Orthognathic surgery, commonly known as jaw surgery, corrects significant skeletal and dental irregularities by aligning the upper and lower jaws for improved function and appearance. A primary concern following this procedure is relapse, the tendency for the surgically repositioned jaw segments to gradually shift back toward their original, misaligned position. Relapse risk is influenced by mechanical, biological, and muscular forces, requiring a multi-faceted approach that extends beyond the operating room. Successfully maintaining the new skeletal position depends on immediate post-operative care, long-term mechanical support, and the retraining of surrounding soft tissues.
Ensuring Initial Surgical Stability
The immediate success of orthognathic surgery relies on the stability achieved at fixation. Rigid internal fixation (RIF) is the standard method, utilizing small titanium plates, screws, and sometimes wires to secure the bone segments at the osteotomy sites. This hardware provides the initial framework necessary to maintain the corrected skeletal relationship. Even with RIF, stability can vary, as procedures involving large movements or specific rotations, such as counter-clockwise rotation of the mandible, are inherently less stable.
The first six to twelve weeks post-surgery represent the bone healing phase where non-chewing is paramount. Patients must adhere strictly to a liquid or non-chew diet to prevent excessive force on the healing bone segments. Advancing the diet too quickly can stress the fixation hardware, potentially leading to plate or screw failure and increasing the risk of early skeletal relapse. Adequate nutrition, particularly a diet rich in protein, calcium, and vitamins C and D, supports tissue repair and bone regeneration.
The Necessity of Orthodontic Retention
After initial bone healing, mechanical retention devices prevent the teeth and jaws from shifting. Post-surgical orthodontic treatment, including retainers and splints, continues the overall treatment plan and is distinct from surgical fixation. Retention is required because the soft tissues surrounding the teeth and jaws, such as the gingiva and ligaments, possess a “memory” that attempts to pull the teeth back toward their pre-treatment locations.
Various appliances manage these forces, including removable Hawley retainers and clear vacuum-formed retainers. These are often worn full-time initially, transitioning to nighttime-only wear for an extended period. Fixed or bonded retainers, which consist of a thin wire cemented to the back surface of the front teeth, provide continuous, long-term stability against dental relapse. Occlusal splints may also be used early post-operatively to guide the bite and provide temporary stabilization while soft tissues adapt. Retention protocols must be followed diligently, as minor lapses can permit unwanted movement.
Addressing Muscular and Behavioral Factors
Beyond skeletal and dental mechanics, active forces generated by the surrounding musculature and patient habits are long-term drivers of relapse. The chewing muscles, such as the masseter and pterygoids, have a strong memory and can exert significant pressure that slowly overcomes mechanical fixation. Poor oral habits, referred to as orofacial myofunctional disorders, contribute substantially to this muscular relapse.
Detrimental habits include tongue thrusting, where the tongue pushes against the back of the front teeth during swallowing, and habitual clenching or grinding (bruxism). Mouth breathing causes the tongue to rest in an incorrect low position, failing to provide internal support for the upper jaw. Myofunctional Therapy (MT) is a specialized program designed to retrain the tongue and facial muscles to rest and function in a neutral position that supports the new jaw alignment.
MT teaches correct oral rest posture, where the tongue rests fully against the palate, supporting the maxilla and counteracting outward forces. This retraining is important in high-angle cases or where significant mandibular advancement occurred, as muscle tension is often increased. Treatment involves personalized exercises performed over six to twelve months to establish new, stable muscular patterns.
Long-Term Monitoring and Early Detection
Maintaining the results of jaw surgery requires long-term professional oversight. Regular follow-up appointments with the surgeon and the orthodontist monitor the stability of the skeletal and dental correction. This monitoring schedule often includes checkups at the one-year and five-year marks, as subtle changes can accumulate over time.
Diagnostic tools, particularly periodic lateral cephalometric X-rays, quantitatively assess skeletal changes. These images allow the healthcare team to measure precise angular and linear movements of the maxilla and mandible, such as changes in the SNB angle or the position of Point B. Early detection of minor skeletal or dental relapse allows for timely intervention, such as adjusting the orthodontic retention protocol or initiating additional myofunctional exercises, before the movement becomes clinically significant. Collaborative communication between the patient, the surgeon, and the orthodontist maintains the long-term success of the procedure.