AN EXPERIMENTAL STUDY OF THE EFFECTS OF REMOVAL OF THE MASTICATORY MUSCLES ON THE GROWTH OF THE MANDIBLE IN THE GUINEA PIG

저작근의 제거가 Guinea Pig의 하악골 성장에 미치는 영향에 관한 실험적 연구

Fifteen young pigs were used in this study. The animals were divided into three groups 1. Group for removal of the temporal muscle, 2. Group for removal of the masseter muscle, 3, Group for removal of masseter and internal pterygoid muscles. The animals were anesthetized with $3.5\%$ chloral hydrate intraperitoneally. In the right side the head was shaved. The masticatory muscle was removed. The animals were sacrificed four months later. The head was separated from trunk and cleaned by boiling in a solution of potassium hydroxide. The results were as follows; 1. In the group for removal of the temporal muscle, the Coronoid process of the mandible was resorbed. 2. In the group for removal of the masseter muscle, there was produced asymmetrical growth of the mandible, attrition of the molar teeth in the control side, and resorption of the mandibular angle. 3. In the group for removal of the Masseter and Internal muscles, the changes were more severe than that of the group for removal of the masseter muscle. The mandibular angle was completely absent. 4. The growth of the bone seems definitely related to the presence of the muscular tissue actively pulling upon it.