Abstract
BACKGROUND: Bleaching procedures alter enamel microstructure, impacting composite bonding. Biomimetic remineralizing agents may restore the bond strength post-bleaching. This in-vitro study aimed to evaluate and compare the role of remineralizing agents on the shear bond strength of composite to in-office bleached enamel using the total-etch technique. MATERIAL AND METHODS: 28 human maxillary premolars were extracted for orthodontic purposes and split into buccal and palatal halves. The 55 samples were divided into five groups. Bleaching procedure was conducted and remineralizing agents were applied twice daily for 5 minutes over 24 days. The five groups included a negative control (Group 1) and groups treated with GC Tooth Mousse Plus (Group 2), Curodont Repair (Group 3), Regenerate Paste (Group 4), and CTx4 Gel (Group 5). A universal composite restorative was applied after total-etch and adhesive application. Shear bond strength was evaluated using an Instron 3366 universal testing machine with a 0.5mm/min loading rate. SEM analysis to assess the failure mode was evaluated on the representative samples. The normality of the data was assessed using the Shapiro-Wilkinson test. Inferential statistics were done using the Whitney U Test (between the groups). RESULTS: Results of all the test groups (Groups 2-5) had statistically significant differences (P< 0.05) when compared with the negative control group (Group 1). There was a significant difference between Group III (Curodont Repair - p11-4 peptide) and Group IV (Regenerate Paste-NR5 Technology) with Group IV being the superior one. CONCLUSIONS: The null hypothesis was rejected. Remineralizing agents enhance the shear bond strength of composite to in-office bleached enamel using the total-etch technique. Regenerate paste (nR5 Technology) showed statistically better results than Curodont Repair paste (p11-4 peptide). Key words:CPP-ACP, Nano-hydroxyapatite, NR-5 Technology, Remineralization, Shear bond strength, Self-assembling peptide P11-4, Tooth bleaching.