Reproducibility of extra-oral tongue motion in a normal cohort using a 3D motion capture system

Al Hadi, Noor Alhuda (2021). Reproducibility of extra-oral tongue motion in a normal cohort using a 3D motion capture system. University of Birmingham. M.Sc.

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Abstract

Aim: The aim of this study was to determine the magnitude of reproducible tongue motion in a normal cohort of healthy individuals using a 3D motion capture system.
Design: Single centre, case-controlled study.
Materials and methods: Thirty volunteers comprising of 15 female and 15 male staff and students at Birmingham Dental hospital were recruited with an age range of 21 to 44, and mean age of 27.5 years. Volunteers had to meet inclusion and exclusion criteria, namely to be aged 18-60 and be medically fit and well. Subjects were imaged using a markerless, high fidelity 3D facial motion capture system. Two sets of motions were captured per subject; up-down and right-left tongue movement at two different time points, T1 and T2, at least 30 minutes apart. Following capture the all 3D images were re-orientated to the principle planes. Four stabilising landmarks were placed on the forehead and one tracked landmark on the tip of the tongue was used. T1 and T2 sequences were superimposed on to one another and dynamic time warping was used to account for variability in speed. Mean and absolute mean differences between the maximum tongue tip position in the x, y and z directions were calculated for each of the two movements at both time points and subsequently analysed.
Results: The up and down range of motion (ROM) of the tongue was 48.3 ± 10.0mm (95% CI 45.7mm to 51.0mm) and for right to left ROM was 66.4 ± 7.8mm (95% CI 63.4mm to 69.4mm). Based on a paired t-test the mean displacement of the tongue tip in the x, y and z-direction, was not statistically significantly different between T1 and T2 for any of the tongue movements. The mean absolute differences of the tongue tip in the x, y and z-direction, at T1 and T2, were all statistically significantly less than
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5.0mm. Apart from during tongue tip elevation in the z-direction which was not statistically significantly different to 5.0mm.
Conclusions: This study has shown that ROM of the tongue is reproducible in the x, y and z-directions for right to left tongue movement with all differences in mean and mean absolute measurements being less than 5.0mm. However, for up to down tongue movement, whilst ROM of the tongue was reproducible in the x, y and z- directions, the upper limit of the 95% confidence interval for the mean absolute difference was greater than 5.0mm when the tongue is in its most elevated position in the z-direction. The average ROM in the up and down direction was 48.3mm and from right to left was 66.4mm.
For interventional studies, differences in tongue tip position in the order of 6-7mm are likely to be due to a lack of reproducibility rather than treatment effect. This should be taken into account when designing future studies. It is vital to rehearse tongue motion to reduce the magnitude of the reproducibility error.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):