Department of Preventive Dentistry, Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan.
Department of Removable Partial Prosthodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Med Sci Monit. 2019 May 27;25:3933-3940. doi: 10.12659/MSM.913186.
BACKGROUND The purpose of this study was to assess the effect of different exposure levels of a dental implant's first thread on adjacent bone stress and strain using the finite element analysis method. MATERIAL AND METHODS Three-dimensional models of 2 threaded implants and abutments with a mandibular bone segment were constructed to represent the covered (C) and exposed models. In the exposed models, the implant was first placed in the bone, and rotated around its axis a quarter-turn each time to simulate 4 different levels of first thread exposure at the mid-lingual side: Upper Flank (UF), Thread Crest (TC), Lower Flank (LF), and Thread Root (TR) models. Oblique forces were applied and analysis was performed. RESULTS Maximum compressive stress magnitude and distribution varied according to the exposed thread profile. In the exposed group, peak stress ranged from 136 MPa to 197 MPa in TC and LF models, respectively, compared to 141 MPa in C model. In LF, UF, and C models, peak stress was observed at the mid-lingual side of the crestal region, while in TC and TR models, peak stress shifted distally in accordance with thread profile. However, alveolar bone volumes which exhibited compressive microstrain levels within the physiological loading and maintenance windows were relatively close in all models. CONCLUSIONS Results suggest that the exposed thread profile influences stress and strain outcomes in the adjacent bone; however, this influence is only limited to a small region around the exposed thread.
本研究旨在通过有限元分析方法评估牙科种植体第一螺纹不同暴露水平对相邻骨的应力和应变的影响。
构建了带有下颌骨段的 2 个螺纹种植体和基台的三维模型，以代表覆盖（C）和暴露模型。在暴露模型中，先将种植体置于骨中，然后沿其轴旋转四分之一圈，每次模拟中侧第一螺纹暴露的 4 个不同水平：上翼（UF）、螺纹顶（TC）、下翼（LF）和螺纹根（TR）模型。施加斜向力并进行分析。
最大压缩应力大小和分布随暴露螺纹轮廓而变化。在暴露组中，TC 和 LF 模型中的峰值应力分别为 136 MPa 至 197 MPa，而 C 模型中的峰值应力为 141 MPa。在 LF、UF 和 C 模型中，峰值应力出现在嵴顶区域的中侧，而在 TC 和 TR 模型中，峰值应力随螺纹轮廓向远端转移。然而，在所有模型中，表现出生理负荷和维持范围内压缩微应变水平的牙槽骨体积相对接近。
结果表明，暴露的螺纹轮廓会影响相邻骨的应力和应变结果；然而，这种影响仅限于暴露螺纹周围的一个小区域。
