title: Evaluation of active and arrested carious dentin using a pH-imaging microscope and an X-ray analytical microscope.
abstract: A pH-imaging microscope was tested on carious teeth to examine the acid-base characteristics of active and arrested carious dentinal lesions and compared with an assessment of mineral loss in carious affected lesions using an x-ray analytical microscope. Extracted human molars, 22 active and 83 arrested carious teeth, were sliced vertically to maximize the presence of visible carious lesions. The pH change on the dentin surface was measured with a pH-imaging microscope, and the mineral loss was measured with an x-ray analytical microscope. The pH value of intact dentin and active and arrested carious dentinal lesions showed 7.0 (n=105), 5.8 (n=22) and 6.6 (n=83), respectively (analyzed by Kruskal-Wallis). The mineral loss was distinguishable in active dentinal lesions (4.92 times as much as intact dentin), while arrested lesions showed a slight mineral loss (2.19 times as much as intact dentin). The changes in pH value and mineral loss were significantly correlated (Pearson's correlation coefficients r=-0.8024) in active carious dentin lesions and weakly correlated (r=-0.1480) in arrested carious dentin lesions. Changes in tooth substance with the progression of the active carious process were reflected in a reduction in pH value and an increase in the amount of mineral loss.
authors.affiliation: Tokyo Medical and Dental University, Tokyo, Japan. noricoh@aol.com
authors.forename: Noriko
authors.initials: N
authors.lastname: Hiraishi
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kitasako
authors.forename: Toru
authors.initials: T
authors.lastname: Nikaido
authors.forename: Richard M
authors.initials: RM
authors.lastname: Foxton
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nomura
mesh_terms: D000293:Adolescent; D000328:Adult; D003731:Dental Caries / Q000175:diagnosis / Q000473:pathology*; D003732:Dental Caries Activity Tests; D003804:Dentin / Q000473:pathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008853:Microscopy / Q000379:methods; D008875:Middle Aged; D008963:Molar; D011199:Potentiometry; D012666:Semiconductors; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric; D013499:Surface Properties