Management and Control of Isotonic Contraction Generated Stress: Evalua- Tion of Masseter Muscle Deformation Pattern by Means of Ecography A. Busato1, G. Balconi2, v. Vismara1, L. Bertelè3, G. Garo4, D. De Gregorio5

Both dissection and ultrasound demonstrate that the structure of the masseter muscle is very complex, composed of three distinct parts and organized in layers (1): the superficial masseter is formed by two layers (internal and external), the middle masseter has only one layer and the deep masseter has three separate layers (outward, central and inward). When speaking of the function of the muscle we generally refer to it as a whole and not as separate parts. The main functions it is responsible for are the elevation of the mandible and the generation of considerable force during the clenching of the dental arches, which can be as high as 90/100 kg per cm2 (Figure 1). The objective of the following study is to observe the behavior of the six layers of the masseter during an isometric contraction at maximum exertion (2) with the deformation pattern analysis method. The literature often postulates that the deep masseter has a preMANAGEMENT AND CONTROL OF ISOTONIC CONTRACTION GENERATED STRESS: EVALUATION OF MASSETER MUSCLE DEFORMATION PATTERN BY MEANS OF ECOGRAPHY