Tooth transplants

The loss of the permanent first molar on the lower jaw in children and adolescents leads to significant deformations of the dental arch and, as a consequence, the entire dental-maxillary system.

Tooth loss in adults has a detrimental effect on chewing function and forces patients to resort to dental prosthetics, which does not always satisfy them in functional and cosmetic terms. In this regard, dentists have long and persistently developed various types of odontoplasty: auto-, allotransplantation and implantation of tooth roots.

Autotransplantation of teeth

Autotransplantation of teeth is indicated in the following cases:

1. when removing an impacted tooth, the correction of which into a correct bite using conservative orthodontic methods is impossible;
2. if it is necessary to replace a defect in the dental row, if the orthodontic treatment involves tooth extraction;
3. in case of complex anomalies of teeth eruption, when conservative orthodontic treatment does not produce the desired results;
4. if it is possible to remove the wisdom tooth and use it to replace previously removed first or second molars.

The issues of autotransplantation of teeth have been thoroughly developed by N. A. Chudnovskaya (1964), V. A. Kozlov (1974), and others.

Autotransplantation of a tooth is contraindicated in case of general and local diseases that disrupt the process of bone regeneration (inflammatory processes in the jaws and oral mucosa, tuberculosis, other chronic and acute infectious, endocrine, oncological diseases, etc.).

Only unerupted teeth that are in the stage of complete crown formation but with roots that are not fully formed (or at the beginning of their formation) should be transplanted with a bifurcation clearly outlined on the radiograph. The transplant is transplanted with a dental sac.

Wisdom tooth transplantation is performed simultaneously with the removal of the roots of the first lower molar (in two separate stages).

Stage I of the operation: removal of the roots of the first permanent lower molar and preparation of a receptive bed in its alveolus. The first lower molar or its roots are removed with forceps as atraumatically as possible, granulation, granuloma or cyst are scraped out of the alveolus; if there is a gingival fistula, it is curetted with a small spoon. The interradicular septum is partially resected. The wound is washed with an antibiotic solution and a gauze swab soaked in antibiotic is inserted into it, which is left in place until the moment of transplantation of the wisdom tooth germ.

Stage II of the operation:

• an unerupted wisdom tooth with a dental sac is extracted by sawing off the outer wall of the jaw to the depth of the bone plate within the location of the wisdom tooth;
• the extracted tooth and its sac are immediately placed in a pre-prepared bed, from which a tampon with an antibiotic is removed;
• A splint-cap is made from quick-hardening plastic in the area of the transplant and adjacent teeth, which is secured when the patient's teeth are closed.

On the 25th day after the operation, the splint-cap is removed. Due to the splint-cap manufacturing technique, the transplant is exposed to physiological load from the very first minutes after transplantation, which has a beneficial effect on the process of bone regeneration around the transplanted tooth and its trophism.

Radiographs taken after surgery using this method show gradual formation of bifurcation, formation of a tooth root cavity, root growth and engraftment of the transplant, mainly of the periodontal type. The contact surface of the crown of the transplanted tooth gradually reaches the level of the occlusal surface of the adjacent teeth and contacts the antagonists.

Two months after the operation, the first signs of the pulp's reaction to the effect of the device for electroodontodiagnostics are detected. Gradually, the indicators of the transplanted tooth's electrical excitability approach those of the symmetrical tooth and become equal to them.

According to some authors, the sensitivity of a transplanted tooth is caused not by the restoration of the pulp, but by the ingrowth of the root of the tooth into the canal, and of connective tissue and bone containing nerve endings into the pulp chamber.

Based on observations, it has been established that the reason for non-integration of teeth is, as a rule, a significant excess of the volume of the newly created alveolus compared to the volume of the tooth root. This occurred, for example, when the impacted tooth was located near the alveolus that arose after the extraction of the second molar or its roots, as a result of which both cavities in the bone (at the site of the second molar and the transplanted wisdom tooth) inevitably merged into a single one, the dimensions of which exceeded the volume of the tooth root. To avoid this, it is recommended to place the extracted impacted tooth in a preservative liquid (100 ml of isotonic sodium chloride solution and 10 ml of 96% ethyl alcohol) for 2 months and store it in a refrigerator at a temperature of 4-6 ° C. After 2 months, a cavity-alveolus is formed in the young bone tissue formed at the site of the previous operation and the preserved tooth is placed in it. A year after autotransplantation, against the background of complete clinical well-being, complete or ending restoration of bone tissue around the transplanted tooth is noted, and the periodontal gap line remains unchanged only in certain areas. In other places, the bone is tightly adjacent to the root of the tooth.

