Journal of
Oral Rehabilitation
Journal of Oral Rehabilitation 2014 41; 323--329
Determination of a pressure pain threshold cut-off value for the diagnosis of temporomandibular joint arthralgia C. O. CUNHA*, L. M. S. PINTO-FIAMENGUI*, A. C. P. C. CASTRO†, J. R. P. LAURIS‡ & P . C . R . C O N T I * *Department of Prosthodontics, Bauru School of Dentistry, University of Sao Paulo, Bauru, †State Hospital of Bauru, Bauru, and ‡Department of Public Health, Bauru School of Dentistry, University of Sao Paulo, Bauru, Brazil
Temporomandibular joint (TMJ) disorders are divided by the American Academy of Orofacial Pain into five categories. The most common ones are joint pain, as arthralgia and joint disorders, as disc displacements. An important clinical presentation of arthralgia is the painful tenderness to manual palpation or decreased pressure pain threshold (PPT). The authors conducted a study to determine the appropriate PPT value to discriminate asymptomatic TMJ individuals from those with moderate to severe arthralgia. Fortynine individuals was evaluated and divided into groups: TMJ arthralgia, asymptomatic disc displacement and control group. Magnetic resonance images were obtained for all the groups, and algometry was performed on the TMJ lateral pole. Patients with arthralgia filled out a visual analogue scale (VAS). ANOVA test with 1% of significance analysed the data. Specificity, sensitivity and ROC curve were also determined. Arthralgia group had significant lower PPT (mean SUMMARY
Introduction Temporomandibular joint (TMJ) disorders are divided by the American Academy of Orofacial Pain into five categories: joint pain, joint disorders, joint diseases, fractures and congenital development disorders (1). Joint pain and joint disorders, such as arthralgia and disc displacement, are the most common TMJ disorders. An important clinical presentation in arthralgia is the painful tenderness to manual palpation or decreased pressure pain threshold (PPT), determined with an algometer (pressure device with which an © 2014 John Wiley & Sons Ltd
of 107 kgf cm 2) than the others. Asymptomatic disc displacement group (mean of 164 kgf cm 2) has shown significant lower PPT than the control (mean of 235 kgf cm 2). 8966% of specificity and 70% of sensitivity were obtained when 136 kgf cm 2 was applied to the TMJ (ROC area = 090). This value was considered to be the most appropriate to detected moderate to severe TMJ arthralgia. Indeed, the presence of disc displacement seems to significantly decrease PPT levels in asymptomatic subjects. The PPT value of 136 kgf cm 2 can be used in the calibration procedures of the professionals involved with temporomandibular disorders and orofacial pain. KEYWORDS: temporomandibular joint, arthralgia, pain threshold, magnetic resonance imaging, temporomandibular disorders, sensitivity and specificity Accepted for publication 8 February 2014
increasing pressure is applied until the patient feels that the pressure has become unpleasant or ‘painful’) (2). Manual palpation is the most used test for the diagnosis of arthralgia; however, the interpretation of patient’s response to that is still controversial (3). This is particularly important, because for most of the temporomandibular disorders (TMD) classification and diagnostic systems and protocols, TMJ pain reported from the manual palpation is crucial for the determination of management strategies. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) constitute a diagnostic doi: 10.1111/joor.12158
324
C . O . C U N H A et al. protocol that is widely used for clinical and research purpose. It was developed to establish a standardised and reproducible examination procedures and diagnostic criteria for diagnoses of TMD groups. The RDC/ TMD is composed by two Axis (Axis I, clinical assessment and Axis II, behavioural assessment). The group II and III in the Axis I are related to articular problems. Pain reported in the manual palpation of the TMJ is used as one of the criteria for arthralgia diagnosis in the RDC/TMD (Group IIIa – Axis I). A study performed by Truelove et al. in 2010, with 614 TMD community and clinic cases and 91 controls individuals, aimed to estimate the criterion validity of the RDC/TMD Axis I TMD diagnoses. The results for that study showed that the Axis I TMD diagnoses did not reach the targets set by Dworkin and LeResche (4) at sensitivity of ≥070 and specificity of ≥095. For Group II (disc displacements) and Group III (arthralgia, arthritis, arthrosis) diagnoses, all estimates for sensitivity were below target (003–053), and specificity ranged from below to on target (086–099). Truelove et al. concluded that a revision of the current Axis I TMD diagnostic algorithms is needed to improve their validity (5). Manual palpation performed without training or calibration can result in inadequate amount of the pressure applied during the examination and, consequently, poor discriminative values; the pressure must be strong enough to detect TMJ pain in symptomatic patients but delicate enough to do not cause pain in ‘healthy’ individuals (6). The determination of an ‘ideal’ pressure value is determinant to establish calibration programmes that make the manual palpation a reliable technique of detection of musculoskeletal type of pain, based on acceptable figures of sensitivity and specificity. The present study aims to (i) determine, based on an acceptable specificity levels, the more appropriate PPT value able to discriminate asymptomatic individuals from those with moderate to severe TMJs arthralgia, as well as to (ii) determine the impact of disc displacement with reduction (DDWR) on PPT values in asymptomatic individuals.
