Development of subgingival calculus detector utilizing optical fiber: Verification of its potential for clinical application

The removal of subgingival deposits, especially calculus, plays a crucial role in basic periodontal therapy. However, manual detection methods affect accuracy owing to the operator's skill. To avoid this uncertainty, we have developed a calculus detection device named "Sensor probe" and evaluated its ability to detect calculus for future clinical applications. The Sensor probe consisted of a 635 nm-wavelength semiconductor laser and a 0.5 mm-diameter single-mode optical fiber. Initially, the performance of the device was evaluated using clinically obtained extracted teeth with calculus covered with a stainless-steel shielding plate with pinhole. Then, the effect of the optical fiber's end shape on calculus detection performance was analyzed. Lastly, the performance of the Sensor probe was compared to that of a conventional periodontal probe in terms of accuracy, sensitivity, and specificity for calculus detection using calculus-covered extracted teeth. The results indicated that Sensor probe detected dental calculus through the pinhole with a diameter of 300 μm or more when applied from a distance of 100 μm. The results analyzing the effect of the optical fiber's end shape on calculus detection performance showed that cutting the fiber end at an angle of 45° resulted in the most effective calculus detection. This may be because the laser light refracted on the cut surface and concentrated on the fiber side. Moreover, by comparing the performance of this device to a conventional periodontal probe revealed that the Sensor probe showed improved calculus detection accuracy in deeper periodontal pockets. This improvement was particularly significant in the apical third, where detection is typically difficult. In conclusion, a Sensor probe that uses an optical fiber with a 45° angled end may facilitate subgingival calculus detection. In future clinical applications, Sensor probes could lead to more accurate and efficient calculus removal, especially for deeper periodontal pockets.