Is mandibular bone anchored maxillary protraction better than facemask treatment?

We all know that Class III treatment can be quite challenging due to unfavourable growth. We also hope that early intervention protraction may intercept the development of this type of malocclusion.

When considering interceptive treatments, it is important to weigh the burden of care against the potential benefits. Several studies have explored the use of facemasks for maxillary protraction and have indicated promising treatment outcomes. Recent advancements also include the use of bone-anchored appliances for both the maxilla and mandible.

However, research on these methods has been limited. This new trial examined the long-term effects of a hybrid hyrax and facemask treatment compared to a hybrid hyrax used with mandibular bone anchorage. I found the results both interesting and clinically relevant.

A multinational team from Belgium, Saudi Arabia and Sweden did this study. The EJO published the paper.

What did they ask?

They did this trial to answer this question

“What are the short and long-term effects of Hybrid Hyrax and facemask (FM) vs Hybrid Hyrax and mentoplate (MP) with Alt-Ramec treatment”?

What did they do?

They did a single centre 2 arm parallel randomised trial with a 1:1 allocation.

The PICO was

Participants

Mixed dentition children with Class III malocclusion. This was defined anterior crossbites or end to end incisor relationships at the start of treatment.

Intervention

Hybrid Hyrax anchored by two miniscrews in the anterior palate and bands to the first molars.  They used the Alternate RME and constriction protocol (Alt-RAMEC).  In this group they used facemask treatment until the patients had a positive overjet of at least 2mm or had been treated for six monghs. This group was called the FM group.

Comparision

This group was treated in the same way as the HH and Alt-RAMEC treatment. In addition  the clinician fitted a mentoplate. The operator fixed this with two to four screws to the mandible via a small gingival incision. This procedure was done using general anaesthetic.  The patient then wore intermaxillary elastics. The end point of treatment was after 6 months or overjet greater than 2mm. This group was called the MP group.

Outcome

The primary outcome was a change in the Wits analysis. Secondary outcomes included other cephalometric measurements generated from CBCT images.

After the phase I treatment was completed, they treated all the patients with fixed appliances.

The team gathered data at the beginning of treatment, one year after treatment, and five years after treatment.

They did a sample size calculation that showed they needed 12 patients per group.

They used a pre-prepared randomisation with allocation concealment in sealed envelopes. An intermediary allocated the patients. The clinician played no part in this process.

As with all orthodontic trials, it was not possible to blind either the clinician or the patient. However, the data were collected and analysed blind.

What did they find?

28 patients took part in the study. There were no marked differences between the groups at the start of treatment. At the end of the five years, 24 patients remained in the trial.

What did they find?

They produced a fair amount of cephalometric data. I decided to concentrate on the Wits analysis.

This revealed changes of 4.42mm for the FM group and 2.86mm for the MP groups at T1. At T2 (after five years), this had decreased to 3.3mm (FM) and 1.5mm (MP). These were not statistically significant.  There were no other differences.

In short, the treatment for both interventions was successful. However, using the Mentoplate did not confer any advantages over the facemask treatment.

Their conclusion was:

“Early Class III treatment using HH and Alt-RAMEC protocols with mandibular bone anchorage did not produce better outcomes than HH and Alt-RAMEC Facemaks treatment”.

What did I think?

This study was a well-conducted small evaluation of a complex protraction treatment. The team effectively adhered to randomized control trial (RCT) protocols and produced a clear and concise paper. Several significant findings emerged from this research. Firstly, the trial enhances our understanding of methods to intercept developing Class III problems. Importantly, it demonstrates the effectiveness of protraction in patients who are cooperative. Additionally, it was encouraging to observe that these changes remained relatively stable over five years, which aligns with similar trials.

It’s important to note that this study did not include an untreated control group. Consequently, the treatment effect has not been compared to typical facial growth. Other trials have explored this topic and contributed to our understanding of the treatment. These reveal less treatment effect.

The most important finding was that using mandibular anchorage with plates was not more effective than a facemask. This discovery is clinically relevant, especially considering that placing the plates is an invasive procedure that requires general anesthesia. We can use this information when obtaining consent from patients. I believe my patients would likely not choose the option of bone anchorage in the mandible, as it does not offer any advantages.

It was great to see another nice randomised triall looking at a clinically relevant question.