The January 2009 American Journal of Orthodontics features a study relating to the efficiency of Invisalign therapy by Kravitz and his colleagues at the University of Illinois Dental School . The study compares actual achieved results on 37 Invisalign patients with expected results as extrapolated from the final aligner. The mean accuracy was 41% overall. The best accuracy for rotational corrections was 54% dropping to about 30% for cuspids with greater than 15 degrees rotation. Related parameters of tooth movement such as extrusion, intrusion and tipping are similarly unimpressive. This technique has been used on some 300,000 patients over the last ten years. Align Technology itself reports that 20-30% of patients require “midcourse correction” to achieve pretreatment goals while in two other studies orthodontists report 70-80% of patients require such “midcourse correction”, case refinement or conversion to fixed appliances in order to satisfactorily complete cases.
In the May 2010 issue of The American Journal of Orthodontics appears a study by Smithpeter and Covell which analyzes the relationship between orthodontic patients who tongue thrust and open bite of the front teeth. In this context , “ open bite “ means the front teeth are apart when the back teeth bite. Vertical overlap of the front teeth is termed “ overbite “ whereas “ open bite “ ( also termed “ reverse overbite “ ) can be related to a growth discrepancy of the jaws and/ or tongue thrusting. When swallowing or at rest, the tongue should NOT be positioned between the front teeth.
In a September 12, 2010 New York Times editorial entitled “ Is Newer Better? Not Always”, the comparative effectiveness aspects of the Obamacare legislation are examined. While there is much to debate about this bill, there can be little doubt that together, evidence based healthcare and comparative effectiveness studies are complimentary strategies which if implemented should benefit patients by making it easier to identify high quality and cost effective treatments that work as compared to other choices that may be available.
Evidence based healthcare (EBH) in Orthodontics means that for a given procedure, material or technique, valid studies confirm its effectiveness…in other words, it should work if used in the intended way. Comparative effectiveness studies (CES) determine how a given procedure, material or technique performs relative to others with respect to several factors like: time effectiveness, quality of the result, cost effectiveness and undesirable side effects. There is a consensus that not all of our treatment choices meet both criteria but in a perfect world, they would. That is, the treatments we select should be shown to work reliably and they are better in most respects than the alternatives with fewer side effects.
One unfortunate potential complication of orthodontic treatment is shortening of the roots which results in less future support of the affected tooth (teeth). The process is not pain inducing, cannot be predicted or prevented and despite decades of investigation it remains unclear just why it occurs in some patients but not in others.