Peter B. Robinson

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This study investigates the hardness, structure, composition, and thickness of coatings on two dental instruments and the changes which occurred when the instruments were subjected to conditions that closely match their clinical use. One group of instruments had a titanium nitride coating that was approximately 8 micrometers thick and had a hardness of 19.5(More)
An in vitro apparatus was used to study mosquito repellent evaporation and penetration characteristics with skin. The mosquito repellents 2-ethyl-1,3-hexanediol, N,N-diethyl-m-toluamide, N,N-diethyl-p-toluamide, 1-(butylsulfonyl)hexahydro-1H-azepine, and N,N'-dicyclohexamethyleneurea were studied. In vitro repellent duration, calculated from repellent(More)
A three-dimensional finite element model of a human premolar with a composite resin Class II MOD has been used to investigate the temperature changes and induced thermal stresses associated with the imbibing of a hot liquid. Regions of high tensile stress were revealed and their possible clinical significance with respect to microleakage and failure in the(More)
Fifty-seven of 159 rural elementary school students had an explosive spread of pruritus and rash--a rarely described manifestation of epidemic hysteria. In a sample of 13 children (23%), each child examined had irregular, macular, erythematous lesions that were excoriated and actively changed during examination. Rash occurred only at sites readily(More)
STATEMENT OF PROBLEM Monophase addition-cured silicone impression materials in stock trays are considered to be alternatives to two-phase systems used with custom trays. PURPOSE This study compared the number of surface defects in addition-cured silicone impressions recorded with monophase materials in stock trays and two-phase impressions in custom(More)
STATEMENT OF PROBLEM Impressions free from voids are important for the fabrication of accurate restorations. Any material or technique that reduces the incidence of bubbles is welcome. PURPOSE The aim of this study was to determine whether the use of a surfactant designed for clinical use (Hydrosystem) reduced the number of visible air bubbles on the(More)
AIM To evaluate the performance of an anterior hybrid composite resin restorative material (Opalux). DESIGN Single-centre clinical trial. MATERIALS AND METHODS Scores were obtained based on USPHS criteria for marginal adaptation, anatomic form, colour match, surface roughness and marginal discolouration. INTERVENTIONS The restorative material was(More)
Composite resin has such good aesthetic qualities that it is often difficult to identify the tooth-restoration interface, yet this is particularly important should the material require complete removal. Following the in-vitro removal of direct and indirect composite resin restorations from Class II cavities significant changes in cavity size and shape were(More)
The effect of anticonvulsant drugs on bone growth and calcium metabolism was studied in Wistar strain rats. Animals were treated for 40-48 days with diphenylhydantoin (DPH) or sodium valproate (SV), or were thyroparathyroidectomized (TPTX) and maintained with thyroxine supplements. Bone growth, measured radiographically as increase in bone length, was(More)