Amy S. Kim

Trimodal detection of early childhood caries using laser light scanning and fluorescence spectroscopy: clinical prototype

Abstract. There is currently a need for a safe and effective way to detect and diagnose early stages of childhood caries. A multimodal optical clinical prototype for diagnosing caries demineralization in vivo has been developed. The device can be used to quickly image and screen for any signs of demineralized enamel by obtaining high-resolution and high-contrast surface images using a 405-nm laser as the illumination source, as well as obtaining autofluorescence and bacterial fluorescence images. When a suspicious region of demineralization is located, the device also performs dual laser fluorescence spectroscopy using 405- and 532-nm laser excitation. An autofluorescence ratio of the two excitation lasers is computed and used to quantitatively diagnose enamel health. The device was tested on five patients in vivo as well as on 28 extracted teeth with clinically diagnosed carious lesions. The device was able to provide detailed images that highlighted the lesions identified by the clinicians. The autofluorescence spectroscopic ratios obtained from the extracted teeth successfully quantitatively discriminated between sound and demineralized enamel.

Pharmacokinetics of Fluoride in Toddlers After Application of 5% Sodium Fluoride Dental Varnish

The prevalence of dental caries (tooth decay) among preschool children is increasing, driven partially by an earlier age of onset of carious lesions. The American Academy of Pediatrics recommends application of 5% sodium fluoride varnish at intervals increasing with caries risk status, as soon as teeth are present. However, the varnishes are marketed for treatment of tooth sensitivity and are regulated as medical devices rather than approved by the US Food and Drug Administration for prevention of dental caries (tooth decay). The objective of this research is to examine the safety of use in toddlers by characterizing the absorption and distribution profile of a currently marketed fluoride varnish. We measured urinary fluoride for 5 hours after application of fluoride varnish to teeth in 6 toddlers aged 12 to 15 months. Baseline levels were measured on a separate day. The urine was extracted from disposable diapers, measured by rapid diffusion, and extrapolated to plasma levels. The mean estimated plasma fluoride concentration was 13 μg/L (SD, 9 μg/L) during the baseline visit and 21 μg/L (SD, 8 μg/L) during the 5 hours after treatment. Mean estimated peak plasma fluoride after treatment was 57 μg/L (SD, 22 μg/L), and 20 μg/kg (SD, 4 μg/L) was retained on average. Retained fluoride was 253 times lower than the acute toxic dose of 5 mg/kg. Mean plasma fluoride after placement of varnish was within an SD of control levels. Occasional application of fluoride varnish following American Academy of Pediatrics guidance is safe for toddlers.

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

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 auto-fluorescence (AF). In conventional fluorescence imaging, varying AF across a tooth surface can mask low-level porphyrin signals. Laser-induced auto-fluorescence 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.

Guided fluorescence diagnosis of childhood caries: preliminary measures correlate with depth of carious decay

The current rise in childhood caries worldwide has increased the demand for portable technologies that can quickly and accurately detect and diagnose early stage carious lesions. These lesions, if identified at an early stage, can be reversed with remineralization treatments, education, and improvements in home care. A multi-modal optical prototype for detecting and diagnosing occlusal caries demineralization in vivo has been developed and pilot tested. The device uses a 405-nm laser as a scanned illumination source to obtain high resolution and high surface contrast reflectance images, which allows the user to quickly image and screen for any signs of demineralized enamel. When a suspicious region is located, the device can be switched to perform dual laser fluorescence spectroscopy using 405-nm and 532-nm laser excitations. These spectra are used to compute an auto-fluorescence (AF) ratio of the suspicious region and the percent difference of AF ratios from a healthy region of the same tooth. The device was tested on 7 children’s teeth in vivo with clinically diagnosed carious lesions. Lesion depth was then visually estimated from the video image using the 405-nm scanned light source, and within a month the maximum drill depth was assessed by a clinician. The researcher and clinicians were masked from previous measurements in a blinded study protocol. Preliminary results show that the ratiometric percent difference measurement of the AF spectrum of the tooth correlates with the severity of the demineralization as assessed by the clinician after drilling.

Developing laser-based therapy monitoring of early caries in pediatric dental settings

Optical imaging modalities and therapy monitoring protocols are required for the emergence of non-surgical interventions for treating infections in teeth to remineralize the enamel. Current standard of visual inspection, tactile probing and radiograph for caries detection is not highly sensitive, quantitative, and safe. Furthermore, the latter two are not viable options for interproximal caries. We present preliminary results of multimodal laser-based imaging and uorescence spectroscopy in a blinded clinical study comparing two topical therapies of early interproximal caries in children. With a spacer placed interproximally both at baseline and followup examinations, the 405-nm excited red porphyrin uorescence imaging with green auto uorescence is measured and compared to a 12-month follow-up. 405-nm laser-induced uorescence spectroscopy is also measured from the center of selected multimodal video imaging frames. These results of three subjects are analyzed both qualitatively by comparing spectra and quantitatively based on uorescence region segmentation, and then are compared to the standard of care(visual examination and radiograph interpretation). Furthermore, this study points out challenges associated with optically monitoring non-surgical dental interventions over long periods of time in clinical practice and also indicates future direction for improvement on the protocol.

Special Section on Optical Imaging, Sensing, and Light Interactions in Cells and Tissues: Trimodal detection of early childhood caries using laser light scanning and fluorescence spectroscopy: clinical prototype

Abstract. There is currently a need for a safe and effective way to detect and diagnose early stages of childhood caries. A multimodal optical clinical prototype for diagnosing caries demineralization in vivo has been developed. The device can be used to quickly image and screen for any signs of demineralized enamel by obtaining high-resolution and high-contrast surface images using a 405-nm laser as the illumination source, as well as obtaining autofluorescence and bacterial fluorescence images. When a suspicious region of demineralization is located, the device also performs dual laser fluorescence spectroscopy using 405- and 532-nm laser excitation. An autofluorescence ratio of the two excitation lasers is computed and used to quantitatively diagnose enamel health. The device was tested on five patients in vivo as well as on 28 extracted teeth with clinically diagnosed carious lesions. The device was able to provide detailed images that highlighted the lesions identified by the clinicians. The autofluorescence spectroscopic ratios obtained from the extracted teeth successfully quantitatively discriminated between sound and demineralized enamel.

Trimodal detection of early childhood caries using laser light scanning and fluorescence spectroscopy

Abstract. There is currently a need for a safe and effective way to detect and diagnose early stages of childhood caries. A multimodal optical clinical prototype for diagnosing caries demineralization in vivo has been developed. The device can be used to quickly image and screen for any signs of demineralized enamel by obtaining high-resolution and high-contrast surface images using a 405-nm laser as the illumination source, as well as obtaining autofluorescence and bacterial fluorescence images. When a suspicious region of demineralization is located, the device also performs dual laser fluorescence spectroscopy using 405- and 532-nm laser excitation. An autofluorescence ratio of the two excitation lasers is computed and used to quantitatively diagnose enamel health. The device was tested on five patients in vivo as well as on 28 extracted teeth with clinically diagnosed carious lesions. The device was able to provide detailed images that highlighted the lesions identified by the clinicians. The autofluorescence spectroscopic ratios obtained from the extracted teeth successfully quantitatively discriminated between sound and demineralized enamel.