Parathyroid Hormone: Is It Really the Cause for Increased Tooth Mobility after Orthognathic Surgery?

Introduction: Following orthognathic surgery, increased tooth mobility is observed clinically and is utilized for postsurgical orthodontic tooth movement. It was suggested that the increase may result from a surgery-associated alteration of parathyroid hormone (PTH) and calcium metabolism. Materials and Methods: 30 young adult patients were divided into a mandibular osteotomy group (Group A, n = 20) and an untreated control group (Group B, n = 10). Tooth mobility was evaluated using the Periotest device. Tooth mobility, serum PTH and calcium levels were determined repeatedly for both groups. Results: The tooth mobility was increased significantly in the Group A patients in the first 10 days post-surgery. All serum PTH and calcium mean levels were within normal ranges. No significant differences were found between the measurements of both groups. The serum calcium levels recorded at the 1st post-surgery day were slightly lower in the operated patients compared to the control group. Conclusion: It can be concluded that the increased facility of orthodontic tooth movement immediately post-surgery was confirmed by Periotest measurements, while no association was found with surgery-related altered levels of PTH and calcium. Since dietary effects can be ruled out, the increase of clinical tooth mobility may rather result from preoperative orthodontic forces and/or the post-surgical elimination of masticatory muscular influences.