Efficacy of the dual-action GA-KR12 peptide for remineralising initial enamel caries: an in vitro study

Objective To investigate the antibiofilm and remineralising effects of the dual-action peptide GA-KR12 on artificial enamel caries. Materials and methods Enamel blocks with artificial caries were treated with sterilised deionised water as control or GA-KR12. The blocks underwent biochemical cycling with Streptococcus mutans for 3 weeks. The architecture, viability, and growth kinetics of the biofilm were determined, respectively, by scanning electron microscopy (SEM), confocal laser scanning microscopy, and quantitative (culture colony-forming units, CFUs). The mineral loss, calcium-to-phosphorus ratio, surface morphology, and crystal characteristics of the enamel surface were determined, respectively, using micro-computed tomography, energy dispersive spectroscopy, SEM, and X-ray diffraction (XRD). Results SEM showed confluent growth of S. mutans in the control group but not in the GA-KR12-treated group. The dead-to-live ratios of the control and GA-KR12-treated groups were 0.42 +/- 0.05 and 0.81 +/- 0.08, respectively (p < 0.001). The log CFUs of the control and GA-KR12-treated groups were 8.15 +/- 0.32 and 6.70 +/- 0.49, respectively (p < 0.001). The mineral losses of the control and GA-KR12-treated groups were 1.39 +/- 0.09 gcm(-3) and 1.19 +/- 0.05 gcm(-3), respectively (p < 0.001). The calcium-to-phosphorus molar ratios of the control and GA-KR12-treated groups were 1.47 +/- 0.03 and 1.57 +/- 0.02, respectively (p < 0.001). A uniformly remineralised prismatic pattern on enamel blocks was observed in the GA-KR12-treated but not in the control group. The hydroxyapatite in the GA-KR12-treated group was better crystallised than that in the control group. Conclusion The dual-action peptide GA-KR12 inhibited the growth of S. mutans biofilm and promoted the remineralisation of enamel caries.