American Board of Orthodontics (ABO) Practice Exam 2025 - Free Orthodontics Practice Questions and Study Guide

The condyle plays a crucial role in Posselt's envelope of motion, specifically as a center of rotation. In orthodontics and dental movement, the condyles, which are the rounded ends of the mandible, articulate with the temporal bone of the skull at the temporomandibular joint (TMJ). This anatomical relationship is fundamental to understanding how the jaw moves in three-dimensional space. The position and movement of the condyle directly influence the path that the teeth follow during various jaw functions such as opening, closing, and lateral excursions.

Posselt’s envelope of motion illustrates the limits of these movements and showcases the range of motion available to the mandible, determined largely by the spatial orientation of the condyles. Thus, the condyle functions as the pivotal point around which movements of the mandible, including translation and rotation, occur. This understanding is essential for orthodontic treatment planning and assessing the functional dynamics of the jaw in relation to tooth positioning and occlusion.

The other concepts, such as a pivot point for lateral movement, while relevant, do not encompass the full extent of the condyle's role in defining the entire range of mandibular motion outlined in Posselt's envelope. Rather, they refer to specific aspects of movement rather