Real-time porphyrin detection in plaque and caries: a case study

Abstract

An ultrathin scanning fiber endoscope, originally developed for cancer diagnosis, was used in a case study to locate plaque and caries. The imaging system incorporated software mitigation of background autofluorescence (AF). In conventional fluorescence imaging, varying AF across a tooth surface can mask low-level porphyrin signals. Laserinduced autofluorescence signals of dental tissue excited using a 405-nm laser typically produce fluorescence over a wavelength range extending from 440-nm to 750-nm. Anaerobic bacterial metabolism produces various porphyrin species (eg. protoporphyrin IX) that are located in carious enamel, dentin, gingivitis sites, and plaque. In our case study, these porphyrin deposits remained as long as one day after prophylaxis. Imaging the tooth surface using 405-nm excitation and subtracting the natural AF enhances the image contrast of low-level porphyrin deposits, which would otherwise be masked by the high background AF. In a case study, healthy tissues as well as sites of early and advanced caries formations were scanned for visual and quantitative signs of red fluorescence associated with porphyrin species using a background mitigation algorithm. Initial findings show increasing amplitudes of red fluorescence as caries severity increases from early to late stages. Sites of plaque accumulation also displayed red fluorescence similar to that found in carious dental tissue. The use of real-time background mitigation of natural dental AF can enhance the detection of low porphyrin concentrations that are indicators of early stage caries formation.

Dental Applications of Optical Coherence Tomography (OCT) in Cariology

“…With the QLF-D Biluminator™ 2 (Inspektor Research Systems bv, Amsterdam, The Netherlands), a tool becomes available that makes it possible to additionally image and quantify the red fluorescence of oral bacteria induced by various porphyrin species as products of anaerobic bacterial metabolism. Thus, detection of low porphyrin concentrations would be an indicator of early stage caries formation [49]. Now, OCT, contrary to histopathological assessment, can provide submicrometer resolved tomographic images of tissues in vivo.…”

“…Thus, detection of low porphyrin concentrations would be an indicator of early stage caries formation [49]. Now, OCT, contrary to histopathological assessment, can provide submicrometer resolved tomographic images of tissues in vivo.…”

Gingivitis resolution followed by optical coherence tomography and fluorescence imaging: A case study

“…In summary, the LIAF results demonstrate the association between mature plaque biofilm and inflammation [28]. A lower red-fluorescent signal was observed as the gingivitis receded, and although it increased slightly after the tissue contracted, we believe this increase was a result of the emitted fluorescent light no longer being blocked by the overgrowth of tissue [29]. Using the LIAF information, we can demonstrate the association of plaque accumulation with gingival inflammation and combine this function with OCT/OCTA for crossvalidation.…”

Caries Management Aided by Fluorescence-Based Devices

“…The number of fluorophores present in the examined area is linearly proportional to the emission intensity, the fluorescent property is thus a very useful tool for quantification [11].…”