Conhecimento termográfico do músculo orbicular da boca

Abstract

Introduction: Oral Motor Therapy, one of the areas of the Speech-Language-Hearing Sciences, aims to understand stomatognathic system functioning and restore its functions. Rehabilitation strategies for functional changes are developed according to the knowledge of what occurs in healthy muscles. There are different ways to study muscle behavior dynamically and quantitatively, such as infrared thermography – a non-invasive and non-ionizing imaging diagnostic method that transforms information about the heat emitted by the human body into an analyzable image. The orbicularis oris muscle is of great importance in the performance of oral functions, being the target of interest for speech-language-hearing pathologists who seek to understand the factors that affect the functioning of this muscle or are affected by it. Objective: This thesis aimed to develop a thermographic analysis protocol for the orbicularis oris muscle and shed light on the temperature behavior during this muscle’s functional performance. Methods: Three articles were designed to structure the thesis. The first one, entitled “Proposal of a protocol for thermographic assessment of the orbicularis oris muscle”, was an observational, analytical, cross-sectional study. The area of the orbicularis oris muscle was defined based on its anatomy, according to the thermographic image of 11 children and 13 adults. Then, this area was divided into four quadrants, and each quadrant was analyzed using four different shapes – triangle, rectangle, triangle with a rounded side, including the vermilion of the lips, and a personalized shape that encompassed only the region of the orbicularis oris muscle, not including the vermilion of the lips. The study collected maximum and mean temperature data and analyzed variation coefficients. In the second article, “Comparison between anatomical thermal points and anatomical thermal areas of the orbicularis oris muscle”, six anatomical thermal points corresponding to the areas of interest were studied: left nasolabial, right nasolabial, left corner of the mouth, right corner of the mouth, left lower labial, and right lower labial. Next, the anatomical thermal areas corresponding to the areas of interest were studied: upper right rectangle, upper left rectangle, lower right rectangle, and lower left rectangle. The study analyzed maximum and mean temperature data from both points and areas of each region of interest, comparing the points with the anatomically closest areas, using the Spearman correlation test. Finally, in the third article, “Thermographic behavior of the orbicularis oris muscle under different provocative tests”, the temperature behavior of the orbicularis oris muscle was studied before, during and after provocative tests of sustained contraction and mastication. The orbicularis oris muscle was analyzed qualitatively and quantitatively from anatomical thermal areas, using mean temperature data. Results: In the first article, a similar dispersion was found for the four analysis forms of the orbicularis oris muscle, both for mean and maximum temperatures, in children and adults. The rectangle was found to have the lowest variation coefficient in more regions. The second article identified that, except for the comparison of temperatures between maximum upper right rectangle and maximum right corner of the mouth and between maximum upper left rectangle and maximum left corner of the mouth, all other values had a significant difference, showing that areas and points have different temperatures. However, the correlation analysis identified a strong correlation between point and area. As for the third article, the qualitative analysis showed a change in temperature during the provocative tests. The comparison between mean temperatures showed a significant increase in temperature, confirming the qualitative findings. The mean variation per test was 0.57 ºC in lip tightening, 0.2 ºC in lip protrusion, 0.57 ºC in peanut chewing, 0.43 ºC in cookie chewing, and 0.37 ºC in bread roll chewing. The mean temperature decreased during intervals between tests, which, however, was not enough to return to the initial temperature, identifying an accumulation of temperature between tests. Conclusions: Currently, the best way to analyze the orbicularis oris muscle is through quadrants, using the maximum or mean temperature, in a rectangle, starting from an initial ellipse that encompasses the entire muscle. The temperatures of anatomical thermal points are different from those of anatomical thermal areas, although they correlate positively. The temperature in the region of the orbicularis oris muscle increased with the provocative tests. The 2-minute interval between tests was not enough for the resting temperature to return to basal temperature. Thermography was found to be an effective method in identifying these temperature changes.