[Transposition of masseter muscle insertion and its influence on anatomical musculo-skeletal changes in the adult...

Unilateral surgical transposition of the masseter muscle from the masseteric fossa to the central area of the mandibular body below the molar teeth was performed in ten adult rabbits. Six months later the animals were sacrificed, the masseter muscles were dissected and then removed to be fully dried and weighed; the skull was cleaned for anatomical examination of the mandible and the teeth. It was noticed that the transposed muscles were firmly attached and functionally adapted, but underwent a drastic reduction of their weight. The smooth surface of the mandibular body which became activated by the new muscular pull was now rough and irregular due to osseous neoformation. The original area of attachment (masseteric fossa) was remodelled not only regressively but also by bone apposition (exostoses) in some sites. The dental arches kept normal, except for alveolar bone resorption next to the first molar in two animals and accentuated sagittal deviation in another one.