Now, international research has discovered similar lines in baby teeth can indicate whether a young person will be predisposed to greater weight gain in early adolescence.
University of Otago Sir John Walsh Research Institute dentistry researcher Dr Carolina Loch and assistant research fellow Sophie White were responsible for the New Zealand section of the international project which found the lines were biorhythms — markers of the body’s biological clock which control many aspects of the metabolism.
Dr Loch said all aspects of the body’s metabolism had a clock. Some things had a 24-hour circadian rhythm while others had near weekly rhythms.
"This relates to many aspects of our metabolism, not only tooth growth."
She said the study found adolescents with a faster dental biorhythm (five or six-day cycle) weighed less, gained less weight, and had the smallest change in their body mass index over 14 months.
Those with a slower biorhythm (seven or eight-day cycle) produced the greatest weight gain.
"Less growth lines equal a faster biorhythm and a faster metabolism."
Dr Loch said the results were unique.
"They show a previously unknown link between markers of biorhythms in teeth — similar to the growth rings we see in trees, our teeth also show a similar structure, and weight gain."
The duo collected shed baby teeth and took monthly weight, height, and lower leg length measurements of 125 children in 19 Dunedin schools.
"While teeth were also collected in other centres [the United Kingdom, United States and France), the New Zealand arm of the project was unique because we were actually collecting growth data from living participants."
One surprising find was participants with slower biorhythms were six times more likely to have a very high body mass index, she said.
"Although development of obesity is a multifactorial process and will depend on lifestyle, socioeconomic, and psychological factors, we show baby teeth can be a biological marker for predisposition to greater weight gain in early adolescence, many years before the health risks associated with obesity will develop."
