Mohamed Sara Ibrahim Soliman, Alattar Shymaa Ibrahim, Bakry Abdulrhman Atef, Ouda Shaimaa Lofty Mohamed
Oral and Maxillofacial Prosthodontics, Faculty of Dentistry, Ain-Shams University, Cairo, Egypt.
, 114 Degla Gardens 6th of October, Giza, Egypt.
BMC Oral Health. 2025 May 28;25(1):833. doi: 10.1186/s12903-025-06199-5.
The OT-Bridge is reported as a simple versatile rehabilitation technique that guarantees tight stable prosthesis even with absence of few screws. However, to provide implant patients with intriguing prospects for rehabilitation with this system, vast research is still required to understand the biomechanical behavior of the OT-Bridge. This investigation aimed to evaluate the stresses induced in an All-on-six maxillary OT-Bridge prosthesis in different circumstances that vary in number and geometric distribution of the retaining screws using finite element analysis.
MATERIALS & METHODS: This study comprised five test groups based on the number and distribution of the connection screws used to anchor an all-on-six OT-Bridge superstructure as follows; Group I: six screws, Group II: five screws eliminating the right central screw, Group III: four screws with two anterior screws eliminated unilaterally, Group IV: four screws with two anterior screws eliminated bilaterally, and Group V: three screws eliminating both central incisors and right canine screws. The computer simulation was done through three main stages: experimental model designing, SolidWorks modelling, and model analysis using ABAQUS . The analysis was run under a unilateral axial load (250 N) and an oblique load (150 N). The maximum generated von Mises Stresses (vMS) for the; bridge, prosthetic screws, seeger rings, equators, fixtures, cancellous bone, and cortical bone were recorded to compare the five test groups.
The highest vMS induced in the bridge (677 and 437 MPa under vertical and oblique load, respectively) were in group IV. The highest equator vMS were in groups III and IV (122, 121.9 MPa) under vertical load, while under oblique load, they were in groups V and III (66.2, 65.7 MPa). The vMS in screws, implants, and two bony segments exhibited the most significant increase in group V. The bilateral anterior screw elimination (group IV) compared to the unilateral elimination (group III) increased the vMS on the bridge, screws, and implants.
The OT-Bridge is considered a biomechanically efficient prosthetic system even in the absence of one-third of the anchoring screws in all-on-six prostheses. However, unilateral rather than bilateral elimination of two anterior screws results in better stress distribution pattern.
Not applicable.
OT桥被报道为一种简单通用的修复技术，即使缺少几颗螺钉也能保证义齿稳固。然而，为给种植患者提供使用该系统进行修复的诱人前景，仍需大量研究来了解OT桥的生物力学行为。本研究旨在通过有限元分析评估在不同情况下，即固位螺钉数量和几何分布不同时，全口六颗种植体上颌OT桥义齿中产生的应力。
本研究基于用于固定全口六颗种植体OT桥上部结构的连接螺钉数量和分布，分为五个测试组，如下：第一组：六颗螺钉；第二组：五颗螺钉，去除右侧中央螺钉；第三组：四颗螺钉，单侧去除两颗前部螺钉；第四组：四颗螺钉，双侧去除两颗前部螺钉；第五组：三颗螺钉，去除两颗中切牙和右侧尖牙螺钉。计算机模拟通过三个主要阶段完成：实验模型设计、SolidWorks建模以及使用ABAQUS进行模型分析。分析在单侧轴向载荷（250 N）和斜向载荷（150 N）下进行。记录桥体、修复螺钉、西格环、赤道、种植体、松质骨和皮质骨产生的最大冯·米塞斯应力（vMS），以比较五个测试组。
桥体中诱导产生的最高vMS（垂直载荷和斜向载荷下分别为677和437 MPa）出现在第四组。垂直载荷下，赤道处最高vMS出现在第三组和第四组（分别为122、121.9 MPa），而斜向载荷下，出现在第五组和第三组（分别为66.2、65.7 MPa）。第五组中，螺钉、种植体和两个骨段中的vMS增加最为显著。与单侧去除（第三组）相比，双侧前部螺钉去除（第四组）增加了桥体、螺钉和种植体上的vMS。
即使在全口六颗种植体义齿中缺少三分之一的锚固螺钉，OT桥仍被认为是一种生物力学有效的修复系统。然而，单侧而非双侧去除两颗前部螺钉会产生更好的应力分布模式。
不适用。
