Interproximal dental caries detection using Photothermal Radiometry (PTR) and Modulated Luminescence (LUM)

Abstract.

Frequency-domain photothermal radiometry (FD-PTR or PTR) has been used to detect mechanical holes and demineralized enamel in the interproximal contact area of extracted human teeth. Thirty four teeth were used in a series of experiments. Preliminary tests to detect mechanical holes created by dental burs and 37% phosphoric acid etching for 20 s on the interproximal contact points showed distinct differences in the signal. Interproximal contact areas were demineralized by using a partially saturated acidic buffer system. Each sample pair was examined with PTR before and after micro-machining or treating at sequential treatment periods spanning 6 hours to 30 days. Dental bitewing radio graphs showed no sign of demineralized lesion even for samples treated for 30 days. μ-CT, TMR and SEM analyses were performed. Although μ-CT and TMR measured mineral losses and lesion depths, only SEM surface images showed visible signs of treatment because of the minimal extent of the demineralization. However, the PTR amplitude increased by more than 300% after 80 hours of treatment. Therefore, PTR has been shown to have sufficient contrast for the detection of very early interproximal demineralized lesions. The technique further exhibited excellent signal reproducibility and consistent signal changes in the presence of interproximal demineralized lesions, attributes which render PTR a reliable probe to detect early interproximal demineralization lesions. Modulated luminescence was also measured simultaneously, but it showed a lower ability to detect these interproximal demineralized lesions than PTR.