Is postural platform suited to study correlations between the masticatory system and body posture? A study of repeatability and a meta-analysis of reported variations.

Aim: To evaluate the repeatability of different static posturographic parameters with regard to the analysis of correlations between the masticatory system and body posture.

Materials And Methods: In 15 healthy subjects (26.4±3.7 years, 9 females and 6 males) with no malocclusion, posturographic recordings were carried out by vertical force platform under mandibular rest position (RP) and dental intercuspidal position (ICP). Six different posturographic parameters were recorded at baseline, 30 min, 1 day and 7 days. Repeatability analysis was based on the method of the moment estimator (as percentage over the baseline scores, i.e. method error) and interclass correlation coefficients (ICC). Moreover, a meta-analysis of the variations in posturographic recordings between different occlusal conditions, i.e. RP vs. ICP, from previous studies was also performed.

Results: Only the sway area and velocity yielded acceptable errors and ICCs up to 14.8% and 0.94, respectively. The spatial parameters, i.e. displacement of the centre of pressure from the theoretical point, performed poorly with lowest errors and greatest ICCs of 149.0% and 0.64, respectively. At the meta-analysis, ten studies were included and a total of 281 variation scores were calculated, with most of the greater and significant variations seen for the spatial parameters.

Conclusions: The sway area and velocity show acceptable reliability, but a threshold of 25% should be used as a true variation between two different recording conditions, i.e. RP vs. ICP. Considering that most of the previous results on the relevant correlations between the masticatory system and body posture are based on spatial parameters, with the poorest repeatability, corresponding conclusions should be interpreted with caution.