Effects of Temporomandibular Disorder on Masticatory Efficiency

Temporomandibular disorders (TMD) are defined by pain in the temporomandibular joint (TMJ) and related tissues, limitations in the movements of the lower jaw, and TMJ noises.1,2 TMD are classified into four groups as temporomandibular joint disorders, masticatory muscle disorders, headache attributed to TMD and associated structures.3,4 Of these, masticatory muscle disorders are the most common TMD subtype seen in dental clinics.5-7 In general, two major symptoms are seen associated with masticatory muscle disorders: Pain and dysfunction. Pain is the vast majority of complaints about masticatory muscle disorders. The other important complaint is dysfunction, which occurs as a limitation in the opening range of the mandible.8 It is known that individuals with experimental muscle pain are slower than healthy individuals when biting hard food and show lower maximum voluntary clenching capacity.9 Also, it has been reported that the maximum bite force decreased in patients with temporomandibular disorders.10 These consequences directly affect patients' quality of life. Therefore, rehabilitation of limited masticatory functions is one of the important therapeutic goals for TMD patients.11 In TMD patients, masticatory functions can be measured objectively with bite force, bite force endurance, electromyography, and jaw kinematics, etc. Another objective method that can be used to determine masticatory functions is the masticatory efficiency test. In the literature, there are few studies that measure masticatory efficiency in TMD patients.12-16 Only two of these studies investigated the effect of TMD treatment and used the sieve method to measure masticatory efficiency.15,16 Although the sieve method is considered the gold standard, the procedure is complex and time consuming.17,18 To eliminate these disadvantages, masticatory efficiency measurement with two-color chewing gum tests which are simple and do not require special equipment or training can be used. The effect of many different conditions and treatments on masticatory efficiency was evaluated with this method.19 However, to our knowledge, there is no study in the literature evaluating TMD treatment with this method.

The aim of this study was to compare the masticatory efficiency with a two-color chewing gum test before and after treatment of the masticatory muscle-related temporomandibular disorder.