Instrumented Assessment of Oral Motor Function in Healthy Subjects and People with Systemic Sclerosis

The aim of the present study was to provide quantitative data of oral function in healthy subjects (HSs), validity of measurements and estimation of measurement bias, as well as quantify oral impairment in persons with scleroderma (SSc). 151 HSs and 12 subjects with SSc were recruited and assessed using instrumented tools, measuring maximal mouth opening; lip strength; and tongue strength, protrusion, retraction, and endurance. Twenty HSs were also retested 3-5 weeks later in order to assess the test-retest reliability of the measurements. Intraclass correlation coefficients proved to be satisfactory (>0.8) for both inter-rater and test-retest reliabilities of all measurements except for tongue retraction. In the HS group, maximal mouth opening and tongue and lips strength values were larger (P < 0.05) for males than females, while no significant differences were found for other variables. Older subjects had statistically significantly lower tongue retraction values and tongue endurance values than younger subjects. The SSc group showed a statistically significant decrease (P < 0.05) in almost all the measurements. Assessment procedures proved to be valid and reliable. Gender and height were predictors of mouth opening, lip and tongue strength, while age correlates with tongue retraction and endurance. Measurements highlighted the strong impact of SSc on oral functions and in particular on tongue protrusion, tongue strength, and endurance.