Evaluation of different esthetic brackets discoloration and light transmittance in vivo

SUMMARY The number of individuals applying for orthodontic treatment is increasing day by day. The non-aesthetic metallic appearance of the orthodontic brackets are not well tolerated by most of adult patients, especially those with high aesthetic expectations. The ceramic brackets make it possible for patients with such concerns to accept the orthodontic treatment more easily. Hence, the purpose of this study was to evaluate the extent to which the aesthetic brackets maintain their color stability when exposed to the conditions in the oral environment, and to assess the changes in the light transmittance. We aimed to determine the brackets that maintain the color and the light transmittance characteristics at the best level during the treatment process. The first hypothesis we tested in the presented study is that the ceramic brackets would preserve the color stability and transmittance after 3 months of clinical exposure. And the second is whether there would be any difference between the monocrystalline and polycrystalline brackets related with the aforementioned parameters. According to the power analysis it was necessary to evaluate a minimum of n = 45 samples of each brand with a 5% of error margin and 95% of confidence interval. Considering the patients that would withdraw the involvement of the study, the sample size was determined as 50 individuals in each group. Patients in the course of fixed orthodontic treatment in the Department of Orthodontics of Bezmialem Vakif University Hospital were included in the study. 4 monocrystalline (3M Gemini, Inspire Ice, Hubit Perfect Clear, AO Radiance) and 4 polycrystalline (3M Clarity Advanced, AO 20/40 bracket, Dentsply Sirona Resolve, GC Chic) brackets were evaluated. The brackets were attached to the arch wire between the first and second molar and between the canine and the first premolar on the right and left sides. The light transmittance of the brackets before intraoral use and after three months of clinical exposure was measured using the LEDEX ™ cm 4000 radiometer (Dentmate Technology Co., Ltd. New Taipei City 24872, Taiwan, M443509, M452752). The probe of the Optima LED light source (Optima 10, B.A. International, Northampton, England, UK) was hold perpendicularly to the bracket surface. All transmittance measurements were recorded with 10 seconds of irradiation and the mean value was calculated by making each measurement three times. Measurement of color change was performed using VITA Easyshade Compact (VITA Zahnfabrik, Bad Sackingen, Germany) conforming to CIE (Commision de l Comm Eclairage) L*a*b* color space which is one of the most popular and widely used systems in color measurement. For the best results, the mean value was recorded by making each measurement three times. No additional force was applied to the teeth and no adverse effects were observed in the course of treatment. These two sets of data from color and light transmittance measurements went through statistical analysis where Kolmogorov Smirnov analysis, Mann Whitney U test, Kruskal Wallis test, Wilcoxon test, Spearman Correlation analysis were employed. A p value of less than 0.05 was considered to be significant in the 95% confidence interval for statistical significance. In the rejection of the first hypothesis, the color stability and transmittance of the ceramic brackets after 3 months of clinical exposure demonstrated statistically significant differences. According to National Bureau of Standarts (NBS) criteria all the brackets showed a clinically detectable color change. Darkening of the color and decrease in the light transmittance were recorded. A negative correlation was found between these two parameters. The second hypothesis of whether there would be any difference between the monocrystalline and polycrystalline brackets related with the aforementioned parameters was verified partially regarding some of the parameters as follows; L0, L1, Tr0, Tr1, a0, a1, b0, Δa ve Δb.