The limit of mandibular incisor correction is dependent on the amount of crowding and the incisor position within the mandibular alveolar bone. Moving teeth outside of the alveolar bone can have detrimental effects on the periodontium. The purpose of this study was to evaluate in 3D incisor angulation, B point, root apex position changes, facial and lingual cortical bone thickness at four levels on each tooth, and 2D lower incisor angulation to the true vertical plane and intercanine width changes. Pre- and post-treatment Cone Beam Computed Tomography images of 67 orthodontic patients were included from the BU repository. 276 mandibular incisors and 138 canines were evaluated. A mandibular plane was used as a horizontal reference plane. 3D measurements of angular changes in apex to constructed Menton plane for all four lower incisors increased by a statistically significant amount. (p<0.0001) Intercanine width (p=0.0032), arch length discrepancy (p<0.0001) incisor angulation for each incisor also showed statistically significant differences (mean change 2.3°, mean p=0.009). Changes in L1-NB were also found to be statistically significant (p < 0.005). Incisor bone thickness changes were statistically significant. Lingual bone change in LL1 at point A, was –0.18 mm, p=0.0072: at point B, -0.38, p<0.0001: at point C, -0.56, p<0.0001: at apex point -0.65 mm, p<0.0001. Similar lingual bone thickness changes were noted for all incisors. The results show that lingual bone loss increased from superior reference point (A) to apex, suggesting that roots are tipped around the center of resistance.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/35683 |
| Date | 20 May 2019 |
| Creators | George, Kelsey Ann |
| Contributors | Briss, David |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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