Does the material of orthodontic brackets influence metal artifact expression in CBCT? A comparison between endomass and exomass artifacts

• Grant number: 25/05860-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Radiology
• Principal Investigator: Rocharles Cavalcante Fontenele
• Grantee: João Guilherme dos Santos Cunha
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Exomass artifacts are caused by materials with high atomic number and high physical density located outside the field of view (FOV), being common in cone beam computed tomography (CBCT) acquisitions with a small FOV. Endomass artifacts, on the other hand, occur when these materials are within the FOV. Orthodontic appliances generate a significant amount of endomass artifacts, although their effect on exomass artifacts remains uncertain. This study aims to evaluate the influence of different orthodontic appliance materials on the expression of endomass and exomass metal artifacts on CBCT scans. Twenty-eight human teeth will be adapted to two plaster phantoms, representing the upper and lower dental arches. Four acetate plates will be fabricated for each arch (no brackets, metallic brackets, self-ligating ceramic brackets with a NiTi clip, and ceramic brackets). CBCT scans will be acquired with a medium FOV (endomass group) and a small FOV (exomass group) using OP300 and Eagle 3D scanners. A oral and maxillofacial radiologist will conduct an objective analysis of image quality, selecting three axial reconstructions per scan that allow visualization of all teeth, brackets, and the metallic wire. Images will be analyzed using ImageJ software, with regions of interest (ROIs) measuring 1.20 × 1.20 mm positioned on teeth 11, 41, 16, and 46, according to the established protocol. ROI positioning standardization will be ensured by the ROI Manager tool. For each ROI, the standard deviation of gray values and the contrast-to-noise ratio will be calculated. Results will be compared using a two-way analysis of variance (ANOVA) with Tukey's post-hoc test (¿=5%). Based on the results of this study, we expect to determine the impact of different orthodontic appliance materials on the formation of endomass and exomass artifacts. (AU)