In experiments with autotransplantation of mandibular dental rudiments (by swapping the same-named ones among them), V. N. Zemchikov (1972) established that this operation usually ends with their engraftment and development, although the surgical trauma inflicted on the rudiments during isolation and transplantation to a new location distorts their morphogenesis and the course of mineral and protein metabolism in further development. In order to reduce the harmful effect of this trauma, the transplanted rudiment should be brought closer to the mandibular vascular-nerve bundle, right up to contact with it.

When developing the technique of transplanting an impacted tooth into the dental arch, a number of dental surgeons emphasized the importance of moving the tooth to the correct position without rupturing the vascular-nerve bundle, but noted that this is only possible if the position of the tooth allows only its crown to be moved, while the root apex is left "in its original position." The proposed operation involves removing only the layer of bone tissue between the compact bone and the root of the tooth being moved along its entire length, followed by fixing it with a splint in the achieved position. Sutures are placed on the edges of the alveolus around the transplant tooth. This delicate operation with preservation of the thinnest vessel can only be performed by a very experienced dental surgeon who has specialized in tooth transplantation.

It is also important where the dental autotransplant is placed. When transplanted into a natural alveolus, it grows together more favorably - according to the periodontal type, and into an artificial one - according to the osteoid type, i.e. a less favorable type, in which the viability of the transplanted teeth is reduced by 1-3 years; in addition, the use of such teeth (which have grown together according to the osteoid type) as a support for fixed dentures leads to progressive resorption of the roots, while with the periodontal type of fusion such changes are not observed.

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Allotransplantation of teeth

Allotransplantation of teeth is of great practical interest and has therefore long attracted the attention of experimenters and clinicians.

Transplantation of dental rudiments is indicated in the case of the appearance (or presence from birth) of defects in the dental arches in children that impair chewing and speech function, are not amenable to orthodontic treatment and threaten to disrupt the growth and development of the alveolar processes, in particular:

• if a child with a mixed or permanent bite has two or more adjacent teeth or their rudiments missing, lost as a result of previously suffered periodontitis or trauma, with the alveolar process preserved and the absence of pronounced destructive changes in it;
• in the absence of large molars of the lower jaw or their rudiments in young children (6-8 years old), which entails the rapid development of deformation of the alveolar process, a delay in the development of the corresponding half of the jaw;
• in case of congenital adentia.

Based on the results of experimental studies conducted in this area by various authors (V. A. Kozlov, M. M. Maksudov, G. E. Dranovsky, etc.), the following conclusions can be drawn:

1. the most favorable time for transplanting dental rudiments is the period when they already contain the main structures without any pronounced differentiation or formation;
2. the taking of rudiments from the donor and their transplantation to the recipient should be carried out in strict compliance with aseptic requirements and with an attempt to cause minimal trauma to the transplant;
3. The transplanted rudiments must be brought into contact with the recipient tissues over their entire surface, thereby ensuring strong fixation and nutrition of the sac;
4. The rudiments must be isolated from oral infection with blind sutures or glue for the entire period of their engraftment and development.

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Implantation of dental roots

There are 5 types of implants: subgingival, periosteal, interdental, intraosseous, and combined. G. K. H. Fallashussel (1986) considers subgingival implants as a special type and adds a group of transosseous implants, while P. Telsch (1984) considers it appropriate to differentiate between closed and open implants: a closed implant is one that is completely covered by mesenchymal tissue (e.g. a magnet), while an open implant is one that penetrates the epithelium. In addition, J. G. Schwarz (1983) subdivides implants depending on their shape into screw-shaped, needle-shaped, cylindrical, in the form of a natural tooth root, flat, and combined intraosseous-subperiosteal.

