Abstract
ABSTRACTIntroduction: Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments. The aim of this in vitro study was to evaluate the effect of CPP-ACP paste and CO2 laser irradiation on demineralized enamel microhardness and shear bond strength of orthodontic brackets. Methods: Eighty caries-free human premolars were subjected to a demineralization challenge using Streptococcus mutans. After demineralization, the samples were randomly divided into five equal experimental groups: Group 1 (control), the brackets were bonded without any surface treatment; Group 2, the enamel surfaces were treated with CPP-ACP paste for 4 minutes before bonding; Group 3, the teeth were irradiated with CO2 laser beams at a wavelength of 10.6 µm for 20 seconds. The samples in Groups 4 and 5 were treated with CO2 laser either before or through CPP-ACP application. SEM photomicrographs of a tooth from each group were taken to observe the enamel surface. The brackets were bonded to the buccal enamel using a conventional method. Shear bond strength of brackets and ARI scores were measured. Vickers microhardness was measured on the non-bonded enamel surface. Data were analyzed with ANOVA and Tukey test at the p< 0.05 level. Results: The mean shear bond strength and microhardness of the laser group were higher than those in the control group and this difference was statistically significant (p< 0.05). All groups showed a higher percentage of ARI score 4. Conclusion: CO2 laser at a wavelength of 10.6 µm significantly increased demineralized enamel microhardness and enhanced bonding to demineralized enamel.
Highlights
Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments
The aim of this study was to evaluate the effect of Casein phosphopeptide (CPP)-ACP paste with and without CO2 laser irradiation on microhardness of demineralized enamel and shear bond strength of orthodontic brackets
Kolmogorov-Smirnov test showed that shear bond strength of the teeth in the five groups had a normal distribution
Summary
Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments The aim of this in vitro study was to evaluate the effect of CPP-ACP paste and CO2 laser irradiation on demineralized enamel microhardness and shear bond strength of orthodontic brackets. The samples were randomly divided into five equal experimental groups: Group 1 (control), the brackets were bonded without any surface treatment; Group 2, the enamel surfaces were treated with CPP-ACP paste for 4 minutes before bonding; Group 3, the teeth were irradiated with CO2 laser beams at a wavelength of 10.6 μm for 20 seconds. In addition to mechanical control of oral hygiene, several chemical methods can be used, including different forms of fluoride such as varnishes and fluoride-releasing adhesives and CPP-ACP-containing paste and newer methods such as laser irradiation, which can decrease the risk of demineralization and remineralize previously demineralized enamel.[4]. A systematic review by Azarpazhooh and Limeback[9] found little evidence for long-term remineralization effect of CPP-ACP whereas a recent systematic review showed that CPP-ACP was able to remineralize early lesions compared to placebo but its effect was not significant compared to fluoride.[10]
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