Class II Skeletal Growth Modification Treatment: Has Hope Triumphed Over Evidence?

The Reference Manual presents the following information on the management of Class II skeletal malocclusions [1]: Growth-modifying effects in some studies did not show an influence on the Class II skeletal pattern ,${}^{177-179}$ while other studies dispute these findings.${}^{180,181}$ There is substantial varia-tion in treatment response to growth modification treatments (headgear or functional appliance) and no reliable predictors for favorable growth response have been found.${}^{168,174}$

The fundamental question here is not can we correct Class II skeletal malocclusions orthodontically but can we correct them via growth modification? A neophyte reader will interpret the first sentence as indicating that the literature on this question is equivocal. However, if a critical reader examines the evidence cited in references 177-179 and 180,181, it is clear that the Class II skeletal pattern cannot be modified by orthodontic or orthopedic appliances. How can I say this? The 3 studies that found no growth modifying effects were 1 systematic review and 2 randomized controlled trials [2, 3, 4]. The 2 studies that “dispute” these studies were both retrospective case control studies [5, 6]. Retrospective case controlled studies are low on the evidence pyramid and suffer from problems of bias related to the validation of information obtained and the selection of an appropriate control group.

As an orthodontist who has taught management of the developing dentition and occlusion to pediatric dental residents for over two decades, each year I experience the same moral distress when it comes to discussing Class II skeletal growth modification treatment with my students. In theory, we should all agree that teaching any subject in 2022 requires utilization of the best available evidence from the peer-reviewed literature [7]. In practice, however, not all of the stakeholders involved in the administration and oversight of pediatric dental and orthodontic residency programs seem to agree on what constitutes the best evidence and unfortunately some spurious information finds it’s way into the curriculum. My late friend Bill Proffit used to say, “You’re entitled to your own opinion but not your own facts”. At the end of the residency program, our student’s ability to synthesize a cogent, evidence-based opinion on any topic is frequently confounded by their exposure to diverse sources of information such as politically driven policy statements, clinical practice guidelines, reference manuals, clinical experience with individual faculty and board examinations just to name a few. What is incumbent on us, their teachers, is to educate them that all evidence in the peer-reviewed literature is not equal, that some sources of information are not a substitute for the rigors of scientific investigation and not all purported scientific investigation is actually science at all.

The topic of Class II skeletal growth modification remains fraught with tension. While pediatric dentistry and orthodontics have shared the aspirational goal of modifying skeletal growth, the accrued evidence has proved this strong theory very weak in practice. A more practical goal for our specialties should be to graduate a generation of evidencebased critical thinkers who are primarily driven by achieving reliable, repeatable clinical outcomes for their patients.

Acknowledgement

The opinions expressed in this paper are solely Dr. Ackerman’s and do not represent those of Boston Children’s Hospital and Harvard School of Dental Medicine.