背景:大型跨弓自由端手术导向器可以遮挡视野,由于自由端稳定性不足,影响手术准确性。这项体外研究旨在评估设计用于下颌自由端植入物放置的新型数字非跨弓手术指南的准确性,结合牙齿底切保留和螺钉骨支持。
方法:使用缺少左磨牙的下颌牙科模型来制造单侧(跨弓)牙齿支撑的手术导向器(GTI,n=20)。随后,制造了另外两种类型的手术导向器:GTII(覆盖两颗牙齿,n=20)和GTIII(覆盖三颗牙齿,n=20)。这些新颖的手术导向器被设计为利用支撑齿的底切来保持并在导向器的自由端通过螺钉-骨支撑来增强稳定性。此外,将60个相同的导向块组装在三种类型的手术导向器上,以便于植入物插入。在幻影的头上,将120个植入物复制品放置在牙模型上的联邦国际牙医(FDI)牙齿位置#36和#37处,采用手术引导和引导块的组合。为了评估准确性,使用口内光学扫描比较了计划和放置的植入物位置.角度和线性偏差的差异,包括冠状/根尖3D偏差,横向偏差以及深度偏差,被测量。使用双向ANOVA和Bonferroni检验(α=0.05)进行统计分析。
结果:GTI表现出最大的差异,包括每个植入部位顶部和顶点的角度和线性偏差。尤其是在深度,在植入部位#36,GTI(0.27±0.13mm)的平均偏差值是GTIII(0.13±0.07mm)的两倍,几乎是GTII的两倍(0.14±0.08毫米)。然而,在植入部位#37,这种偏差增加到GTI(0.63±0.12mm)和II(0.14±0.09mm)之间的几乎五倍关系,以及GTI和III之间(0.13±0.09mm)。在植入部位#36或#37处的新型手术引导件之间不存在显著差异。
结论:这项研究提供了一种实用的方案,用于提高植入物放置的准确性并减少在下颌磨牙部位使用的自由端手术导向器的尺寸。
BACKGROUND: Large cross-arch free-end surgical guides can obscure the visual field, compromising surgical accuracy due to insufficient stability at the free-end. This in vitro study aims to evaluate the accuracy of novel digital non-cross-arch surgical guides designed for implant placement at the mandibular free-end, incorporating tooth undercut retention and screw-bone support.
METHODS: A mandibular dental model lacking left molars was utilized to fabricate unilateral (cross-arch) tooth-supported surgical guides (GT I, n = 20). Subsequently, two additional types of surgical guides were fabricated: GT II (covering two teeth, n = 20) and GT III (covering three teeth, n = 20). These novel surgical guides were designed to utilize the undercut of the supporting teeth for retention and enhance stability with screw-bone support at the guide\'s free-end. Furthermore, 60 identical guiding blocks were assembled on the three types of surgical guides to facilitate the implants\' insertion. On a phantom head, 120 implant replicas were placed at the Federal Dentaire Internationale (FDI) teeth positions #36 and #37 on the dental model, employing a combination of surgical guides and guiding blocks. To assess accuracy, planned and placed implant positions were compared using intraoral optical scanning. Discrepancies in angulation and linear deviations, including the coronal/apical 3D deviations, lateral deviation as well as depth deviation, were measured. Statistical analysis was performed using two-way ANOVA and Bonferroni test (α = 0.05).
RESULTS: GT I exhibited significantly largest discrepancies, including angular and linear deviations at the crest and apex at every implant site. Especially in depth, at implant site #36, the mean deviation value of GT I (0.27 ± 0.13 mm) was twice as large as GT III (0.13 ± 0.07 mm), and almost twice as large as GT II (0.14 ± 0.08 mm). However, at implant site #37, this deviation increased to almost a five-fold relationship between GT I (0.63 ± 0.12 mm) and II (0.14 ± 0.09 mm), as well as between GT I and III (0.13 ± 0.09 mm). No significant discrepancies existed between the novel surgical guides at either implant site #36 or #37.
CONCLUSIONS: This study provides a practical protocol for enhancing accuracy of implant placement and reducing the size of free-end surgical guides used at mandibular molar sites.