Role of the lateral pterygoid muscle and meniscotemporomandibular frenum in spontaneous growth of the mandible and in growth stimulated by the postural hyperpropulsor.

Our experimental studies in young rats represent an attempt to elucidate the respective roles of the lateral pterygoid muscle (LPM), the temporomandibular frenum (TMF), and the postural hyperpropulsor (Hp) in the control of the growth rate, the growth direction, and the growth amount of the condylar cartilage. Even after surgical resection of the LPM, the growth of the condylar cartilage and the lengthening of the mandible continue but are significantly decreased. Also, the stimulating effect of postural hyperpropulsion on the condylar cartilage and mandibular growth is much less intense after resection of the LPM. The TMF, which has a blood-circulating and a biomechanical component, appears to be a mediator of the LPM in the control of the condylar cartilage growth. After the surgical resection of the TMF, the growth the condylar cartilage and the lengthening of the mandible continue but are significantly diminished.