Editing Temporomandibular joint dysfunction (section)

===Bruxism===
{{Main|Bruxism}}

Bruxism is an oral [[parafunctional habit|parafunctional activity]] where there is excessive clenching and grinding of the teeth. It can occur during sleep or whilst awake. The cause of bruxism itself is not completely understood, but psychosocial factors appear to be implicated in awake bruxism and [[dopamine]]rgic dysfunction and other [[central nervous system]] mechanisms may be involved in sleep bruxism. If TMD pain and limitation of mandibular movement are greatest upon waking, and then slowly resolve throughout the day, this may indicate sleep bruxism. Conversely, awake bruxism tends to cause symptoms that slowly get worse throughout the day, and there may be no pain at all upon waking.

The relationship of bruxism with TMD is debated. The global prevalence of bruxism and TMD co-occurrence is 17%, with regional variations: 70% in North America; 24% in South America; 14% in Europe; and 9% in Asia.<ref>{{Cite journal |last=Zieliński |first=Grzegorz |last2=Pająk-Zielińska |first2=Beata |last3=Pająk |first3=Agnieszka |last4=Wójcicki |first4=Marcin |last5=Litko-Rola |first5=Monika |last6=Ginszt |first6=Michał |date=2025-03-18 |title=Global co-occurrence of bruxism and temporomandibular disorders: A meta-regression analysis |url=https://dmp.umw.edu.pl/en/ahead-of-print/201376/ |journal=Dental and Medical Problems |issue=2 |pages=0–0 |doi=10.17219/dmp/201376 |issn=1644-387X|doi-access=free }}</ref> Many suggest that sleep bruxism can be a causative or contributory factor to pain symptoms in TMD.<ref name="Scully 2008">{{cite book |last=Scully |first=Crispian| name-list-style = vanc |title=Oral and maxillofacial medicine : the basis of diagnosis and treatment |year=2008 |publisher=Churchill Livingstone |location=Edinburgh |isbn=9780443068188 |edition=2nd |pages=8,14,30,31,33,101,104,106,291–295,338,339,351}}{{page needed|date=May 2013}}</ref><ref name="Glick 2003">{{cite book |vauthors=Greenberg MS, Glick M |title=Burket's oral medicine diagnosis & treatment |year=2003 |publisher=BC Decker |location=Hamilton, Ont |isbn=978-1-55009-186-1 |edition=10th}}{{page needed|date=May 2013}}</ref><ref name="Tyldesley 2003">{{cite book|vauthors=Tyldesley WR, Field A, Longman L |title=Tyldesley's Oral medicine|year=2003|publisher=Oxford University Press|location=Oxford|isbn=978-0192631473|edition=5th}}{{page needed|date=May 2013}}</ref><ref name="Shetty 2010">{{cite journal | vauthors = Shetty S, Pitti V, Satish Babu CL, Surendra Kumar GP, Deepthi BC | title = Bruxism: a literature review | journal = Journal of Indian Prosthodontic Society | volume = 10 | issue = 3 | pages = 141–8 | date = September 2010 | pmid = 21886404 | pmc = 3081266 | doi = 10.1007/s13191-011-0041-5 }}</ref> Indeed, the symptoms of TMD overlap with those of bruxism.<ref name="De Meyer 1997">{{cite journal | vauthors = De Meyer MD, De Boever JA | title = [The role of bruxism in the appearance of temporomandibular joint disorders] | journal = Revue Belge de Médecine Dentaire | volume = 52 | issue = 4 | pages = 124–38 | year = 1997 | pmid = 9709800 }}</ref> Others suggest that there is no strong association between TMD and bruxism.<ref name="Cawson 2002">{{cite book |vauthors=Cawson RA, Odell EW, Porter S |title=Cawsonś essentials of oral pathology and oral medicine |year=2002 |publisher=Churchill Livingstone |location=Edinburgh |isbn=978-0-443-07106-5 |edition=7th}}{{page needed|date=May 2013}}</ref> A systematic review investigating the possible relationship concluded that when self-reported bruxism is used to diagnose bruxism, there is a positive association with TMD pain, and when more strict diagnostic criteria for bruxism are used, the association with TMD symptoms is much lower.<ref name="Manfredini 2010">{{cite journal | vauthors = Manfredini D, Lobbezoo F | title = Relationship between bruxism and temporomandibular disorders: a systematic review of literature from 1998 to 2008 | journal = Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics | volume = 109 | issue = 6 | pages = e26-50 | date = June 2010 | pmid = 20451831 | doi = 10.1016/j.tripleo.2010.02.013 }}</ref> Self-reported bruxism is probably a poor method of identifying bruxism.<ref name="Shetty 2010" /> There are also very many people who grind their teeth and who do not develop TMD.<ref name="Wassell 2008" /> Bruxism and other parafunctional activities may play a role in perpetuating symptoms in some cases.<ref name="Buescher 2007">{{cite journal | vauthors = Buescher JJ | title = Temporomandibular joint disorders | journal = American Family Physician | volume = 76 | issue = 10 | pages = 1477–82 | date = November 2007 | pmid = 18052012 | url = http://www.aafp.org/afp/2007/1115/p1477.html }}</ref>

Other parafunctional habits such as pen chewing,<!-- <ref name="Scully 2008" /> --> lip and cheek biting<!-- <ref name="Glick 2003" /> --> (which may manifest as [[morsicatio buccarum]] or [[linea alba (cheek)|linea alba]]), are also suggested to contribute to the development of TMD.<ref name="Scully 2008" /> Other parafunctional activities might include jaw thrusting, excessive gum chewing, [[nail biting]] and eating very hard foods.