Editor's Choice

Abstract

Every day in the life of an orthodontist, it is possible to marvel at the change in facial proportions as a child matures into adulthood. When remembering the history of esthetics as based on Greek art and architecture, have you ever wondered how the normal changes of growth relate to the law of “divine proportions” or the “golden ratio”? In this longitudinal study of untreated subjects, records were gathered between 1951 and 1976 with photos taken at 6.5, 17, and 30 years of age. Although this study was inspired by the early work of Ricketts, he focused primarily on beautiful faces, but these authors evaluated “normal” or average faces. This study shows that facial proportions change only to a limited degree over time. The authors concluded that “facial proportions seem to be predetermined already in childhood, with only slight variations during growth.” In addition, divine facial proportions were only rarely achieved in ordinary people. There is, however, great variation between people. Medical emergencies are just that–they can occur at any time with little warning. So when you place brackets and wires in a patient's mouth, are you contributing to the problem of obtaining a magnetic resonance (MR) image if the need arises unexpectedly? The aims of this study were to determine (1) whether braces need to be removed before medical MR imaging, and (2) whether the orthodontist should routinely use materials that do not cause MR image distortion. For example, ceramic, titanium, and plastic brackets cause little or no distortion of MR images. This in-vivo study shows clearly that some stainless steel brackets can cause cranial MR images to be unusable for diagnostic purposes. Different stainless steel alloys respond differently to magnetic fields. Those made of 17-4 stainless steel (17% chrome, 4% nickel) are attracted to a magnet, whereas objects of 18-8 stainless steel are not affected by magnetic fields. The authors concluded that future studies might show that it is advisable to completely avoid fixed appliances that contain 17-4 stainless steel. Neuroradiologists currently ask the orthodontist to remove stainless steel orthodontic appliances before cranial MR scans because they often cause distortion of the images. This lengthy article is a must read for all clinicians. The objectives of this investigation were to compare the importance of risk factors for temporomandibular joint disorder (TMD) in the population and to investigate the feasibility of prevention. Epidemiologic measurements were used to evaluate the possible etiologic importance of 2 risk factors: third molar extraction and severe mandibular retrognathia. Incidence data for temporomandibular joint and muscle disorders (TMJMD) associated with third molar extraction were available for more than 34,000 adolescents insured by the same company. The second study was part of a large case-control study that examined mandibular retrognathia as a risk factor for TMD in women. Subjects and controls were recruited from among 190,000 eligible enrollees. The authors concluded that, in general, risk factors explain only a small portion of the TMJMD in the population, but they do explain much of it in exposed persons. This review supports the current consensus that prevention, by screening for risk factors and intervening in the population, is probably not justified. However, modification of certain risk factors among exposed persons to prevent TMJMD might be warranted. To more fully understand the rationale behind this detailed epidemiologic study, I encourage you to read the entire article.