Y. Jo Wong DDS, MS, BSc
Whether an association exists between posterior cross-bite and temporomandibular joint (TMJ) muscular pain, clicking, and headache is unclear. However, one seems to exist between unilateral functional cross-bite accompanied by mandibular midline deviation and certain temporomandibular disorders.
Is there an association between posterior cross-bite and temporomandibular disorders (TMDs)?
The authors searched one electronic database (Medline) for articles published in English between January 1970 and August 2009. The inclusion criteria were human studies on malocclusion or posterior cross-bite with TMDs. They included randomized control trials, retrospective studies with controlled or reference groups, controlled clinical trials, and prospective studies. Out of the 210 articles found, 14 clinical studies fulfilled the inclusion criteria. Manual searching of six orthodontic/dentofacial-orthopedic journals for the same period did not yield additional information.
Of the 14 clinical studies involving 12,826 subjects, eight studies (ranging from 27-4724 subjects) reported an association between TMDs and posterior cross- bite, while six studies (ranging from 337-3428 subjects) reported no association. Both groups included males and females, who were primarily 10-16 years-old. Temporomandibular joint- and muscle-tenderness on palpation had significant association with posterior cross-bite -in four studies, but not in four other studies. Temporomandibular joint sounds and clicking had a significant correlation with posterior cross-bite in four studies -but this correlation was not significant in two other studies. Three studies reported a significant association between headache and posterior cross-bite.
There may be an association between a unilateral functional cross-bite with mandibular midline deviation and some signs and symptoms of TMDs (-muscular pain, TMJ pain, clicking, joint sounds and headache).
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Importance and Context:
Posterior cross-bite occurs in 4-23 percent of young children and adolescents in different countries, with higher prevalence in the primary dentition due to sucking habits. Previous reviews have yielded conflicting conclusions regarding an association between posterior cross-bite and TMDs, offering no help to clinicians in deciding whether or not to treat children with posterior cross-bite to prevent future TMDs. The present review sought to address this issue.
Strengths and Weaknesses of the Systematic Review:
The authors did not conduct a comprehensive review; they only searched one database and six related journals from the same time period, published in English. They did not search for unpublished grey literature. It was not clear how many reviewers were involved or which reviewer performed the literature search. All 14 of the included studies were observational, case-controlled trials. The authors did not assess study quality or outline individual study designs. Likewise, it was unclear whether data selection was performed in duplicate or independently, and how disagreements were resolved. Although the number of study participants ranged from 4724 subjects to 27 subjects, the authors did not comment if more weight was allocated to studies with a higher number of subjects. The authors did not present any quantitative results; notably, there was no quantitative association of posterior cross-bites and TMDs compared to a control population and TMDs.
Strengths and Weaknesses of the Evidence:
The evidence consisted mainly of weaknesses. Studies relied on patient-reported outcomes, which are not very reliable sources, especially in young children. There was much clinical heterogeneity across studies, including study populations of different age groups (children, adolescents, adults), poorly defined TMD signs and symptoms, and poorly defined types of posterior cross-bites. Studies did not include long-term follow up.
Implications for Dental Practice:
There is inconclusive evidence associating posterior cross-bite and TMDs. Therefore it is unclear if prophylactic orthodontic treatment to correct posterior cross-bite will prevent future development of TMDs.