A 2-year follow-up of mandibular posture following an increase in occlusalvertical dimension beyond the clinical rest position with fixed restorations

While resting mandibular posture is continuously changing, repeatable relat ions of 'physiologic rest position' (PRP) and 'clinical rest position' (CRP ) are described in the literature. The PRP is defined as a position of mini mal muscle activity and CRP as a more closed clinical reference relation. R elaxed resting posture (RRP) is a repeatable postural range obtained by ope rator-induced relaxation techniques. This article reports on measurements o f mandibular posture in a patient group following an increase in occlusal v ertical dimension (OVD) with fixed restorations beyond CRP over 2 years. Th e relationship of CRP and RRP in the restored and a non-restored control gr oup is compared. The relationship of RRP and corresponding masseteric EMG v alues to baseline minimal EMG levels is reported far both groups. Resting f ace height adapted to the increased OVD and remained consistent over 1 and 2 years. The RRP was greater and significantly different from CRP in both g roups (P = 0.0001). Results indicated that both CRP and RRP were postural r anges and not specific postural positions. The RRP occurred at minimum base line EMG levels for both groups and appears to be consistent with physiolog ic rest position. The possibility of achieving minimal EMG levels at varyin g interocclusal rest space relations is discussed.