Tomographic Evaluation of the Lower Incisor's Bone Limits in Mandibular Symphysis of Orthodontically Untreated Adults

The amount of available bone in the lower incisor region is critical for periodontal preservation when planning large anteroposterior dental movements. The aims of this study were to evaluate bone limits of the lower incisors in the mandibular symphysis and to verify whether they are influenced by facial growth patterns, lower incisor inclinations, skeletal anteroposterior relationships, or patient age. Tomographic images of 40 orthodontically untreated patients were evaluated and measurements of width and height of the mandibular symphysis, thickness on the lingual and labial sides of the alveolar bone, and thickness of the entire alveolar bone were performed in sagittal view. The following cephalometric measurements were also evaluated: growth pattern (FHI), lower incisor inclination (IMPA), and skeletal anteroposterior relationships (AO-BO). Pearson's correlation test was used to assess associations among bone measurements, cephalometric measurements, and patients' ages. Weak to moderate positive correlations between FHI and bone measurements on the labial side of the incisors and total alveolar width were found. The height of the symphysis had a moderate negative correlation with FHI. It was concluded that patient age, FHI, and IMPA influenced bone limits of the lower incisors in the mandibular symphysis, while AO-BO had no influence.