Reciprocal interaction between dental alloy biocorrosion and Streptococcus mutans virulent gene expression
Corrosion of dental alloys is a major concern in dental restorations. Streptococcus mutans reduces the pH in oral cavity and induces demineralization of the enamel as well as corrosion of restorative dental materials. The rough surfaces of dental alloys induced by corrosion enhance the subsequent accumulation of plaque. In this study, the corrosion process of nickel–chromium (Ni–Cr) and cobalt–chromium (Co–Cr) alloys in a nutrient-rich medium containing S. mutans was studied using inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test. Our results showed that the release of Ni and Co ions increased, particularly after incubation for 3 days. The electrochemical corrosion results showed a significant decrease in the corrosion resistance (Rp) value after the alloys were immersed in the media containing S. mutans for 3 days. Correspondingly, XPS revealed a reduction in the relative dominance of Ni, Co, and Cr in the surface oxides after the alloys were immersed in the S. mutans culture. After removal of the biofilm, the pre-corroded alloys were re-incubated in S. mutans medium, and the expressions of genes associated with the adhesion and acidogenesis of S. mutans, including gtfBCD, gbpB, fif and ldh, were evaluated by detecting the mRNA levels using real-time reverse transcription polymerase chain reaction (RT-PCR). We found that the gtfBCD, gbpB, ftf and Idh expression of S. mutans were noticeably increased after incubation with pre-corroded alloys for 24 h. This study demonstrated that S. mutans enhanced the corrosion behavior of the dental alloys, on the other hand, the presence of corroded alloy surfaces up-regulated the virulent gene expression in S. mutans. Compared with smooth surfaces, the rough corroded surfaces of dental alloys accelerated the bacteria-adhesion and corrosion process by changing the virulence gene expression of S. mutans.
KeywordsReverse Transcription Polymerase Chain Reaction Inductively Couple Plasma Atomic Emission Spectrometry Fructan Artificial Saliva Dental Alloy
This investigation was supported by the National Natural Science Foundation of China (Project Numbers: 81201201, 81300912 and 81472928), by the Natural Science Foundation of Jiangsu Province (Project Number: BK20130898), and by the Shanghai Leading Academic Discipline Project (Project Number: T0202).
- 1.Papadopoulou K, Eliades T. Microbiologically-influenced corrosion of orthodontic alloys: a review of proposed mechanisms and effects. Aust Orthod J. 2009;25:63–75.Google Scholar
- 3.Ristic L, Vucevic D, Radovic L, Djordjevic S, Nikacevic M, Colic M: Corrosive and cytotoxic properties of compact specimens and microparticles of Ni-Cr dental alloy. J Prosthodont;23:221-226.Google Scholar
- 9.Chang JC, Oshida Y, Gregory RL, Andres CJ, Barco TM, Brown DT. Electrochemical study on microbiology-related corrosion of metallic dental materials. Biomed Mater Eng. 2003;13:281–95.Google Scholar
- 10.Zhang SM, Tian F, Huang QF, Zhao YF, Guo XK, Zhang FQ: Bacterial diversity of subgingival plaque in 6 healthy Chinese individuals. Exp Ther Med;2:1023-1029.Google Scholar
- 14.Lemos JA, Abranches J, Burne RA. Responses of cariogenic streptococci to environmental stresses. Curr Issues Mol Biol. 2005;7:95–107.Google Scholar
- 16.Wen ZT, Nguyen AH, Bitoun JP, Abranches J, Baker HV, Burne RA: Transcriptome analysis of LuxS-deficient Streptococcus mutans grown in biofilms. Mol Oral Microbiol;26:2-18.Google Scholar
- 23.Gene`va S Dentistry—metallic materials for fixed and removable restorations and appliances. International Organization for Standardization. 2006. ISO 22674-22006.Google Scholar
- 29.Schroeder VA, Michalek SM, Macrina FL. Biochemical characterization and evaluation of virulence of a fructosyltransferase-deficient mutant of Streptococcus mutans V403. Infect Immun. 1989;57:3560–9.Google Scholar
- 30.Aoki H, Shiroza T, Hayakawa M, Sato S, Kuramitsu HK. Cloning of a Streptococcus mutans glucosyltransferase gene coding for insoluble glucan synthesis. Infect Immun. 1986;53:587–94.Google Scholar
- 31.Nakano YJ, Kuramitsu HK. Mechanism of Streptococcus mutans glucosyltransferases: hybrid-enzyme analysis. J Bacteriol. 1992;174:5639–46.Google Scholar
- 32.Senadheera MD, Guggenheim B, Spatafora GA, Huang YC, Choi J, Hung DC, Treglown JS, Goodman SD, Ellen RP, Cvitkovitch DG. A VicRK signal transduction system in Streptococcus mutans affects gtfBCD, gbpB, and ftf expression, biofilm formation, and genetic competence development. J Bacteriol. 2005;187:4064–76.CrossRefGoogle Scholar
- 35.Lim YJ, Oshida Y, Andres CJ, Barco MT. Surface characterizations of variously treated titanium materials. Int J Oral Maxillofac Implants. 2001;16:333–42.Google Scholar