Accuracy of infrared thermography of the masticatory muscles for the diagnosis of myogenous temporomandibular disorder

Thermographic findings related to facial pain - a survey of 40 subjects

OBJECTIVE

The purpose of this study was to assess how thermography findings relate painful symptoms and signs of temporomandibular disorders (TMD).

METHODS

Thermography, combined with chewing of paraffin wax, was performed on 40 subjects. The results were analyzed according to gender and pain-related TMD symptoms and clinical signs.

RESULTS

The overall temperatures after chewing were higher in TMD patients than in controls. For females, the most significant findings were the thermal increase between the relaxed state and subjects' state after chewing in temporal and temporomandibular joint (TMJ) regions. For males, all calculated parameters demonstrated a poor ability to discriminate TMD from controls.

CONCLUSION

Thermography could be a potential tool in diagnostics of female TMD patients. The results suggest that the thermal information assessed in specific facial areas could help to discriminate TMD patients from non-TMD patients and could be used to quantify the pain associated with TMD.

Use of Infrared Thermography in Medical Diagnosis, Screening, and Disease Monitoring: A Scoping Review

Thermography provides non-invasive, radiation-free diagnostic imaging. Despite the extensive literature on medical thermography, a comprehensive overview of current applications is lacking. Hence, the aim of this scoping review is to identify the medical applications of passive infrared thermography and to catalogue the technical and environmental modalities. The diagnostic performance of thermography and the existence of specific reference data are evaluated, and research gaps and future tasks identified. The entire review process followed the Joanna Briggs Institute (JBI) approach and the results are reported according to PRISMA-ScR guidelines. The scoping review protocol is registered at the Open Science Framework (OSF). PubMed, CENTRAL, Embase, Web of Science, OpenGrey, OSF, and PROSPERO were searched using pretested search strategies based on the Population, Concept, Context (PCC) approach. According to the eligibility criteria, references were screened by two researchers independently. Seventy-two research articles were identified describing screening, diagnostic, or monitoring studies investigating the potential of thermography in a total of 17,314 participants within 38 different health conditions across 13 therapeutic areas. The use of several camera models from various manufacturers is described. These and other facts and figures are compiled and presented in a detailed, descriptive tabular and visual format. Thermography offers promising diagnostic capabilities, alone or in addition to conventional methods.

Surface electromyography in the assessment of masticatory muscle activity in patients with pain-related temporomandibular disorders: a systematic review

Background

Temporomandibular disorders (TMD) are a set of painful conditions affecting the orofacial region that are prevalent and constitute the most frequent type of non-dental pain complaint in the maxillofacial area. Pain-related TMD (TMD-P) is characterized by ongoing pain in the masticatory muscles, the temporomandibular joint, or surrounding structures. Due to the multiple factors that contribute to the development of this condition, it can be challenging to accurately diagnose. One of the useful method for assessing patients with TMD-P is surface electromyography (sEMG). The aim of this systematic review was to provide a comprehensive overview of the current scientific literature on the evaluation of masticatory muscle activity (MMA) in individuals diagnosed with TMD-P, through the utilization of sEMG.

Methods

To gather relevant information, electronic databases such as PubMed, Web of Science, Scopus, and Embase were searched using specific keywords including: "pain" AND ("temporomandibular disorder*" OR "temporomandibular dysfunction*") AND "surface electromyography" AND "masticatory muscle activity." The inclusion criteria were studies assessing MMA in patients with TMD-P using sEMG. The Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies was utilized to evaluate the quality of the studies that were included in the review.

Results

The search strategy identified 450 potential articles. Fourteen papers met the inclusion criteria. Global quality rating for significant part of the articles was weak. Most studies showed greater sEMG activity of the masseter (MM) and temporal anterior (TA) muscles at rest in TMD-P subjects than in the asymptomatic controls, while the MM and TA muscles were less active in the pain-related TMD group compared to the non-TMD group during maximal voluntary clenching (MVC).

Conclusion

There were differences in MMA in the TMD-pain population compared to a healthy control group during various tasks. The diagnostic efficacy of surface electromyography in assessing individuals with TMD-P remains unclear.

The Thermal Influence of Oral Rehabilitation on the Cranio-Cervico-Mandibular Complex: A Thermographic Analysis

PURPOSE

Assess the thermal effect of prosthodontic treatment on the cranio-cervico-mandibular complex using infrared thermography.

