Evaluation of the color stability of different types of polycarbonate brackets

Document Type : Original Article

Authors

Department of Orthodontics, Faculty of Dentistry, Alexandria University.

Abstract

Objective: To investigate the discoloring effect of certain foods and photoaging on the color stability of the three different types of polycarbonate brackets. Materials and Methods: Eighty four brackets were selected and divided into three groups: (1) Composite brackets with ceramic like filler (Silicon brackets); (2) Composite unfilled brackets (Spirit brackets) and (3) Polyoxymethylene brackets (Brilliant brackets). Seven specimens of three different esthetic brackets were exposed to tea, coke, curry and accelerated photogeing device to a xenon lamp to simulate natural day light. The brackets were analyzed at the beginning of the experiment and after 24 and 72 hours and 25 days of exposure. Color measurements were performed by means of Vita Easy shade Spectrophotometer according to CIELCh coordinates lightness, chroma and hue and color changes (∆E) were computed. Results: Almost all investigated brackets showed clinically unacceptable discoloration during in vitro exposure to food dyes and UV light with the exception of the polyoxymethylene brackets which showed nonperceptible color change after storage 25 days in coke and UV. Tea and curry discolor all brackets and showed a sharp increase in discoloration after 24 hour. Most of the brackets became yellower after UV light exposure. Conclusions: These current in vitro findings indicate that even newly developed plastic brackets, consisting of composite materials or modern polymers (polyoxymethylene) may have clinically unacceptable color stability in the long-term.

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