Passive eruption patterns in first molars

OBJECTIVE: The purpose of this study is to determine the eruption patterns of maxillary and mandibular first molars from the first occlusal contacts to adulthood. Previous studies have failed to obtain measurements into adulthood or have not been longitudinal in design. By using a measurement during the subjects' adulthood, a better estimate of the changes that occur between the tooth and the gingival margin throughout growth and aging can be obtained. 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 (14 males and 14 females). Measurements were recorded for the maxillary first molars (Teeth 3 and 14), and the mandibular first molars (Teeth 19 and 30). 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. Bitewing Radiographs were also used to measure changes in alveolar bone height at 12, 20, and 40. RESULTS AND CONCUSIONS: Alveolar bone heights and their changes over time measured from the CEJ indicate that the sample population had a stable periodontium. Crown heights at age 20 and 40 were significantly greater than age 11. At age 40, crown heights were significantly greater than age 20. Teeth continue to erupt into a patient's forties in the absence of bone loss and attrition.