METHODS

The treatment group was composed of adults of both sexes who underwent a prosthodontic treatment in which at least posterior occlusal contacts were added and/or the vertical dimension of occlusion was reestablished. The control group (CG) was constituted of adult subjects of both sexes, with no more than a single missing posterior tooth, excluding third molars. Thermograms were taken of the treatment group with a Flir i7 IR camera both before oral rehabilitation (TGB; n = 33) and two months after treatment was concluded (TGA; n = 19). CG (n = 33) had only one occasion for data acquisition.

RESULTS

Statistically significant differences were found when the thermal difference (ΔT) and the health status of the orbicularis oris muscle were compared between the TGB and the TGA groups (p = 0.020 and p = 0.003, respectively). By comparing the health status of the masseter muscle between the CG and TGB, statistically significant differences were also observed (p = 0.030).

CONCLUSION

A prosthodontic treatment appears to have a minimum or null effect on the ΔT and/or on the health status of the TMJ and the temporal muscle. In contrast, orbicularis oris muscles exhibited significant thermal variations.

Role of thermography in the assessment of temporomandibular disorders and other musculoskeletal conditions: A systematic review

The aim of this review was to evaluate whether thermal imaging may constitute a reliable assessment method of musculoskeletal and temporomandibular disorders (TMD/MSD). A systematic review was conducted in the Pubmed, Scopus, Cochrane library, Web of Science, and Lilacs databases. The search terms were "musculoskeletal disorders,""temporomandibular disorders,""infrared thermography,""thermography," and "infrared imaging." The inclusion criteria were: studies published between January 1985 and January 2021, performed in humans, with sample size equal or greater than 20 patients, written in English, Portuguese, French and/or Spanish, and full text available. The exclusion criteria were: systematic reviews, case studies, and/or studies focused on pathologies beyond the review's domain. The risk of bias was evaluated using CASP 2018. A total of 2032 articles were retrieved. Of these, 25 studies met the inclusion criteria and were included to withdraw the following information: title, type of study, first author and year of publication, objective, number of participants, comparisons, and principal conclusions. No RCT were found. Despite some disparity, points of convergence among the majority of authors could be found. In general, healthy individuals show subtle thermal differences between contralateral homolog areas. Concerning orofacial structures, unilateral symptomatic individuals may show thermal differences equal or greater than 0.4°C. Infrared thermography accuracy in diagnosing TMD/MSD is still considered low to moderate. Despite some limitations, IRT might constitute a valuable supporting diagnostic tool in the medical field of TMD and MSD.

Thermal Condition of Muscle Area Around the Temporomandibular Joint in Patient with Systemic Lupus Erythematosus Using Infrared Thermography Application: A Case Report

Recently, the use of infrared thermography in medical has been increasingly developed and widely used in medical devices to detect diseases, including one used in the field of dentistry, which can be used to detect joint conditions in case of temporomandibular disorder (TMD). Some literature has shown this method of infrared thermography was used to determine the surface temperature of the skin based on the emission of infrared radiation from the body. Thermal measurement is also a noninvasive method that does not provide patient inconvenience, but its application until now has not been so wide. The case study reported on the description of thermal condition of muscle area around temporomandibular joint (TMJ) in a 42-year-old woman with systemic lupus erythematosus (SLE) disease. She had experienced TMD. Infrared thermography is applied to observe the thermal condition of the muscle area around the right and left joints by thermal detection. Thermal measurement was obtained on infrared image capture, and the temperature difference was found to be greater than 0.3°C. Several studies have shown that temperature in the area around TMJ was higher, and thermal asymmetry was greater in individuals with joint disorder/TMD when compared with normal groups.

