Evaluation of Hyoid Position and Retroglossal Airway After Mandibular Alveolar Archwise Distraction Osteogenesis.

The interaction between form and function in the craniofacial region is a well-accepted fact in orthodontics. The aim of the present study is to objectively evaluate if mandibular sagittal symphyseal distraction causes an increase in the retroglossal airway size and hyoid position in a retrospective clinical study. The pretreatment (T0) and 3 months post-distraction (T1) cone-beam computed tomography images of 12 patients (mean age 17.1 years) were retrieved. The retroglossal airway volume and hyoid-mandibular plane distance, hyoid-C3 distance, sella-nasion-B point angle angle, lower incisor to mandibular plane, and Mandibular plane angles were measured using 3D medical imaging software. The average amount of distraction at the superior border of the bony transport segment was 6.2 mm and 4.4 mm at the inferior border. The changes in retroglossal airway volume (2943.2 mm), incisor to mandibular plane (6.5°), and mandibular plane (2.1°) were significant. The changes in hyoid-mandibular plane distance and hyoid-C3 distances were not significant. However, a downward repositioning in Hyoid position was observed along with the mandibular clockwise rotation. This study showed that symphyseal dentoalveolar distraction osteogenesis, as a complementary to orthodontic therapy, can affect the form and size of the pharynx. Therefore, the airway size should be one of the diagnostic and decisive factors for an ideal treatment planning.

Effects of local platelet-rich plasma injection on the rate of orthodontic tooth movement in a rat model: A histomorphometric study.

INTRODUCTION: The aims of this study were to determine the effects of different concentrations of platelet-rich plasma (PRP) on alveolar bone density and orthodontic tooth movement. METHODS: Seventy-six rats were divided into 2 groups: a moderate concentration PRP injection group (n = 38) and a high concentration PRP injection group (n = 38). In each group, 5 time points were studied: 3, 7, 14, 21, and 60 days. Before orthodontic mesialization of the maxillary first molars, moderate and high concentrations of PRP were injected on the right sides of the molar buccal sulcus, and the left sides served as the controls. Tooth movements were measured on 3-dimensional digital models. Alveolar bone volume density and osteoclastic activity in the first molar intraradicular areas were evaluated by histomorphometric analysis. RESULTS: Alveolar bone density was decreased in the experimental groups compared with the control groups (P = 0.0001) at 3, 7, 14, and 21 days. On day 3, osteoclastic activity of the experimental groups was higher than that of the controls (P = 0.044, P = 0.0001). On day 21, the amounts of tooth movement in the high-concentration experimental group were 1.7 times greater than in the high-concentration control group and 1.4 times greater than in the moderate-concentration experimental group (P = 0.001). On day 60, alveolar bone density increased to the original levels in all groups. CONCLUSIONS: Injection of both moderate and high concentrations of PRP may accelerate orthodontic tooth movement by decreasing alveolar bone density on paradental tissues by enhancing osteoclastic activity in a transient way.