title: Synthesis of carboxylic block copolymers via reversible addition fragmentation transfer polymerization for tooth erosion prevention.
abstract: Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and (1)H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion.
authors.affiliation: College of Dentistry, Howard University, Washington, DC 20059, USA CREST Center for Nanomaterials, College of Engineering, Howard University, Washington, DC 20059, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Lei
authors.affiliation: College of Dentistry, Howard University, Washington, DC 20059, USA CREST Center for Nanomaterials, College of Engineering, Howard University, Washington, DC 20059, USA twang@howard.edu.
authors.forename: T
authors.initials: T
authors.lastname: Wang
authors.affiliation: CREST Center for Nanomaterials, College of Engineering, Howard University, Washington, DC 20059, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Mitchell
authors.affiliation: Colgate-Palmolive Company, Piscataway, NJ 08855, USA.
authors.forename: J
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Colgate-Palmolive Company, Piscataway, NJ 08855, USA.
authors.forename: L
authors.initials: L
authors.lastname: Kilpatrick-Liverman
mesh_terms: D000180:Acrylic Resins / Q000138:chemical synthesis* / Q000737:chemistry; D000818:Animals; D002118:Calcium / Q000737:chemistry; D002417:Cattle; D002850:Chromatography, Gel; D003743:Dental Enamel / Q000737:chemistry / Q000648:ultrastructure; D003764:Dental Materials / Q000138:chemical synthesis* / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000138:chemical synthesis* / Q000737:chemistry; D013053:Spectrophotometry; D013054:Spectrophotometry, Atomic; D017550:Spectroscopy, Fourier Transform Infrared; D014077:Tooth Erosion / Q000517:prevention & control
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; C006903:carbopol 940; D019904:Polymethyl Methacrylate; D017886:Durapatite; D002118:Calcium
keywords: RAFT polymerization; binding; dental erosion; enamel; hydroxyapatite; surface