Innovative Polymers for TMD Rehabilitation Devices

In diagnostic and training procedures during oral rehabilitation in Temporomandibular Disorders (TMD), the need for devices and materials that can exert the muscular activity, thus improving muscle rehabilitation, is constantly increasing. In this preliminary work, the mechanical behavior of four innovative poly(styrene-block-isobutylene-block-styrene) copolymers (SIBS) was compared to the one of Silasto®, a silicone elastomer already used in TMD rehabilitation. INNOVIA SIBS and the three KANEKA SIBS formulations (Sibstar® 073T, Sibstar® 102T, and Sibstar® 062M) showed a typical elastomeric tensile behavior, (i.e. sigmoid curve), while Silasto® showed a brittle elastic performance. The influence of styrene content, hardness, and molecular weight on the mechanical properties of SIBS copolymers, already highlighted in literature, is in agreement with the results obtained in this work. In the creep/ recovery tests and in the stress relaxation/recovery tests, the investigated materials experienced a different time-dependent increase of strain. Silasto® showed a constant linear deformation under the applied load, confirming the result obtained in the tensile test. Instead, SIBS copolymers exhibited a visco-elastic behavior, undergoing increased deformation with time under an applied constant stress. These preliminary results allow assessing the advantages of the SIBS family of materials in respect of the already used Silasto®. In fact, their viscoelastic behavior allows to obtain a slow deformation recovery, that is one of the fundamental requirements for a correct muscle rehabilitation in selected patients.