Overdevelopment of the upper jaw (upper pronation): causes, symptoms, diagnosis, treatment

In children, upper prognathism accounts for 50-60% of the total number of all deformations of the dental and jaw system.

[ 1 ]

Causes of upper prognathism (excessive development of the upper jaw)

Among the endogenous etiological factors, the most important are rickets and respiratory dysfunction (for example, due to hypertrophy of the palatine tonsils). Among the exogenous ones are thumb sucking, bottle feeding, etc.

Depending on the etiology, the structure of prognathia may be different. Thus, prognathia caused by endogenous factors (for example, impaired nasal breathing) is combined with lateral compression of the upper jaw, close arrangement of teeth in the anterior section. If it is caused by exogenous factors, then a significant expansion of the alveolar arch is noted, due to which the teeth in it are located freely, even with gaps (tremas), i.e. fan-shaped.

A certain role in the development of maxillary prognathism is played by the incorrect installation of permanent large molars during their eruption. During eruption, these teeth are installed in a single-tubercle closure: the chewing tubercles of the lower large molars articulate with the same tubercles of the upper ones. Only after the chewing surfaces of the milk large molars are worn down and the lower jaw is medially displaced, the upper first large molar with its medial-buccal tubercle is installed in the intertubercular grooves of the lower ones.

If the physiological abrasion of the tubercles of the milk teeth is delayed or does not occur at all, then the first large molars remain in the position in which they erupted. This causes a delay in the development of the lower jaw, which remains in a distal position; upper prognathism develops.

[ 2 ], [ 3 ], [ 4 ], [ 5 ]

Symptoms of upper prognathism (excessive development of the upper jaw)

It is necessary to distinguish between true prognathism, in which the lower jaw has a normal shape and size, and false (apparent) prognathism, caused by underdevelopment of the lower jaw. In false prognathism, the size and shape of the upper jaw do not deviate from the norm.

The main symptom of excessive development of the upper jaw is its disfiguring forward protrusion; the upper lip is in a forward position and is unable to cover the front part of the dental row, which is exposed along with the gum when smiling.

The lower part of the face is lengthened by increasing the distance between the base of the nasal septum and the chin. The nasolabial and chin furrows are smoothed.

The lower lip in the area of the red border contacts the palate or the back surface of the upper front teeth, the cutting edges of which do not contact the lower ones at all, even with increased forward protrusion of the lower jaw.

The cutting edges of the lower front teeth rest against the mucous membrane of the palatal surface of the alveolar process or the anterior part of the hard palate, injuring it.

The upper dental arch is narrowed and extended forward; the palatine vault is high and has a Gothic shape.

Often, true upper prognathism is combined with underdevelopment of the lower jaw, which aggravates the disfigurement of the face, especially its profile. In this case, the face is as if slanted downwards ("bird face").

Treatment of upper prognathism (excessive development of the upper jaw)

Upper prognathism should be treated in childhood by using orthodontic devices. If such treatment is not carried out in a timely manner or is ineffective, surgical methods must be used.

In adults with excessively pronounced prognathism that is not amenable to treatment with equipment, good results are achieved by removing the front teeth and resecting the alveolar process. However, despite the ease of implementation and good cosmetic results, the method cannot be called effective, since the functional capacity of the masticatory apparatus after such treatment is significantly reduced. Considering that the resection of the alveolar process ends with the installation of a fixed bridge prosthesis, which excludes the possibility of further growth of the upper jaw, this operation is permissible only in adults.

Operation A. Ya. Katz

In this sense, it is more gentle, since it provides for the preservation of teeth: after the detachment of the mucoperiosteal flap on the lingual surface of the alveolar process within the upper 6-10 teeth, the palatal part of each interdental space is removed with a bur. The mucoperiosteal flap is placed and sutured to its original place.

This intervention weakens the resistance of the alveolar ridge to the action of the sliding arch, which is installed after the operation. The operation described is indicated when the upper teeth are fan-shaped and there are certain gaps between them. Due to these gaps, it is possible to reposition the front teeth back and gather them into a tight row, achieving contact between the approximal surfaces of their crowns.

Symmetrical extraction of upper premolars

Symmetrical removal of the upper teeth in combination with compactosteotomy is performed in cases where the reposition of all the front teeth cannot be achieved by the orthodontic method alone, i.e. when each of them contacts two adjacent teeth. In addition, it is indicated for prognathism combined with lateral narrowing of the upper jaw or with an open bite. In such cases, one (usually the first) premolar is removed from each side, and then the operation is performed as in the treatment of an open bite.

14 days after compact osteotomy, orthodontic appliances are installed to gradually move the teeth back.

Other methods of treating prognathism

Osteotomy and retrotransposition of the frontal section of the upper jaw according to Yu. I. Vernadsky or P. F. Mazanov is undertaken when there is a need for rapid (one-stage) elimination of prognathism, especially in cases of its combination with an open bite, which was already discussed above.