Material and methods Sample composition The sample was obtained from Brazilian Caucasian women seeking regular dental treatment (control group) or presenting with complaint of pain and/or
noise in TMJ area at the Bauru School of Dentistry, University of Sao Paulo, Brazil. Individuals presenting with primary muscular, dental or neuropathic pain as well as those with systemic conditions (e.g. fibromyalgia, osteoarthritis and autoimmune arthritis like rheumatoid arthritis) were excluded. The presence of any factor that prevented magnetic resonance imaging (MRI), like metal inside the body (e.g. stents, metal plates or orthodontic appliances), and the use of medication such as analgesics and anti-inflammatory drugs were also initial exclusion criteria. After the initial screening, subjects were evaluated using the RDC/TMD (4) classification system, to be preliminarily allocated in one of the three groups, according to the clinical examination (RDC IIIa group-arthralgia, IIa group-DDWR and asymptomatic or control group). As the main goal of the present study was to determine the influence of symptoms (pain) and morphological alteration (DDWR) in the PPT, bilateral TMJ MRIs were obtained of the entire sample to endorse the clinical diagnosis. Bilateral sagittal and coronal images (T1 and T2) were obtained with the mouth in closed and full opened positions, with a 15 Tesla device. An experienced radiologist, blinded for the initial group distribution, gave the MRI diagnosis. Based on that, to be assigned to the control (comparison/asymptomatic) group, a normal disc–condyle relationship should have been present (posterior band of the disc located at least at the 12 o’clock position in relation to the condyle) (4). Likewise, the DDWR group had to have this feature confirmed by the image finding (posterior band being between 10 and 11 o’clock relative to the condyle in closed-mouth images with reduction in the disc in open-mouth images) (4). To be included in the arthralgia (symptomatic) group, the disc position was not an exclusion criterion. The final sample was composed of 49 individuals, all females, aged between 18 and 50 years. Fifteen females (mean age of 27 years) with no TMJ pain or noise, and normal disc/condyle were included in the control group. Patients with asymptomatic DDWR and without tenderness to TMJ palpation (Group IIa from the RDC/TMD) were included in the DDWR group, which was composed of 14 females (mean age of 31 years), while 20 females with TMJ arthralgia (Group IIIa from the RDC/TMD), regardless of the disc/condyle relationship, composed the arthralgia or symptomatic group (mean age of 37 years). Patients © 2014 John Wiley & Sons Ltd
PPT CUT-OFF VALUE IN TMJ ARTHRALGIA from the later group filled out a visual analogue scale (VAS) (100-mm line where the patient registered pain intensity by marking a point on the line between the two extremes where the left extreme of the scale is marked ‘no pain’ and the right one is marked ‘the worst imaginable pain’), and to be part of the group, the pain level reported by the patient should have been equal or >50 mm (50%) (7). The Research Ethics Committee of the Bauru School of Dentistry approved the experiment. All individuals were informed about the research and experimental procedures and requested to sign an informed consent. Algometry examination (PPT determination) The PPT measurement was conducted with the aid of a digital algometer*. The device had a rod at one end with a flat circular tip of 1 cm2 diameter through which was applied an increasing and constant pressure of 05 kgf cm 2 s 1 (8) perpendicular to the lateral pole of the left and right TMJ, always in this sequence to all individuals. Prior to PPT measurement, the individuals were informed to push a button, which was in its possession, in the exact moment when the increasing stimulus performed with the device changed from a sensation of pressure into pain. When the button was pushed, the algometer automatically recorded the value of the PPT. During the exam, the individual’s head was firmly supported by the operator’s non-dominant hand (9). The PPT values were obtained once in both TMJs, but only the findings of one side (which represented the subject’s complaint) were considered for statistical analysis purposes. Patients were asked to identify their ‘most painful side’ prior PPT measurement. Statistical analysis One-way analysis of variance (ANOVA) test was used to detect differences between groups. The ANOVA test was followed by post hoc Tukey’s test. A 1% significance level was used for all these tests. Sensitivity and specificity values were calculated for each PPT values and plotted on the receiver operator characteristic (ROC) curves. The more appropriate PPT value chosen to
*(KRATOSTM, Cotia, Brazil). © 2014 John Wiley & Sons Ltd
better discriminate symptomatic from asymptomatic TMJs was based on acceptable specificity and sensitivity levels. It is important to emphasise that for calculation of both, cut-off value and the ROC curve area, the PPT values of the sample of asymptomatic individuals were composed by the individuals of the control group plus the DDWR group’s individuals.
