The Implementation of Infrared Thermography as Complementary Diagnostic Tool in Orthodontic Treatment Plan—Pilot Study

Abstract

Highlights: What are the main findings? Thermographic findings could not be associated with Trevisi cephalometric landmarks in a children-adolescent population. Infrared thermography may be a valuable complementary diagnostic tool in orthodontics. What is the implication of the main finding? Masticatory muscular thermal asymmetries of the masticatory muscles could not be related with cephalometric landmarks. Orbicular oris muscle thermic behavior may be important in the diagnosis of lip incompetence, parafunctional habits and/or hypotonia. Introduction: Infrared thermography (IRT) is a non-invasive, non-ionizing imaging modality capable of rapidly capturing surface temperature variation. In dentistry, particularly orthodontics and TMD evaluation, IRT may serve as a valuable complementary tool to be added in conventional diagnostic protocols. Objective: Correlate possible relationships between thermographic findings of orofacial structures and cephalometric landmarks. Methods: An infrared imaging camera, FLIR® i7, was used to record the regions of interest, correspondent to the temporal, masseter and orbicular oris muscles, in adolescents (n = 22). Bilateral temperature differences were considered as thermal asymmetries with a conventional threshold of 0.3 °C to distinguish an eventual hyperactivity or hyperfunctions of detrimental structures. The Trevisi cephalometric parameters that were taken into consideration for the study were SNA, SNB, ANB, OccltoSn, Wits relation to base and Molar/canine classes. Results: Most of the participants showed a normal temperature difference ΔΤ for the upper and lower orbicular oris muscle, right vs. left, 96% and 92%, respectively. The other ROIs presented a mixed pattern of thermal asymmetries; however, no statistically significant differences were found when crossed with the cephalometric landmarks. Conclusions: Asymmetrical patterns of infrared thermography can aid on the diagnosis and treatment plan of an orthodontic appointment, since the actual stability of pos-orthodontic treatment is highly dependent on the muscular activity of the tongue and lips, in particular when the patient has atypical swallowing. Our findings suggest that this technique can be used to quantify anatomical landmarks relevant to craniofacial morphology in specific populations, particularly at ages where muscular functional activity is strongly correlated with dentoskeletal development.