American Board of Orthodontics (ABO) Practice Exam

Replacement resorption, also known as ankylosis, occurs when the periodontal ligament is damaged and the tooth begins to fuse with the surrounding bone. This can lead to several sequelae in the affected teeth, one of which is the mobility of the tooth. When a tooth undergoes replacement resorption, the natural supports that hold the tooth in place are compromised. The loss of the periodontal ligament means there is less cushioning and anchorage for the tooth, which can lead to an increase in mobility. In a healthy tooth, the periodontal ligament provides both support and the ability to withstand functional forces; when this structure is compromised, the stability of the tooth can be negatively affected. Mobility is an important clinical sign that indicates a problem with a tooth’s support system. In cases of replacement resorption, the mobility may increase as the resorption process progresses and the attachment to the bone becomes more rigid in nature, leading to a clinical scenario where even minimal forces can demonstrate increased movement of the tooth. While pulp calcification, root fractures, and internal resorption can occur in various dental conditions, they are not directly associated with the characteristic process of replacement resorption. Thus, mobility stands out as a common occurrence in teeth affected by this process.