A comparison of terahertz pulsed imaging with transmission microradiography for depth measurement of enamel demineralisation in vitro

Emma Pickwell, Vincent P. Wallace, Bryan E. Cole, Sophia Ali, Christopher Longbottom, Richard J. M. Lynch, Michael Pepper

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    50 Citations (Scopus)

    Abstract

    Terahertz pulsed imaging (TPI) is a relatively new, non-ionising and non-destructive imaging technique for studying hard tissues which does not require tooth section preparation, unlike transmission microradiography (TMR). If TPI can measure the depths of caries/demineralisation lesions accurately the same tooth samples could be reused and remeasured during in vitro and in situ studies on de- and/or remineralisation. The aim of this study was to compare TPI and TMR for measuring the depths of a range of artificially induced bovine enamel demineralised lesions in vitro. Bovine slabs with artificial caries, induced to different levels of demineralisation by two different but standard demineralisation techniques (‘acid gel’ and ‘carbopol’) were measured by TPI and TMR and the readings compared. The set of TPI/TMR measurements obtained on the gel-demineralised slabs showed an extremely high coefficient of determination (r2 = 0.995). Detailed analysis of the results and theoretical considerations (involving the relationship between refractive index profiling and mineral loss profile) are used to explain the findings and show that for acid gel lesions TPI is measuring demineralisation in the range of 47% of that of TMR depth plus an intercept of 16 µm, with further calculations allowing the TMR depths to be determined to within 5% using TPI.
    Original languageEnglish
    Pages (from-to)49-55
    Number of pages7
    JournalCaries Research
    Volume41
    Issue number1
    DOIs
    Publication statusPublished - 2007

    Keywords

    • Terahertz pulse imaging
    • Enamel demineralization
    • Lesion depth

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