Association between Orthopedic and Dental Findings: What Level of Evidence is Available?

OBJECTIVE: The aim of this systematic review was to provide comprehensive access to and an analysis of the specialist literature published through December 2005 describing a correlation between orthopedic (leg-length inequality, pelvis obliquity, column diseases and head posture) and dental findings (occlusion, mandibular position, temporomandibular joints, masticatory muscles). METHOD: Four medical and dental internet sources (PubMed; Medpilot.de; databases of the Deutsche Arzte-Verlag and Quintessenz-Verlag) were screened for relevant articles using carefully selected retrieval strategies and keywords. Bibliographies of relevant articles were examined for further pertinent publications. All relevant articles were tabulated according to their year of publication, the subject area discussed, and the levels of scientific evidence. RESULTS: Our electronic inquiry yielded 359 relevant articles (electronic search: 195, search in bibliographies: 164), 355 of which could be analyzed. A correlation between dental findings and spinal column diseases was described in 266 articles, head posture in 216, pelvis obliquity in 53, and leg-length inequality in 35 papers. In 131 publications, conclusions were drawn from dental to orthopedic findings, whereas they were drawn from orthopedic to dental findings in 171 articles. The number of relevant articles rose significantly, particularly since the 1980's. Classification in levels of evidence reveals three publications (0.8%) with level II (randomized controlled trials), 63 (17.7%) with level III (experimental studies with no randomization, cohort studies, or case-control studies), 178 (50.1%) with level IV (non-experimental studies, such as cross-sectional trials, case series, case reports), and 111 (31.3%) with level V (narrative review or expert opinion without explicit critical appraisal). CONCLUSIONS: 1) While there is great interest in possible correlations between orthopedic and dental findings in the specialist literature, most publications fail to provide the hard facts and solid evidence characteristic of high-quality research. 2) This literature analysis attests to the importance of searching electronic databases while making the inherent weaknesses of such searches obvious. Manual literature searches remain essential.