Experimental pain and fatigue induced by excessive chewing

Abstract

Background: The study was aiming to optimize excessive gum chewing as an experimental model to induce jaw muscle pain and fatigue similar to those in painful TMDs with durations that would allow immediate investigations of jaw-motor function. Further, if any sex differences would be detected in the expression of pain. Methods: This randomized, double blinded study included 31 healthy participants of both sexes. A standardized chewing protocol of either 40-or 60-min of chewing was used with a wash-out period of 1 week. Subjective fatigue, pain characteristics and functional measures were assessed. For statistical analyses, Wilcoxon Signed Rank test, Mann-Whitney Rank Sum test and Friedman's ANOVA with Tukey post-hoc test were used. Results: High subjective fatigue scores that lasted up to 20 min after the end of the trial were significantly induced both in the 40-and 60-min chewing trials (P < 0.001*). Significant but mild pain was induced only in the 60-min trial (P = 0.004*) and only in men (P = 0.04*). Also, the induced pain area was significantly bigger in the 60-min trial (P = 0.009*). However, this increase in pain and pain area did not last to the first 10-min follow-up. There were no significant differences neither between the 40-and 60-min chewing trials, except regarding the pain area (P = 0.008*), nor between the sexes. Conclusion: Taken together, excessive chewing in its current form does not seem to be a proper pain experimental model. The model needs further adjustments in order to mimic TMD-pain especially in women and to prolong the pain duration.

Influence of masticatory side switch frequency on chewing mixing ability and sensory perception in adults with healthy dentitions: A randomized crossover trial

“…First, in accordance with the low values expressed by the participants regardless of the masticatory style, healthy dentate young adults are unlikely to perceive muscle fatigue after chewing soft gum 12 times for 40 cycles each with rest intervals of 3-5 minutes. Masticatory muscular fatigue should only appear after chewing gum for longer than 40 minutes [42]. Second, although the test-retest results indicated high reliability for perceived muscle fatigue using the visual analog scale, fatigue could be assessed with more sensitivity by applying objective methods, such as surface electromyography or isokinetic dynamometry [43].…”

“…In addition, high inter-individual and intra-individual variability exists in masticatory laterality, avor perception, and salivary ow because many factors alter these behaviors and sensations [23]. For example, a positive correlation between salivary ow and time to maximum avor intensity has been observed while chewing gum but not while eating a vanilla custard dessert [41,42]. By controlling for most of these factors with a randomized crossover design, the use of a stable and non-committable test food, and ensuring an equal number of chewing cycles, our results provide new insights into the relationship between MSS frequency, salivary ow, and avor intensity.…”

Uptight responses between clenching and forearm raising with factors of visual feedback and maintenance effort in healthy young women: An experimental study on factorial design

“…All subjects had 28–32 teeth that arranged well with the Class I molar relationship and optimal 2 to 5 mm overbite and overjet. The exclusion criteria included known signs, symptoms, or history of temporomandibular disorders, craniocervical disorders [ 17 ], previous craniofacial trauma, bruxism history, known periodontal problems, history of tooth restorations or orthodontic treatment or orthognathic surgery, gum-chewing habit (over 30 min a day) [ 18 ], or disease history of the upper limbs. All volunteers signed informed consent, and the FMMU Institutional Review Board Committee approved the procedures.…”