Results Significant differences were detected between groups, when PPTs were considered (Table 1 and Fig. 1). The arthralgia group had significant lower PPT values (107 kgf cm 2 044) than the others, while the DDWR group has shown significant lower PPT (164 kgf cm 2 040) when compared to the control one (235 kgf cm 2 056). The control group used for the calculation of both, cut-off value and the ROC curve area (control plus DDWR group, n = 29), has a PPT mean of 201 kgf cm 2 (044). For the arthralgia group, VAS values ranged from 56 to 100 mm with a mean value of 704 mm. The MRIs for the arthralgia group revealed that, of the twenty TMJs included in the statistical analysis, nine of them revealed articular effusion, five of them disc displacement without reduction and six of them were judged to be within normal limits. When comparing the PPT values of the asymptomatic individuals (control group plus DDWR group) with the arthralgia one, a specificity of 8966% and a sensitivity of 70% were obtained when 136 kgf cm 2 was applied to the lateral pole of the TMJ. Using this cut-off value, the ROC curve (ranging from 0 to 1) was 090 ( 2).
Discussion The correct diagnosis of an articular or muscular TMD is extremely important because it has a strong impact Table 1. Pressure pain threshold values comparison between groups
Groups comparison
Difference of means in the PPT values (kgf cm 2)
P-value
Control 9 DDWR Control 9 Arthralgia DDWR 9 Arthralgia
0702 1280 0578
Oral Rehabilitation
Journal of Oral Rehabilitation 2014 41; 323--329
Determination of a pressure pain threshold cut-off value for the diagnosis of temporomandibular joint arthralgia C. O. CUNHA*, L. M. S. PINTO-FIAMENGUI*, A. C. P. C. CASTRO†, J. R. P. LAURIS‡ & P . C . R . C O N T I * *Department of Prosthodontics, Bauru School of Dentistry, University of Sao Paulo, Bauru, †State Hospital of Bauru, Bauru, and ‡Department of Public Health, Bauru School of Dentistry, University of Sao Paulo, Bauru, Brazil
Temporomandibular joint (TMJ) disorders are divided by the American Academy of Orofacial Pain into five categories. The most common ones are joint pain, as arthralgia and joint disorders, as disc displacements. An important clinical presentation of arthralgia is the painful tenderness to manual palpation or decreased pressure pain threshold (PPT). The authors conducted a study to determine the appropriate PPT value to discriminate asymptomatic TMJ individuals from those with moderate to severe arthralgia. Fortynine individuals was evaluated and divided into groups: TMJ arthralgia, asymptomatic disc displacement and control group. Magnetic resonance images were obtained for all the groups, and algometry was performed on the TMJ lateral pole. Patients with arthralgia filled out a visual analogue scale (VAS). ANOVA test with 1% of significance analysed the data. Specificity, sensitivity and ROC curve were also determined. Arthralgia group had significant lower PPT (mean SUMMARY
Introduction Temporomandibular joint (TMJ) disorders are divided by the American Academy of Orofacial Pain into five categories: joint pain, joint disorders, joint diseases, fractures and congenital development disorders (1). Joint pain and joint disorders, such as arthralgia and disc displacement, are the most common TMJ disorders. An important clinical presentation in arthralgia is the painful tenderness to manual palpation or decreased pressure pain threshold (PPT), determined with an algometer (pressure device with which an © 2014 John Wiley & Sons Ltd
of 107 kgf cm 2) than the others. Asymptomatic disc displacement group (mean of 164 kgf cm 2) has shown significant lower PPT than the control (mean of 235 kgf cm 2). 8966% of specificity and 70% of sensitivity were obtained when 136 kgf cm 2 was applied to the TMJ (ROC area = 090). This value was considered to be the most appropriate to detected moderate to severe TMJ arthralgia. Indeed, the presence of disc displacement seems to significantly decrease PPT levels in asymptomatic subjects. The PPT value of 136 kgf cm 2 can be used in the calibration procedures of the professionals involved with temporomandibular disorders and orofacial pain. KEYWORDS: temporomandibular joint, arthralgia, pain threshold, magnetic resonance imaging, temporomandibular disorders, sensitivity and specificity Accepted for publication 8 February 2014