G. Strub (1983) identifies 4 different types of bone-tissue-implant connections depending on the materials:

1. bone connection (bioglass, glass ceramics);
2. bone contact (titanium, carbon, aluminum oxide ceramics);
3. enveloping with connective tissue (polymers, acrylates);
4. combination (all non-bioactive materials).

Depending on their proximity to anatomical structures, a distinction is made between intraosseous and subperiosteal implants.

Intraosseous - are directly fixed in the bone, and subperiosteal lie on the bone (rest on it), the size and structure of the bones determine the shape and size of the implant. Intraosseous implants are most often given the shape of a screw, cylinder, bracket or sheet.

Subperiosteal implants, which repeat the shape of the alveolar process of the jaw on which they are placed, are made according to the impression obtained during the first surgical intervention, and are placed during the second operation. The implant consists of an internal (fixing) part and an external (supporting) part.

Based on the nature of the function they perform, implants can be divided into retaining and supporting, designed to fix both removable and non-removable prosthetic structures.

Implants inserted in the frontal section of the lower jaw are intended exclusively for stabilizing removable dentures in the event of a complete absence of teeth. Screw-shaped and bracket-shaped implants are most often used for these purposes.

To create distal support for terminal defects of dental arches, leaf-shaped structures are most appropriate, which can be used on both jaws without the risk of damaging important anatomical structures. Their incorporation is technically simple, and the implants themselves, when correctly placed, evenly distribute mechanical loads on the jaw bone. Such implants can be manufactured by milling from titanium, partially with a titanium powder coating.

Based on clinical and experimental data, V. V. Los (1985) identifies general and local indications and contraindications for the use of intraosseous implants. Implantation can be performed on individuals who, according to the conclusion of an internist consultant, do not have systemic diseases that cause sluggish wound healing.

Implantation is contraindicated in cases of periodontitis, blood diseases, endocrine diseases, allergic conditions, various types of tumors or tumor-like formations.

Local indications: presence of a pronounced alveolar ridge in the area of extracted teeth, when the mandibular canal and airways are at a distance that allows for the placement of an intraosseous implant. Any implantation must be performed with the patient's mandatory consent. It can be performed on people of all age groups. Patients with a labile nervous system are prescribed sedatives for 2-3 days before the operation.

Preparation for dental implantation

The diagnostic models compared in the bite determine the possibility of placing a prosthesis with support on the implant and natural teeth. If necessary, the occlusal plane is aligned. Contact intraoral radiographic images provide an idea of the condition of the tissue at the site of the proposed implantation, the location of the mandibular canal and the maxillary sinus.

Implantation technique according to V. V. Los

Under local anesthesia, an incision is made along the center of the alveolar ridge to the bone with an ophthalmic scalpel. Its length is 1-1.5 cm, which slightly exceeds the size of the implant. Bluntly, the edges of the wound are spread apart until the alveolar ridge is exposed. Then, the implant is tried on in the wound to avoid errors in determining the direction and length of the implant planned in the bone. The bone is cut according to the size of the implant. For this, carbide or special burs are used, the diameter of which is 0.1-0.2 mm less than the transverse size of the implant.

In the meliodistal angles of the wound, perpendicular to the crest of the alveolar process and parallel to the existing teeth that limit the defect, perforation holes 5-7 mm deep are created. By connecting 3-4 holes lying on one line, a ready-made implant bed is obtained. Its depth is controlled by a special probe. Exclusion of bone overheating is achieved by working at low speeds and constant irrigation of the bone wound with a cold physiological solution.

To prevent metallosis, the wound is washed, the injured bone is scraped off and bone shavings are extracted from it with a stream of saline solution. Then the implant is fitted into the groove until it stops and wedged into the bone with light blows of a surgical hammer through a mandrel. The correctness of the operation is indicated by:

1. The implant is immobile and stabilized in the bone.
2. Its intraosseous part is immersed under the cortical plate.
3. The neck is at the level of the periosteum.
4. The supporting element of the implant is located parallel to the supporting teeth.
5. There is a gap of 2-3 mm between the supporting part and the opposing teeth.
6. A distance of 5-7 mm is maintained between the mandibular canal and the implant or the air sinus and the implant.

