CDABO student case display: orthodontic correction of a Class II malocclusion.
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Adolescent↗
Biomedical subjects
R K Risinger
Publications and source records attributed to R K Risinger.
The rhythms of human premolar eruption: a study using continuous observation.
New optical technology now allows for precise observation of erupting human premolars. Continuous overnight tracking of an erupting tooth with a video microscope system shows that eruption occurs almost exclusively during the early evening. During the day, slight intrusion is likely to occur. When Moiré magnification is used to provide extremely high resolution (0.05 micrometer), slight movements of the erupting tooth in concert with the arterial pulse can be observed, and a previously unknown cyclic movement with a period of 20 to 50 seconds is seen consistently. Rhythms in skeletal growth and tooth eruption suggest that treatment to influence jaw growth and move teeth may be most effective at specific times of the day.
Bicuspid↗
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↗