title: Reciprocal interaction between dental alloy biocorrosion and Streptococcus mutans virulent gene expression.
abstract: 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.
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, 20001, China.
authors.forename: Songmei
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Oral Implantology, College of Stomatology, Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Department of General Dentistry, University of Rochester Eastman Institute for Oral Health, Rochester, 14642, USA.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, 20001, China.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Yu
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, 20001, China. fqzhang810@136.com.
authors.forename: Fuqiang
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of General Dentistry, University of Rochester Eastman Institute for Oral Health, Rochester, 14642, USA. xiuxin_liu@urmc.rochester.edu.
authors.forename: Xiuxin
authors.initials: X
authors.lastname: Liu
mesh_terms: D018441:Biofilms / Q000254:growth & development; D002858:Chromium Alloys / Q000737:chemistry*; D003343:Corrosion; D055664:Electrochemical Techniques; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D008670:Metals / Q000737:chemistry; D060888:Real-Time Polymerase Chain Reaction; D013295:Streptococcus mutans / Q000378:metabolism* / Q000502:physiology; D013499:Surface Properties; D013997:Time Factors
chemical_list: D002858:Chromium Alloys; D008670:Metals