Infrared Imaging Holds Promise for Detecting Active Caries Lesions
Despite advances in the biocompatibility and esthetics of modern restorative materials, direct composites do not always bond well to the surrounding tooth structure.
Despite advances in the biocompatibility and esthetics of modern restorative materials, direct composites do not always bond well to the surrounding tooth structure. In these cases, microleakage from fluids and bacterial acids can lead to secondary caries around previously restored lesions. Noting the prevalence of these failures, Nai-Yuan N. Chang, DDS, PhD, a researcher at the University of California, San Francisco School of Dentistry, asserts that “dentists now spend more time replacing failed restorations than placing new ones due to the maladaptation of bonding materials to tooth structure.”
In a study published in the Journal of Biomedical Optics, Chang and colleagues investigated emerging imaging modalities as a means of detecting active lesions. “Clinically, there are no established imaging technologies that can provide diagnostic information with high specificity and sensitivity when assessing lesion activity,” Chang reports. To address this deficit, the team examined whether shortwave infrared (SWIR) and thermal imaging could be combined with air drying to accurately diagnose secondary lesion activity. The idea underlying both methods is that active lesions are more porous than healthy tooth structure, and these pores hold water. In the SWIR-based approach, clinicians can detect active lesions by observing changes in SWIR reflectivity as the tooth dries out. In comparison, thermal imaging relies on temperature changes caused by water evaporating from the pores during air drying.
The researchers analyzed 109 suspected secondary lesions with both SWIR and thermal imaging, and also assessed the lesions using optical coherence tomography (OCT), which is an advanced technique that emits near-infrared light to create high resolution three-dimensional images. These findings were compared with the SWIR and thermal imaging results to see if these simpler methods could reliably detect active lesions.
Reporting in the paper, “Assessment of the Activity of Secondary Caries Lesions With Short-Wavelength Infrared, Thermal, and Optical Coherence Tomographic Imaging,” the authors note that, overall, SWIR proved superior to thermal imaging. In addition, they found the SWIR imaging results closely correlated with the OCT findings. Chang, who characterizes the research as a “developmental milestone” in the quest for simpler and more reliable diagnostic technologies, says the study could help pave the way to new approaches in caries management.
From Decisions in Dentistry. May 2023;9(5):9.