Dental growth rhythms
Research type
Research Study
Full title
Growth rhythms in human permanent tooth enamel
IRAS ID
203541
Contact name
Patrick Mahoney
Contact email
Sponsor organisation
University of Kent
Duration of Study in the UK
5 years, 0 months, 2 days
Research summary
BACKGROUND
Human tooth enamel grows incrementally. Each increment is marked by a growth line, like shells and trees. The number of days of enamel growth between adjacent lines, termed Retzius periodicity, varies within and between mammalian species, though it remains constant within the permanent teeth of any one individual. Thus, humans are born with a pre-determined biorhythm, and evidence of this rhythm is retained within enamel.IMPORTANCE
Retzius periodicity correlates with species-specific body mass, when compared between mammals. Through its influence on body mass, it is hypothesized that this biorhythm is further linked to the timing of many life history events and related characteristics, such as birth weight, age at sexual maturity, and life span. Teeth preserve well after death. Therefore, Retzius periodicity holds great potential for
investigating aspects of a species’ biology from fossilized teeth.PROBLEM
It is not known if ’links’ between the biorhythm, body mass, and life history, hold within humans. One prior study on a few adults (n=4) suggested they might. My published pilot research on a small sample of human deciduous teeth (n=14) indicates the biorhythm does not follow predictions derived from correlations across mammals. My pilot research indicates the biorhythm in human deciduous teeth may exist to produce tooth enamel, regardless of body mass.QUESTIONS
1. Assess if Retzius periodicity corresponds with average and relative enamel thickness in permanent third molars (n=100).2. Determine if Retzius periodicity corresponds with permanent third molar crown formation time (n=100).
3. Identify if Retzius periodicity varies between men and women (n=100).
4. Assess if Retzius periodicty corresponds with rate of enamel growth (n=100).
WHERE?
This enamel histology research project will be undertaken in the Human Osteology Research Lab, University of Kent.HOW?
This five year project will use human permanent third molars, previously extracted by dentists in the 1950s. All teeth are anoymised. Only the sex of the individual and the tooth type has been documented.REC name
South Central - Hampshire A Research Ethics Committee
REC reference
16/SC/0166
Date of REC Opinion
31 Mar 2016
REC opinion
Favourable Opinion