Dentofacial and Maxillofacial Deformities (part 2)

Chin Deformities

Patients with small chins may be treated with a variety of implants, or the chin itself may be moved forward. The advantages of moving the chin forward are several. Often the chin deformity is more complex than simple recession. Frequently patients need the chin to be moved forward and down slightly to improve its vertical height. An osseous genioplasty, or bony chin advancement, is a simple procedure that moves a patient's own chin. Because some of the muscles of the neck are attached to the undersurface of the chin, improvement in neck anatomy can be dramatic. Perhaps no other operation offers as dramatic of an improvement in appearance than advancement of the chin. In patients with large chins, chin reductions can also be carried out in a simple fashion. Frequently patients with chin deformities have coexisting deformities of the nose and upper and lower jaws. Such deformities can be diagnosed and recommendations made regarding preliminary orthodontic management.

 

Upper Jaw Deformities

The upper jaw (maxilla) often presents with a variety of abnormalities. One of the most common is called vertical maxillary excess. In patients with excess bone of the upper jaw, the face appears long, patients have a gummy smile, and frequently the chin is recessed and the nose large in the profile view. In patients with maxillary recession, the upper jaw can be moved forward. Children with cleft lip and palate frequently have maxillary recession and are candidates for maxillary (LeFort I) advancement. Patients without a cleft lip and palate may also find their upper teeth are behind their lower teeth. Frequently this is due to deficiency in the upper jaw. Again, the upper jaw can be moved forward to correct the dental, as well as aesthetic, deformity. Patients with short faces may require maxillary lengthening. Patients with upper facial asymmetry often have associated abnormalities of the lower jaw (mandible). Asymmetry may arise because of congenital conditions such as hemifacial microsomia or Goldenhar Syndrome, or more commonly from trauma to the temporomandibular joint region earlier in life. Asymmetry is corrected by repositioning the upper, and often lower, jaw in a combined surgical-orthodontic approach.

 

Lower Jaw Deformities

The lower jaw, or mandible, is subject to many abnormalities as well. Mandibular excess (protrusion) and mandibular deficiency (retrusion) are very common in the general population. In patients with mandibular deficiency, a history of snoring and possibly sleep apnea may also be present. Patients with nighttime wakefulness, restless sleep, noisy breathing, and daytime somnolence with poor school or job performance may have associated sleep apnea. Mandibular deficiency is corrected after orthodontic treatment by moving the lower jaw forward. Occasionally the chin may also need to be repositioned. Mandibular excess, if severe, is corrected by moving the lower jaw back. In more mild cases of mandibular excess, the problem is corrected by moving the upper jaw forward. It is extremely important to determine whether preexisting disorders of the temporomandibular joint mechanism exist. Together with the orthodontist, other dental specialists, and the plastic surgeon specializing in maxillofacial or craniofacial surgery, a treatment plan can be outlined with special attention paid to the temporomandibular joint. Temporomandibular joint ankylosis, or fusion, may limit the opening of the jaw. This may result from trauma or congenital conditions, or be acquired secondary to tumors and etiologies. Ankylosis can be treated by a variety of techniques ranging from simple release of the fused joint to more extensive reconstruction using the patients' own rib with a cartilage cap (costochondral graft).

 

Combined Upper and Lower Jaw Deformities

It is not unusual in cases of facial asymmetry, severe mandibular excess, and maxillary deficiency that combined upper and lower jaw surgery may be necessary. Although slightly more difficult cases, excellent results can be obtained using a surgical-orthodontic approach.

 

Trauma to the Jaws

Treatment of trauma to the jaws requires the special expertise of craniofacial surgeons to achieve the best results. Post-traumatic deformities can also be predictably managed once a treatment plan has been established.

 

Pre-Prosthetic Surgery

Patients requiring dental implants in both the upper and lower jaws frequently do not have enough of their own bone to support a dental implant long term. In order to prepare patients undergoing dental implants, a variety of techniques have been utilized to augment the existing bone. Using the patient's own bone from the hip (iliac) and other sites, a variety of onlay and inlay bone grafts can be carried out. Our experience in complex craniofacial and maxillofacial care makes us uniquely suited for this type of work. Often creative solutions in difficult situations are required and, fortunately, this defines the job of the plastic surgeon specializing in maxillofacial and craniofacial surgery.

 

Distraction Osteogenesis

Distraction osteogenesis of the craniofacial skeleton is a new technique whereby extensive jaw surgery can be accomplished with less invasive techniques. Initially invented by a surgeon working in Russia for orthopedic limb lengthening, devices have been applied to the lower and upper jaws to allow gradual repositioning of the facial bones. These techniques may be especially suitable in younger children. In children with very small lower jaws, who have difficulty breathing and who have obstructive sleep apnea, mandibular advancement may be carried out by the technique of distraction osteogenesis. This often obviates the need for more complex surgery and lessens the hospital stay. As instrumentation improves, these techniques will become less invasive, more widespread, and more suitable for patients with simpler dentofacial deformities.

 

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