Early treatment for class III malocclusion

Orthodontists have long-debated the relative merits of early treatment in the management of malocclusion, but the evidence base is almost exclusively weak. Should we undertake arch development in the mixed dentition to reduce the need for later extractions in the permanent dentition? Or start our functional appliance therapy at a similar stage to maximize skeletal change? What about the early elimination of a crossbite associated with a mandibular displacement? In recent years, there have been a number of attempts to appropriately synthesize current data, but this has been challenging. One recent finding has been the potential for early functional appliance treatment to reduce maxillary incisor trauma in adolescence, although the evidence is only really marginal at best (Thiruvenkatachari et al. 2013). The problem associated with many of these questions is of course, that there are often just too few studies available to analyse that are not at a high risk of bias. This is exemplified by another fairly recent systematic review investigating orthodontic treatment for posterior crossbites (Agostino et al. 2014). Out of literally hundreds of studies, only a small handful were regarded as being of sufficient quality to systematically evaluate, and all they can really tell us is that a quad-helix is marginally more effective than a removable appliance. In the current age of evidence-based medicine this all comes as a bit of a disappointment.

It is therefore reassuring to see that a UK-based team has been busily investigating another early intervention with a poor evidence base for over a decade now — the effectiveness of early protraction facemask treatment in the management of class III malocclusion (Mandall, et al. 2010). Here, they report their most recent findings and provide some of the highest-quality evidence to help answer a simple question: In a young child with a developing class III malocclusion associated with mid-facial retrusion, does early maxillary expansion and a protraction facemask reduce the need for orthognathic surgery in later life? (Mandall et al. 2016). This is an important question and the answer potentially impacts upon all practising orthodontists. So what did they find?

This was a multicentre randomized controlled trial involving eight UK hospital orthodontic departments spread around the country. Children aged between 7 and 9 years and diagnosed with mid-facial retrusion combined with the majority of permanent incisors in crossbite were randomized to early treatment involving bonded maxillary expansion and facemask therapy (combined with class III traction) or no treatment. The early effects of this randomization have been previously reported (Mandall, et al. 2010) — in this part of the investigation, the authors report on whether these subjects were thought to require orthognathic surgery or not, based upon an evaluation at the age of fifteen. The results were conclusive, early protraction headgear was successful in reducing the perceived need for orthognathic surgery. Indeed, it was very successful, with the odds of needing surgery being 3.5 times more likely in the control group compared to the early intervention group. Interestingly, this was not associated with the maintenance of early improvements that were seen in cephalometric values in the experimental group, although the majority of these individuals did have a positive overjet at the age of fifteen.

No trial is perfect and in this case there are a few points to consider. Perhaps the most important is the subjective method of evaluating whether these children would need surgery or not and the fact that the subjects were still only 15 years old at the time of evaluation. A panel consensus method was used and whilst this was done with allocation blinding and seems to have been fairly clear-cut in the majority of cases (only seven generated any significant discussion), this evaluation could have been carried out independently, rather than by members of the research team that provided the treatment. A final point is the fact that one unit only treated a single case! This suggests that there were either no class III cases in this particular region or that there was potentially some selection bias!

None-the-less, Nicky Mandall and her team should be congratulated for carrying out this trial, which has had a long period of follow up, and has provided orthodontists with important high-quality information to inform their clinical practice. The next time you see a young child with maxillary retrusion and a class III incisor relationship, you might consider early intervention. At last, a randomized clinical trial that has actually found a clinically significant difference between interventions!