title: Interactions between dodecyl phosphates and hydroxyapatite or tooth enamel: relevance to inhibition of dental erosion.
abstract: Tooth surface modification is a potential method of preventing dental erosion, a form of excessive tooth wear facilitated by softening of tooth surfaces through the direct action of acids, mainly of dietary origin. We have previously shown that dodecyl phosphates (DPs) effectively inhibit dissolution of native surfaces of hydroxyapatite (the type mineral for dental enamel) and show good substantivity. However, adsorbed saliva also inhibits dissolution and DPs did not augment this effect, which suggests that DPs and saliva interact at the hydroxyapatite surface. In the present study the adsorption and desorption of potassium and sodium dodecyl phosphates or sodium dodecyl sulphate (SDS) to hydroxyapatite and human tooth enamel powder, both native and pre-treated with saliva, were studied by high performance liquid chromatography-mass Spectrometry. Thermo gravimetric analysis was used to analyse residual saliva and surfactant on the substrates. Both DPs showed a higher affinity than SDS for both hydroxyapatite and enamel, and little DP was desorbed by washing with water. SDS was readily desorbed from hydroxyapatite, suggesting that the phosphate head group is essential for strong binding to this substrate. However, SDS was not desorbed from enamel, so that this substrate has surface properties different from those of hydroxyapatite. The presence of a salivary coating had little or no effect on adsorption of the DPs, but treatment with DPs partly desorbed saliva; this could account for the failure of DPs to increase the dissolution inhibition due to adsorbed saliva.
authors.affiliation: School of Oral and Dental Sciences, University of Bristol, Bristol, UK. Electronic address: s.b.jones@bristol.ac.uk.
authors.forename: Siân B
authors.initials: SB
authors.lastname: Jones
authors.affiliation: School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors.forename: Michele E
authors.initials: ME
authors.lastname: Barbour
authors.affiliation: School of Oral and Dental Sciences, University of Bristol, Bristol, UK; Department of Preventive, Restorative and Pediatric Dentistry, University of Bern, Bern, Switzerland.
authors.forename: R Peter
authors.initials: RP
authors.lastname: Shellis
authors.affiliation: Genesis Oral Bioscience, Regents Mews, Surrey, UK; School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK.
authors.forename: Gareth D
authors.initials: GD
authors.lastname: Rees
mesh_terms: D000327:Adsorption; D002851:Chromatography, High Pressure Liquid; D003743:Dental Enamel / Q000187:drug effects*; D017886:Durapatite / Q000627:therapeutic use*; D006801:Humans; D013058:Mass Spectrometry; D010710:Phosphates / Q000494:pharmacology / Q000627:therapeutic use*; D012463:Saliva / Q000187:drug effects; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D013818:Thermogravimetry; D014077:Tooth Erosion / Q000188:drug therapy*
chemical_list: D010710:Phosphates; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D017886:Durapatite
keywords: Dodecyl phosphates; Dodecyl sulphate; Enamel; Erosion; High-performance liquid chromatography–mass spectroscopy; Hydroxyapatite; Saliva; Thermogravimetric analysis