Dentin collagen biomodification by cross-linkers: effect on collagen stiffness, degradation and longevity of resin-dentin bond produced by dry-bonding technique

• Grant number: 14/14664-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: October 01, 2014
• End date: January 31, 2015
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Josimeri Hebling Costa
• Grantee: Luciana Bianchi
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The overall objective of of this study, which consists of two experiments will investigate the effect of different cross-linking promoting agents (cross-linkers) on the stiffness and degradation of collagen and the breakdown of resin-dentin bond produced by dry-bonding technique. In experiment 1, will be used 65 human pre-molars, which dentin discs will be obtained with 0.3 mm thick (n = 40 teeth) or specimens (1x1x6 mm) dentin (n = 25 teeth). After complete demineralization phosphoric acid, dentin disks are used for LVDT analysis (stiffness collagen) and the other samples for analysis of dry mass loss and release of hydroxyproline (HYP) during periods of 7 days, 1 month and 2 months after treatments. Treatments, lasting 60 seconds, will be: deionized water (positive control), application of carbodiimide (EDC) 0.5 M, proanthocyanidin (PA) 5%, or glutaraldehyde (GA) in two concentrations, 5% and 25% (negative) control. In experiment 2, 64 premolars will be used. After obtaining the dentin flat surfaces, they are etched with phosphoric acid for 15 seconds, followed by treatment with the same solution described above except for the GA to 25%. Thus, 16 teeth per treatment will be used. In half of these teeth, 60 seconds of application of treatment solutions elapsed, the dentin is dried with air jets, followed by the application of the adhesive system Prime & Bond 2.1. The other teeth, wet technique (controls) will be used. Specimens (0.81 mm ²) will be obtained for the mechanical microtensile testing. The specimens belonging to the same tooth will be divided into three groups according to the following aging periods: 24 hours, 6 or 9 months. Types of fracture will also be analyzed after the microtensile test and some specimens per group (n = 8) shall be prepared for analysis nanoleakage. Statistical tests for data analysis will be selected according to the characteristics of the data set of each response variable, ie, adherence to the normal curve and homoscedasticity. Statistical inferences are based on a significance level of 5%. (AU)