Orthodontic preparation is critical to the success of orthognathic surgery. Recognition and correction of existing dental compensations allows full correction of skeletal discrepancies. Presurgical orthodontic goals are important to define at the start of treatment and may not always include complete arch leveling or space closure, or ideal interdigitation. Orthodontic preparation dictates the skeletal movements that are possible at the time of surgery. Different malocclusion types have characteristic dental compensations that can be identified and described. Proper planning, monitoring, and communication between surgeon and orthodontist are critical to avoid potential pitfalls in the orthodontic preparation.

Keywords

Orthodontics

Orthognathic surgery

Treatment planning

Key points

Introduction

Proper orthodontic preparation is critical to the outcome of orthognathic surgical treatment (Box 1, Table 1). All orthodontic tooth movement should be planned before treatment, even if some movements are completed after the surgery. The ultimate goal is to create a situation in which the teeth are in proper position relative to their underlying skeletal bases.1 This goal creates a presurgical dental discrepancy that is at least as great as the skeletal discrepancy so that the occlusion acts as a guide for the surgeon to produce the optimal position of the skeletal parts during surgery. Because normal physiologic processes tend to compensate for the skeletal problem, significant tooth movement is generally needed to create the most esthetic and balanced outcome for the patient. Patients undergoing orthognathic treatment with orthodontic preparation should be well informed about the orthodontic procedures and what to expect from treatment and retention.2

Presurgical goals

There is no universal agreement among orthodontists and surgeons about the goals of orthodontic treatment before surgery. Some teams prefer nearly ideal interdigitation of presurgical plaster models before proceeding, whereas others are content to do the detailed finishing after surgery. In general, the guiding principle is that the teeth need to be moved sufficiently to allow the maxilla and mandible to be put in the desired position.3 If this general principle is used as a guide, it is possible to define certain parameters of presurgical goals.

Three concepts and a corollary for orthodontic preparation

Whenever Possible, Treatment Should Be Planned so that the Orthodontic and Surgical Relapse Tendencies Are in Opposite Directions

The idea is to be well informed regarding possible posttreatment changes that will affect the stability of the final correction. When possible, it makes sense to plan orthodontic movements in a direction that causes any orthodontic change to be in the opposite direction to the expected surgical change. For example, if the maxilla is to be surgically expanded in a transverse direction, the surgical posttreatment tendency is to narrow slightly after treatment.7 Expanding the maxillary dentition orthodontically, either intentionally or inadvertently, has a relapse tendency in the same direction and therefore is additive to the surgical change. In contrast, if the arch is constricted orthodontically, the orthodontic relapse tends to expand the arch slightly. If this is combined with a surgical tendency to narrow, the resultant changes are offsetting rather than...