title: Load dependency and reliability of microhardness measurements on acid-etched enamel surfaces.
abstract: The load dependency of hardness measurements was investigated on sound and demineralized enamel samples. For all samples investigated, the Knoop hardness number (KHN) varied as a function of the applied load. Higher loads enhanced indenter penetration into the test surface. The variation in KHN values observed in demineralized enamel, both surface-softened and surface-etched, was explained by a decrease in porosity as a function of depth. The reading error for indentations made on surface enamel etched with 37% phosphoric acid gel for 30 s was found to be slightly elevated compared to indentations made on a polished sound enamel surface. It was concluded that the surface microhardness technique can be used for the longitudinal investigation of etched surface enamel.
authors.affiliation: Faculteit Geneeskunde en Farmacie, Eenheid Prothetische Tandheelkunde, Vrije Universiteit Brussel, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Collys
authors.forename: D
authors.initials: D
authors.lastname: Slop
authors.forename: R
authors.initials: R
authors.lastname: Cleymaet
authors.forename: D
authors.initials: D
authors.lastname: Coomans
authors.forename: Y
authors.initials: Y
authors.lastname: Michotte
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D002417:Cattle; D003743:Dental Enamel / Q000737:chemistry*; D006244:Hardness; D006245:Hardness Tests; D006801:Humans; D016062:Porosity; D015203:Reproducibility of Results; D013499:Surface Properties; D017001:Tooth Demineralization / Q000175:diagnosis