title: Terahertz pulsed imaging study to assess remineralization of artificial caries lesions.
abstract: We compare terahertz-pulsed imaging (TPI) with transverse microradiography (TMR) and microindentation to measure remineralization of artificial caries lesions. Lesions are formed in bovine enamel using a solution of 0.1 M lactic acid/0.2% Carbopol C907 and 50% saturated with hydroxyapatite adjusted to pH 5.0. The 20-day experimental protocol consists of four 1 min treatment periods with dentifrices containing 10, 675, 1385, and 2700 ppm fluoride, a 4-h/day acid challenge, and, for the remaining time, specimens are stored in a 50:50 pooled human/artificial saliva mixture. Each specimen is imaged at the focal point of the terahertz beam (data-point spacing = 50 μm). The time-domain data are used to calculate the refractive index volume percent profile throughout the lesion, and the differences in the integrated areas between the baseline and post-treatment profiles are used to calculate ΔΔZ((THz)). In addition, the change from baseline in both the lesion depth and the intensity of the reflected pulse from the air/enamel interface is determined. Statistically significant Pearson correlation coefficients are observed between TPI and TMR/microindentation (P < 0.05). We demonstrate that TPI has potential as a research tool for hard tissue imaging.
authors.affiliation: GlaxoSmithKline, St Georges Avenue, Weybridge, Surrey, KT13 0DE, United Kingdom. david.r.churchley@gsk.com
authors.forename: David
authors.initials: D
authors.lastname: Churchley
authors.forename: Richard J M
authors.initials: RJ
authors.lastname: Lynch
authors.forename: Frank
authors.initials: F
authors.lastname: Lippert
authors.forename: Jennifer Susan O'Bryan
authors.initials: JS
authors.lastname: Eder
authors.forename: Jesse
authors.initials: J
authors.lastname: Alton
authors.forename: Carlos
authors.initials: C
authors.lastname: Gonzalez-Cabezas
mesh_terms: D015519:Bone Density / Q000502:physiology*; D003731:Dental Caries / Q000473:pathology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D055069:Terahertz Imaging / Q000295:instrumentation*