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OBJECTIVE: The purpose of this study is to determine the eruption patterns of maxillary and mandibular central incisors from the first occlusal contacts to adulthood while comparing the differences in male and female eruption patterns. Previous studies have failed to obtain measurements into adulthood. We hope by using a final measurement during a subjects' adulthood we can better estimate final eruption times and measurements.
METHODS: The material for this research project was obtained from the Meredith Facial Growth Study from the University of Iowa Orthodontics Department. Records from a set of 64 subjects (35 males and 29 females) were used. Each of these patients had intraoral models taken throughout adolescence into adulthood. A final model was available for each subject in their twenties. Twenty-eight subjects had final records available in their forties (15 males and 13 females). Measurements were recorded for the maxillary central incisors (Teeth 8 and 9), and the mandibular central incisors (Teeth 24 and 25). Measurements points were the incisal edge of the tooth to the most apical (deepest) curvature of the gingival margin. Measurements were taken at eleven time points for all sixty-four subjects starting at year 8 and yearly until age 18 with a final measurement taken on a model from the patient's twenties. A subset of twenty-eight subjects contained measurements in their forties.
RESULTS AND CONCUSIONS: Differences between male and female mean crown heights were only present on maxillary incisors at early ages. Tooth 8 at ages 8 to 12 and for tooth 9 at ages 10 to 11. All other ages and all other teeth showed no gender differences. Eruption rates differ for males and female for tooth 8 only. Teeth 9, 24, 25 all showed no differences in their rate of increasing crown height over time. A significant age effect for teeth 8 and 9 and also teeth 24 and 25 in the subset studies was found. There was no significant factor between age and gender. Teeth heights at age 20 and 40 were significantly greater than age 11. At age 40 heights were significantly greater than age 20. Teeth continue to erupt unto a patient's forties.