Importance of Standardized Palpation of the Human Temporomandibular Joint

Aims: To test whether standardized palpation around the lateral pole of the condyle can influence mechanical sensitivity and unpleasantness and evoke referred sensations/pain in healthy individuals. Methods: Palpometers (0.5, 1.0, and 2.0 kg) with spherical extensions were applied around the lateral pole of the condyle in relaxed and protruded positions of the mandible for 2, 5, and 10 seconds in 30 healthy participants. Mechanical sensitivity, unpleasantness, and referred sensations/pain were assessed using a 0 to 100 numeric rating scale (NRS) for each palpation. The NRS scores were compared using analysis of variance and McNemar test. Results: Participants reported significantly higher mechanical sensitivity and unpleasantness scores for the 2.0-kg stimulus compared to the 0.5- and 1.0kg stimuli for 2, 5, and 10 seconds (mean NRS > 50; P < .001). Application of a 1.0-kg stimulus was significantly different from the 0.5- and 2.0-kg stimuli applied for 5 seconds (mean NRS < 50; P < .001). One-third of participants reported referred sensations/pain. Conclusion: Application of a 2.0-kg stimulus around the lateral pole of the condyle is painful and unpleasant regardless of time of palpation. Application of a 1.0-kg stimulus for 5 seconds was found to be nonpainful and not unpleasant in healthy participants. Thus, this study supports the Diagnostic Criteria for TMD recommendation for standardized examination of the TMJ and indicates that referred sensation/pain is a common finding in healthy individuals.

DC/TMD;lateral pole of the condyle;mechanical sensitivity;palpation;referred sensation/pain

1. Dworkin SF, LeResche L. Research diagnostic criteria for temporomandibular disorders: Review, criteria, examinations and specifications, critique. J Craniomandib Disord 1992;6: 301–355.

2. Schiffman E, Ohrbach R, Truelove E, et al. Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for clinical and research applications: Recommendations of the International RDC/TMD Consortium Network and Orofacial Pain Special Interest Group. J Oral Facial Pain Headache 2014;28:6–27.

3. Bendtsen L, Jensen R, Jensen NK, Olesen J. Muscle palpation with controlled finger pressure: New equipment for the study of tender myofascial tissues. Pain 1994;59:235–239.

4. Bernhardt O, Schiffman EL, Look JO. Reliability and validity of a new fingertip-shaped pressure algometer for assessing pressure pain thresholds in the temporomandibular joint and masticatory muscles. J Orofac Pain 2007;21:29–38.

5. Jensen K, Andersen HO, Olesen J, Lindblom U. Pressure-pain threshold in human temporal region. Evaluation of a new pres- sure algometer. Pain 1986;25:313–323.

6. Futarmal S, Kothari M, Ayesh E, Baad-Hansen L, Svensson P. New palpometer with implications for assessment of deep pain sensitivity. J Dent Res 2011;90:918–922.

7. Kothari SF, Kothari M, Zambra RF, Baad-Hansen L, Svensson P. Standardization of muscle palpation—Methodological con- siderations. Clin J Pain 2014;30:174–182.

8. Cunha CO, Pinto-Fiamengui LM, Castro AC, Lauris JR, Conti PC. Determination of a pressure pain threshold cut-off value for the diagnosis of temporomandibular joint arthralgia. J Oral Rehabil 2014;41:323–329.

9. Svensson P, Baad-Hansen L, Pigg M, et al. Guidelines and recommendations for assessment of somatosensory func- tion in oro-facial pain conditions—A taskforce report. J Oral Rehabil 2011;38:366–394.

10. Goulet JP, Clark GT, Flack VF. Reproducibility of examiner per- formance for muscle and joint palpation in the temporomandib- ular system following training and calibration. Community Dent Oral Epidemiol 1993;21:72–77.

11. International Network for Orofacial Pain and Related Disorders Methodology. TMD assessment/diagnosis. International Association for Dental Research. http://www.iadr.org/ INfORM/DC-TMD. Accessed September 6, 2018.

12. Svensson P, Arendt-Nielson L. Clinical and experimental as- pects of temporomandibular disorders. Curr Rev Pain 2000; 4:158–165.

13. Masuda M, Iida T, Exposto FG, et al. Spatio-temporal effects of standardized palpation on referred sensations and pain from the masseter muscle in healthy individuals. Int J Oral Med Sci

2018;17:9–17.

14. Svensson P, Graven-Nielsen T, Arendt-Nielsen L. Mechanical hyperesthesia of human facial skin induced by tonic painful stimulation of jaw muscles. Pain 1998;74:93–100.

15. Castrillon EE, Exposto FG, Sato H, et al. Entropy of masseter muscle pain sensitivity: A new technique for pain assessment. J Oral Facial Pain Headache 2017;31:87–94.

16. Arima T, Svensson P, Arendt-Nielsen L. Experimental grinding in healthy subjects: A model for postexercise jaw muscle sore- ness? J Orofac Pain 1999;13:104–114.

17. Kjøgx H, Zachariae R, Pfeiffer-Jensen M, et al. Pain frequency moderates the relationship between pain catastrophizing and pain. Front Psychol 2014;5:1421.

18. Kothari SF, Baad-Hansen L, Oono Y, Svensson P. Somatosensory assessment and conditioned pain modula- tion in temporomandibular disorders pain patients. Pain 2015; 156:2545–2555.

19. Shaefer JR, Jackson DL, Schiffman EL, Anderson QN. Pressure-pain thresholds and MRI effusions in TMJ arthralgia. J Dent Res 2001;80:1935–1939.

20. Goulet JP, Clark GT. Clinical TMJ examination methods. J Calif Dent Assoc 1990;18:25–33.

21. Dworkin SF, LeResche L, DeRouen T, Von Korff M. Assessing clinical signs of temporomandibular disorders: Reliability of clinical examiners. J Prosthet Dent 1990;63:574–579.

22. Sessle BJ, Hu JW, Amano N, Zhong G. Convergence of cu- taneous, tooth pulp, visceral, neck and muscle afferents onto nociceptive and non-nociceptive neurones in trigeminal sub- nucleus caudalis (medullary dorsal horn) and its implications for referred pain. Pain 1986;27:219–235.

23. Perl ER. Pain mechanisms: A commentary on concepts and issues. Prog Neurobiol 2011;94:20–38.

24. Craig AD. Pain mechanisms: Labeled lines versus convergence in central processing. Annu Rev Neurosci 2003;26:1–30.