Common Jaw Problems
Common Patterns of Facial Bone Imbalance
The growth and development of the jaws is a gradual process which begins soon after conception and continues until adulthood. During this time, an alteration of normal growth may occur, resulting in a facial bone imbalance.
Because the bones, teeth, and soft tissues of the face are intimately related to each other, a change in the growth of one structure will affect the growth of the surrounding structures. As a result, growth disturbances of the jaws typically result in predictable patterns of facial bone imbalance. Once a particular facial bone imbalance is identified, the surgeon and orthodontist can focus on the specific factors related to that particular pattern:
The cause of the facial bone imbalance (mouth breathing, tongue thrusting, etc.)
Associated issues (obstructive nasal breathing, speech issues, difficulty closing lips, difficulty chewing, etc.)
Necessary pre-operative preparation (speech therapy, sleep study, etc.)
Necessary surgical procedures
A proper follow-up protocol
This section will provide an overview of the more common patterns of facial bone imbalance.
Mandibular deficiency results from a lack of growth of the mandible (lower jaw). When viewed in profile, the lower jaw and chin appear deficient. The soft tissues of the lower jaw are unsupported resulting in a protruding and rolled lower lip, a deep fold between the lower lip and the chin (mento-labial fold), a full neck with a lack of definition, and the development of jowels at a young age. Treatment typically requires corrective jaw surgery to reposition the jaws. In many instances, additional procedures are performed such as a genioplasty (chin repositioning) and submental liposuction (liposuction of the neck area) to achieve the maximal aesthetic result.
Images of Mandibular Deficiency
Profile view before and after corrective jaw surgery for mandibular deficiency
Frontal view before and after corrective jaw surgery for mandibular deficiency
Mandibular excess results from an overgrowth of the mandible (lower jaw), typically with a concomitant undergrowth of the upper jaw. The lower jaw and chin appear prominent and the upper lip and tissues at the base of the nose may appear unsupported. The lower teeth are positioned in front of the upper teeth when the mouth is closed and there is difficulty keeping the lips closed. Treatment typically requires corrective jaw surgery of the upper and lower jaws. If the lower jaw is also asymmetric, additional special imaging studies may be required to determine the etiology of the asymmetry. An asymmetric lower jaw may require additional procedures such as a genioplasty (chin repositioning) and custom facial implants to achieve facial symmetry.
Images of Mandibular Excess
Profile view before and after corrective jaw surgery for mandibular excess pattern
Frontal view before and after corrective jaw surgery for mandibular excess
Maxillary Excess (Long face)
Maxillary excess results in a clockwise rotation of both jaws with vertical overgrowth of the maxilla (upper jaw) resulting in an excessive amount of visible tooth and gum (gummy smile) and a small and retrusive lower jaw. The upper jaw is often narrow in width. The long and narrow upper jaw combined with a small and retrusive lower jaw produces difficulty with lip closure. The nose is usually affected as well, with a nasal tip that is overly rotated in an upwards direction. This pattern of facial bone imbalance is thought to be caused as a result of childhood nasal obstruction and subsequent mouth breathing. The combination of this upper and lower jaw imbalance results in a larger–than–normal vertical height of the lower face (Long face syndrome). Proper correction typically involves improving nasal breathing, widening of the upper jaw, and repositioning of both jaws. In certain cases, additional procedures such as chin repositioning and liposuction will help to achieve maximum aesthetic results.
Images of Maxillary Excess (Long face)
Profile view before and after corrective jaw surgery for maxillary excess
Frontal view before and after corrective jaw surgery for maxillary excess
Anterior Open Bite
In this pattern of facial bone imbalance there is a separation between the front teeth when the jaws are in their closed position. Commonly the upper jaw is narrow with a high arched palate. This pattern of facial bone imbalance is typically caused by habits (tongue thrusting, tongue biting, thumb sucking, etc). The most common associated habit is tongue thrusting (see chapter 20). It is important to begin the process of reversing the causative habit prior to repositioning the jaws to help prevent relapse after the surgery is completed. Commonly, evaluation and treatment with a speech therapist is recommended to help reverse the habit. Correction typically involves widening and repositioning of the upper jaw. The lower jaw may require repositioning as well to achieve optimal results.
