A dental professor has discovered that tooth enamel indicates a biological clock linking tooth growth to other metabolic processes.
New York University dental professor Dr Timothy Bromage discovered the clock – or biological rhythm – while observing incremental growth lines in tooth enamel, which appear much like the annual rings on a tree.
It controls many metabolic functions and is based on the circadian rhythm – which is a roughly 24-hour cycle that determines sleep and feeding patterns, cell regeneration, and other biological processes in mammals.
The newly discovered rhythm originates in a region of the brain that functions as the main control centre for the autonomic nervous system.
But unlike the circadian rhythm, this clock varies from one organism to another, operating on shorter time intervals for small mammals, and longer ones for larger animals – therefore rats have a one-day interval, chimpanzees six, and humans eight.
Reporting his findings at the 37th annual meeting of the American Association for Dental Research (AADR), he said: ‘The same biological rhythm that controls incremental tooth and bone growth also affects bone and body size and many metabolic processes, including heart and respiration rates.
‘In fact, the rhythm affects an organism’s overall pace of life, and its life span. So, a rat that grows teeth and bone in one-eighth the time of a human also lives faster and dies younger.’
