title: Combinatorial localized dissolution analysis: Application to acid-induced dissolution of dental enamel and the effect of surface treatments.
abstract: A combination of scanning electrochemical cell microscopy (SECCM) and atomic force microscopy (AFM) is used to quantitatively study the acid-induced dissolution of dental enamel. A micron-scale liquid meniscus formed at the end of a dual barrelled pipette, which constitutes the SECCM probe, is brought into contact with the enamel surface for a defined period. Dissolution occurs at the interface of the meniscus and the enamel surface, under conditions of well-defined mass transport, creating etch pits that are then analysed via AFM. This technique is applied to bovine dental enamel, and the effect of various treatments of the enamel surface on acid dissolution (1mM HNO3) is studied. The treatments investigated are zinc ions, fluoride ions and the two combined. A finite element method (FEM) simulation of SECCM mass transport and interfacial reactivity, allows the intrinsic rate constant for acid-induced dissolution to be quantitatively determined. The dissolution of enamel, in terms of Ca(2+) flux ( [Formula: see text] ), is first order with respect to the interfacial proton concentration and given by the following rate law: [Formula: see text] , with k0=0.099±0.008cms(-1). Treating the enamel with either fluoride or zinc ions slows the dissolution rate, although in this model system the partly protective barrier only extends around 10-20nm into the enamel surface, so that after a period of a few seconds dissolution of modified surfaces tends towards that of native enamel. A combination of both treatments exhibits the greatest protection to the enamel surface, but the effect is again transient.
authors.affiliation: Electrochemistry and Interfaces Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Parker
authors.affiliation: Electrochemistry and Interfaces Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Rehab
authors.initials: R
authors.lastname: Al Botros
authors.affiliation: Electrochemistry and Interfaces Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Sophie L
authors.initials: SL
authors.lastname: Kinnear
authors.affiliation: Electrochemistry and Interfaces Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Snowden
authors.affiliation: Electrochemistry and Interfaces Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Kim
authors.initials: K
authors.lastname: McKelvey
authors.affiliation: Unilever Oral Care, Quarry Road East, Bebington, Wirral CH63 3JW, UK.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Ashcroft
authors.affiliation: Unilever Oral Care, Quarry Road East, Bebington, Wirral CH63 3JW, UK.
authors.forename: Mel
authors.initials: M
authors.lastname: Carvell
authors.affiliation: Unilever Oral Care, Quarry Road East, Bebington, Wirral CH63 3JW, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Joiner
authors.affiliation: Unilever Oral Care, Quarry Road East, Bebington, Wirral CH63 3JW, UK.
authors.forename: Massimo
authors.initials: M
authors.lastname: Peruffo
authors.affiliation: Unilever Oral Care, Quarry Road East, Bebington, Wirral CH63 3JW, UK.
authors.forename: Carol
authors.initials: C
authors.lastname: Philpotts
authors.affiliation: Electrochemistry and Interfaces Group, Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK. Electronic address: p.r.unwin@warwick.ac.uk.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Unwin
mesh_terms: D000818:Animals; D002417:Cattle; D003743:Dental Enamel / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D064347:Microscopy, Electrochemical, Scanning; D017942:Nitric Acid / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D014077:Tooth Erosion / Q000139:chemically induced* / Q000628:therapy*
chemical_list: D017942:Nitric Acid
keywords: Biominerals; Dental enamel; Dissolution kinetics; Electrochemical imaging and methods; Finite element method modelling