Effect of dental tissue conditioners and matrix metalloproteinase inhibitors on type I collagen microstructure analyzed by Fourier transform infrared spectroscopy Sergio B. Botta, 1 Patricia A. Ana, 2 Moises O. Santos, 3 Denise M. Zezell, 3 Adriana B. Matos 1 1 Operative Dentistry Department, School of Dentistry, University of Sao Paulo, Sao Paulo, SP, Brazil 2 Biomedical Engineering – Center of Engineering, Modeling and Applied Social Sciences, Federal University of ABC, Santo Andre, SP, Brazil 3 Center for Lasers and Applications, Energetic and Nuclear Research Institute, Sao Paulo, SP, Brazil Received 17 March 2011; revised 8 November 2011; accepted 3 December 2011 Published online 30 January 2012 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.b.32666 Abstract: This study aimed to evaluate the chemical interac- tion of collagen with some substances usually applied in dental treatments to increase the durability of adhesive resto- rations to dentin. Initially, the similarity between human den- tin collagen and type I collagen obtained from commercial bovine membranes of Achilles deep tendon was compared by the Attenuated Total Reflectance technique of Fourier Transform Infrared (ATR-FTIR) spectroscopy. Finally, the effects of application of 35% phosphoric acid, 0.1M ethylene- diaminetetraacetic acid (EDTA), 2% chlorhexidine, and 6.5% proanthocyanidin solution on microstructure of collagen and in the integrity of its triple helix were also evaluated by ATR- FTIR. It was observed that the commercial type I collagen can be used as an efficient substitute for demineralized human dentin in studies that use spectroscopy analysis. The 35% phosphoric acid significantly altered the organic content of amides, proline and hydroxyproline of type I collagen. The surface treatment with 0.1M EDTA, 2% chlorhexidine, or 6.5% proanthocyanidin did not promote deleterious structural changes to the collagen triple helix. The application of 6.5% proanthocyanidin on collagen promoted hydrogen bond formation. V C 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 1009–1016, 2012. Key Words: collagen, Fourier Transform Infrared spectro- scopy, membrane, matrix metalloproteinase, proanthocyanidin How to cite this article: Botta SB, Ana PA, Santos MO, Zezell DM, Matos AB. 2012. Effect of dental tissue conditioners and matrix metalloproteinase inhibitors on type I collagen microstructure analyzed by Fourier transform infrared spectroscopy. J Biomed Mater Res Part B 2012:100B:1009–1016. INTRODUCTION The routine use of esthetic resin composite restorations has encouraged their constant technical improvement. Perform- ing these restorations is operator dependent, and for their retention in the cavity, it is fundamental to obtain microme- chanical bonding between the adhesive systems and dental hard tissues (enamel and dentin). The dentin substrate is a hydrated tissue, which is com- posed (in volume) of approximately 50% mineral, 20% of fluids, and 30% of organic material. 1 The organic material is composed mainly of 85 vol % type I collagen and the remainder is a mixture of noncollagenous proteins. 2 During the restorative procedure, acid conditioners are applied on dentin, acting on the dentin smear layer. The smear layer may be defined as a layer deposited on the entire dentin surface that has been instrumented with any type of cutting or wearing instrument. The smear layer seals the dentin tubule openings and can interfere in the formation of the hybrid layer. Thus, the use of acid condi- tioners has been proposed with the objective of removing and/or treating this smear layer and favor the complete chemical and mechanical adhesion of the adhesive system with the etched dentin tissue, 3 promoting a reduction of failures in composite restorations. Etching procedure causes exposure of the collagen fibrils, facilitating hybrid layer formation. However, at the same time, if these exposed fibers are not completely envel- oped by the resinous monomer, they may be dissolved and will be the site where degradation of the bond interface begins. 4 Another important factor to consider is that exposure of the extracellular matrix in collagenous tissues related to en- dogenous and exogenous stimuli, such as the use of acids, may lead to disturbances in the regulatory mechanisms of Correspondence to: A. B. Matos; e-mail: bona@usp.br Contract grant sponsor: Fundac ¸a ˜ o de Amparo  a Pesquisa do Estado de Sa ˜ o Paulo (FAPESP); contract grant numbers: 1995/5651-0, 2006/05684-1, 2006/06746-0 Contract grant sponsor: Conselho Nacional de Desenvolvimento Cientı´fico e Tecnol  ogico (CNPq); contract grant number: 143395/2009-2 Contract grant sponsor: CEPID; contract grant number: 05/51689-2 V C 2012 WILEY PERIODICALS, INC. 1009