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    The effect of antioxidant treatment on the shear bond strength of different bonding systems to bleached enamel
    (JOURNAL EVOLUTION MEDICAL & DENTAL SCIENCES, 2019) Cetin, Ali Riza.; Yildirim, Cihan.; Unlu, Nimet.; Cobankara, Funda Kont.
    BACKGROUND Nowadays, teeth whitening has become an important procedure in dental practice. According to results of previous studies, the bond strength values of bonded restorations are decreased when the teeth have been whitened with an office or home bleaching technique. The aim of this in-vitro study is to explore the effect of antioxidant implementation on enamel after whitening on the shear bond strength to enamel surface. METHODS The buccal enamel surfaces of 100 extracted teeth were divided non randomly into two groups for bonding with Single Bond [Group A] (3M ESPE) or Clearfil SE [Group B] (Kuraray). Each group was then divided into five random subgroups: 1. the negative control group (NC) received no whitening treatment [Group Al and Group B1]; 2. whitened with 15% carbamide peroxide and that received no antioxidant agents [Group A2 and Group B2]; 3. whitened with 15% carbamide peroxide and implemented 10% sodium ascorbate (SA) [Group A3 and Group B3]; 4. whitened with 35% hydrogen peroxide and that received no antioxidant agents [Group A4 and Group B4]; 5. whitened with 35% hydrogen peroxide and implemented 10% sodium ascorbate [Group A5 and Group B5]. After the restorations were done with a composite (Clearfil ST, Kuraray), they were shear-tested until failure. Two-way analysis of variance (ANOVA) test and Tukey's multiple comparisons test were used to check shear bond strength data at a significance level of p= 0.05. RESULTS Shear bond strength values of used bonding systems immediately after bleaching to whitened enamel, were significantly lower than those of non-whitened enamel (p<0.05). No statistically significant differences in shear bond strengths were found for two adhesive systems, when the antioxidant implemented groups were compared with the non-whitened group (Control) (p>0.05). Thus, the enamel bond strengths of the bonding systems were reversed following sodium ascorbate treatment. CONCLUSIONS It was concluded that the antioxidant sodium ascorbate application could fully neutralize the destructive actions of whitening agents on shear bond strength.
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    Effectiveness of different preventive agents on initial occlusal and proximal caries lesions: A follow-up study
    (ELSEVIER TAIWAN, 2018) Karabekiroglu, Said.; Kahraman, Fatma Betul.; Unlu, Nimet.
    Background/purpose: Monitoring the effects of different caries-preventive agents on initial caries lesions in orthodontic patients is important. Therefore, the purpose of this study is to investigate the efficacy of different preventive methods in preventing occlusal and proximal incipient lesions (ILs) during fixed orthodontic treatment. Materials and methods: Forty-eight subjects at the beginning of fixed orthodontic treatment were included. All subjects were well educated and motivated to use the fluoride toothpaste (Colgate Total, 1450 ppm F) three times a day during the study period. Four different groups were created with a split-mouth design: placebo, fluoride gel, fluoride varnish, and chlorhexidine varnish. The occlusal surfaces of the second molar teeth were assessed with DIAGNOdent pen (DD) during the first 12 months (6th and 12th), and the proximal surfaces of each quadrant were monitored using bitewing radiographs until the 24th month (baseline and 24th month). Results: The mean DD values increased in each group during the first 6 months compared to the baseline, but a significant increment was only obtained in the control and fluoride gel groups (p < 0.05). Fluoride and chlorhexidine varnish had significantly more preventive effects than the control and the fluoride gel for occlusal surfaces at the 6th and 12th month and for intact proximal surfaces at the 24th month, but no significant differences were found between the two varnish groups (p > 0.05). No significant differences were found between the four methods in terms of caries progression for proximal ILs after 24 months. Conclusion: Effective toothbrushing with 1450 ppm fluoridated toothpaste and topical fluoride gel application seems to be inadequate for prevention of new proximal ILs during fixed orthodontic treatment. Fluoride and chlorhexidine varnish showed more protection in relation to occlusal surfaces. (C) 2018 Association for Dental Sciences of the Republic of China. Publishing services by Elsevier B.V.