Images of Anterior Open Bite
Profile view before and after corrective jaw surgery for anterior open bite
Close up view before and after corrective jaw surgery for anterior open bite
A lack of growth of the upper jaw will lead to a pattern of facial bone imbalance referred to as maxillary deficiency. This pattern of jaw positioning, typically found in patients born with a cleft lip and palate, is usually a result of previous surgical procedures performed in early childhood on the upper lip, palate, or jaw. All surgical procedures result in the production of scar tissue which is restrictive to growth. This growth restriction results in a deficiency of the upper jaw. The upper lip and tissues at the base of the nose appear unsupported. The lower teeth are positioned in front of the upper teeth when the mouth is closed and there is difficulty keeping the lips closed. When scar tissue is the cause of the deficiency, this can be the most difficult facial imbalance to correct. If the deficiency is significant, conventional surgery is not adequate. In these circumstances, a procedure called distraction osteogenesis may need to be utilized.
Images of Maxillary Deficiency
Profile view before and after corrective jaw surgery for maxillary deficiency *
Frontal view Frontal view before and after corrective jaw surgery for maxillary deficiency *
* This patient also had corrective nasal surgery performed.
Lack of growth of the midface can lead to a significant facial imbalance. This pattern of growth restriction is commonly associated with several syndromes (craniodysostosis syndromes). Individuals with severe midface deficiency typically have proptosis (bulging eyes), a protruding tongue, and difficulty with mouth and nasal breathing. The midface deficiency commonly results in a significant class III malocclusion. Treatment requires repositioning of all of the bones of the midface. If the deficiency is significant, conventional surgery is not adequate. In these circumstances a procedure called distraction osteogenesis may need to be utilized.
Images of Midface Deficiency
Profile view before and after corrective surgery for midface deficiency
Frontal view before and after corrective surgery for midface deficiency
Facial trauma typically results in immediate changes in facial balance, requiring urgent surgery. However, several factors may lead to a need for corrective surgery months or years after the trauma:
If the initial repair was not performed correctly.
If the trauma affected a growth center, it may halt future growth in that area leading to progressive facial imbalance over time.
If there is damage to the temporomandibular joints (TMJ) .
Corrective surgery performed months or years after a traumatic event requires an experienced facial surgeon to plan and execute. Planning typically requires a special 3-D facial scan as well as the production of an exact replica of the facial skeleton in order to evaluate the deformity in three dimensions and prepare for the procedure. Correction may require multiple surgical procedures, bone grafts, distraction osteogenesis (see chapter 21) or other advanced techniques.
Images of Post Traumatic
Profile view before and after corrective jaw surgery for post traumatic facial imbalance*
Frontal view before and after corrective jaw surgery for post traumatic facial imbalance*
* This patient also had corrective nasal surgery performed.
Maxillary Transverse Constriction
The width of the upper jaw may be constricted, preventing the teeth of the maxilla (upper jaw) from fitting together properly with the teeth of the mandible (lower jaw). This may be an isolated finding or may be a component of one of the common patterns of facial imbalance.
To expand the upper jaw, a special device may be required. This device is similar to a retainer and is designed by an orthodontist to be placed on the teeth near the roof of the mouth. The device has a screw that is turned each day which causes the device to slowly expand the upper jaw.
There are two types of expansion of the upper jaw:
RPE (Rapid Palatal Expansion) – Typically if this device is placed before 13 years of age, the bones in the midline of the upper jaw have not fused yet and the jaw may be able to be expand without surgery. Sometimes this expansion can be performed on older children. This decision will be made by the orthodontist.
SARPE (Surgically Assisted Rapid Palatal Expansion) – If the orthodontist feels that the bones in the midline of the upper jaw have fused, an outpatient surgical procedure is required to separate them prior to activating the expansion. This will allow for proper functioning of the device and adequate expansion.
If a narrow upper jaw is the only issue being addressed, after the expansion, orthodontic treatment will continue and no further surgical procedures are required. If additional repositioning of the jaws is required in addition to the initial SARPE, these movements will be performed at least six months after the widening is completed.