American Board of Orthodontics (ABO) Practice Exam

During orthodontic treatment, the primary cellular activity differs between the tension side and the compression side of the dental arch due to the mechanical forces exerted by braces or other orthodontic appliances.

On the tension side, where the bone is being stretched, there is an increase in the activity of osteoblasts. Osteoblasts are responsible for bone formation, and their activation helps to build new bone in response to the tensile forces. This process is essential for allowing teeth to move in the desired direction and for maintaining the stability of the surrounding bone structure.

Conversely, on the compression side, where the bone is being compressed, osteoclasts are activated. Osteoclasts are responsible for the resorption of bone, which allows for the remodeling process that occurs as the teeth move through the alveolar bone. This resorption creates space for the teeth to shift into their new positions.

The distinction between these two processes—osteoblast activation on the tension side and osteoclast activation on the compression side—is fundamental to understanding the biological responses during orthodontic tooth movement. This coordinated activity ensures that as teeth are moved, the surrounding bone continuum adjusts appropriately, facilitating a successful treatment outcome.