We often encounter defects of soft tissue and bone tissue in implantation. Defects of soft tissue will affect the aesthetic effect of treatment. Defects of bone tissue often affect the success rate of implantation. Although there are various ways to solve these problems, more and more experts believe that it is a good way to prevent such problems as far as possible. In this paper, Professor Chen Ning communicated with readers about the alveolar ridge preservation technology, hoping to reduce or prevent soft tissue and bone tissue defects, improve the success rate and aesthetic effect of implantation, and simplify the implant treatment procedure.

Healing of extraction wound

Histological changes of wound healing after tooth extraction

Dentists are very concerned about the changes in the shape of the extracted teeth after wound healing. Histological changes of tooth extraction wound begin with bleeding and blood clot formation (30 minutes to several hours), blood clot mechanization and granulation tissue formation at 3-7 days after tooth extraction, vascular-rich connective tissue filling and immature woven bone formation at 14 days after tooth extraction, and new fibroid bone filling at 30 days after tooth extraction. Full alveolar bone and began bone remodeling; 30-45 days after extraction, a large number of bone formation began; 60 days after extraction, mineralized bone bridge formed on the surface of the extraction wound and gradually cortified; 180 days after extraction, normal bone structure formed in the extraction socket.

Alveolar ridge changes after tooth extraction

A large number of animal experiments and clinical studies showed that the alveolar ridge morphology changed significantly with the healing of the extraction wound. The main manifestations were that the height and width of alveolar ridge decreased, bone mineral density decreased, and gingival soft tissue also changed. Clinical studies such as Lang (N.P.) showed that the width and height of alveolar ridge healed naturally after 6 months of tooth extraction decreased by 3.8 mm and 1.24 mm on average, while those of Michael S. Block showed that the width and height of alveolar ridge healed naturally after 6 months of tooth extraction decreased by 4.4 mm and 1.2 mm on average. Many studies have found that after tooth extraction, alveolar ridge cheek and lingual bone wall changes, but the absorption of buccal alveolar ridge bone is more obvious (Fig. 1). Some researchers analyzed the changes of alveolar bone with and without teeth. The results showed that the area and height of alveolar ridge decreased by 32% and 24% respectively three months after tooth loss. Table 1 shows the changes of bone tissue after tooth extraction.

Preservation of alveolar ridge in dental implants

Preservation of alveolar ridge in dental implants

Alveolar ridge changes

The results of experimental study and clinical observation show that 50% of the original height and width of alveolar ridge will be lost within one year after extraction, and 2/3 of the loss occurs within three months after extraction. The absorption of alveolar ridge height and width on buccal side is significantly more than that on lingual side, and the absorption of alveolar ridge width is more than that on alveolar ridge height. Absorbed alveolar ridges are difficult to regenerate by themselves. At the same time, alveolar ridge soft tissue changes after tooth extraction, mainly gingival soft tissue retraction, keratinized gingiva reduction or even disappearance.

Definition of alveolar ridge preservation

Ridge Preservation or Alveolar Preservation is the use of biomaterials for filling and covering alveolar fossa during tooth extraction, while the use of biomaterials for processing areas outside alveolar fossa during tooth extraction, such as GBR, is called Ridge Augmentation Technology. It is different from alveolar ridge preservation. In addition, many experts believe that the concepts of extraction site Preservation (ESP) and alveolar ridge preservation are similar, so when the extraction site is followed up with implant therapy, it can also be called Implant Site Preservation (ISP).

In the narrow sense, alveolar ridge preservation refers only to the filling treatment with biological materials in the extraction socket during tooth extraction; in the broad sense, alveolar ridge preservation includes the narrow sense of alveolar ridge preservation and implant implantation in the process of tooth extraction wound healing, that is, immediate implantation and early implantation.

Because according to research, immediate implantation and early implantation can also reduce or prevent alveolar ridge atrophy. Therefore, the treatment of extraction wound after extraction can be shown in Figure 2.

Preservation of alveolar ridge in dental implants

Indications, Taboos and Significance

Suggested indications for alveolar ridge preservation

There is no definite and authoritative conclusion on the indication of alveolar ridge preservation. Therefore, according to our literature review and clinical experience, the recommended indications for alveolar ridge preservation are as follows, for the reference of stomatologists:

1. For some reasons, it is inappropriate for immediate or early implanters, such as lack of initial stability, pregnancy and too young age.

2. The alveolar ridge shape of the patients is good, and there is no obvious serious defect in the bone wall and gingival soft tissue of the extraction fossa.

3. Incremental maxillary sinus elevation and Onlay bone grafting may be necessary in the implant area in the future.

4. Alveolar ridge preservation has a good cost-effectiveness for patients.

Contraindications to recommendations for alveolar ridge preservation

The suggested taboos include:

1. Conventional contraindications in oral and maxillofacial surgery, such as severe hematological diseases, diabetes, oral and maxillofacial infections, etc.

2. Severe bone tissue defects or soft tissue defects exist in the extraction wound, such as the disappearance of labial bone plate in alveolar fossa or the presence of alveolar bone tissue with fewer apices due to horizontal bone resorption in advanced periodontal disease.

3. Severe infection was found in the extraction wound.

4. The preserved area of alveolar ridge was treated with radiotherapy.

5. Patients are being treated with bisphosphonates, such as osteoporosis.