Thermal Pattern Analysis for Detecting Subclinical Inflammation

Objective: To detect the subclinical and suspected inflammatory tissue changes on the jaws by combining infrared thermography with X-ray radiography. Materials and Methods: The study included 150 patients who were referred for panoramic X-rays. Patients selected included 72 males and 78 females, with ages ranging from 18 to 50 years. Infrared thermography (IRT) was applied in the study for screening suspected jaw inflammation. IRT findings were compared with panoramic radiography (a reference standard). After the diagnosis of periapical diseases, each participant in the study was examined thermographically by using an infra-red camera (Teledyne FLIR, Model T560), extra-oral on the face, directed at the maxilla and mandible regions. Thermograms were captured in frontal view, right view, and left view. All thermograms and panoramic radiographs (OPG) were processed and visually enhanced using Fiji ImageJ software for better thermographic and radiographic analysis. The thermographic findings were then compared with the radiographic findings (OPG x-rays). Results: The statistical analysis of infrared thermography findings showed that 20% of the cases were positive (inflammatory or suspicious), and 80% of cases were negative (normal pattern). The thermal pattern of infrared thermography showed IRT-positive cases as follows: pulpitis with apical periodontitis 13 (8.7%), acute periapical abscess 9 (6.0%), chronic periapical abscess 5 (3.3%), and suspected 3 (2%). The last three suspected cases were unspecified and considered as IRT-positive cases (inflammatory or suspicious). When IRT findings were compared with OPG findings, they showed a sensitivity of 92.6%, a specificity of 95.9%, and an accuracy of 95.3%. Analysis also showed good agreement between IRT and OPG findings (Cohen’s κ = 0.848), and disagreement was limited (FP = 5 vs FN = 2). For two modalities, analysis showed no significant difference in paired positive and negative classifications (exact McNemar test, p = 0.453). Conclusion: Thermal pattern analysis in the orofacial region can be helpful for the early detection of inflammatory or suspected diseases as a supplement to radiography for confirming positive or suspicious findings.