Acurácia de medidas lineares em TCFC para planejamento de implantes osteointegráveis em regiões adjacentes à artefatos metálicos

Abstract

The objective of this study was to evaluate the influence of the presence of metallic artifacts in the accuracy of linear measurements for preoperative planning of dental implants, in images of cone-beam computed tomography (CBCT) obtained with different acquisition protocols. The study was based on the evaluation of bone height and thickness, in the anterior and posterior mandible region, of three dry skulls, which were submitted to CBCT, with nine acquisition protocols, with and without the presence of metallic artifacts (fused metal cores).The acquisition protocols used different voxels (0.2, 0.25 and 0.4 mm), FOVs (field of view) (16 x 13 and 16 x 08 cm) and degree of rotation of the apparatus (180o and 360 o). Three evaluators, with experience in tomographic images, evaluated each CBCT exam three times, with a week's interval. To verify intra- and inter-rater reliability, the intraclass correlation coefficient (ICC) was calculated. Two-factor ANOVA was used to compare the measurements in the groups, with Tukey's post-hoc test, with significance level set at 5%. The ICC values ranged from 0.92 to 0.99 for the intra-, and 0.93 to 0.98 for the inter-rater tests. In the posterior region, the bone height values were significantly lower in the presence of metallic artifacts for all acquisition protocols, except for protocol 1 (voxel 0.2 mm, FOV 16 x 13 cm and 360 o) (p = 0.392). In the anterior region, the observed values for measurements with smaller voxel size, independently of FOV and rotation degree showed to be more reliable. In the evaluation of the accuracy of bone thickness measurements in the posterior region, there was no significant difference between groups with and without metallic artifacts, regardless of the acquisition protocol used. In the anterior region, in the presence of artifacts, the protocols with the smallest voxels, showed lower approximation with the actual values. It can be concluded that the measurements of bone height and thickness for the planning of dental implants in the mandible may be affected by the presence of metallic artifacts in adjacent anatomical regions.