Some people have claimed that clear aligners can actually reduce the tendency to grind, and use this as a selling point for clear aligners. Is this actually true?
In short, neither.
The majority of published literature shows no significant impact on bruxism, although there may be an increase in masticatory muscle activity at the start of treatment which settles over time.
One study (link) looked at patients with existing sleep bruxism and treated them with occlusal splints, clear aligners and a placebo splint for 6 months and found no decrease in the sleep bruxism index for the patients wearing clear aligners overall. However, it was observed that in the earlier stages of treatment (month 1 and 3) there was a slight increase in phasic contractions related to SB in clear aligner wearers compared to placebo.
Another study (link) looked at healthy subjects wearing clear aligners over a 5 day period and found no evidence that clear aligners caused an increase in SB or masticatory muscle activity.
A further study (link) showed that there was a short term increase in masticatory muscle soreness in the first 4 weeks of treatment.
There are very few high quality studies on clear aligners and bruxism, and it is important to be honest with patients about this.
Based on the available evidence it seems that clear aligners seem to neither cause nor reduce SB - baseline activity appears to remain the same on average over the course of treatment.
However, given the lack of robust evidence and given that an individual’s perception of jaw pain and night time grinding is personal, it is probably sensible to consent for increased jaw discomfort, particularly at the start of treatment.