Mysteries of asymmetries

Abstract

I am going to discuss the treatment of asymmetries, the cause of which may be dental, functional, skeletal, or combinations of the three. I will spend minimal time reviewing dental and functional asymmetries because they have been well described in the literature. A dental asymmetry diagnosed in the mixed or transitional dentition should be intercepted early to establish more symmetric maxillary and mandibular dental arches. Orthodontic objectives may include maintaining or regaining arch length or correcting significant dental asymmetries through tooth movement. In the permanent dentition, dental asymmetries are corrected through tooth movement. Difficulty arises when the maxillary dental midline is coincident with the patient’s facial midline and the asymmetry is in the mandibular arch, which is often the case. Alteration of the well-positioned maxillary arch by treating or matching it to the asymmetric mandibular arch may result in esthetic compromise. The limit of maxillary midline deviation found to be esthetically acceptable to patients is approximately 2 mm on either side of the patient’s facial midline. For this reason, mandibular permanent tooth removal or opening space for prosthetic replacement of an additional mandibular tooth may be necessary to resolve the asymmetry in the mandibular arch. Functional asymmetries may be diagnosed by accurately determining if the patient presents with a discrepancy between centric relation and maximum intercuspal position. If a functional asymmetry is diagnosed in the mixed dentition, interception should be instituted as early as is practical to establish more ideal maxillary skeletal width and to eliminate the functional mandibular shift. The objective should be to establish coincidence of dental midlines with each dental midline centered on their respective skeletal bases while eliminating the functional component of the malocclusion. After this first phase of maxillary sutural expansion, the clinician