True molar intrusion attained during orthodontic treatment: A systematic review

Introduction: The aim of this systematic review was to quantify the amount of true molar intrusion attainable during orthodontic treatment. Methods: A literature search was conducted to identify clinical trials that assessed true molar intrusion through superimposition of lateral cephalogram tracings. Craniofacial growth had to be factored out when appropriate. Electronic databases (Pubmed, Medline, Medline In-Process & Other Non-Indexed Citations, all EBM reviews, Embase, Web of Science, and Lilacs) were searched with the help of a senior health-sciences librarian. Abstracts that appeared to fulfill the initial selection criteria were selected, and the full-text original articles were then retrieved and analyzed. Only articles that fulfilled the final selection criteria were finally considered. Their references were also hand-searched for possible missing articles from the database searches. Results: Thirty abstracts met the initial inclusion criteria, and these articles were retrieved. From these, 29 were later rejected because they did not either quantify true molar intrusion or factor out normal craniofacial growth when required. Only 1 article remained, and it showed a mean maxillary molar intrusion of 0.96 mm (SD, 0.54) in 12 subjects. Conclusions: True molar intrusion appears to be achievable in the maxillary arch, although the amount of evidence is minimal. The clinical significance of the magnitude of the true intrusion reported is questionable as the sole treatment option to correct open-bite malocclusions. Better quantification method of the true intrusion attained has to be utilized.