Advances in infrared thermography: Surgical aspects, vascular changes, and pain monitoring in veterinary medicine

One of the main functions of infrared thermography (IRT) consists in detecting temperature changes in organisms caused by variations in surface blood circulation. IRT is a useful tool that has been used mainly as a diagnostic method for various stress-causing pathologies, though recent suggestions indicate that it can be used to assess the block quality of certain body regions. In the field of anaesthesiology, IRT has been applied to brachial and epidural blocks, while in algology, changes in surface blood circulation associated with sympathetic activity have been investigated. Thermography has also been employed to complement pain level scales based on the facial expressions of patients in critical condition, or after surgery. In addition, it has been used as a tool in research designed to evaluate different surgical procedures in human medicine, as in the case of surgical burrs for placing dental implants, where IRT helps assess the degree of heating associated with bone devascularisation, reduction in vascular perfusion as a consequence of stroke, and changes in the autonomous nervous system, or the degree of vascular changes in flaps applied to burn patients. In veterinary medicine, thermography has brought several benefits for animals in terms of evaluating lesions, diseases, and surgical procedures. The aim of this review is to evaluate how IRT can be used as a tool in surgical procedures, cases of vascular change, and pain monitoring in veterinary medicine with an emphasis on small animals.

Infrared thermography of the crânio-cervico-mandibular complex in wind and string instrumentalists

PURPOSE

Musculoskeletal disorders can be common in wind and string instrumentalists. The musical gesture technique associated to musical performance can promote an asymmetrical isometric contraction with the hyperactivity of specific muscular groups and the overload of articular surfaces which can cause discomfort or pain. The aim of this investigation was to assess specific anatomical regions of interest within the cranio-cervico-mandibular complex in order to determine and evaluate the presence of muscular hyperactivity associated to musical performance.

METHODS

An infrared imaging camera, FLIR®, was used to record the regions of interest in wind (n = 48) and string instrumentalists (n = 29). Bilateral temperature differences were considered as thermal asymmetries with a conventional threshold of 0.3 ºC to distinguish pathological from healthy states. The regions of interest (ROI) were the anterior triangle of the neck, the sternocleidomastoid and trapezius muscles regarding the postural and stabilizing muscles of the head and neck. On the orofacial region, the anatomical sites were the anterior temporal muscle, the masseter muscle and the temporomandibular joint. A Pearson chi-square test was performed to compare the assessed areas.

RESULTS

Between 30-37% of all participants showed ROI in an asymmetric pattern. The most affected sites were the temporal muscle and the TMJ for both groups. The anterior triangle of the neck showed statistical differences (p = 0.044) between string and wind instrumentalists, while the temporal (p = 0.034) and trapezius muscle (p = 0.028) when comparing large and small mouthpieces of brass instruments. Although female participants showed a higher prevalence of asymmetrical patterns regarding the ROI, no statistical differences were found between genders.

CONCLUSIONS

Infrared thermography exhibited significant differences between wind and string instruments within the CCMC. Regarding the issue of occupational health in performing arts, it is an advantage being able to quantify asymmetrical patterns sites of the CCMC to understand the underlying physiological responses to repetitive movements, overloading and muscular hyperactivity that occur during musical performance.

Infrared thermography assessment of patients with temporomandibular disorders

OBJECTIVES

To assess patients with and without temporomandibular disorders (TMD) infrared thermography according to the differences in thermal radiance using quantitative sensitivity and specificity tests; and to evaluate the thermal asymmetry and the correlation of the thermal intensity with the intensity of pain upon palpation.

METHODS

This cross-sectional study performed a quantitative evaluation of clinical and thermographic examinations. The volunteers were evaluated for the presence of TMD using RDC/TMD (Diagnostic Research Criteria for Temporomandibular Disorders), and were divided into two groups: TMD group (n = 45); control group (n = 41), composed of volunteers without TMD, according to the Fonseca Anamnestic Index. The images were assessed for selected regions of interest for the masseter, anterior temporal and TMJ muscles. The mean values ​​of the areas of both groups were compared under the receiver operating characteristic curve. Spearman correlation analysis (non-parametric data) between pain level and mean temperature, by region, and the Pearson's χ² test was used to verify the association between the presence of temperature and pain asymmetry. The level of significance was set at p < 0.05.

RESULTS

Both Groups, with and without TMD, presented with absolute and non-dimensional mean temperature without statistical differences (p>0.05). When correlating temperature with intensity of pain upon palpation, a negative correlation was observed for the masseter muscle.

CONCLUSION

Infrared Thermography resulted in low area under the curve, making it difficult to differentiate TMD via thermographic analysis. The intensity of pain upon palpation in patients with TMD may be accompanied by a decrease in local temperature.

