Biomechanical Strategies in the Realization of the Primary Resting Function of the Stomatognathic System: A Study Using EMA and CBCT

The key role in the functional efficiency of the stomatognathic system is attributed to biomechanical processes, which influence both its stabilization and the dynamic functions it supports (e.g. swallowing, chewing, speech). The biomechanical parameters observed in the resting function include, on the one hand, the vertical tongue position and, on the other hand, the closure of the oral cavity with the formation of an interocclusal space [1, 2].

Our study involved a diagnostic assessment including CBCT (Cone Beam Computed Tomography) and EMA (electromagnetic articulography) examinations conducted on six females: three representing the biological, functional, and articulatory norm, and three with functional speech articulation disorders (F80.0; ICD-10-classification).

Based on the results, a normative biomechanical function pattern of the stomatognathic system in its resting position was developed. The key muscle involved in this function is the tongue, whose coronal part stabilizes in the periodontal area of the palate. Different tongue parts contribute to system closure, forming a negative pressure region (space of Donders), where the apex, along with the laminal-predorsal tongue part, stabilizes near the incisive papilla; the postdorsum stabilizes in the region of the soft palate; the lateral edges of the tongue form lateral closure.

In the next step, three types of disordered tongue resting positions were identified depending of the apex position: behind the lower teeth, interdentally at the incisal edge of the lower dental arch, and on the upper teeth.

The results enabled the reconstruction of biomechanical strategies for the formation of both normal and disordered resting functions of the stomatognathic system. This approach allows for a detailed description of the arrangement of all tongue parts. A change in the normative contact zones between the tongue and surrounding structures triggers a compensatory biomechanical strategy in function execution, which may be related to morphological changes in the occlusion and the realization of dynamic functions.

References

[1] Engelke W., Jung K., Knösel M. (2011). Intra-oral compartment pressures: a biofunctional model and experimental measurements under different conditions of posture. Clinical Oral Investigations 15, 165–176.

[2] Dupas P.H. (2005). Nouvelle approche du dysfonctionnement cranio-mandibulaire; du diagnostic à la gouttière. Cahiers de Protheses.