Alveolar bone is a specialized structure in the upper (maxilla) and lower (mandible) jawbones. It contains the tooth sockets, known as alveoli, and forms directly around the teeth as they develop and erupt. This process creates the distinct ridge that holds them.
The existence of alveolar bone is dependent on the presence of teeth; it develops with them and disappears after they are lost. This structure is composed of two main types of bone tissue. A dense outer layer, called cortical bone, provides strength, while a porous inner layer, called cancellous bone, contains bone marrow and blood vessels.
The Function of Alveolar Bone
The primary role of the alveolar bone is to anchor teeth securely within the jaw. Each tooth is housed in a socket, or alveolus, a cavity in the bone that conforms to the shape of the tooth’s root. This embedment allows teeth to withstand the significant forces generated during chewing, swallowing, and speaking. The bone distributes these pressures across the jaw, protecting the teeth and surrounding structures from damage.
This connection between tooth and bone is not a direct fusion. They are joined by the periodontal ligament, a tissue made of connective fibers that run from the tooth root into the alveolar bone. This fibrous connection holds the tooth firmly in its socket while also allowing for a minute amount of movement, providing a cushioning effect during chewing.
Beyond its structural duties, alveolar bone serves a physiological purpose. It houses the blood vessels that supply nutrients to the periodontal ligament and contains nerves. The bone also acts as a mineral reservoir, storing and releasing ions like calcium. This dynamic tissue responds to mechanical demands by constantly remodeling to maintain its structure and function.
Causes of Alveolar Bone Loss
The most common cause of alveolar bone loss is tooth extraction or loss. The bone’s form and density are maintained by physical stimulation from the tooth root during functions like chewing. When a tooth is removed, this stimulation ceases. The body then begins a process of resorption, where the bone in the empty socket breaks down because it is no longer needed.
Periodontitis, a severe form of gum disease, is another major cause of alveolar bone destruction. This condition begins with a bacterial infection in the gums that, if untreated, triggers a persistent inflammatory response. The body’s immune system, while fighting the infection, releases substances that destroy the periodontal ligament and supporting alveolar bone. This can cause teeth to become loose and fall out as their foundation erodes.
Physical trauma can also lead to alveolar bone loss. An injury to the mouth can fracture the jaw or damage the tooth sockets, leading to bone deterioration. Poorly fitting dentures can also be a factor. If they do not fit correctly, they can exert uneven pressure on the alveolar ridge, accelerating the natural resorption process that occurs after tooth loss.
Preservation and Regeneration of Alveolar Bone
Preventing alveolar bone loss begins with diligent oral hygiene and early treatment of gum disease. Controlling bacterial plaque manages the primary trigger for periodontitis, protecting the bone from the inflammatory damage it causes. Regular dental check-ups are important for identifying gum inflammation before it progresses to bone destruction.
When a tooth is extracted, a procedure known as socket preservation can be performed to minimize bone loss. This technique involves placing a bone grafting material into the empty socket immediately after the tooth is removed. This material acts as a scaffold, encouraging the body to build new bone and helping maintain the alveolar ridge for future restorations.
For areas where bone has already been lost, bone grafting procedures can rebuild the structure. In this process, bone material from the patient, a donor, or a synthetic source is surgically placed in the deficient area. Over several months, the patient’s bone integrates with the graft, creating a solid foundation often necessary before a dental implant can be placed.
Dental implants are an effective method for stimulating and preserving alveolar bone over the long term. An implant is a small titanium post surgically placed into the jawbone to function as an artificial tooth root. As the bone heals, it fuses to the implant in a process called osseointegration. This bond allows the implant to transmit chewing forces to the bone, providing the stimulation required to maintain its density and prevent resorption.