Long-Term Stability of Lower Jaw Advancement Surgery: What a Five-Year Study Reveals

Published 29 August 2026
Reviewed by Dr. Advaitha Anand, BDS MDS (Conservative Dentistry & Endodontics)

Understanding Class 2 Malocclusion and Jaw Surgery

For individuals with a skeletal Class 2 malocclusion—a condition where the lower jaw is positioned further back than normal—jaw correction can be an important part of their care. One common surgical option is a bilateral sagittal split osteotomy (BSSO), a procedure used for mandibular advancement (moving the lower jaw forward). During this procedure, the jaw is repositioned and secured using rigid fixation, which is a medical method of holding the bones firmly in place.

While patients often wonder about the long-term stability of such major procedures, a new retrospective cohort study has tracked how well the skeletal and dental corrections hold up over a period of up to five years.

How the Study Was Conducted

The study evaluated 32 patients who underwent mandibular advancement with BSSO and rigid fixation. The researchers analyzed the patients’ records and took cephalometric measurements—which are specialized measurements of the bones and soft tissues of the skull and jaw—at four distinct intervals:

Before the surgery (preoperative)
Immediately after the surgery (immediate postoperative)
One year after the surgery (12 months)
During a long-term follow-up period of more than three years

The researchers compared these measurements over time using a statistical test called the Wilcoxon signed-rank test to see if the jaw position, bite, or facial tissues shifted significantly.

What the Researchers Discovered

The study found that the surgical procedure achieved a significant immediate correction. On average, the patients’ lower jaws were advanced by 5.42 millimeters (with a variation of plus or minus 1.71 millimeters). Immediately after surgery, measurements showed a significant correction in the jaw structure, including an increased SNB angle (which measures the forward position of the lower jaw) and a decreased ANB angle (which measures the relationship between the upper and lower jaws). Along with these bone changes, patients experienced significant improvements in their occlusal (bite) alignment and their soft tissue facial profile.

Most importantly, the study revealed that the skeletal and bite corrections remained highly stable over the long term. There were no statistically significant changes in the skeletal and bite parameters between the one-year mark and the final long-term evaluation.

The researchers did note, however, that soft tissue remodeling—gradual changes in the skin, lips, and facial muscles—continued to occur throughout the follow-up period. Despite these ongoing adjustments in the facial soft tissues, the overall stability of the underlying bones and teeth was fully maintained.

Limitations of the Research

When interpreting these results, several key limitations must be considered:

Study Size: The research was based on a small sample size of only 32 patients.
Study Design: This was a retrospective cohort study, meaning it looked back at existing patient files rather than tracking a group of patients in real-time through a prospective clinical trial.
Specific Treatment: The study evaluated patients who received a specific combination of BSSO and rigid fixation. The outcomes might not be identical for patients who undergo different types of jaw surgery or other fixation methods.

What This Means for Patients

This study provides helpful information for patients who are exploring treatment options for a receded lower jaw. The findings suggest that a bilateral sagittal split osteotomy combined with rigid fixation can successfully correct a Class 2 malocclusion and maintain stable bone and bite alignment for several years. While the bone structure itself remains highly stable after the first year of healing, patients should expect that their facial appearance will continue to mature and adjust as the soft tissues of the face gradually remodel around the new jaw position.

Because every patient’s dental and skeletal structure is unique, anyone considering corrective jaw procedures should consult with their orthodontic and surgical specialists to discuss their individual options and potential outcomes.