The Diagnostic Value of Electromyography in Identifying Patients With Pain-Related Temporomandibular Disorders

Introduction: Orofacial pain disorders can be divided into several subgroups. One of them is temporomandibular disorders (TMD) with recognizable signs such as joint noises, limitations in the range of motion, or mandibular deviation during function and symptoms-pain in the muscles or joint. Surface electromyography (sEMG) is a diagnostic tool that ensures reliable and valid evaluation of muscle activity. sEMG detects electrical potentials and on this account may conceivably be employed in the TMD recognition. The aim of this study was to assess the sensitivity, specificity, and accuracy of electromyography in diagnosing subjects with temporomandibular disorders, including pain-free TMD and pain-related TMD. Methods: The sample comprised 88 patients with cleft lip and palate and mixed dentition. TMD has been recognized on the grounds of Axis I of the Research Diagnostic Criteria for TMD (RDC/TMD). To evaluate the electrical activity of the temporal and masseter muscles in the rest position and during maximum voluntary contraction, a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany) was used. The analysis of the receiver operating characteristic (ROC) curve gave information about accuracy, cut-off point value, sensitivity and specificity of the normalized sEMG data. Results: The highest diagnostic efficiency of sEMG in terms of identifying subjects with TMD and pain-related TMD was observed for the mean values of temporal and masseter muscle activity as well as the Asymmetry Index of the masseter muscles in a rest position. A moderate degree of EMG accuracy in differentiating between pain-related TMD and non-TMD children was observed for the mean values of masseter muscle activity and the Asymmetry Index of the masseter muscles at rest. Conclusion: An evaluation of electromyography exhibits its diagnostic usability in recognition of patients with pain-related TMD and it could be used as an adjunctive tool in the identification of this disorder. Clinical Trial Registration: This clinical research was registered in the ClinicalTrials.gov database under the number NCT03308266.

Is infrared thermography effective in the diagnosis of temporomandibular disorders? A systematic review

OBJECTIVE

The aim of this study was to systematically review the scientific efficacy of infrared thermography (IT) on the diagnosis of temporomandibular joint disorders (TMDs).

STUDY DESIGN

An electronic search was performed in 8 databases for publications up to May 2018. Additionally, a hand search of the reference lists was conducted. There were no restrictions on language or on year of publication. Two independent reviewers selected the studies, reviewed the abstract information, and assessed the quality. The methodology of the included articles was evaluated by using the QUADAS-2 tool.

RESULTS

Nine studies fulfilled the eligibility criteria and were included in the systematic review. Four studies concluded that IT presents low accuracy or is not an accurate instrument for TMD diagnosis, but there was substantial variation in sensitivity, specificity, and receiver operating characteristic curve values. Five studies concluded that IT appears to be promising or may be a complementary diagnostic aid in the evaluation of TMDs. These studies presented sensitivity values ranging from 70% to 90% and specificity values ranging from 62% to 92%. All studies were judged as being "at risk of bias" and as having "concerns regarding applicability."

CONCLUSIONS

The literature is still lacking in sufficient number of studies regarding the reliability of IT for the diagnosis of TMDs.

Comparative thermographic analysis at pre- and postcryolipolysis treatment: Clinical case report

INTRODUCTION

Although the exact cryolipolysis mechanisms on adipose tissue remain unknown, the current literature indicates that it may occur a crystallization followed by an ischemic reaction which generates an inflammatory process.

OBJECTIVE

To evaluate thermographically, the tissue's circulatory pattern of a patient submitted to the cryolipolysis technique and the beginning of the inflammatory process, through variations of temperature gradients and the evaluation of the pains degree of the patient in these same moments.

METHODS

A descriptive study, of an interventional case report, performed in an 18-year-old patient who had clearly visible fat in the lower abdomen area, with a skin fold greater than 2 centimeters and body mass index ≤ 30 kg/m² .

RESULTS

Comparing the maximum temperatures showed on the last thermography with the pre-application image, an increase of 0.4°C was observed, which is suggestive of abnormality. Regarding the minimum temperatures verified, there was a significative decrease in the temperature with the procedure, which was observed on the last 5 minutes (ΔT = 9.8°C). However, in 48 hour, the minimum temperature began to recover (ΔT = 0.3°C).

CONCLUSION

The observed data indicate that there was a significant decrease in the temperature during the cooling phase, whereas in the recovery phase, the inverse was found.

