Underdevelopment of the lower jaw (microgenia, retrognathia): causes, symptoms, diagnosis, treatment

Congenital absence of the mandible or its separate fragments, as well as the "double" jaw are extremely rare in practice. Usually the surgeon is faced with either underdevelopment, or excessive development of the lower jaw, ie, with microgenia or prognosis.

The prevalence and severity of these deformations varies greatly among patients. It can be total, subtotal, partial; symmetric (two-sided) and asymmetric. Therefore, in analyzing the deformation of the lower jaw in our clinic, it is suggested to isolate its components: microarray (shortening of the jaw branch), microbiology (shortening of the jaw body), as well as macroramigo and macrobondy. This allows you to accurately determine the nature of deformations and purposefully specify the treatment plan.

Diagnostic signs and treatment of these deformations have been thoroughly studied and described by VF Rudko, AT Titova, and others. VF Rudko points out that in diagnosing the underdevelopment of the mandible, three basic criteria should be guided: external manifestations of deformity, the state of bite and X-ray manifestations.

Congenital one-sided microgenia is usually combined with underdevelopment of the entire half of the face, macrostoma, etc., and with the acquired microgeny in early childhood, the initial shortening of the jaw is combined with secondary deformations of neighboring healthy parts of the face.

Symptoms of underdevelopment of the lower jaw (microgenia, retrognathy)

When combined deformations of the jaws by the type of microgenia, pathological changes can be observed from the ENT organs in the form of curvature of the nasal septum, chronic rhinitis, and reduction of the sense of smell.

The most significant changes from the outer ear are observed in congenital microgenies. Such patients sometimes completely lack the auricle and external auditory canal, the permeability of the auditory (eustachian) tube is broken, adhesive or chronic purulent otitis is noted, the hearing, certain parameters of the function of external respiration (decrease in the ZHEL and an increase in MOU) are significantly impaired.

Treatment of underdevelopment of the lower jaw (microgenia, retrognathy)

To treat the underdevelopment of the lower jaw by a surgical method is possible only after the doctor has ascertained that orthodontic treatment can not give the desired result. Therefore, even before hospitalization of the patient, it is necessary to consult him with a highly qualified orthodontist. First, it is necessary to establish the degree of functional and cosmetic disorders, in order to compare it with the degree of always inevitable surgical risk and the expected effect of the planned surgical intervention. This circumstance should be taken into account in all reconstructive operations in the maxillofacial area.

Secondly, it is necessary to decide the optimal timing of the planned intervention. In this respect, the opinions of the scientists are quite clear. For example, A. A Limberg recommends early interventions for underdevelopment of the lower jaw .

VF Rudko rightly believes that the early correction of the shape of the jaw allows solving the following problems:

1. creation of conditions for more correct further growth;
2. prevention of the development of secondary deformation of the upper jaw and the entire facial part of the skull;
3. elimination of an already existing facial cosmetic flaw. If the underdevelopment of the lower jaw is combined with ankylosing of the temporomandibular joint, the surgeon needs to eliminate the microgenia and ankylosis at the same time.

There are various methods of surgical treatment of underdevelopment of the lower jaw. In some cases, surgical interventions are performed in the form of moving the entire lower jaw forward by placing a piece of rib cartilage between the posterior edge of the articular head and the anterior edge of the bony protrusion at the external auditory canal; if retrognatia is combined with deforming arthrosis, V. Heiss (1957) placed an articular disc at the back of the joint, without damaging the disk bundle.

Unfortunately, such a retrocondylar brace (cartilage, disc) can disrupt the function of the joint and eventually cause the inflammation of the entire joint and its ankylosing. This does not give us any reason to recommend such an intervention. More promising is the elongation of the entire alveolar process according to O. Hofer (1942) or N. Kole (1959).

The operations that can extend the body of the lower jaw are often used : according to the method of G. Eiselsperg (1913), M. Grayr (1913), P. Gadd (1910), V. Kasanjian (1924) or other interventions that simultaneously solve two tasks: lower jaw and eliminate the open (or reverse) bite.

Unfortunately, all of them are associated with the inevitable dissection of the gingival mucosa, and therefore with the infection of dissected bone tissue, the possibility of postoperative osteomyelitis, an unpredictable outcome. Therefore, they can only be carried out under the guise of effective antibacterial prophylaxis before and after surgery.

In this respect, operations on the jawbone are less "threatening" , but they are performed through submandibular access, ie, extraorally: osteotomy according to V. Blair (1920), A. A. Limberg (1924), A. Lindemann (1922), G. Pertes (1958), M. Wassmund (1953). G. Perthes, E. Sclossmann (1958), AI Evdokimov (1959), A. Smith (1953) (Figure 277).

