The Influence of Guiding Concept on the Accuracy of Static Computer-Assisted Implant Surgery in Partially Edentulous Cases: An In Vitro Study

<i>Background and Objectives</i>: Static Computer-Assisted Implant Surgery (sCAIS) can be performed with different drill guiding systems. This study aimed to compare the accuracy of two guiding concepts of sCAIS in partially edentulous cases. <i>Materials and Methods</i>: Forty polyamide models of partially edentulous maxillae with seven implantation sites were fabricated. In total, 140 replica implants were placed with keyless (KL) and drill-key (DK) guiding systems using static, full-arch, tooth-supported surgical guides. Three-dimensional crestal and apical, angular and vertical deviations from the planned implant positions were compared using Mann-Whitney U and Kruskal-Wallis H tests. Intergroup homogeneity of variance homogeneity was examined using Levene's test to assess the precision. <i>Results</i>: Overall median 3D crestal and apical deviations of implants placed in the KL group were significantly higher compared to the DK group (0.86 mm [0.63-0.98] vs. 0.72 mm [0.52-0.89], <i>p</i> = 0.006 and 1.26 [0.98-1.52] vs. 1.13 [0.70-1.45], <i>p</i> = 0.012). In the subgroup analysis, implants placed with a KL system showed higher 3D crestal (<i>p</i> = 0.029), 3D apical (<i>p</i> < 0.001) and angular (<i>p</i> < 0.001) deviations in the extended anterior area, higher 3D crestal (<i>p</i> < 0.001) deviations in the proximal posterior single-tooth gap and higher vertical (<i>p</i> < 0.001) deviations in the distal site of free-end situation. Contrarily, the KL group showed lower 3D crestal (<i>p</i> = 0.007), 3D apical (<i>p</i> < 0.001), angular (<i>p</i> < 0.001) and vertical (<i>p</i> = 0.003) deviations in the distal posterior single-tooth gap, lower 3D apical (<i>p</i> = 0.007) and angular (<i>p</i> = 0.007) deviations in the distal site of free-end situation and lower vertical (<i>p</i> = 0.019) deviations in the proximal site of free-end situation. <i>Conclusions</i>: The deviations of both guiding concepts did not exceed the recommended safety margins. Statistically significant differences in deviations were found between two guiding concepts. Guiding concepts with superior accuracy varied across different sites of implantation.