The Canary System
PTR-LUM technology to detect early caries and monitor remineralization therapy
QDT-101 Clinical Trial
Protocol: A single center study to evaluate the safety and operability of "The Canary System™" with healthy volunteers.
Objective: The primary objective of this study was to evaluate safety and explore operability of The Canary System™ prototype in healthy volunteers. The secondary objectives of this study were to:
- Establish the baseline calibration profile;
- Assess the effect of tooth surface hydration on the baseline calibration profile;
- Assess the effect of biofilm and plaque on the baseline calibration profile;
- Assess the effect of tooth and surface type on the baseline calibration profile; and
- Compare the profile for diseased teeth to the baseline profile for clean, healthy, permanent teeth.
Methodology: The study was a randomized, non-blinded, sequential (cohorts 1-3; healthy tooth surfaces) and parallel (cohorts 4 & 5; diseased tooth surfaces) design. Ten subjects were enrolled in each of the five cohorts.
Detection Methods: When a modulated laser beam is shone on dental enamel surface, optical energy is converted to radiative emissions (surface glow; modulated luminescence (LUM)) as well as non-radiative decay (thermal waves; modulated heat) detected by photothermal radiometry (PTR). As dental caries develop, optical and thermal properties of dental tissue change and corresponding changes can be found in the combined PTR-LUM response. In this study, PTR and LUM amplitude (A) and phase (P) responses at various modulation frequencies from healthy and carious dental enamel (ICDAS 0-6) were measured. This investigational study was performed using The Canary System™™ (prototype 1), under the approval of Health Canada. Over 500 regions on healthy tooth surfaces of 50 subjects were probed to construct a healthy baseline for each output channel.
Primary Results: The Canary System™ did not cause any adverse events. In addition, this device did not elicit any soft or hard tissue trauma. Results indicated that there was little or no difference in signal between wet or dry tooth surfaces; anterior and posterior healthy tooth surfaces provided the same signal, and the presence of surface stain and biofilm did not affect the signal from healthy tooth surfaces. In selected carious enamels, we observed a shift from the baseline in PTR, LUM or both signals depending upon the type, depth and nature of the lesion.
Secondary Results: A simplified scaling system is being tested based on all four-output response channels of healthy and carious lesions. This scaling system is used to identify near surface or subsurface lesions. During the in-vivo scanning, unusual jumps in LUM-P standard deviation (STD) were found and were directly correlated to accidental slips at the probing tip-tooth surface contacts. Therefore, LUM-P-STD was used as a real time stability and repeatability criterion for the highest possible quality PTR-LUM detection of early caries. In–vivo application of this first prototype also helped to develop a more sophisticated scanning tip so as to accommodate complicated tooth geometries as well as to detect caries underneath healthy enamel and on interpoximal surfaces.
Conclusion: Results from this first clinical trial showed that The Canary System™ is safe and discriminates between healthy and carious enamel with little or no tooth preparation.