Tongue and Lip Strength and Endurance in Healthy Young Adults With and Without Orofacial Myofunctional Disorders.

Background/objectives: Based on the premise that tongue and lip force is affected in individuals with orofacial myofunctional disorders (OMDs), orofacial myofunctional therapy (OMT) programs typically include the strengthening of orofacial muscles through isometric and isotonic exercises. The purpose of this study is to examine whether there is indeed a measurable difference in maximum tongue and lip strength and endurance between subjects with and without OMDs, as well as to explore Oral Health-Related Quality of Life (OHRQoL) in this population.

Methods: Sixty healthy young adults (mean age 18.9 years, SD 0.69 years, range 18.0-21.4 years) participated in this study. Perceptual evaluation of orofacial functions was conducted using the Orofacial Myofunctional Evaluation with Scores (OMES) protocol. Participants were divided into three groups, namely those with physiological orofacial functions (POF; n = 20), those with inconsistent orofacial functions (IOF; n = 11), and those with consistent OMDs (OMD; n = 29). Maximum isometric pressure and endurance of tongue and lips were measured using the Iowa Oral Performance Instrument (IOPI). OHRQoL was assessed using the Oral Health Impact Profile (OHIP-14).

Results: The OMES total scores did not differ significantly between the three groups, though the subscale 'function' showed significant differences (13.637; p = 0.001). No statistically significant differences in maximum isometric pressure or endurance for tongue and lips, nor for OHIP scores, were measured between the three groups.

Conclusions: Although orofacial muscle strengthening is commonly part of OMT, current findings suggest the superfluity of these types of exercises in the treatment of OMDs in healthy young adults and may indicate the need to focus on awareness and rehabilitation of pathological functions in these individuals. Re-evaluation of the efficacy of OMT programs in different populations may be an important strategy going forward.