I read a fascinating discourse on Ravi Nanda’s Facebook Group group about expansion, which became a little side-tracked, delving into the effects of maxillary protraction or facemask therapy. The discussion included a debate from some of the best and most experienced thinkers about the relative impact of including RPE or Alt-RAMEC as part of the protocol. This led me to think about my use of protraction.
I have used protraction for years and am rarely disappointed (and often flattered) with the occlusal effects. What is far less certain are the prolonged skeletal effects.
Let’s look at a study.
Many of you (particularly those based in the U.K.) will be aware of a fantastic multi-centred clinical trial by Nicky Mandall. I thought it would be helpful to summarise the study and include my own (likely contestable) interpretation.
The study involved two groups- an untreated control and an active treatment group allocated to protraction facemask therapy. Participants were under ten (7 to 9 years) and evaluated at 18 months, three years, and six years. The link to the latter is here.
Skeletal effects
The findings are fascinating. Let’s look at the skeletal impact first – ANB improved by 2.1 degrees with treatment and worsened by 0.5 degrees in the control after 15 months. What happened after six years? This difference dissipated to just 0.7 degrees. Does that sound familiar? And perhaps remind you of the long-term effects of functional appliance therapy?
Dental effects
And what about the dental effects? Maxillary incisors remained proclined in both groups (about 7 degrees). The lower incisors had retroclined a little more (2.7 vs. 0.4 degrees) in the treatment group at six years. There were no statistical differences between the groups here.
The big difference, however, between the groups was at the occlusal level, with the overjet being improved in both groups over the six years (This ties in with my feeling that Class IIIs can get worse but typically don’t. And rarely do so in the presence of mild skeletal discrepancies or positive overjets in early adolescence). The overjet, however, was 3mm more positive in the active treatment group and 1.7mm more in the control group after six years. So, if protraction headgear has a sustained benefit, the safe bet would be to pin this to occlusal rather than skeletal effects.
You may think some of these findings are incongruous- no skeletal distinction? Or difference in incisor inclination? So why the difference in overjet? It seems to relate to occlusal plane rotation with more clockwise rotation of the maxillary occlusal plane with facemask therapy. There is a knock-on effect on the mandibular occlusal plane and, indeed, in the position of B point.
Need for orthognathic surgery
But the most exciting finding is that a panel of expert orthodontic raters adjudged the need for surgery to be appreciably reduced (from 66% to 36%) in the protraction group at a 6-year follow-up. The panel made this assessment based on radiographs, models, and clinical photographs. Remember, the groups were essentially identical at the skeletal level at this point. Like me, it appears that these orthodontists may be ‘flattered’ by occlusal change.
How do I use this information?
I use it to inform the ongoing use of protraction headgear in a subset of my patients. I also use it during explanation and consent to suggest that protraction will likely lead to an improved bite long-term but that we know less about the effects on the jaws. I also use it to inform thoughts around the potential remit of skeletal-borne protraction. I am, I’m afraid, much less enthusiastic than many and fear that the invasiveness that is becoming routine in this respect might flatter many in the short term with long-term results likely undershooting (I will post on the fledgling evidence on this topic soon). Of course, I look forward to being proved wrong!
