Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Paper Caries Res 2010;44:309–316 DOI: 10.1159/000315932 Effect of Iron on Matrix Metalloproteinase Inhibition and on the Prevention of Dentine Erosion M.T. Kato   a A.L. Leite   a A.R. Hannas   a R.C. Oliveira   a J.C. Pereira   b L. Tjäderhane   c M.A.R. Buzalaf   a Departments of a  Biological Sciences and b  Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil; c  Institute of Dentistry, University of Oulu, and Oulu University Hospital, Oulu, Finland situ experiment, the mean wear ( 8 SD) found for the F gel (0.79 8 0.08 m) was significantly reduced in more than 50% when compared to the placebo gel (1.77 8 0.33 m), but the FeSO 4 gel completely inhibited the wear (0.05 8 0.02 m). Since FeSO 4 was able to inhibit MMP in vitro, it is possible that the prevention of dentine wear by the FeSO 4 gel in situ might be due to MMP inhibition, which should be investi- gated in further studies. Copyright © 2010 S. Karger AG, Basel It has been shown that a rinse with a 10 mmol/l ferrous sulphate (FeSO 4 ) solution after an erosive attack can sig- nificantly reduce dentine wear [Sales-Peres et al., 2007]. However, the mechanism of action of iron for inhibiting dentine erosion has not been investigated so far. Dentine-erosive demineralisation results in the expo- sure of an outer layer of fully demineralised organic ma- trix followed by a partly demineralised zone until the sound inner dentine is reached [Kinney et al., 1995]. Deg- radation of the dentine matrix occurs after it has become accessible by the removal of mineral, i.e. the dentine ma- trix cannot be degraded unless it is demineralised [Kleter et al., 1994]. Removal of the completely demineralised Key Words Dental erosion  Dentine  Iron  Matrix metalloproteinase Abstract It is known that some metal salts can inhibit matrix metallo- proteinase (MMP) activity, but the effect of iron has not been tested yet. On the other hand, it has recently been suggested that MMP inhibition might influence dentine erosion. Based on this, the aims of this study were: (1) to test in vitro the ef- fect of FeSO 4 on MMP-2 and -9 activity, and (2) to evaluate in situ the effect of FeSO 4 gel on dentine erosion. MMP-2 and -9 activities were analysed zymographically in buffers con- taining FeSO 4 in concentrations ranging between 0.05 and 1.5 mmol/l or not. Volunteers (n = 10) wore devices contain- ing bovine dentine blocks (n = 60) previously treated with the following gel treatments: FeSO 4 (1 mmol/l FeSO 4 ), F (NaF 1.23%; positive control) and placebo (negative control). The gels were applied once and removed after 1 min. Erosion was performed extraorally with Coca-Cola 4 times per day for 5 min over 5 days. Dentine wear was evaluated by profilom- etry. The data were analysed by Kruskal-Wallis and Dunn’s tests (p ! 0.05). FeSO 4 inhibited both MMP-2 (IC 50 = 0.75 mmol/l) and MMP-9 (IC 50 = 0.50 mmol/l) activities. In the in Received: February 25, 2010 Accepted after revision: April 15, 2010 Published online: June 10, 2010 Marília Afonso Rabelo Buzalaf Department of Biological Sciences, Bauru School of Dentistry University of São Paulo, Al. Octávio Pinheiro Brisolla, 9–75 Bauru, SP 17012-901 (Brazil) Tel. +55 14 3235 8346, Fax +55 14 3227 1486, E-Mail mbuzalaf  @  fob.usp.br © 2010 S. Karger AG, Basel 0008–6568/10/0443–0309$26.00/0 Accessible online at: www.karger.com/cre