Search PubMed⌕ Search

Biomedical subjects

W R Proffit

Publications and source records attributed to W R Proffit.

124 records · Page 7Linked to original sources
PubMedDate not supplied

Continuous overnight observation of human premolar eruption.

Such observation was made possible by transmitting the image of a mobile ceramic ruling on the erupting maxillary second premolar to a video-microscope via a coaxial fibreoptic cable. The cable was inserted into a reference bar secured to the adjacent first molar and first premolar. The image of the ruling was superimposed with the image from a surveillance camera focused on the patient and continuously recorded on video-tape along with the participant's blood pressure, pulse rate, electromyographic activity and occlusal contact sounds. Overnight data from 12 individuals clearly revealed a circadian rhythm in eruption during the prefunctional spurt. On average, the maxillary second premolar erupted 41 microns during an 11-h overnight observation, with almost all the eruption occurring in the late evening from 8 p.m. to 1 a.m. After 1 a.m., eruption typically ceased, with a tendency for intrusion to occur until 7 a.m. Sleep increased the rate of eruption during the late evening, but did not influence the eruption rate during the early morning. Haemodynamic changes, including blood pressure and pulse rate, did not have a significant impact on the rhythm of eruption. The observed eruption rhythm is most probably caused by changing hormone levels and their effect on the periodontal ligament. The late-evening eruption of human premolars coincides with the late-evening secretion of growth hormone and thyroid hormone typically found in humans.

Adolescent↗
PubMedDate not supplied

Lip and tongue pressures related to dental arch and oral cavity size in Australian aborigines.

Although the oral cavity and dental arches of the Australian aborigine are large, studies of lingual and labial pressures indicate that the tongue is neither unusually large nor strong. The Australian aborigine's pharyngeal cavity is smaller in height and depth than that of the American; just the opposite is true for the oral cavity. To the extent that environmental factors are important at all, the resting pressure of the lips, not tongue pressure during swallowing, is probably the significant determinant of dental arch dimensions.

Adolescent↗