Further development of the idea of interventions on the mandible branches was found in the works of V. Caldvell, W. Amoral (1960), N. Obwegesser (1960). Dal Pont (1961, Figures 276, 279), and also in works on this problem in 1961-1996: K. Thoma (1961), K. Chistensen (1962), V. Convers (1963), N. P Gritsaya, VA Sukacheva (1977, 1984), AG Katza (1981, 1984), and others.

Extraoral access also has significant disadvantages: the possibility of injuring the branches of the facial nerve, branching of the external carotid arteries, parenchyma of the parotid salivary gland; leaving a "trace" of the operation - a scar on the skin. Therefore, in recent years, branch operations have been increasingly carried out through intraoral access, but with the study (before surgery) of the sensitivity of the mouth microflora to antibiotics and the introduction of the most appropriate of them immediately before and after surgery.

M. M. Soloviev. VN Trizubov et al. (1991) with mesial bite, when the slit along the sagittal between the central incisors reaches 10 mm or more, in order to normalize the occlusion, simultaneous intervention on both jaws is performed - horizontal osteotomy of the upper jaw and bilateral osteotomy in the region of the mandible branches with subsequent counter movement. We think that it is permissible to carry out under two absolutely necessary conditions: the absence of a patient's reduction in the general resistance of the organism (background diseases) and the presence of the surgeon not only rich experience, but also all the necessary tools for the operation to be completed in the shortest possible time, with a minimum loss of patient's blood, against the backdrop of highly professional anesthetic support of such a traumatic operation, in which all 12 pairs of cranial nerves will react. It is desirable to use the most gentle methods of osteotomy.

In the case of a combination of microgenia with ankylosis of the temporomandibular joint, the elongation of the mandibular branch is made simultaneously, and the joint head is formed by lyophilized homogeneity either with the help of an autograft, a coronoid process, metatarsal bone with a metatarsophalangeal joint, and ribs.

In recent years, endoprostheses from tantalum or titanium, etc., are often used.

Various defects in the region of only one chin can be eliminated by the method of N. Obwegesser, V. Convers. D. Smith, using a bone taken in the area of the chin or jaw body, a plastic implant, chopped cartilage, Filatov's stem, fat, etc.

If the patient does not have an obstruction, you can limit the removal of the chin bone protrusion to the underdeveloped side and move the cutaneous muscle flap in the desired direction; unfortunately, in patients aged 15-16 years, such an operation does not achieve the desired result: after 2 years some flattening of the healthy side is revealed (due to the continuation of its growth and the developmental lag in the opposite side), which then requires correction.

Surgical intervention is often complemented by orthodontic and orthopedic treatment.

To prevent various mistakes and complications in operations concerning underdevelopment of the mandible, the following recommendations should be observed.

1. After a careful analysis of all the results obtained during the examination of the patient (history, palpation, laboratory tests, panoramic radiography, tomography, etc.), it is necessary to draw up a well-grounded and clearly formulated treatment plan, taking into account the age and sex of the patient, his general condition, the degree of deformation of the lower jaw and adjacent areas of the face.
2. If the patient is older than 15 years, and the shortening of the lower jaw does not exceed 1 cm, if there is no forward standing of the upper jaw and the bite remains intact, contour plasty should be limited.
3. When the lower jaw is shortened by more than 1 cm, which causes external disfigurement of the face and bite violation, the position of the lower jaw (at any age) should be corrected, and then contour plasty and orthodontic correction of the occlusion should be performed.
4. Elongation of the jaw body with the help of bone plasty should be performed after the end of the main period of the formation of the facial part of the skull, i.e. In children older than 12-13 years.
5. If you need to extend the lower jaw, you need to answer the following questions:
   • Which part of the jaw is elongated?
   • Is it enough to produce a plastic osteotomy or have to transplant a bone?
   • What will be the source of the transplant (auto-, xeno-, allogeneity)?
   • Will there be a report of a wound with the oral cavity during surgery, will there be a need for antibiotic therapy?
   • What is the microflora of the oral cavity and to which antibiotics is it most sensitive?
   • How will the immobilization of the lower jaw and transplant be ensured after the operation?
   • How will the patient's diet and what kind of diet (drinker, spoon Nesmeyanov, etc.)?
   • What anesthesia is optimal for this patient?
   • Who will provide individual care for the patient and his feeding in the first days after the operation?

Horizontal osteotomy of the jaw branch

The horizontal osteotomy of the jaw branch is best done through a vertical intraoral cut in front of it. Fasten fragments of the branch with a polyamide thread or chrome catgut. Vertical osteotomy of the jaw branch in recent years, almost no surgeons.

