Relationship between alveolar bone thickness, root apex position, and cephalometric skeletal indexes in the upper anterior teeth of adults with Class Ⅱ malocclusion.

Abstract

Abstract Objectives To measure the alveolar bone thickness and root apex position in the upper anterior teeth of adults with Class Ⅱ malocclusion, and to explore the correlation with the corresponding cephalometric skeletal indexes. Materials and Methods Retrospective data collection was done on 90 adult patients with Class Ⅱ malocclusion. Measurement of sagittal skeletal patterns (SNA, SNB, ANB), vertical skeletal patterns (GoGn-SN), labial, lingual and total alveolar bone thickness in the root apex area (Tlabial, Tlingual, Ttotal), the labial, lingual and total rotation range of root (Rlabial, Rlingual, Rtotal), calculating root apex position (Pdistance, Pangle), and conducting correlation research. Results Tlabial(1.08 ± 0.96mm) and Rlabial (8.65 ± 7.33°) were significantly smaller then Tlingual(5.07 ± 1.7mm) and Rlingual(35.68 ± 14.82°) (P < 0.01) respectively; Ttotal was 6.15 ± 2.06mm, and Rtotal was 44.33 ± 14.38°; The maxillary central incisor root apex was situated at about 20% of the labial side of the alveolar bone (Pdistance: 19.04 ± 14.58%, Pangle: 21.10 ± 15.64%). Pearson correlation showed that: Ttotal, Rlingual and Rtotal were negatively correlated with GoGn-SN (r=-0.415, P < 0.01; r=-0.358, P < 0.05; r=-0.444, -0.411, P < 0.01); Ttotal, Rlingual and Rtotal were positively correlated with SNB (r = 0.316, P < 0.05; r = 0.421, P < 0.01; r = 0.476, P < 0.01). Conclusions In Class Ⅱ malocclusion the root apex is located on the labial side of the alveolar bone, and the thickness of the alveolar bone on the labial side is thin. The labial side of the maxillary incisor and the total alveolar bone thickness should be carefully examined in patients with high mandibular plane angle and mandibular retraction. Clinical Relevance: The study shows that it is important to evaluate the alveolar bone thickness and root apex position before orthodontic treatment, and to guide clinical practice from cephalometric measurement.