The size and alignment of the lower jaw can significantly impact an individual’s health and well-being. When the lower jaw is underdeveloped or set back, it can lead to various functional challenges. Medical professionals, including oral and maxillofacial specialists and orthodontists, address these discrepancies. These interventions improve jaw function and overall oral health.
Understanding Lower Jaw Discrepancies
An underdeveloped lower jaw, also known as micrognathia or mandibular hypoplasia, can stem from congenital factors or develop later in life due to trauma or other conditions. This can lead to functional issues beyond facial appearance.
One common problem is malocclusion, where the upper and lower teeth do not align properly, affecting chewing and biting. Difficulties with the temporomandibular joint (TMJ), which connects the jawbone to the skull, can also arise from jaw misalignment. Breathing problems, particularly obstructive sleep apnea (OSA), frequently occur because a small lower jaw can cause the tongue to fall backward and block the airway, especially during sleep. Infants with micrognathia may also experience feeding difficulties and poor weight gain. Addressing these issues improves health.
Non-Surgical Expansion Techniques
For growing children, non-surgical methods, primarily orthodontic approaches, can guide lower jaw development. These techniques utilize functional appliances to encourage forward growth of the mandible. Functional appliances work by repositioning the lower jaw forward, which can influence the growth and remodeling of the jaw joint.
These appliances, such as the Twin Block, Bionator, or Herbst appliance, are most effective during active growth phases, typically up to age 14. They harness natural growth patterns and muscle forces to bring the bite into better alignment. While functional appliances may enhance mandibular length, their long-term effectiveness in significantly increasing growth is debated. Treatment with these appliances usually lasts between 6 to 18 months, often followed by additional orthodontic treatment to refine tooth positions.
Surgical Expansion Procedures
For more significant lower jaw discrepancies or in adult patients where growth modification is no longer an option, surgical interventions are often considered. Orthognathic surgery, commonly known as corrective jaw surgery, is performed by oral and maxillofacial surgeons.
A primary procedure for lower jaw advancement is mandibular advancement surgery, which repositions the lower jawbone to improve its alignment with the upper jaw. This procedure involves precise cuts in the lower jawbone, known as a bilateral sagittal split osteotomy (BSSO). The jawbone is then carefully moved to its new, advanced position and secured using small titanium plates and screws. This surgery corrects severe overbite, improves oral function, and alleviates breathing difficulties like sleep apnea. Maxillomandibular advancement (MMA) is a related procedure that moves both the upper and lower jaws forward to relieve airway obstruction, often used for obstructive sleep apnea.
Recovery and Long-Term Considerations
After lower jaw expansion, whether through non-surgical or surgical means, a period of recovery and ongoing care is necessary. Following surgery, initial healing involves managing swelling, which peaks around three to four days post-surgery and subsides over several weeks. Patients follow a soft-food diet for several weeks to allow the jaw to heal.
Physical therapy and specific exercises may be recommended to regain full jaw movement. Complete healing of the jawbones after surgery can take between 9 to 12 months. For both surgical and non-surgical cases, orthodontic treatment often continues after the initial expansion to fine-tune tooth alignment and ensure a stable bite. Long-term outcomes can include improved facial aesthetics, enhanced chewing and speaking abilities, and better breathing, especially for individuals with sleep apnea. Continued monitoring and retention protocols are important to maintain the achieved results.