Symmetry in the developmental stages of permanent human teeth: a comparative study between maxilla and mandible.

Abstract

Objective: The aim of this study was to assess symmetry of developmental stage of permanent teeth between the left and right side of the jaw, as well as between the maxilla and the mandible.

Methods: A sample of 150 panoramic radiographs of individuals aged 6-20 years (69 males, 81 females) were selected from an open-access radiographic collection (Maxwell Museum of Anthropology's orthodontic collection, Albuquerque, USA). All developing immature permanent teeth (n = 489) were scored by the first author using Moorrees and Demirjian tooth stages. Symmetry of developing teeth was assessed between the left and right sides of the jaw, as well as between the maxilla and the mandible using McNemar test with p < 0.05 considered significant.

Results: No significant differences were found comparing left and right sides within the maxilla (n = 489), (McNemar, p = 0.759 M, p = 0.736 D), or within the mandible (McNemar, p = 0.262 M, p = 0.707 D) using either tooth scoring method. Percentage agreement for individual teeth between left and right sides was least for third molars. Significant differences were observed comparing maxillary and mandibular teeth for both tooth scoring methods (n = 978), (McNemar, p = 0.00 M, p < 0.001 D). Percentage agreement for individual teeth between the maxilla and mandible was least for incisors.

Conclusion: In the present sample, differences in tooth formation were not significantly different in left and right side of the jaw while a significant difference (p = 0.00 M, p < 0.001 D) was observed between maxilla and mandible.