Poly(alkyl methacrylate) tooth coatings for dental care: evaluation of the demineralisation-protection benefit using a time-resolved in vitro method

An in vitro method for the time-resolved quantification of acid-mediated tooth demineralisation has been developed and evaluated against putative non-permanent protective formulations based on a series of poly(alkyl methacrylate)s. Using a thermostatted carousel, dentally relevant substrates consisting of hydroxyapatite discs or sections of bovine teeth have been exposed to aqueous citric acid under controlled conditions, before and after being treated with the polymeric coatings. The dissolution of phosphate was monitored by the determination of 31P by Inductively Coupled Plasma—Mass Spectrometry and by the spectrophotometric phosphovanadomolybdate method. Dose-response plots constructed for both groups of treated substrates have revealed that the coatings significantly reduce erosion rates but are less effective at inhibiting tooth demineralisation than the standard fluoride treatment. The approach has enabled an evaluation of the erosion-protection efficiency of each coating

Towards the determination of surface energy at the nanoscale : a further assessment of the AFM-based approach.

Towards the validation of the atomic force microscopy-based approach to the determination of surface energy at the nanometer scale, this paper explores the applicability of the technique by comparing atomic force microscopy-derived surface energy values with those from conventional contact angle measurements from a range of self-assembled organosilane structures ((3-aminopropyl)triethoxysilane, (3-glycidoxypropyl)trimethoxysilane, 3-(triethoxysilyl)propylsuccinic anhydride and trimethoxy(propyl)silane) and also from films of an ultra-low-surface-energy polymer, poly(1H,1H,2H,2H-perfluorodecyl methacrylate). The close agreement between the two sets of data indicates the validity of the AFM method, while unique attributes are indicated by the high resolution (ca. 1000 atoms) that is inherent to the approach and by the capability to study materials that are not compatible with the probing liquids used for goniometric determinations

Self-assembled structures of alkanethiols on gold-coated cantilever tips and substrates for atomic force microscopy : molecular organisation and conditions for reproducible deposition

Measurements of surface-liquid interactions (contact-angle goniometry) and tip-surface adhesion forces (atomic force microscopy) combined with infrared spectroscopic studies have been used to investigate surface-preparation and solution-deposition conditions for the reproducible formation of self-assembled molecular structures on gold-coated tips and substrates for atomic force microscopy. Preliminary data show that surface-saturated self-assembled monolayers form reproducibly on prolonged (> 20 h) exposure of gold-coated glass substrates to ethanolic solutions of omega-functionalised alkanethiols in the concentration range 80-160 mmol dm(-3). The data also show that exposure for 16 h to alkanethiol concentrations in the range 160-240 mmol dm(-3) promote bilayer formation whereas concentrations of 240-320 mmol dm(-3) result in the deposition of multilayers, the average orientation of which is parallel to that of the first molecular layer; the use of parent 1-undecanethiol solutions at concentrations of 1-80 mmol dm(-3) results in incomplete monolayer coverage. (C) 2009 Elsevier B.V. All rights reserved