Mandibular rotation revisited: What makes it so important?

Orthodontists have long been aware that mandibular rotation takes place during growth, but most have underestimated its importance. This is so because the distinction between the true rotation and the rotation of the mandibular plane is typically not made. Traditionally, orthodontists have focused on the mandibular plane, which changes little because modeling on the lower mandibular border largely hides the true rotation that occurs. Furthermore, orthodontists must understand that changes in tooth position—over which they have great control—play an important role in determining the true rotational changes that occur. Such an appreciation is of particular importance when evaluating Class II cases, for which true rotation is critically important, in terms of both the development and solution of the problem. Clinically, they must be aware of and able to use the various centers of rotation to prevent deleterious changes from occurring and to orthopedically correct the problems that have developed. Orthodontists must understand that true rotation is the primary determinant of chin position and a major determinant of condylar growth direction, mandibular modeling, and dentoalveolar compensations. They must learn how to take advantage of the mandible's capacity to adapt to rotational changes.