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Remineralising dentine caries using an artificial antimicrobial peptide: An in vitro study
John Yun Niu1, Iris Xiaoxue Yin2, William Ka Kei Wu3
1Faculty of Dentistry, The University of Hong Kong, Hong Kong, China; Department of Oral Medicine, Shanxi Provincial People's Hospital, Taiyuan, Shanxi, China.
Objective:
To investigate the antibacterial and remineralising effects of a novel dual-action antimicrobial peptide, GA-KR12, on artificial dentine caries.
Methods:
Human dentine blocks with artificial carious lesions were allocated to two groups - Group 1: dentine blocks treated with the novel antimicrobial peptide GA-KR12 twice daily; Group 2: dentine blocks received water as the negative control. Two groups underwent Streptococcus mutan biofilm-remineralisation cycles at 37 °C for 7 days. The morphology, viability and growth kinetics of the S. mutans biofilm were evaluated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and colony-forming unit (CFU) counting, respectively. The dentine blocks' lesion depths and mineral loss, changes in chemical structure, dentine surface morphology and crystal characteristics were determined using micro-computed tomography, Fourier transform infrared (FTIR), SEM and X-ray diffraction (XRD), respectively.
Results:
The surface of the dentine blocks in Group 1 was partially covered by S. mutans with damaged cell structure. Group 2 showed affluent growth of S. mutans covering the dentine surface when compared to Group 1. The dead-to-live ratio of Group 1 and Group 2 were 0.78 ± 0.01 and 0.47 ± 0.08, respectively (p < 0.001). The Log CFUs of Group 1 and Group 2 were 7.14 ± 0.30 and 8.24 ± 0.20, respectively (p < 0.001). The lesion depths of Group 1 and Group 2 were 109 ± 1 µm and 135 ± 3 µm, respectively (p < 0.001). The mineral loss of Group 1 and Group 2 were 0.59 ± 0.08 gHApcm-3 and 0.81 ± 0.07 gHApcm-3, respectively (p < 0.001). FTIR showed the amide I-to-hydrogen phosphate (HPO42-) ratios of Group 1 and Group 2 were 0.25 ± 0.05 and 0.39 ± 0.05 (p < 0.001), respectively. SEM images showed Group 1 had less exposed dentine collagen fibres than Group 2. The XRD revealed that the hydroxyapatite in Group 1 was well crystalised.
Conclusion:
This study demonstrated that the novel antimicrobial peptide GA-KR12 inhibited the growth of S. mutans biofilm and enhanced the remineralisation of artificial dentine caries.
