Correlating Pain and Thermal Changes in Inflammatory Periapical and Periodontal Lesions using Visual Analogue Scale and Infrared Thermography: A Prospective Observational Study

Introduction: The diagnosis of inflammatory periapical lesions remains a challenge, as it typically requires invasive testing methods that might adversely affect individuals. With the modern imaging modality of infrared thermography, the mapping and analysis of the exact temperature of the affected inflammatory site can be performed due to its non invasive and non ionising properties. Aim: To measure and compare the thermal levels (°C) and to correlate them with pain using the Visual Analogue Scale (VAS) score in patients with inflammatory periapical and periodontal lesions using infrared thermography. Materials and Methods: The present prospective observational study was conducted in the Department of Oral Medicine and Radiology, Indira Gandhi Institute of Dental Sciences, Puducherry, India, from October 2022 to April 2023. Study included a total of 60 patients diagnosed with inflammatory lesions such as apical periodontitis, periapical abscess, periodontal abscess and endo-perio lesions. Thermal levels (°C) were measured at baseline, on the 3rd day and on the 5th day of follow-up using the FLIR ONE® Pro thermal device. Pain was assessed using the VAS score at baseline and on the 5th day of follow-up. The comparison of thermal changes in inflammatory lesions was statistically analysed using repeated measures of Analysis of Variance (ANOVA) and its correlation with pain using the VAS score was analysed using the Spearman’s correlation test. Results: There were 30 males and 30 females, and mean±Standard Deviation (SD) age of study participants was 39.87±13.17 years. The mean thermal levels (°C) at baseline, on the 3rd day and on the 5th day of follow-up for dental caries with apical periodontitis were 35.38, 34.38 and 33.21; for periapical abscess, they were 36.41, 35.04 and 33.89; for periodontal abscess, they were 35.61, 34.13 and 33.44; and for endoperio lesions, they were 34.86, 34.07 and 33.23, respectively. A significant difference was observed in the thermal levels among the different odontogenic lesions on all three days (p-value <0.05). The correlation coefficients between the thermal levels (°C) and VAS scores at baseline and on the 5th day were 0.119 and -0.043, respectively, which were not statistically significant (p-values=0.366 and 0.743, respectively). Conclusion: The present study was conducted to measure and compare the thermal levels of inflammatory lesions and the results showed a gradual decrease in thermal levels during follow-up. Hence, infrared thermography can be a useful diagnostic tool for temperature mapping in the identification of inflammatory lesions such as apical periodontitis, periapical abscess, periodontal abscess and endo-perio lesions.