种植体分布时的应变显著小于两种植体分布时的应变（P < 0.05），并且在前磨牙和磨牙区使用种植体时记录到的应变最小。无论种植体分布如何，使用Locator附着体的种植体上的应变往往介于使用球帽和磁性附着体的应变之间。
在大多数种植体分布情况下，磁性附着体比球帽和Locator附着体更能降低种植体上的应变。对于无腭覆盖义齿下方使用以降低种植体应变而言，最有利的非夹板式附着体是磁性附着体以及在前磨牙和磨牙区放置的四种植体。
