Synergy of sodium trimetaphosphate (STMP) and dentin matrix protein-1 (DMP-1) on demineralized dentin as a biomimetic strategy

• Grant number: 16/06869-7
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: August 29, 2016
• End date: September 29, 2016
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Linda Wang
• Grantee: Rafael Simões Gonçalves
• Supervisor: Ana Karina Barbieri Bedran-Russo
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Institution abroad: University of Illinois at Chicago (UIC), United States
• Associated to the scholarship: 15/02559-0 - Use of TMP on the inhibition of dentin endogen enzymes and on biomimetization of demineralized dentin substrate, BP.DR

Abstract

Dentin matrix protein-1 (DMP-1) is an acidic non-collagenous protein (NCP) that exhibits important role during tooth biomineralization. Therefore, we hypothesize that sodium trimetaphosphate (STMP) associated with DMP-1 will induce biomineralization of demineralized dentin. In the present study, the synergy of STMP and DMP-1 on demineralized dentin as a biomimetic strategy will be systematically investigated. Twenty-eight dentin slabs (1.5mm x 3.0mm x 0.25mm) will be obtained from coronal portion of ten human molar. All dentin slabs will be demineralized (14% EDTA/10d), and then treated with 1M NaCl and 0.25% trypsin-EDTA for removal of endogenous non-collagenous proteins. An extreme caries lesion scenario will be created by collagenase digestion. Slabs will be randomly distributed into 4 groups according to their biomimetic strategy treatment: G1- NCPs-depleted demineralized dentin (NCPs-DDD); G2- NCPs-DDD + STMP 1.5% + Ca(OH)2; G3- NCPs-DDD + DMP-1; G4- NCPs-DDD + DMP-1 + STMP 1.5% + Ca(OH)2. For dentin matrix treatment and nucleation, dentin slabs from G3 and G4 will be incubated overnight with rDMP-1 (150µg/mL) in PBS. After incubation, the samples will be rinsed with deionized water and, slabs from G2 and G4 will be subjected to a phosphorylation treatment by immersing each slab in 50mL of STMP 1.5% solution + Ca(OH)2 for 24h in each solution, at 37ºC. To determine the role of STMP in dentin matrix depleted or not of NCPS, 16 dentin slabs (n=4) will be cryosectioned (5µm-thick) and prepared for Goldner's trichrome staining and Alizarin red analysis, and submitted for cross-sectional nanohardness analysis and reduced modulus of elasticity. To verify the synergy of STMP and non-phosphorylated DMP-1 in demineralized dentin, 12 dentin slabs (n=3) will be prepared and assessed by cross-sectional nanohardness, reduced modulus of elasticity and TEM to determine mechanical recovery and mineralization pattern, respectively. The data will be evaluated according to their distribution to determine the most appropriate statistical tests. (AU)