Hamid Nurrohman1, Syozi Nakashima2, Tomohiro Takagaki2, Alireza Sadr2, Toru Nikaido2, Yuya Asakawa3, Motohiro Uo3, Sally J Marshall4, Junji Tagami2. 1. Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, CA, USA. 2. Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. 3. Advanced Biomaterials, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan. 4. Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, CA, USA.
Abstract
BACKGROUND: Immobilization of phosphoproteins on type-I collagen via covalent binding may induce extra- and intrafibrillar mineralization. OBJECTIVE: This study tested the hypothesis that methacrylate phosphate esters immobilized on reconstituted type-I collagen can mimic the nucleating role of phosphoproteins. METHODS: Three functional monomers (MDP, GPDM and Phenyl-P) that differed in chemical structure and steric hindrances around the phosphate moiety were evaluated. Reconstituted type-I collagen was either left untouched (control) or treated by 5% monomer/ethanol for 20 s. All samples were incubated in simulated dentinal fluid as mineralizing medium at 37°C for 7 or 14 days. The extra- and intrafibrillar mineralization were examined by SEM and TEM/SAED crystallography, respectively. RESULTS: FT-IR spectroscopy showed that the phosphate groups were incorporated on reconstituted collagen, irrespective of their chemical structure. MDP immobilization induced dense growth of extrafibrillar mineral over time, while with GPDM- and Phenyl-P-immobilized collagen, mineralization was moderate and sparse, respectively. TEM/SAED evidence disclosed that intrafibrillar minerals exclusively occurred in MDP-immobilized collagen. CONCLUSIONS: Immobilization of MDP, which had the lowest steric hindrance, could induce significant biomimetic extra- and intrafibrillar mineralization; resembling the lowest level of hierarchy organization of dentin.
BACKGROUND: Immobilization of phosphoproteins on type-I collagen via covalent binding may induce extra- and intrafibrillar mineralization. OBJECTIVE: This study tested the hypothesis that methacrylate phosphate esters immobilized on reconstituted type-I collagen can mimic the nucleating role of phosphoproteins. METHODS: Three functional monomers (MDP, GPDM and Phenyl-P) that differed in chemical structure and steric hindrances around the phosphate moiety were evaluated. Reconstituted type-I collagen was either left untouched (control) or treated by 5% monomer/ethanol for 20 s. All samples were incubated in simulated dentinal fluid as mineralizing medium at 37°C for 7 or 14 days. The extra- and intrafibrillar mineralization were examined by SEM and TEM/SAED crystallography, respectively. RESULTS: FT-IR spectroscopy showed that the phosphate groups were incorporated on reconstituted collagen, irrespective of their chemical structure. MDP immobilization induced dense growth of extrafibrillar mineral over time, while with GPDM- and Phenyl-P-immobilized collagen, mineralization was moderate and sparse, respectively. TEM/SAED evidence disclosed that intrafibrillar minerals exclusively occurred in MDP-immobilized collagen. CONCLUSIONS: Immobilization of MDP, which had the lowest steric hindrance, could induce significant biomimetic extra- and intrafibrillar mineralization; resembling the lowest level of hierarchy organization of dentin.
Authors: H Nurrohman; K Saeki; K Carneiro; Y C Chien; S Djomehri; S P Ho; C Qin; S J Marshall; L B Gower; G W Marshall; S Habelitz Journal: J Mater Res Date: 2016-01-26 Impact factor: 3.089