American Board of Orthodontics (ABO) Practice Exam

Chronic injections of parathyroid hormone (PTH) have been shown to influence tooth movement significantly, primarily by accelerating the rate at which teeth move within the alveolar bone during orthodontic treatment. Research indicates that the application of PTH can enhance the osteoclastic activity and bone remodeling processes, leading to an increased rate of tooth movement. Specifically, studies have reported that the rate of movement can increase by approximately 1.6 to 2 times compared to control groups not exposed to PTH.

This increase in tooth movement can be attributed to the hormone's role in stimulating bone resorption in the areas where the tooth is being displaced, promoting faster adaptation of the surrounding bone to the applied forces from orthodontic appliances. As a result, the enhanced cellular and molecular responses associated with chronic PTH administration create a more favorable environment for efficient orthodontic tooth movement.

In contrast, the other options suggest various effects—like slowing down movement, having no effect, or improving stability—which do not align with the established understanding of how chronic PTH influences tooth mobility in the context of orthodontics.