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Reasons for Jaw Bone Loss
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Reasons For Jaw Bone Deterioration And Loss
Tooth extractions, disease, injury and deformity all may contribute to jaw bone deterioration and loss. Bone grafts may be needed to restore the height and density of the alveolar ridge.
Healthy jaw bone structures are critical for tooth retention and good oral health, as well as for aesthetic reasons. When bone is missing, or of poor quality, teeth don't function, feel or look as well as they should, or may fall out. When teeth are missing, the mouth area of the face eventually loses structure, a cause for concern for most patients.
Some of the reasons why teeth bone in the jaw may be missing or of poor quality include:
- Developmental deformity
- Previous dental procedures
The following are some of the most common factors that may contribute to jaw bone deterioration and loss, thereby necessitating the need for a bone graft procedure that potentially may restore shape and function to the jaw:
Tooth removal may involve bone loss. Natural teeth are embedded in the jaw bone and attached via a root structure which, depending on the location and size of the tooth, varies in size, shape and complexity. Bone tissue is maintained by putting stress or load on it through the periodontal ligament; activities such as biting and chewing stimulate the root structure, which in turn stimulates the bone that the root is attached to.
When a permanent (adult) tooth is removed and not replaced, bone stimulation stops at that particular site, and the alveolar bone – the portion of the jaw bone that anchors the teeth in the mouth – no longer receives this physical stimulation and starts to resorb. Bone resorption is the natural process by which large cells called osteoclasts break down bone.
The amount of bone and gum loss and the rate at which this loss progresses varies greatly among individuals; however, the majority occurs during the first eighteen months after the tooth is removed, and continues in varying degrees throughout life.
Learn about the anatomy of the jaw.
Find out why teeth are important for jaw bone health.
Periodontal (gum) disease is an infection that affects the tissue and bone supporting the teeth. It begins when the bacteria in plaque (a sticky, colorless film that forms on teeth) causes the gums to become inflamed.
In its mildest form – gingivitis – the gums redden, swell and bleed easily, usually with little or no discomfort. Gingivitis is often caused by inadequate oral hygiene, and is reversible with professional treatment and good oral care.
In some cases or if left untreated, gingivitis may develop into periodontitis. Over time, plaque extends below the gum line, and the toxins produced by the bacteria in the plaque irritate the gum tissue, which leads to chronic inflammation. The tissues and bone that support the teeth then start to break down. The gums then separate from the teeth, periodontal pockets form and these pockets tend to easily trap bacteria and become more infected. Eventually, the teeth in the affected area loosen and may either fall out or need to be removed.
Dentures and bridgework may appear to correct the problem of missing teeth, at least in terms of appearance and function, but most are not designed to mimic a natural tooth's ability to stimulate bone material in the jaw.
Some dentures are supported and held in place by implants, which may provide sufficient stimulation for preserving bone health. With bridgework, the anchoring teeth on each side of the appliance undergo added stress from biting but also continue to stimulate the underlying bone; however, the bone structure under the portion of the bridge that spans the gap where teeth are missing receives no direct stimulation.
Unanchored dentures rest on top of the gum line and provide no direct stimulation of alveolar bone. This type of denture depends on support from the gums and, especially, the underlying bone structure to keep it in place. As bone resorption progresses, patients often report that their dentures become progressively looser and do not fit as well as they did when they first started wearing them. After several years, bone and gum tissue may shrink to a point where new (or relined) dentures and even denture adhesives cannot provide adequate retention.
For those who do wear dentures, proper care, repair and refitting is critical for maintaining oral health.
If a tooth is knocked out or broken off to the extent that no biting surface is left (below the gum line), bone stimulation stops. Some common forms of tooth/jaw trama include:
- Knocked-out (avulsed) teeth. When teeth are lost due to injury, bone usually is lost, as well. The result is either a horizontal or vertical bone defect, similar to what occurs after teeth are removed, but often more severe.
- Fractures. If a fracture in the jaw bone fails to heal (which requires the formation of a bony union), what forms instead is called a non-union, or fibrous union. This causes gaps between the broken bone segments that are typically 1mm-1.5mm in size, and may include a tooth or teeth and/or the surrounding structures.
- Prior Trauma. Teeth with a history of trauma may become necrotic, or die, after the trauma, sometimes even years after the injury. In some instances, bone loss also occurs, due to the resorption of bone and tooth structures.
Misalignment issues may create an environment within the mouth where certain tooth structures no longer have an opposing tooth structure. The unopposed tooth may over-erupt, leading to deterioration of the underlying bone.
Long-standing issues arising from lack of treatment, normal wear-and-tear and temporomandibular joint (TMJ) problems can create abnormal physical forces that interfere with the teeth's ability to chew and grind properly. Over time, and if the problem is significant, bone deterioration may occur with certain tooth structures.
Benign tumors, though not life-threatening, may grow rather large and require the need for major bone grafting. One particular type, called an ameloblastoma, often requires the removal of an entire section of the jaw.
Arising primarily from the soft tissues inside the mouth, malignant tumors almost always spread into the jaws, thus requiring the removal of a section of the jaw and major reconstructive grafting. Grafting in such cases may be more challenging because surgery for the treatment/removal of the cancerous tumor typically removes some of the surrounding soft tissue, as well.
Involving a different type of infection than those associated with periodontal disease, osteomyelitis is a bacterial infection in the bone and bone marrow of the jaw. The resulting inflammation can lead to a reduction of blood supply to the bone. Treatment usually requires removal of the affected bone and antibiotic therapy. Once the infection is resolved, a graft replacement is usually required.
Osteoradionecrosis is an injury that occurs when a high dose of radiation is given to treat mouth cancer, and some of the bone is killed in the process. To treat this condition, a portion of the jaw must be removed, and the bone that remains can be difficult to graft successfully due to compromised blood and tissue supply.
A number of conditions, collectively referred to as syndromes, are characterized by defects at birth, such as missing portions of the teeth, facial bones, jaws or skull.
When back teeth (molars) are removed from the upper jaw (maxilla), air pressure from the maxillary sinus (an air cavity in the body of the maxilla) causes resorption of the bone that formerly held the teeth in place. As a result, the sinuses become enlarged, a condition called hyperpneumatized sinus, which basically means "sinus with an increased air space."
This condition usually develops over a period of several years, and may result in insufficient bone for the placement of a dental implant. This condition is typically treated with a surgical procedure called a sinus augmentation, or "sinus lift."
To learn more, talk to your oral surgeon.
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