Assessment of Occlusal Sensitivity to Articulating Foils in Patients With Temporomandibular Disorders Compared to Healthy Controls: A Case-Control Study
Conditions: Temporomandibular Disorder (TMD), Chronic Pain
Sponsor: University of Zagreb

01 September 2025 
Study Protocol 
 
Title: Occlusal Sensitivity to Articulating Foils in Patients with Temporomandibular Disorders and 
Healthy Controls 
 
Background  
 
Occlusal sensitivity is defined as the ability to detect fine objects between antagonistic teeth 
during biting, i.e., in the position of maximum intercuspation. Two main methods are typically 
used to investigate occlusal perception and the threshold of periodontal sensation. The first 
measures the minimal detectable force applied to the teeth using monofilaments (Ryuhei K. et 
al., Osaka Dent Univ. 2020). The second evaluates the threshold of interocclusal thickness 
sensitivity, i.e., the ability to detect thin articulating foils between teeth (Suganuma T. et al., J 
Prosthet Dent. 2007). 
In healthy individuals, the threshold of occlusal perception on natural teeth varies between 2 µm 
and 77 µm (average 24 µm), with a tendency to increase with age. Periodontal 
mechanoreceptors play a primary role in occlusal sensitivity, which has been demonstrated by 
significant impairment after local anaesthesia (Jacobs R. et al., J Periodontal Res. 1994). 
However, patients with implants or prostheses retain some degree of occlusal perception 
(Enkling N. et al., Clin Implant Dent Relat Res. 2012), suggesting the involvement of additional 
mechanoreceptors beyond those in the periodontal ligament. 
Evidence also indicates that patients with pain-related temporomandibular disorders (TMD) 
demonstrate impaired occlusal perception (La Touche R. et al., J Oral Rehabil. 2019) and 
reduced adaptability to experimental occlusal interferences compared to healthy controls 
(Michelotti A. et al., J Orofac Pain. 2012; Le Bell Y. et al., Acta Odontol Scand. 2006). This 
supports the hypothesis that occlusal perception may be altered in patients with TMD. 
 
Objectives 
 
To evaluate differences in occlusal sensitivity between patients with pain-related TMD and 
healthy controls. 
 
To assess the relationship between occlusal perception, psychosomatic characteristics, and 
clinical manifestations of TMD. 
 
Study Design 
 

01 September 2025 
This is a case-control study designed to compare occlusal sensitivity in patients with 
temporomandibular disorders and healthy control subjects. 
 
Participants 
 
Case Group 
Patients will be recruited from the Department of Removable Prosthodontics and the 
Department of Oral Medicine, School of Dental Medicine, University of Zagreb. Eligible 
participants will present with dysfunction of the jaw region and/or pain in the masticatory system. 
Diagnosis of pain-related TMD will be based on the Diagnostic Criteria for Temporomandibular 
Disorders (DC/TMD) (Schiffman E. et al., Oral Facial Pain Headache. 2014), assessed by a 
TMD specialist (Alajbeg IZ). Eligible diagnoses include myalgia, referred myofascial pain, and/or 
arthralgia. 
 
Control Group 
The control group will consist of healthy volunteers matched by age and sex to the case group, 
without evidence of neurological lesions that may affect sensory perception. 
 
Inclusion Criteria: 
 
- 
Reported pain in the temporomandibular joint (TMJ) and/or masticatory muscles 
persisting for more than 3 months. 
 
- 
Spontaneous pain >30 mm on the Visual Analogue Scale (VAS) at the time of the first 
examination. 
 
Exclusion Criteria: 
 
- 
Posterior tooth loss resulting in loss of occlusal support zones. 
 
- 
Posterior removable dentures. 
 
- 
Poor oral hygiene or periodontal disease. 
 

01 September 2025 
- 
Orofacial pathology unrelated to TMD diagnosis. 
 
- 
Acute pain (<3 months duration). 
 
- 
History of head and neck trauma. 
 
- 
Headache not related to TMD (per ICHD-II criteria). 
 
- 
Pain caused by fibromyalgia. 
 
- 
Systemic diseases or diagnosed psychiatric disorders. 
 
- 
History of pain medication abuse or current substance abuse. 
 
Methods 
 
The study will be conducted following approval from the Ethics Committee of the School of 
Dental Medicine, University of Zagreb. All procedures will comply with the ethical principles of 
the Declaration of Helsinki and STREGA guidelines. Participants will receive detailed oral and 
written information about the study and may withdraw at any time without consequence. Written 
informed consent will be obtained prior to participation. For underage participants, consent will 
be provided by a parent or legal guardian. 
Occlusal perception will be tested by assessing the participant’s ability to detect articulating foils 
of varying thicknesses placed between the upper and lower first molars. Each participant will 
undergo multiple trials, including a false test. The sequence of foil application will be 
randomised by computer software. After each trial, participants will report whether they perceive 
the presence of a foil. Responses will be recorded for statistical analysis. 
 
Expected Outcomes 
 
Primary outcome: Threshold of occlusal sensitivity in TMD patients vs healthy controls. 
 
Secondary outcomes: Association between occlusal perception, psychosomatic characteristics, 
and clinical signs of TMD.