Analysis of the Transmitted-light through the Human Teeth in vivo

Objectives: The author reported the colorimetric analysis of the transmitted-light through human extracted tooth crown to the contents of the root canal. The purpose of the present study was to examine the applicability of colorimetric analysis to the human teeth in vivo. Methods: This study was approved by the Tohoku University Graduate School of Dentistry Research Ethical Committee. The purpose and the method of the present study were explained to the subjects (n = 11) and written informed consent was obtained from all of them. For this purpose human upper central incisors (19 vital teeth and 3 non-vital teeth) were examined. Infrared and green laser lights simultaneously illuminated the labial surface of the tooth crown via two optical fibers (outer diameter; 0.5 mm). The transmitted-light through the tooth crown was collected from the palatal surface of the examined tooth and led to the light detector via another optical fibers. The intensities of transmitted infrared light (TIL) and the transmitted green light (TGL) were simultaneously measured. Results: The intensities of TIL and TGL were smaller when the lights were illuminated and collected from the cervical area than the incisal area. The intensities of TIL and TGL were significantly smaller with the non-vital teeth than the vital teeth (p<0.05, Mann-Whitney U-test). Conclusion: The results indicated that the analysis of TLI through tooth crown was applicable to pulp vitality diagnosis.