Association of midline discrepancy with tempromandibular joint disorder. A systematic review

AIM: The aim is to evaluate the association between midline discrepancies and tempromandibular disorders (TMDs). METHODS: Literature search was performed by using various search engines to include human studies in English. TMDs include a wide variety of signs and symptoms such as pain in and around TMJ, jaw muscles, clicking and locking of jaws, pain during mandibular movement and restricted mandibular movements. The etiology is multifactorial, including one or several of the following factors like severe malocclusions (increased overjet, retroclination of incisors, cross bite, CR CO discrepancies etc), stress and psychological factors, structural abnormalities as possible etiology. There are controversies concerning the association between different traits of malocclusion and TMDs. The aim of the present study was to find out any association between signs and symptoms of TMDs with midline discrepancies, which represent an important trait of malocclusion. RESULT: Of the seven studies evaluated in this systematic review for investigating the association between midline discrepancy and TMD, six had moderate grade (B) of evidence. Four studies of moderate grade evidence (B) showed a significant association between the presence of midline shift and TMDs, and the remaining studies (two) had non-significant association. Only one study had a strong grade of evidence (A) and interestingly it denies the presence of midline shift to be a causative factor for TMDs. So, it can be concluded that the results are inconclusive regarding the association of midline discrepancies with TMDs. Nonetheless, this requires concrete evidence which necessitates further long term research into this aspect.