Evaluation of physical properties of esthetic brackets after clinical use: Study in situ

AimThe aim of this study was to investigate the surface morphology, dimensional stability, and frictional behavior of ceramic brackets with metal-inserted slots after different intervals of intraoral use.MethodsEighty-eight brackets were evaluated. The sample was divided into four groups (n = 22 per group): group C (control, as received from the manufacturer) and groups T12, T24, and T36 (brackets recovered after 12, 24, and 36 months of treatment, respectively). Surface morphology was analyzed with optical and scanning electron microscopy. Dimensional stability was verified with a measuring microscope, and sliding resistance on 0.019 × 0.025-in stainless steel wires was evaluated using a universal testing machine.ResultsSigns of corrosion and wear occurred gradually from the 12th to the 36th month, being more significant at the metal slot base and at the porcelain/metal junction. The depth of the slot and the internal height between the tie-wings increased after clinical use, showing a significant difference at 36 months (P < 0.05). There was a progressive increase in the coefficient of friction versus time of clinical use and a maximum increase of 22% after 36 months (P < 0.05).ConclusionsCeramic brackets with metal-inserted slots had significant changes in physical properties during clinical use. The dimensional changes encountered were small and appeared clinically nonsignificant. However, the progressive increase in the coefficient of friction must be taken into consideration because it may compromise the clinical performance of the appliance.