Expressão de artefatos de diferentes braquetes e fios ortodônticos em exames de tomografia computadorizada de feixe cônico

Abstract

The use of images obtained through cone beam computed tomography (CBCT) has been introduced in dental practice and has been increasingly employed for diagnoses, treatment planning, and research due to its three-dimensional (3D) characteristics. It is important to consider a subset of patients who undergo the examination with orthodontic appliances, as these can generate artefacts and interfere with image quality. Therefore, the aim of this study is to investigate the influence of artefacts produced by orthodontic brackets and wires made of different materials in CBCT scans. For this purpose, two dental arches were created using plaster and extracted human teeth, to which acetate plates with attached brackets were affixed. There were four pairs of plates: one pair without brackets (control), one pair with metal brackets, another pair with ceramic brackets, and another pair with self-ligating ceramic brackets with NiTi clips. Wire changes were made during image acquisitions, alternating between nitinol and steel archwires. The sample was divided into a control group and test groups. In the control group, the arches received plates without brackets and archwire, while the other groups were divided as follows: metal brackets without archwire, with NiTi archwire, with steel archwire; ceramic brackets without archwire, with NiTi archwire, with steel archwire; self-ligating brackets without archwire, with NiTi archwire, with steel archwire. Image acquisitions were performed using a fixed exposure protocol (OP300, Instrumentarium). The images were evaluated by a specialist in dental radiology and imaging. Prior to image evaluation, slices were selected for grayscale measurement, with two axial slices from the upper arch and two from the lower arch. Grayscale values were measured using rectangular regions of interest placed on the buccal and lingual sides of the selected teeth. Grayscale values were calculated as difference between control group (dMGV), noise and contrast-tonoise ratio (CNR) and compared among the groups using ANOVA with a significance level of 5%. In the buccal region, the maxilla generally exhibited higher values of dMGV compared to the mandible; however, statistically significant differences were observed for the ceramic appliance without a wire (p<0.05). There was no statistically significant difference in noise values between the maxilla and mandible in the buccal region (p≥0.05). In the lingual region, the mandible exhibited higher values when ceramic brackets were present without a wire (p<0.05). For the tooth region, there was more noise in the maxilla in all conditions compared to the mandible (p<0.05). In the buccal, lingual, and tooth regions, the mandible had higher CNR values compared to the maxilla (p<0.05). There was a statistically significant difference only in the buccal region for the ceramic with NiTi group. Therefore, orthodontists should pay attention to the type of brackets and wires when requesting a CBCT examination during treatment and be aware of the artefacts generated in the images.