Influência do posicionamento dos retentores intrarradiculares em diferentes FOVs e modos de escaneamento na detecção de faturas radiculares e na intensidade dos artefatos em imagens de TCFC

Abstract

This study assesed the influence of the positioning of intraradicular post in different fields of view (FOVs) and scanning modes in the detection of root fractures and in the intensity of the artifacts in CBCT images. This research was an ex vivo study. The study sample was composed by uniradicular premolars teeth in two methods of analysis. In the quantitative analysis of the artifacts, 20 single-rooted premolars, which were divided into two groups according to the metal post used (10 teeth with nickel chrome metal posts (NiCr) and 10 teeth with silver palladium metal posts (AgPd). For the artifact qualitative analysis of artifacts and root fracture detection, 40 teeth were used in the sample (20 NiCr restored teeth and 20 AgPd restored teeth), divided into 10 control teeth (sound) and 10 experimental teeth (fractured). All teeth were coated with wax, inserted into the alveolus of a right upper incisive in a patially dentated maxilla of a dry human skull. The CBCT scans were acquired using Orthophos XG 3D (Sirona Dental Systems, Bernsheim, Alemanha) CBCT system with 85kV and voxel of 0.100mm fixed parameters and adjustable parameters for FOV size and mA values (80 mm x 80 mm / 7mA and 50 mm x 55mm / 5mA) according to the CBCT's program. The images were acquired in two methods of positioning within the FOV: 1- pre-established by the manufacturer - central position (anterior teeth region) and lateral position (left posterior teeth regions); 2- established by the operator - four diagonal positions constituting four quadrants (Q1, Q2, Q3 and Q4). All variables were evaluated by two oral and maxillofacial radiologistsand scores were established for fracture detection ans artifact analysis -the degree of interference and artifact characterisation. Artifact quantification was performed using ImageJ. Data analysis was done using ANOVA Two-way and Tukey tests. The kappa interobserver coefficient was 0.73 for root fracture detection and 0.65 for artifact interference. For artifact quantitative analysis, NiCr and AgPd posts in the central and Q2 quadrant potions within the FOV showed less hyperdense artifacts. For the scanning modes, NiCr posts in Q1 and Q2 positions within the FOV and AgPd posts inQ1 position within the FOV differed from each other in the smallest FOV hyperdense areas. The central and Q2 positions within the FOV showed higher sensitivity values. The High Definition-HD scanning mode did not show significant differences from Standard Mode-SM for fracture detection, however there were differences between the metal posts. Evaluating the interference of the artifacts, in the teeth with NiCr and AgPd in both sizes of FOV, the Q2 quadrant presented the best result and the Q3 quadrant with the greatest interference of the artifacts. Teeth with AgPd showed greater interference from artifacts in the diagnosis of fracture compared to teeth with NiCr in all positions within the FOV. Regarding the characterization of the artifacts, the positions Q1 and Q2 in the teeth with NiCr and the position Q1 in the teeth with AgPd, showed significant differences in the lowest FOV for hyperdense areas. Among the FOV sizes, in the group of teeth with NiCr, there was a significant difference in positions Q1 and Q2 for hyperdense areas, and Q2 for hypodense areas. In groups of teeth with AgPd, differences were found in positions Q1 and Q2 for hypodense areas. In conclusion, the position within the FOV and FOV size interfere in artifact intensity and root fracture detection. Low dose scanning modes and smaller FOV sizes should be chosen whenever possible.