A longitudinal study of tooth growth in a single individual based on long‐ and short‐period incremental markings in dentine and enamel

Abstract

AbstractGround sections of teeth from a single individual revealed approximately 30 fluorescent lines in the dentine resulting from successive courses of tetracycline antibiotics given over a period of approximately 12 years. In addition, many teeth showed long‐period incremental markings in the dentine. Short‐period daily cross‐striations in the enamel were used to calculate the periodicity of the long‐period incremental lines in both enamel and dentine. The incremental markings in the dentine were then used to calibrate the time of administration of each of the courses of tetracycline antibiotics. Enlarged micrographs of the teeth, constructed using fluorescence microscopy, were used to measure the increase in height of different teeth throughout the growth period on each occasion the tetracycline antibiotics were given. The times of initial mineralization of the teeth and the duration of crown formation were also determined for each tooth section. Line plots of tooth height against age were computed and used to calculate the rate of increase in tooth height during crown and root formation for one example of each tooth type. Initial rates of increase in height during enamel apposition and coronal dentine formation were fast, between 10 μm and 14 μm per day. During the latter phase of crown formation and during early root formation, tooth height increased at a slower rate of between 4 μm and 6 μm per day. Rates of increase in tooth height then rose to between 13 μm and 26 μm per day during the second half of root formation before falling off to a rate of approximately 4 μm per day during root completion (as the root apex formed). The times of initial crown mineralization and the total crown formation times estimated in this individual were all within the range known for modern humans but there was comparatively early mineralization of the third permanent molar. These findings are discussed in the context of other studies on human dental development.