The alveolar crest is the most coronal portion, or the top, of the alveolar process. It is an extension of both the mandible and maxilla and holds the tooth sockets. The alveolar crest is often the first portion of the alveolar process that is damaged by periodontal disease and is therefore the first bone that is lost. The loss of bone at the alveolar crest can prevent a dental implant from achieving long-term success as the bone will not have the density or stability required to support the implant or prosthesis. For patients who have suffered a significant amount of alveolar bone resorption, an alveolar bone graft will be required to build-up the alveolar crest. This type of bone graft will not only provide the tissue required for implant osseointegration but will also add strength and density for the support of implant hardware. To assist in the preservation of the natural alveolar bone, good dental hygiene should be consistently maintained.
Alveolar crestal defects are classified according to ridge height and width:
- Class I – normal apicocoronal ridge height with loss of buccolingual tissue
- Class II – normal buccolingual ridge width with loss of apicocoronal tissue
- Class III – loss of width and height due to a combination of defects
Periodontal disease can cause loss of the alveolar bone, or the bony ridge in the jaw that holds the teeth and supports its roots. The loss of bone typically follow one of four alveolar defect patterns — horizontal defects, angular or vertical defects, dehiscence, and fenestrations. Of the four types of defects, horizontal and vertical defects are the most common. However, general bone loss caused by periodontal disease is most likely to be horizontal bone loss. Generally what occurs with this alveolar defect is that the bone is resorbed by the body and the height of bone decreases uniformly across the affected area. Tooth loss is common with periodontal disease, which creates a two-fold problem. An implant may be a viable solution to replace teeth for functional, health, and aesthetic purposes, yet not enough bone exists to support an implant. In cases of alveolar defect, a bone graft is often necessary.
A common issue of patients needing dental implants is bone loss, or alveolar ridge defects. For a dental implant to be successful, there must be enough bone to support it. Bone grafts are often done, however, new treatment modalities exist, such as alveolar distraction osteogenesis. This procedure involves using a custom made distraction device to augment a deficient alveolar ridge. In studies using this method, the vertical bone gain was significant and did not require a bone transplant. Although some complications were seen as with any alveolar ridge augmentation, the procedure has been identified as a viable one for the augmentation of the alveolar ridge without the need for bone grafting. Bone grafting may have more potential for rejection and complications than alveolar distraction osteogenesis, potentially making this procedure a preferred one by many periodontists. Each patient will need a thorough evaluation to determine if this method is appropriate for their specific needs.
Although dental implants are done for more than aesthetic reasons, including preservation of oral health and function, patients want cosmetically pleasing results. A successful dental implant will be barely, if at all noticeable to the average person and will look and function like a natural tooth. A significant part of the dental implant procedure is to manage soft tissue retraction and exposure of the implant area, since this can have a marked effect on the aesthetic outcome of the procedure. For example, the alveolar mucosa, or the mucosal lining of the dental alveoli, can be affected during an implant procedure when the buccal flap is made. The alveolar mucosa is the soft tissue between the lips and the gums, and it’s important for periodontists to keep this area of the mouth intact during the implant procedure whenever possible. Destruction of the alveolar mucosa during an implant procedure may be considered implant failure, particularly when implants are done in the front of the mouth.
There are three primary types of oral mucosa: lining mucosa, masticatory mucosa, and specialized mucosa. Of the types of lining mucosa, there are three kinds: alveolar mucosa, labial mucosa, and buccal mucosa. Alveolar mucosa is the soft, thin mucous membrane that sits above the marginal gingiva and the attached gingiva, and continues across the floor of the mouth, cheeks, and lips. It is bright red in color due to being rich with blood vessels, and is shiny and smooth in appearance. It is made up of nonkeratinized stratified squamous epithelium, making it delicate and sometimes difficult to work with. In oral implantology, it’s crucial to keep the alveolar mucosa intact, particularly when implants are done in the front of the mouth. Disruption of the alveolar mucosa can impact the aesthetic results of the procedure, leading to implant failure. The buccal flap should be made carefully so as to keep the alveolar mucosa intact.
The alveolar nerve inferior, which is also called the inferior dental nerve, plays an important role in implant dentistry. It is a part of the mandibular nerve and supplies sensation to the lower teeth, lower lip, and chin. There are two critical factors when considering the alveolar nerve during a dental implant procedure. The treating physician must ensure that the nerve is sufficiently numbed so the implant procedure isn’t painful for the patient, and that the nerve is not injured as the buccal flap is made and the implant is placed. An inferior alveolar nerve block can help numb the teeth, lower lip, chin, and the front 2/3 of the tongue. The posterior superior alveolar nerve must be avoided during surgery to prevent permanent loss of sensation or chronic pain. Injuries to the alveolar nerve are risky, because they may or may not resolve. Chronic pain or loss of sensation may result in implant failure.
Alveolar preservation, also called alveolar ridge preservation or preservation of the maxillary alveolar ridge, is a procedure used to reduce the amount of bone loss that can occur after extracting a tooth. This procedure is typically done when a tooth is extracted with the intention of placing an implant at a later date. Because of the risk of bone loss after the extraction of a tooth (between 30-60% is expected), it’s important to be proactive if you are confident that an implant will be placed. The procedure involves placing a platelet-rich fibrin (PRF) into the empty socket after the tooth is removed. PRF contains a high concentration of platelets, which are the body’s natural healing mechanism. Additionally, a periodontist can choose to use a scaffold or bone grafting material instead of PRF. Without alveolar preservation, the alveolar ridge will not maintain proper shape and the tissue can become contoured in a way that makes placing an implant challenging.
The alveolar processes are arguably the most crucial anatomical structure in the dental implant industry. The alveolar process is the thick ridge of bone in the jaw that holds the dental alveoli, or tooth sockets. The dental alveoli hold the roots of the teeth in place, and in case of a dental implant, the alveolar process holds implant hardware in place. There are two alveolar processes — the alveolar process of maxilla is on the top part of the mouth, just under the maxillary sinus, and the alveolar process of mandible is on the lower part of the mouth, just above the jawbone. Healthy, strong alveolar processes are crucial to successful dental implants, and in cases of tooth extraction, this bone can be reduced between 30-60%. When there’s not enough bone to support implant hardware in the alveolar process, bone grafting is typically done. Often, alveolar preservation will be used after an extraction when an implant is imminent.
The maxillary sinus is the largest air sinus in the human body, and it has three recesses. The Infraorbital recess is superiorly towards the eye, the zygomatic recess is pointed laterally towards the ear, and the alveolar recess pointed inferiorly towards the upper part of the jaw. It is this specific recess that is critical when considering tooth extraction and tooth implantation. Essentially, the alveolar recess is a depression or cavity in the floor of the maxillary sinus, formed by a septum. When placing a dental implant, the goal is to avoid coming into contact with the alveolar recess of the maxillary sinus, however, due to its close proximity to the roots of maxillary premolars and molars, this can prove to be a significant challenge. A periodontist must accurately assess the distance between the maxillary alveolar ridge and the alveolar recess in order to prevent serious complications during the dental implant process.