Mesurement of lip posture and interaction between lip posture and resting face height

Abstract

A method for measurement of lip incompetence is described. Electromyographic techniques were used to obtain relaxation of the muscles of the lip and of a jaw elevator muscle. Standardized photographs were taken of the subject's profile, from which lip separation and face height were measured. Variation was found in successive measurements of lip posture, some of which appeared to depend upon mandibular posture. With the teeth in occlusion, lip separation was reduced. Active maintenance of lip contact by the subject was often associated with a reduction in lower face height, which may have been a direct consequence of the lip muscle activity, or of jaw elevator activity facilitating the lip closure.

Morphological differences in individuals with lip competence and incompetence based on electromyographic diagnosis

“…EMG data were recorded in an electrically insulated room to prevent interference from outside sources. During EMG recording, the subjects sat in a dental chair in an upright position with the Frankfort–horizontal plane parallel to the floor (Kawamura, 1974; Ingervall, 1978; Yemm et al , 1978). Two bipolar surface electrodes (8·0 mm in diameter)1 were symmetrically attached to the skin about 20 mm apart above the vermillion border of the upper lip (Jarabak, 1957; Harradine & Kirschen, 1983).…”

“…A patient is described as having competent lips when the lips are in light contact at the clinical rest position (Barrett & Hanson, 1974; Gustafsson & Ahlgren, 1975; Simpson, 1976, 1977; Yemm, El‐Sharkawy & Stephens, 1978; Harradine & Kirschen, 1983). The term ‘lip competent’ is not based on the performance of a particular lip function; rather, this term is morphological (Barrett & Hanson, 1974).…”

“…Therefore, an almost involuntary effort is required to hold the lips together. However, in the individual with incompetent lips, distinguishable activity of the lower lip and unusual movement of the tongue are needed to close the lips (Gustafsson & Ahlgren, 1975; Yemm et al , 1978; Harradine & Kirschen, 1983). Therefore, lip incompetence should refer to a functional problem of the lips.…”

Comportamento da ausência de selamento labial passivo ao longo do tempo

“…Apesar de a maioria dos autores relacionar o maior comprimento dos lábios com a menor distância interlabial, ainda não há consenso acerca dessa associação direta (GENECOV; SINCLAIR; DECHOW, 1990;GOCHMAN, 1975;SUBTELNY, 1961;VIG;COHEN, 1979;YEMM;EL-SHARKAWY;STEPHENS, 1978). Burstone (1967) (BISHARA et al, 1998;BISHARA, 1984;MERRIFIELD, 1966).…”

“…A menor distância entre lábios está frequentemente presente em pacientes com deficiência vertical maxilar, lábio superior longo (mudança natural que ocorre com a idade) e em retrusão da mandíbula com mordida profunda (UEDA et al, 2002;VOLPATO, 1991;YATA et al, 2001;YEMM;EL-SHARKAWY;STEPHENS, 1978;ZAMZAM;LUTHER, 2001). …”