Can we correct a Class II with Aligners?

Class II malocclusion is one of the most frequently encountered alignment issues within the orthodontic scope. It has been reported that 37% of school children in Europe and 33% of all orthodontic patients in the USA are currently affected by Class II malocclusion.

In simpler terms, Class II malocclusion can be described as the distal presentation or relationship of the maxilla to the mandible. Angle detailed this condition to be true when the mesiobuccal cusp of the maxillary first permanent molar articulates mesial to the buccal groove of the mandibular first permanent molar.

What’s special about Class II malocclusion is that it can often be accompanied by craniofacial discrepancies, therefore the treatment choice for its correction can play a crucial role in the success of the treatment. Primarily in children or growing patients, Class II malocclusion may be corrected with extraoral headgears, functional appliances, and full fixed appliances with intermaxillary elastics and/or teeth extractions. Whereas in adults, the go-to treatment option would be a combination of fixed appliances with intermaxillary elastics and/or teeth extractions. Severe cases may even require orthognathic surgery to resolve.

But as we look through the commonly sought-after treatment methods to treat a Class II, we do not, very often, find mentions of aligner therapy to do the same. So, does this mean that aligners are not efficient enough to correct malocclusions as complex as the Class II? Are we simply trifling away big bucks to get aligner treatment when it wouldn’t even guarantee its success?

How reliable are aligners?

Aligners have gained a good reputation for successfully correcting minor malalignment. However, experts believe that aligners may not be the right choice in the treatment of complex malalignment, whereas fixed appliances instead would fare better. A study by Brian Patterson et al. aimed to find out if Class II malocclusion can in fact be treated with clear aligners after completing treatment with the initial set of aligners.

After assessing 80 patients in a controlled environment with the help of American Board of Orthodontics (ABO) Model Grading System certified techniques, they were able to gather that not much difference was made with aligners. They realised that the amount of anteroposterior correction in Class II malocclusion patients was only 6.8% of the predicted amount. The amount of overbite correction was, however, 38.9% of the predicted amounts. Overall, they concluded that the clear aligner system (in this case, Invisalign) was unable to produce significant Class II correction of overjet reduction.

However, there might be an exception. Dr. Sam Daher, in his paper, affirms that Class II malocclusion that is 4 mm or less can successfully be treated with Invisalign using sequential distalization. This happens when the upper posterior teeth are encouraged to move distally over a period of time. When the second molar or the last posterior tooth is distalized mid-way, distalization for the next tooth is initiated. This treatment is further reinforced by Class II elastics.

He did mention, contrarily, that patients that exhibit a Class II molar relationship in excess of 4 mm should be considered for extraction(s) or orthognathic surgery.

A collection of case reports compiled by a team from Italy, further cemented this account. In one of these accounts, a 13-year-old boy with severe Class II malocclusion division 2 was treated with Invisalign combined with Class II elastics in the first phase of treatment. After 13 months of therapy, they were able to completely correct the Class II malocclusion and were able to achieve proper overbite and overjet. In particular, the overbite was reduced from 5 mm to 2 mm.

They also relay similar instances through other case reports, suggesting that not only do clear aligners ensure proper oral hygiene and superior aesthetics, but they are also apt to reduce Class II malocclusions when paired with the right sets of treatment auxiliaries.

Conclusion

At this point in time, we are bombarded with information that suggests that clear aligner treatment can successfully achieve certain tooth movements. However, they may not be as refined to achieve other movements predictably. This may or may not include the correction of Class II malocclusion depending on the severity and treatment auxiliaries used.