increasing pressure is applied until the patient feels that the pressure has become unpleasant or ‘painful’) (2). Manual palpation is the most used test for the diagnosis of arthralgia; however, the interpretation of patient’s response to that is still controversial (3). This is particularly important, because for most of the temporomandibular disorders (TMD) classification and diagnostic systems and protocols, TMJ pain reported from the manual palpation is crucial for the determination of management strategies. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) constitute a diagnostic doi: 10.1111/joor.12158
324
C . O . C U N H A et al. protocol that is widely used for clinical and research purpose. It was developed to establish a standardised and reproducible examination procedures and diagnostic criteria for diagnoses of TMD groups. The RDC/ TMD is composed by two Axis (Axis I, clinical assessment and Axis II, behavioural assessment). The group II and III in the Axis I are related to articular problems. Pain reported in the manual palpation of the TMJ is used as one of the criteria for arthralgia diagnosis in the RDC/TMD (Group IIIa – Axis I). A study performed by Truelove et al. in 2010, with 614 TMD community and clinic cases and 91 controls individuals, aimed to estimate the criterion validity of the RDC/TMD Axis I TMD diagnoses. The results for that study showed that the Axis I TMD diagnoses did not reach the targets set by Dworkin and LeResche (4) at sensitivity of ≥070 and specificity of ≥095. For Group II (disc displacements) and Group III (arthralgia, arthritis, arthrosis) diagnoses, all estimates for sensitivity were below target (003–053), and specificity ranged from below to on target (086–099). Truelove et al. concluded that a revision of the current Axis I TMD diagnostic algorithms is needed to improve their validity (5). Manual palpation performed without training or calibration can result in inadequate amount of the pressure applied during the examination and, consequently, poor discriminative values; the pressure must be strong enough to detect TMJ pain in symptomatic patients but delicate enough to do not cause pain in ‘healthy’ individuals (6). The determination of an ‘ideal’ pressure value is determinant to establish calibration programmes that make the manual palpation a reliable technique of detection of musculoskeletal type of pain, based on acceptable figures of sensitivity and specificity. The present study aims to (i) determine, based on an acceptable specificity levels, the more appropriate PPT value able to discriminate asymptomatic individuals from those with moderate to severe TMJs arthralgia, as well as to (ii) determine the impact of disc displacement with reduction (DDWR) on PPT values in asymptomatic individuals.
Material and methods Sample composition The sample was obtained from Brazilian Caucasian women seeking regular dental treatment (control group) or presenting with complaint of pain and/or
noise in TMJ area at the Bauru School of Dentistry, University of Sao Paulo, Brazil. Individuals presenting with primary muscular, dental or neuropathic pain as well as those with systemic conditions (e.g. fibromyalgia, osteoarthritis and autoimmune arthritis like rheumatoid arthritis) were excluded. The presence of any factor that prevented magnetic resonance imaging (MRI), like metal inside the body (e.g. stents, metal plates or orthodontic appliances), and the use of medication such as analgesics and anti-inflammatory drugs were also initial exclusion criteria. After the initial screening, subjects were evaluated using the RDC/TMD (4) classification system, to be preliminarily allocated in one of the three groups, according to the clinical examination (RDC IIIa group-arthralgia, IIa group-DDWR and asymptomatic or control group). As the main goal of the present study was to determine the influence of symptoms (pain) and morphological alteration (DDWR) in the PPT, bilateral TMJ MRIs were obtained of the entire sample to endorse the clinical diagnosis. Bilateral sagittal and coronal images (T1 and T2) were obtained with the mouth in closed and full opened positions, with a 15 Tesla device. An experienced radiologist, blinded for the initial group distribution, gave the MRI diagnosis. Based on that, to be assigned to the control (comparison/asymptomatic) group, a normal disc–condyle relationship should have been present (posterior band of the disc located at least at the 12 o’clock position in relation to the condyle) (4). Likewise, the DDWR group had to have this feature confirmed by the image finding (posterior band being between 10 and 11 o’clock relative to the condyle in closed-mouth images with reduction in the disc in open-mouth images) (4). To be included in the arthralgia (symptomatic) group, the disc position was not an exclusion criterion. The final sample was composed of 49 individuals, all females, aged between 18 and 50 years. Fifteen females (mean age of 27 years) with no TMJ pain or noise, and normal disc/condyle were included in the control group. Patients with asymptomatic DDWR and without tenderness to TMJ palpation (Group IIa from the RDC/TMD) were included in the DDWR group, which was composed of 14 females (mean age of 31 years), while 20 females with TMJ arthralgia (Group IIIa from the RDC/TMD), regardless of the disc/condyle relationship, composed the arthralgia or symptomatic group (mean age of 37 years). Patients © 2014 John Wiley & Sons Ltd
