The effect of passive clear aligners on masticatory muscle activity in adults with different levels of oral parafunction

Background: There is limited knowledge of the possible side-effects of clear aligners on jaw function.Objectives: To determine the short-term effect of passive clear aligners (PCAs) on masticatory muscle activity (MMA), occlusal discomfort (OD) and temporomandibular disorder (TMD) symptoms in adults with different levels of self-reported oral parafunction.Materials and Methods: Participants were screened for oral parafunctional behaviours using the oral behavioural checklist. Respondents in <= 85th and >= 15th percentiles were invited to participate and allocated to a high (HPF: N = 15) or low (lower parafunction [LPF]: N = 16) parafunction group. Participants underwent a TMD clinical examination; somatisation and somatosensory amplification were assessed by questionnaires; OD and stress were assessed by visual analogue scales. While wearing PCAs, awake-time MMA was assessed three times over 9 days using a wearable electromyography device, along with OD, stress and TMD symptoms.Results: The wearing of PCAs was associated with a significant decrease in mean contraction episode amplitude in both groups (p = 0.003). OD levels increased and remained raised in all participants after insertion of the PCAs (p < 0.001), more so in the HPF group (p = 0.048). The HPF group had higher somatisation scores (p = 0.006) and reported more TMD symptoms at all time points (p <= 0.004). No significant changes in stress or TMD symptoms were found in either group during the study period.Conclusions: PCAs were associated with a decrease in MMA in all participants. HPF individuals had greater somatisation and reported greater discomfort when wearing PCAs than LPF individuals.

Automated summary

Passive clear aligners (PCAs) were found to decrease masticatory muscle activity (MMA) in the short term, but individuals with high oral parafunction reported more somatisation and discomfort when wearing PCAs compared to those with low oral parafunction.