THE RELATION BETWEEN LONG-PERIOD INCREMENTAL MARKINGS IN DENTIN AND DAILY CROSS-STRIATIONS IN ENAMEL IN HUMAN TEETH

Ground sections of human permanent teeth were chosen where fluorescent labels in the dentine, resulting from repeated doses of tetracycline antibiotic, were unambiguously associated with accentuated markings in the enamel developing at the same time. Counts of daily cross-striati ons in enamel were continued from one tooth to another in a developmen tal sequence over a period of some 1200 days such that the time interv al between doses of tetracycline could be calibrated. Long-period incr emental markings in the dentine, spaced on average between 15 and 30 m u m apart (and first described by Andresen in 1898) were easily visibl e in the coronal dentine when the ground sections were viewed with pol arized light. The total number of long-period incremental markings in the dentine between the consecutive fluorescent labels was also counte d. A regression plot of daily incremental lines in enamel against long -period lines in dentine demonstrated a regular and consistent relatio n between the two (r = 0.997) over a 1200-1300-day period. These data support the hypothesis that long-period markings in dentine are in fac t regular incremental markings with a constant periodicity in an indiv idual. They also suggest that regular long-period markings in dentine can be used to reconstruct the timing of tooth growth or to retrieve d evelopmental information about dentine formation rates in forensic, ar chaeological and palaeontological studies with some confidence. Copyri ght (C) 1996 Elsevier Science Ltd.