Superluminous Devices Versus Low-Level Laser for Temporomandibular Disorders

The aim of this study is to compare the pain intensity reduction between the mean radiation doses per session of gallium-aluminum-arsenide (GaAIAs) laser with superluminous diodes (SLD) in four of the most common pain-related chronic temporomandibular disorders (TMD) - local myalgia, myofascial pain, myofascial pain with a referral, and arthralgia. This study was implemented on 124 patients with pain-related temporomandibular disorders according to the DC/TMD criteria. We applied trigger point oriented near-infrared laser (785 nm, 100 s, 8 J/cm2) and SLD cluster sessions (the cluster is composed of 49 SLDs with a combination of visible red (633 nm) and infrared (880 nm) diodes, 200 mW, 300 s, 8 J/cm2) for the temporomandibular joints and the affected muscles. Patients were evaluated at the start of the treatment, and after the 6th session of combined phototherapy. The pain intensity scores were measured according to the Visual Analogue Scale (VAS). Our results show that the most statistically manifested pain reduction is found for the SLD dose, р = 0,000118, followed by the overall dose (laser plus SLD); р = 0,001031, and the laser dose; р = 0,030942 (ANOVA dispersion analyses). Consequently, it can be concluded that myalgia is better treated through lower doses of red light compared to infrared laser doses because SLDs combine the prooxidative effect of photons with 633 nm wavelength, a large area of exposure, sufficient tissue penetration, and some positive warming thermal impact of the SLD clusters.

A Survey on Computer Vision for Assistive Medical Diagnosis From Faces

Automatic medical diagnosis is an emerging center of interest in computer vision as it provides unobtrusive objective information on a patient's condition. The face, as a mirror of health status, can reveal symptomatic indications of specific diseases. Thus, the detection of facial abnormalities or atypical features is at upmost importance when it comes to medical diagnostics. This survey aims to give an overview of the recent developments in medical diagnostics from facial images based on computer vision methods. Various approaches have been considered to assess facial symptoms and to eventually provide further help to the practitioners. However, the developed tools are still seldom used in clinical practice, since their reliability is still a concern due to the lack of clinical validation of the methodologies and their inadequate applicability. Nonetheless, efforts are being made to provide robust solutions suitable for healthcare environments, by dealing with practical issues such as real-time assessment or patients positioning. This survey provides an updated collection of the most relevant and innovative solutions in facial images analysis. The findings show that with the help of computer vision methods, over 30 medical conditions can be preliminarily diagnosed from the automatic detection of some of their symptoms. Furthermore, future perspectives, such as the need for interdisciplinary collaboration and collecting publicly available databases, are highlighted.

Factor and Rasch analysis of the Fonseca anamnestic index for the diagnosis of myogenous temporomandibular disorder

BACKGROUND

Rasch analysis has been used in recent studies to test the psychometric properties of a questionnaire. The conditions for use of the Rasch model are one-dimensionality (assessed via prior factor analysis) and local independence (the probability of getting a particular item right or wrong should not be conditioned upon success or failure in another).

OBJECTIVE

To evaluate the dimensionality and the psychometric properties of the Fonseca anamnestic index (FAI), such as the fit of the data to the model, the degree of difficulty of the items, and the ability to respond in patients with myogenous temporomandibular disorder (TMD).

METHODS

The sample consisted of 94 women with myogenous TMD, diagnosed by the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), who answered the FAI. For the factor analysis, we applied the Kaiser-Meyer-Olkin test, Bartlett's sphericity, Spearman's correlation, and the determinant of the correlation matrix. For extraction of the factors/dimensions, an eigenvalue >1.0 was used, followed by oblique oblimin rotation. The Rasch analysis was conducted on the dimension that showed the highest proportion of variance explained.

RESULTS

Adequate sample "n" and FAI multidimensionality were observed. Dimension 1 (primary) consisted of items 1, 2, 3, 6, and 7. All items of dimension 1 showed adequate fit to the model, being observed according to the degree of difficulty (from most difficult to easiest), respectively, items 2, 1, 3, 6, and 7.

CONCLUSION

The FAI presented multidimensionality with its main dimension consisting of five reliable items with adequate fit to the composition of its structure.

