Avaliação por tomografia computadorizada de feixe cônico da posição relativa de mini-implantes instalados com cirurgia não guiada para retenção de overdentures mandibulares

Abstract

Introduction: Parallelism between mini-implants plays a fundamental role in the effectiveness of retentive overdenture systems. Objectives: This cross-sectional study is part of a randomized clinical trial and aimed to evaluate the relative position of mini-implants installed to retain a mandibular overdenture. Furthermore, the aim was to investigate the association of surgical protocol, technical and anatomical factors in the relative position of mini-implants through cone beam computed tomography images. Materials and methods: Tomography scans were analyzed in 73 patients who received four single-body mini-implants. Drilling was performed with a 1.6mm needle drill and 2.2mm Pilot Drill, according to the patient's bone density and the orientation of the surgical guide. Post-insertion CBCT images were analyzed using E-Vol-DX software with bone tissue removal filters. Divergence angles between implants and between the implants and the overdenture insertion path were measured using CliniView 10.2.6 software. Results: The divergence angles between the implants ranged from 0° to 22.3° (mean=4.2; SD=3.7) and from 0° to 26.2° (mean=5.3; SD=4 ,1) in the lateral and frontal projections, respectively (p<0.001). Only 1 (0.2%) and 3 (0.7%) of the measurements were greater than 20° in the lateral and frontal views, respectively. The average angulations between the implant and the overdenture insertion path were 9.3° (SD=7.5) and 4.0° (SD=2.9) for the lateral and frontal views, respectively (p<0.001). Regression analyzes showed a significant association between implant divergence and frontal view projection (p<0.001), greater distance between paired implants (p=0.017), surgical protocol (p=0.002), greater insertion torque final (p=0.011) and deeper preparation with the needle drill (p<0.001). The position of the implants was also associated with divergence in relation to the insertion path (p<0.05) Conclusions: The results showed that the mini-implants in this study were placed with low divergence angles and satisfactory parallelism. Factors such as shorter distances between implants, higher bone density and a flapless surgical approach have contributed positively to improving the parallelism of mini-implants.