Let them eat cake: the struggle between form and substance in orthodontic clinical investigation

Events of the past decade or so argue that there is little support in the literature for much of the specialty's treatment portfolio. The resulting call for 'evidence-based' treatment (not to mention the obvious intellectual bankruptcy of much of the clinical literature) has prompted many to argue that the randomized clinical trial (RCT) represents the future of orthodontic clinical investigation. The RCT, after all, is medicine's gold standard; what more is there to say? A popular, but ultimately divisive, corollary of this mimicry is the smug tendency to discount all other sources of data. In the face of a need for information, this attitude is also a wasteful conceit: in the end, the RCT can be applied only to a very narrow spectrum of orthodontic questions. Randomization implies equal susceptibility. Any prospective participant would have to be informed of this equality as part of the informed consent process. Unfortunately, it would be nearly impossible to enroll fully-informed subjects into any study whose alternatives are of markedly different morbidity: extraction versus non-extraction or orthodontics versus surgery. Thus, when measured against the most vexing clinical questions, the orthodontic RCT is almost by definition an amusing diversion--expensive, but relatively trivial in scope. Like it or not, it seems reasonable to conclude that most of the specialty's comparative clinical data will have to be generated by way of non-randomized designs in which care is taken to minimize the various known sources of bias. There probably is no other way.