Evolution of Skin Temperature after the Application of Compressive Forces on Tendon, Muscle and Myofascial Trigger Point

Some assessment and diagnosis methods require palpation or the application of certain forces on the skin, which affects the structures beneath, we highlight the importance of defining possible influences on skin temperature as a result of this physical contact. Thus, the aim of the present study is to determine the ideal time for performing thermographic examination after palpation based on the assessment of skin temperature evolution. Randomized and crossover study carried out with 15 computer-user volunteers of both genders, between 18 and 45 years of age, who were submitted to compressive forces of 0, 1, 2 and 3 kg/cm2 for 30 seconds with a washout period of 48 hours using a portable digital dynamometer. Compressive forces were applied on the following spots on the dominant upper limb: myofascial trigger point in the levator scapulae, biceps brachii muscle and palmaris longus tendon. Volunteers were examined by means of infrared thermography before and after the application of compressive forces (15, 30, 45 and 60 minutes). In most comparisons made over time, a significant decrease was observed 30, 45 and 60 minutes after the application of compressive forces (p < 0.05) on the palmaris longus tendon and biceps brachii muscle. However, no difference was observed when comparing the different compressive forces (p > 0.05). In conclusion, infrared thermography can be used after assessment or diagnosis methods focused on the application of forces on tendons and muscles, provided the procedure is performed 15 minutes after contact with the skin. Regarding to the myofascial trigger point, the thermographic examination can be performed within 60 minutes after the contact with the skin.

Assessment of the Sensitivity, Specificity, and Accuracy of Thermography in Identifying Patients with TMD

Background

The purpose of the present study was to evaluate the sensitivity, specificity, and accuracy of thermography in identifying patients with temporomandibular dysfunction (TMD).

Material/Methods

The study sample consisted of 50 patients (27 women and 23 men) ages 19.2 to 24.5 years (mean age 22.43±1.04) with subjective symptoms of TMD (Ai II–III) and 50 patients (25 women and 25 men) ages 19.3 to 25.1 years (mean age 22.21±1.18) with no subjective symptoms of TMD (Ai I).

The anamnestic interviews were conducted according to the three-point anamnestic index of temporomandibular dysfunction (Ai). The thermography was performed using a ThermaCAM TMSC500 (FLIR Systems AB, Sweden) independent thermal vision system. Thermography was closely combined with a 10-min chewing test.

Results

The results of our study indicated that the absolute difference in temperature between the right and left side (ΔT) has the highest diagnostic value. The diagnostic effectiveness of this parameter increased after the chewing test. The cut-off points for values of temperature differences between the right and left side and identifying 95.5% of subjects with no functional disorders according to the temporomandibular dysfunction index Di (specificity 95.5%) were 0.26°C (AUC=0.7422, sensitivity 44.3%, accuracy 52.4%) before the chewing test and 0.52°C (AUC=0.7920, sensitivity 46.4%, accuracy 56.3%) after it.

Conclusions

The evaluation of thermography demonstrated its diagnostic usefulness in identifying patients with TMD with limited effectiveness. The chewing test helped in increasing the diagnostic efficiency of thermography in identifying patients with TMD.

Reliability of different methodologies of infrared image analysis of myofascial trigger points in the upper trapezius muscle

BACKGROUND:

Infrared thermography is recognized as a viable method for evaluation of subjects with myofascial pain.

OBJECTIVE:

The aim of the present study was to assess the intra- and inter-rater reliability of infrared image analysis of myofascial trigger points in the upper trapezius muscle.

METHOD:

A reliability study was conducted with 24 volunteers of both genders (23 females) between 18 and 30 years of age (22.12±2.54), all having cervical pain and presence of active myofascial trigger point in the upper trapezius muscle. Two trained examiners performed analysis of point, line, and area of the infrared images at two different periods with a 1-week interval. The intra-class correlation coefficient (ICC_2,1) was used to assess the intra- and inter-rater reliability.

RESULTS:

With regard to the intra-rater reliability, ICC values were between 0.591 and 0.993, with temperatures between 0.13 and 1.57 °C for values of standard error of measurement (SEM) and between 0.36 and 4.35 °C for the minimal detectable change (MDC). For the inter-rater reliability, ICC ranged from 0.615 to 0.918, with temperatures between 0.43 and 1.22 °C for the SEM and between 1.19 and 3.38 °C for the MDC.

CONCLUSION:

The methods of infrared image analyses of myofascial trigger points in the upper trapezius muscle employed in the present study are suitable for clinical and research practices.

