I agree with Dr. Ackerman that "the challenge facing orthodontists [and other orthodontic practitioners] in the 21st century is the need to integrate the accrued scientific evidence into clinical orthodontic practice."
However, drawing broad conclusions from very narrowly focused research can be precarious. One cannot conclude that all birds can’t fly by studying the flight characteristics of the ostrich and penguin, yet that is the equivalent of what was done in this article. Recycling poorly drawn conclusions or, worse, drawing conclusions from inappropriate literature does not promote evidence-based practice, is not a service to the dental community and only serves to create the illusion of fact out of doubtful conclusions by repeating them often.
For example, Dr. Ackerman’s citing of the Tulloch and colleagues1 article’s conclusion that, for children with moderate-to-severe Class II problems, early treatment followed by later comprehensive treatment on average does not produce major differences in jaw relationship or dental occlusion compared with later one-stage treatment, is just such a case.
At best, what can be concluded from that article is that, at the end of stage one, using either headgear alone or a "functional appliance" alone (which was never specifically identified), starting at an average age of 9.9 years, A point changed –0.92 millimeters on average in the headgear group, and B point changed 1.07 mm in the functional group relative to a control group of 0.26 and 0.43, respectively. Then, without retention between phases, giving the treating doctors full treatment discretion during phase II, PAR scores were the same for the two groups at the end of phase II.
That being said, I will list the problems with applying this study broadly to all early orthodontic treatment:
It is no surprise that the Peer Assessment Rating scores were the same since we all know we can straighten teeth no matter when treatment is started. PAR scores do not take into account the final profile, or the skeletal outcome versus the ideal.
For example, according to Dr. James McNamara, "retrusion of the mandible is the most commonly occurring factor contributing to class II malocclusion."2 Yet, PAR scores would treat any reduction in the A Point to Nasion to B Point angle as equal, because they just look at the teeth and their interrelation. If the mandible is the problem, then the mandible is what should be treated. PAR scores would judge concave final profiles equal to full profiles if the occlusions were equal.
If the functional appliance group had a more esthetic final outcome than the headgear group or the control group, it would not show up in the analysis or conclusion. If the functional appliance group corrected the causative skeletal problem and the headgear group just masked the problem by retarding growth in the maxilla to match the retruded mandible, that distinction would not have been reported as well. This critique alone is enough to invalidate any attempt to extrapolate this conclusion to all early treatment.
Dr. Ackerman makes a point of stressing the importance of the psychosocial aspects of orthodontic treatment as an aspect of treatment efficiency. The psychosocial importance of improving a child’s appearance at an early age should not be undervalued. The psychosocial aspects of finishing a child’s orthodontic care before the turbulent teenage years should not be undervalued as well.
The goals of early treatment orthodontics, as taught by Dr. Waldemar Brehm and Dr. Leonard Carapezza, are to bring a child to an orthodontic and orthopedic state of normalcy as early as possible by establishing normal overbite, overjet, molar relationship, jaw relationship and lip seal.3–5 This creates a normal framework, or scaffold, to maximize corrective growth, allowing soft tissue and bony development around a normal orthodontic and orthopedic position. Comparing this comprehensive approach to the rudimentary early treatment in the Tulloch study is an invalid comparison.
Dr. Ackerman’s use of Dr. Gianelly’s conclusion as the definitive conclusion on expansion that the rationale for expanding upper molars in the absence of a crossbite is "challenging to define"6 is quite confusing. Crossbite is just one expression of a constricted maxillary arch. Dr. Gianelly’s critique of Class II correction using mandibular repositioning and growth modification based on unlocking the retruded mandible through maxillary expansion, bite opening and incisor decoupling is based on incorrect assumptions and inappropriately applied research results.
Dr. Gianelly’s assumption that, if the mandible is locked back then, "one implication of this view is that the mandible, in centric occlusion, is in a distal position relative to centric relation" and "the condyles are in a distal position"6 is not necessarily true, and thus the use of this assumption in any critique is unacceptable. Compensatory growth inhibition in Class II patients could be taking place in all parts of the growing mandible and glenoid fossa to keep the condyle in the functionally correct range.
And, indeed, a study published by Cevidanes and colleagues7 supports that view showing "ramus remodelings ... that are missed with conventional cephalometrics."7 Dr. Gianelly’s use of articles by Demisch and colleagues,8 Erickson and Hunter9 and Cohlmia and colleagues10 to support his argument all fall to the same critique.
Constricted maxillas are commonly found in Class II malocclusions, where the constriction is expressed as a posterior posturing and/or growth inhibition of the mandible to maintain intercuspation and, in division 2 cases, a locking back effect on the mandible by the compensatory low inclination of the central incisors. A Class II average transverse discrepancy between the maxillary molars and the mandibular molars is 3 to 5 millimeters.11 Dr. Gianelly comments that "it is not necessary to use RPE, in the absence of a crossbite, to expand the maxillary arch in Class II treatment. It occurs normally during treatment."6 This assumes everyone is using distalization to treat Class II problems. It also assumes that the outcomes of distalization versus mandibular advancement to correct Class II problems are equal. As I argued above, they may not be.
Another problem in Dr. Gianelly’s article is the concept of addressing maxillary crowding by trying to treatment plan maxillary expansion or maxillary E-space preservation to create increased arch length in the maxilla. The lower arch is the template arch form because it is less malleable than the maxilla. The maxilla is expanded to fit the proposed posttreatment mandibular arch form. Any arch length increase in the maxilla is secondary to the goal of coordinated arches.
A much more detailed explanation of expansion, E-space and an integrated arch form approach to resolving space problems in all three dimensions is included in my article.12
Evidence-based dental treatment is a common goal. But, not all evidence is equal, and not all conclusions, published or not, are equally valid. The judicious use of study results to deduce narrow conclusions with acute attention to the materials and methods of that study is an imperative. The use of previous research to draw broad conclusions must be used cautiously in an impartial and discerning manner.
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