Continuous overnight observation of human premolar eruption

Area of Science:

• Dentistry
• Chronobiology
• Physiology

Background:

• Tooth eruption is a complex biological process.
• Understanding the temporal dynamics of tooth eruption is crucial for orthodontics and developmental biology.
• Previous research has not fully elucidated the diurnal patterns of human premolar eruption.

Purpose of the Study:

• To investigate the circadian rhythm of maxillary second premolar eruption in humans.
• To determine the influence of sleep and hemodynamic factors on tooth eruption.
• To explore potential hormonal mechanisms underlying observed eruption patterns.

Main Methods:

• Utilized a video-microscope system with a coaxial fiberoptic cable to record ceramic rulings on erupting maxillary second premolars.
• Simultaneously recorded blood pressure, pulse rate, electromyographic activity, and occlusal sounds.
• Analyzed 11-hour overnight data from 12 individuals to identify eruption patterns and correlations.

Main Results:

• A significant circadian rhythm in premolar eruption was observed, with most eruption occurring between 8 p.m. and 1 a.m.
• Average eruption was 41 microns overnight, with a tendency for intrusion after 1 a.m.
• Sleep enhanced late-evening eruption rates, while hemodynamic changes had no significant impact.

Conclusions:

• Human premolar eruption follows a distinct circadian rhythm, influenced by sleep and likely regulated by nocturnal hormonal fluctuations.
• The observed late-evening eruption coincides with peak secretion of growth hormone and thyroid hormone.
• These findings suggest a hormonal basis for the diurnal variation in tooth eruption.