In places of greatest tension of the flaps the wound is sutured with polyamide thread. The operation lasts 30-40 minutes.

Patients are recommended oral hygiene: irrigation with chamomile decoction with a small amount of hydrogen peroxide, furacilin solution, citral, artificial lysozyme (from chicken egg white). After surgery, an analgesic is prescribed orally.

A week after the operation, the stitches are removed and a control X-ray is performed.

It is easier to perform surgery on the upper jaw: there is less dense bone tissue. Otherwise, surgical interventions on the upper and lower jaws do not have noticeable differences.

Postoperative radiographic control after 5-7 days allows to judge the correctness of the implant position, its relationships with anatomical structures, and gives an idea of the resorption and apposition of bone tissue. Normalization of the bone pattern density around the implant indicates the completion of the process of incorporation of the structure. Examination of the mucous membrane in the implantation area allows to judge the presence or absence of inflammatory phenomena.

In the vast majority of cases, the surgical wound heals by primary intention, but there is always a risk of infection in the oral cavity. To prevent this, special attention is paid to oral hygiene.

Two months after the operation, they begin to repair the dental defect, limited on one side by an implant. The necessary conditions for this are the immobility of the implant and the absence of inflammatory phenomena in the mucous membrane around it.

Natural supporting teeth that limit the defect (preferably two adjacent ones) are processed using the usual method. Silicone impression materials are used to obtain impressions.

V. V. Los prefers cast-in-place denture designs, since, in his opinion, they have higher medical and biological properties. In order to reduce the load on the supporting elements when modeling the intermediate part of the bridge prosthesis, he reduces the area of its chewing surface by 1/3. The intermediate part should not exceed three teeth in length. After checking the design, the bridge prosthesis is fixed to the supporting elements with cement.

After a certain period of adaptation (1-2 weeks longer than usual), such a prosthesis, fixed on an implant and teeth, gives a completely satisfactory functional effect.

At the Ukrainian National Medical University, a group of authors has developed a new method of surgical introduction of intraosseous cylindrical implants "Method of restoration of frontal defects of dental rows"). This operation is carried out in two stages: the first is the formation of an artificial socket in the alveolar process of the jaw, the second is the introduction and wedging of the intraosseous cylindrical implant.

In order to prevent excessive bone trauma and possible complications resulting from its overheating during drilling, as well as to expand the indications for implantation in cases of a narrow alveolar process (occurs in 49.1% of cases), its surgical preparation is carried out, which is carried out as follows: under local anesthesia, a round hole with a diameter of 2.5-3.0 mm is made in the mucous membrane in the center of the alveolar process with a perforator, which is 0.5 mm smaller than the diameter of the implant neck. This leads to the fact that after the implant is inserted, the mucous membrane tightly covers its neck and forms an epithelial "cuff" around it, as a result of which there is no need to dissect soft tissues, apply and then remove sutures. Then, using bone punches, sequentially, due to the compaction of the spongy bone, a channel is created in which an expanding pin is wedged. After two weeks, the 2nd stage is carried out: the expansion pin is removed, and an intraosseous canal is formed using bone punches of the appropriate size, corresponding to the size of the implant, in which it is wedged.

To decide on the choice of implant design, it is necessary to take into account the morpho-functional structure of the alveolar process. For this purpose, Yu. V. Vovk, P. Y. Galkevich, I. O. Kobilnik, I. Ya. Voloshin (1998) determine the vertical structure features of the alveolar process before the operation using clinical-instrumental-radiological methods; however, G. G. Kryklyas, V. A. Lubenets and O. I. Sennikova (1998) established 7 variants of horizontal relief of edentulous alveolar processes exposed by the surgeon, and therefore believe that the surgeon can decide on the choice of implant structure only after he has exposed the crest of the alveolar process and studied its relief.

The use of intraosseous implants opens up wide possibilities for dental prosthetics with fixed bridge structures that can serve for a long time, preventing the development of secondary deformations both in the jaws and in the dental arches.