Nishimura Yuichi, Takahashi Toshihito, Gonda Tomoya, Ikebe Kazunori
Int J Oral Maxillofac Implants. 2021 Mar-Apr;36(2):281-288. doi: 10.11607/jomi.8558.
Implant overdentures with splinted attachments have been used in clinical practice, and the effect of splinting on implants has been reported frequently. However, the effect of implant configuration of more than four implants and covering the palate with an overdenture has not been sufficiently examined. The purpose of this study was to reveal the effects of implant configuration and palatal coverage on both implant and denture strain in maxillary implant overdentures using splinted implants.
Six implants were placed in the anterior, premolar, and molar areas in a maxillary edentulous model. Four strain gauges were attached to the implant surface, and Dolder bar attachments were used to splint implants distributed in various configurations. Two types of maxillary experimental dentures (with/without palatal coverage) were fabricated, and two strain gauges were attached at the midline. A vertical load of 98 N was applied, and the strains on the dentures and implants were measured. The strain measurements were compared using one-way analysis of variance and t test (P = .05).
When comparing the implant strains, the strain was significantly smaller on the anterior and premolar implants when six implants were used, but there was no significant difference among the different implant configurations in the strain on the molar implants. Strains on anterior implants of the palateless overdenture were significantly greater than those of the overdenture with palatal coverage. When four implants were used, the strain on the palatal side of dentures without palate was significantly greater than that on those with palatal coverage. When six implants were used, there was no significant difference in the strain on either side between two types of dentures.
When implants were splinted to each other using a denture without palatal coverage, the strain of dentures when six or two anterior and two posterior implants were used was lower. The difference of denture strains between two types of dentures was not significant when six implants were used, but was significant for all other configurations. Also, the difference of implant strains between two dentures was significant in anterior implants regardless of implant configuration.
带有夹板式附着体的种植覆盖义齿已应用于临床实践，夹板对种植体的影响也屡有报道。然而，超过四颗种植体的种植体配置以及用覆盖义齿覆盖腭部的效果尚未得到充分研究。本研究的目的是揭示种植体配置和腭部覆盖对使用夹板式种植体的上颌种植覆盖义齿中种植体和义齿应变的影响。
在上颌无牙颌模型的前部、前磨牙区和磨牙区植入六颗种植体。在种植体表面粘贴四个应变片，并使用杜德尔杆附着体将分布在不同配置中的种植体进行夹板固定。制作两种类型的上颌实验义齿（有/无腭部覆盖），并在中线处粘贴两个应变片。施加98 N的垂直载荷，测量义齿和种植体上的应变。使用单因素方差分析和t检验比较应变测量结果（P = 0.05）。
比较种植体应变时，使用六颗种植体时，前部和前磨牙种植体上的应变明显较小，但磨牙种植体上不同种植体配置的应变之间无显著差异。无腭覆盖义齿前部种植体上的应变明显大于有腭覆盖的覆盖义齿。使用四颗种植体时，无腭义齿腭侧的应变明显大于有腭覆盖的义齿。使用六颗种植体时，两种类型义齿两侧的应变无显著差异。
当使用无腭覆盖的义齿将种植体相互夹板固定时，使用六颗或两颗前部和两颗后部种植体时义齿的应变较低。使用六颗种植体时，两种义齿之间的义齿应变差异不显著，但其他所有配置均显著。此外，无论种植体配置如何，两种义齿在前部种植体上的种植体应变差异均显著。
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