Title Long-Duration Gum Chewing Is a Risk Factor in the Development and Exacerbation of TMD
Clinical Question In otherwise healthy patients, does having a habit of chewing gum increase the likelihood of experiencing temporomandibular disorder-like symptoms (i.e. crepitus, clicking, and pain) compared to those without a chewing gum habit?
Clinical Bottom Line Patients with increased duration of gum chewing are more likely to exacerbate existing TMD symptoms and develop new onset of symptoms than those without a chewing gum habit. This was supported by a cross-sectional study of patients who reported chewing gum for 30, 60, or 120 minutes in a 24-hour day for the past 2 years. The gum-chewing group showed statistically significantly more TMD symptoms compared to a group of non-gum-chewing controls. Gum chewing is a readily altered and identifiable behavior that dentists can advise their patients to change to improve their TMD symptoms.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
25203577Tabrizi/2014200 patients with variable TMD symptomsCross-Sectional Study
Key results200 patients were divided into two groups based on gum-chewing habits, with no statistically significant difference between the groups on gender, age, and occlusion. There was a higher incidence of clicking and pain with the gum-chewing (experimental) group than the non-gum chewing (control) group (P < 0.05). However, despite the fact that gum-chewing increased the entire experimental group’s symptoms, the pain and clicking levels amongst participants were highly variable (P < 0.05).
25369399Correia/201453 patients with variable parafunctional oral habitsRandomized Controlled Trial
Key results53 subjects were divided into seven groups based on parafunctional habits, then again into five groups for experimental gum chewing. Each subgroup chewed gum for various times. Group A (n=12) chewed for <1hr/day, Group B (n=11) for 1-2 hours/day, Group C (n=6) for 3 hours/day, Group D (n=8) for >3 hours/day, Group E (n=2) for 1-3 times/week for at least 1 hour each time. 63% of Group D showed arthralgia and myofascial pain in the TMJ. 33% of Group C showed arthralgia. Myofascial pain was reported in 83% of Group A and 27% of Group B. 100% of subjects reported masseter hypertrophy. Groups F and G were controls and contained participants that didn’t chew gum and who had either other parafunctional oral habits (n=2) or no parafunctional oral habits (n=12) respectively.
Evidence Search ("chewing gum"[MeSH Terms] OR ("chewing"[All Fields] AND "gum"[All Fields]) OR "chewing gum"[All Fields] OR ("gum"[All Fields] AND "chewing"[All Fields]) OR "gum chewing"[All Fields]) AND tmd[All Fields]
Comments on
The Evidence
Although both studies have an adequate sample size, other areas pertaining to their validity are questionable and unclear. The first article presents with an adequate sample size (n=200) with outcomes assessed by observing the clinical signs of TMD patients who over the past 2 years chewed gum for 0 (control group), 30, 60, and 120 minutes per 24 hour day. The only area of question within this article is the level to which the researchers were “blinded.” The second study also has a representative sample size (n=53) but seems to have many confounding factors and no statement of researcher blindness. They assessed their patients by having them continue their gum chewing habits, grouping them, and evaluating them during a 6 month period. Overall this second study lacked a high validity factor due to a poorly described (if any) randomization process and no mention of when the patients were evaluated within the process. However, some inferences can be made from the results of these studies with the majority of those inferences coming from the first study. Neither study stated any competing interests of importance.
Applicability The patients in these studies were highly variable in both their demographics and TMD symptoms, so the inferences drawn from these articles are applicable to nearly any patient situation involving a gum chewing habit. As a dentist, recommending that patients with long-duration gum chewing habits decrease the time spent chewing gum or stop it completely would be beneficial to all patients as this would provide much less discomfort than continually chewing in presence of TMD symptoms.
Specialty (General Dentistry)
Keywords chewing gum, temporomandibular disorder
ID# 3006
Date of submission 04/04/2016
E-mail silcox@livemail.uthscsa.edu
Author Jace Silcox
Co-author(s) e-mail
Faculty mentor Edward F. Wright, DDS, MS
Faculty mentor e-mail WrightE2@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available