Stepwise osteotomy of the jaw

Stepwise osteotomy of the jaw body can be performed through intraoral access, avoiding external incisions, possible injury of the marginal branch of the lower jaw of the facial nerve and marked postoperative scarring of the skin.

This is a rather traumatic and complicated operation, therefore it must be performed by an experienced surgeon.

Vertical osteotomy of the jaw

Vertical osteotomy of the jaw body (with subsequent osteoplasty) is best performed immediately after the dental row, where the mucosa covering the retromolar region and the front edge of the branch is mobile enough and, moreover, it is well cut off. This avoids the communication of a wound with the oral cavity. To strengthen the seedlings of the bone, chromed (long non-absorbable) catgut No. 6-8 can be used, and for fixing the diluted fragments, tooth-wire wires with hooks for intermaxillary fastening or titanium mini-plates.

Vertical L-shaped osteotomy of the branch and jaw

The vertical L-shaped osteotomy begins in the anterior section of the jaw branch at the level of the mandible opening, then descends lower along the projection of the canal of the lower jaw and dissects the underlying portion of the branch and the angle of the jaw into the anterior and posterior fragments, and when the jawbone is interfered with, into the upper jaw and the lower one; at the level of the second small molar or first large molar, the line of dissection is turned down and brought to the lower edge of the jaw. A similar intervention is carried out on the opposite side. Then pull the chin forward to the required level and, drilling above and below the line of cutting the body of the jaw of the hole, connect its fragments with steel wire, polyamide thread or a long non-absorbable catgut.

Arthroplasty with the use of a double or triple de epidermalized skin flap according to Yu. I. Vernadsky

Arthroplasty with the use of a double or triple de epidermalized skin flap according to Yu. I. Vernadsky is shown only in cases of a relatively incomplete (up to 5 mm) pronounced underdevelopment of the jaw in ankylosis.

Interosseous napkin from Filatov's stem by A. A. Limberg

The interosseous padding from Filatov's stalk according to A. A. Limberg requires multistage surgical treatment, therefore it is better not to use it, especially in children and weakened adults.

If it is necessary to extend the jaw branch more than soft-woven pads, it is better to use a bone or bone-cartilaginous graft.

Cosmetic and functional efficiency of operations (in occasion of microgenia and ankylosis) with application of bone-plastic transplantation is much higher even in the remote terms.

Restoration of the jaw branch by a free autorebran transplantation with the creation of a joint in the region of scales of the temporal bone by AT Titova

The operation is indicated in cases of microgenia due to the syndrome of the 2nd branchial arch or osteomyelitic destruction of the jaw branch in childhood.

After isolating the remaining part of the jaw branch from the scar tissue (if present), the coronal process is crossed horizontally, the branch is removed, and the jaw is moved forward until the chin is in the correct position.

Due to the soft tissue in the area of the coronal process, a pocket with a blind bottom is created. To create a bed for the placement of an aortorber transplant (its cartilaginous part upward), exfoliate the soft tissues in the area of the subchamber of the temporal bone between the zygomatic process and the scales of the temporal bone.

The bone end of the seedlings is placed on the corner of the jaw, previously devoid of the cortical bone plate, and stitched. The wound is sewn up layer by layer, then the jaw clamp is applied to extend the jaw for 10-12 days (if there is a spacer between the teeth) and MM Vankevich is manufactured.

With this form of microgenia, one can also apply arthroplasty according to VS Yovchev.

After osteoplasty about microgenia, it is necessary to transfer the patient to the orthodontist or orthopedist to correct the occlusion.

Outcomes and complications of treatment of underdevelopment of the lower jaw (microgenia, retrognathy)

According to available data, engraftment after contour plasty by grinding autochondria is noted in 98.4% of patients, and recovery of natural contours of the face or maximum cosmetic effect is achieved in 80.5% of patients.

When replanting autodermal subcutaneous grafts and xenogeneic belay shell, the cosmetic effect in the short term (1-2 years) after surgery is satisfactory, but gradually decreases due to resorption of the graft and inadequate replacement with its connective tissue.

After surgical lengthening of the jaw complications occur on average in 20% of patients in the form of sequestration of the ends of the segments of the mandible, necrosis of all or part of the seedling. The reason for these complications is the infection of the seedling bed due to the perforation of the oral mucosa when the ends of the bone defect are exposed and moved to the correct position.

Prevention of complications of underdevelopment of the lower jaw (microgenia, retrognathy)

Prevention of complications of inflammatory nature consists in targeted antibiotic therapy, starting from the first hours after the operation.