Women with more severe degrees of temporomandibular disorder exhibit an increase in temperature over the temporomandibular joint

Aim

The purpose of the present study was to correlate the degree of temporomandibular disorder (TMD) severity and skin temperatures over the temporomandibular joint (TMJ) and masseter and anterior temporalis muscles.

Materials and methods

This blind cross-sectional study involved 60 women aged 18–40 years. The volunteers were allocated to groups based on Fonseca anamnestic index (FAI) score: no TMD, mild TMD, moderate TMD, and severe TMD (n = 15 each). All volunteers underwent infrared thermography for the determination of skin temperatures over the TMJ, masseter and anterior temporalis muscles. The Shapiro–Wilk test was used to determine the normality of the data. The Kruskal–Wallis test, followed by Dunn’s test, was used for comparisons among groups according to TMD severity. Spearman’s correlation coefficients were calculated to determine the strength of associations among variables.

Results

Weak, positive, significant associations were found between FAI score and skin temperatures over the left TMJ (rs = 0.195, p = 0.009) and right TMJ (rs = 0.238, p = 0.001). Temperatures over the right and left TMJ were significantly higher in groups with more severe TMD (p < 0.05).

Conclusion

FAI score was associated with skin temperature over the TMJ, as determined by infrared thermography, in this sample. Women with more severe TMD demonstrated a bilateral increase in skin temperature.

Thermographic characterization of masticatory muscle regions in volunteers with and without myogenous temporomandibular disorder: preliminary results

OBJECTIVES

This study aims to conduct a non-invasive measurement of the cutaneous temperature of selected masticatory muscle regions of volunteers with and without myogenous temporomandibular disorder (TMD), using infrared thermography.

METHODS

23 females (10 myogenous TMD volunteers and 13 controls) were recruited and studied. The temperature at the surface of the facial area over the anterior temporalis and masseter muscles was assessed by medical thermography, using regional lateral views and clinical examination.

RESULTS

The temperature levels measured at the masseter and anterior temporalis muscle regions in myogenous TMD volunteers (32.85 ± 0.85 and 34.37 ± 0.64 ºC, respectively) were significantly lower (p < 0.05) than those measured in controls (33.49 ± 0.92 and 34.78 ± 0.44 ºC, respectively). Medical infrared imaging indicated a mean difference of 1.4 ºC between the masseter and anterior temporalis regions. Analysis of the comparison between the absolute and normalized mean temperatures was performed using the pairwise comparison of receiver operating characteristic curves, and no statistically significant difference was observed (p > 0.05). The sensitivity and specificity of the thermographic assessment for the masseter region was of 70% and 73%, respectively and for the anterior temporalis region was of 80% and 62%, respectively.

CONCLUSIONS

This method of evaluating masticatory muscle regions of this preliminary study seems to indicate that it can be used as an aid in complimentary diagnosing of TMDs.

Application of infrared thermography in computer aided diagnosis

The invention of thermography, in the 1950s, posed a formidable problem to the research community: What is the relationship between disease and heat radiation captured with Infrared (IR) cameras? The research community responded with a continuous effort to find this crucial relationship. This effort was aided by advances in processing techniques, improved sensitivity and spatial resolution of thermal sensors. However, despite this progress fundamental issues with this imaging modality still remain. The main problem is that the link between disease and heat radiation is complex and in many cases even non-linear. Furthermore, the change in heat radiation as well as the change in radiation pattern, which indicate disease, is minute. On a technical level, this poses high requirements on image capturing and processing. On a more abstract level, these problems lead to inter-observer variability and on an even more abstract level they lead to a lack of trust in this imaging modality. In this review, we adopt the position that these problems can only be solved through a strict application of scientific principles and objective performance assessment. Computing machinery is inherently objective; this helps us to apply scientific principles in a transparent way and to assess the performance results. As a consequence, we aim to promote thermography based Computer-Aided Diagnosis (CAD) systems. Another benefit of CAD systems comes from the fact that the diagnostic accuracy is linked to the capability of the computing machinery and, in general, computers become ever more potent. We predict that a pervasive application of computers and networking technology in medicine will help us to overcome the shortcomings of any single imaging modality and this will pave the way for integrated health care systems which maximize the quality of patient care.