Effects of Composite Resin on the Enamel after Debonding: An In Vitro Study—Metal Brackets vs. Ceramic Brackets

Abstract

Fixed orthodontic therapies include several procedures that can affect the enamel surface. The aim of this study was to assess the action of composite resin on the surface of the tooth through variation of enamel changes after debonding metal and ceramic brackets, by means of scanning electron microscopy. An in vitro study was conducted on 48 human premolar specimens, which were extracted within a period of two months for orthodontic purposes. On half of them, metal brackets were bonded, and on the other half, ceramic brackets (Al2O3) were bonded, using light cure adhesive paste and a two-step, etch-and-bonding technique. The brackets were debonded after 24 h using a straight debonding plier. The adhesive remnant index (ARI) was determined by visual observation of the specimen. Post-debonding scans were aligned with the baseline, and the surfaces’ changes were quantified. A quantitative analysis was made on the debonded brackets to determine the presence or absence of enamel on the base pad. Evaluation of pre-bonded and post-clean-up enamel surface revealed no crack and increased roughness in both ceramic and metal brackets, which was higher for the ceramic ones. The enameled band (perikymata), artificial caries, or the superficial fissures revealed in the pretreatment stage were replaced with the loss of the prismatic structure and the presence of remnant adhesive. No enamel substance was found on the base pad. The ARItooth was higher for metallic brackets than for ceramic ones. Metallic brackets and ceramic brackets have undergone mechanical changes by showing fractures in their structure. According to our present investigation, we can conclude that the adhesive composite resin is safe for use on both metal and ceramic brackets in orthodontic treatments, with no iatrogenic enamel damages.