Bentuk dan posisi kondilus sebagai marker pada Temporomandibular Disorder (TMD) melalui radiografi panoramik

Objectives: The purpose of writing this literature review is to describe the condyle shape and position parameters in panoramic radiographs to be used as markers in diagnosing a TMD case. Literature Review: There are several classifications of both normal and pathological condyles in terms of panoramic radiographs, however these require more detailed observation. Panoramic radiographs that are only two-dimentional and only performed when the teeth are biting edge to edge so that they only show the position of the condyle movement and the shape of the condyle from the lateral view. Panoramic radiograph also have limitations in imaging soft tissues such as articular disc which are vital anatomy in analyzing a TMD case. Conclusion: Assessment of the shape and position of the condyles on a panoramic radiograph can be used as an early diagnosis of TMD. 2-dimensional modalities such as TMJ conventional lateral and frontal or 3-dimensional modalities such as CBCT or CT can be used for further assessment of a TMD case, while MRI or ultrasound can be used for soft tissue abnormalities.

EMG Activities of Two Heads of the Human Lateral Pterygoid Muscle in Relation to Mandibular Condyle Movement and Biting Force

Electromyographic (EMG) activities of the superior (SUP) and inferior heads (INF) of the lateral pterygoid muscle (LPT) were recorded in humans during voluntary stepwise changes in biting force and jaw position that were adopted to exclude the effects of acceleration and velocity of jaw movements on the muscle activity. The SUP behaved like a jaw-closing muscle and showed characteristic activity in relation to the biting force. It showed a considerable amount of background activity (5–32% of the maximum) even in the intercuspal position without teeth clenching and reached a nearly maximum activity at relatively lower biting-force levels than the jaw-closing muscles during increment of the biting force. Stretch reflexes were found in the SUP, the function of which could be to stabilize the condyle against the biting force that pulls the condyle posteriorly. This notion was verified by examining the biomechanics on the temporomandibular joint. The complex movements of the mandibular condyle in a sagittal plane were decomposed into displacement in the anteroposterior direction (Ac) and angle of rotation (RAc) around a kinesiological specific point on the condyle. In relation to Ac, each head of the LPT showed quite a similar behavior to each other in all types of jaw movements across all subjects. Working ranges of the muscle activities were almost constant (Ac <3 mm for the SUP and Ac >3 mm for the INF). The amount of EMG activity of the SUP changed in inverse proportion to Ac showing a hyperbola-like relation, whereas that of the INF changed rather linearly. The EMG amplitude of the SUP showed a quasilinear inverse relation with RAc in the hinge movement during which the condyle rotated with no movement in the anteroposterior direction. This finding suggests that the SUP controls the angular relationship between the articular disk and the condyle. On the other hand, the position of the disk in relation to the maxilla, not to the condyle, is controlled indirectly by the INF because the disk is attached to the condyle by tendinous ligaments.