PPT CUT-OFF VALUE IN TMJ ARTHRALGIA from the later group filled out a visual analogue scale (VAS) (100-mm line where the patient registered pain intensity by marking a point on the line between the two extremes where the left extreme of the scale is marked ‘no pain’ and the right one is marked ‘the worst imaginable pain’), and to be part of the group, the pain level reported by the patient should have been equal or >50 mm (50%) (7). The Research Ethics Committee of the Bauru School of Dentistry approved the experiment. All individuals were informed about the research and experimental procedures and requested to sign an informed consent. Algometry examination (PPT determination) The PPT measurement was conducted with the aid of a digital algometer*. The device had a rod at one end with a flat circular tip of 1 cm2 diameter through which was applied an increasing and constant pressure of 05 kgf cm 2 s 1 (8) perpendicular to the lateral pole of the left and right TMJ, always in this sequence to all individuals. Prior to PPT measurement, the individuals were informed to push a button, which was in its possession, in the exact moment when the increasing stimulus performed with the device changed from a sensation of pressure into pain. When the button was pushed, the algometer automatically recorded the value of the PPT. During the exam, the individual’s head was firmly supported by the operator’s non-dominant hand (9). The PPT values were obtained once in both TMJs, but only the findings of one side (which represented the subject’s complaint) were considered for statistical analysis purposes. Patients were asked to identify their ‘most painful side’ prior PPT measurement. Statistical analysis One-way analysis of variance (ANOVA) test was used to detect differences between groups. The ANOVA test was followed by post hoc Tukey’s test. A 1% significance level was used for all these tests. Sensitivity and specificity values were calculated for each PPT values and plotted on the receiver operator characteristic (ROC) curves. The more appropriate PPT value chosen to
*(KRATOSTM, Cotia, Brazil). © 2014 John Wiley & Sons Ltd
better discriminate symptomatic from asymptomatic TMJs was based on acceptable specificity and sensitivity levels. It is important to emphasise that for calculation of both, cut-off value and the ROC curve area, the PPT values of the sample of asymptomatic individuals were composed by the individuals of the control group plus the DDWR group’s individuals.
Results Significant differences were detected between groups, when PPTs were considered (Table 1 and Fig. 1). The arthralgia group had significant lower PPT values (107 kgf cm 2 044) than the others, while the DDWR group has shown significant lower PPT (164 kgf cm 2 040) when compared to the control one (235 kgf cm 2 056). The control group used for the calculation of both, cut-off value and the ROC curve area (control plus DDWR group, n = 29), has a PPT mean of 201 kgf cm 2 (044). For the arthralgia group, VAS values ranged from 56 to 100 mm with a mean value of 704 mm. The MRIs for the arthralgia group revealed that, of the twenty TMJs included in the statistical analysis, nine of them revealed articular effusion, five of them disc displacement without reduction and six of them were judged to be within normal limits. When comparing the PPT values of the asymptomatic individuals (control group plus DDWR group) with the arthralgia one, a specificity of 8966% and a sensitivity of 70% were obtained when 136 kgf cm 2 was applied to the lateral pole of the TMJ. Using this cut-off value, the ROC curve (ranging from 0 to 1) was 090 ( 2).
Discussion The correct diagnosis of an articular or muscular TMD is extremely important because it has a strong impact Table 1. Pressure pain threshold values comparison between groups
Groups comparison
Difference of means in the PPT values (kgf cm 2)
P-value
Control 9 DDWR Control 9 Arthralgia DDWR 9 Arthralgia
0702 1280 0578
