X-ray signs of injuries to jaws and teeth

X-ray diagnostics of traumatic injuries of jaws and teeth

In case of traumatic injuries of the maxillofacial area, an X-ray examination is mandatory. In cases where the clinical diagnosis of fracture is not in doubt, the radiograph is performed not only for the purpose of documentation, but also for obtaining additional valuable information on the nature and location of the fracture, the number, position and displacement of fragments and fragments, the condition of the roots of teeth and wells. On repeated radiographs made after repositioning, the correctness of the comparison of fragments and the dynamics of the fracture course are estimated (the images of the lower jaw are performed after 2 weeks and 2-3 months, the middle zone of the face - 3 to 4 weeks after repositioning).

The fracture of the jaws accounts for about 2% of all fractures of the bones of the skeleton, with fractures of the lower jaw predominating, which are often combined with injuries of other bones of the facial skull.

X-ray signs of fracture. Depending on the mechanism of action, direct (arising in the place of application of force) and indirect, or reflected (arising at a distance from the site of impact), fractures are distinguished.

Fracture can be single and multiple (fracture of the bone in several places).

Taking into account the course of the fracture plane with respect to the long bone, transverse, longitudinal and oblique fractures are distinguished.

Depending on the relationship between the fracture line and the temporomandibular joint, there may be extra- and intra-articular fractures. In connection with the variability of the level of attachment of the capsule, some fractures of the cervix of the condylar process are intraarticular. The fractures of the condylar process are the worst.

The main radiographic signs of fracture are violations of bone integrity and displacement of fragments, indicating a complete fracture of the bone.

At subperiosteal incomplete fractures (cracks) displacement of fragments does not occur. The displacement is due to the acting force and the contraction of the muscles attached to the fragments. Fractures with damage to the skin, rupture of the mucous membranes, passing through the cortical plate of the holes, the maxillary sinus and the nasal cavity are referred to as open. Inflammatory changes in the periodontal and periapical tissues of the teeth located on the fracture line may be the cause of traumatic osteomyelitis.

Displacement of fragments, found on the roentgenogram, is a pathognomonic sign of a fracture that excludes the need for distinctive recognition. To detect the displacement of fragments, it is necessary to perform radiographs in at least two mutually perpendicular projections.

In a clinical picture that is suspicious of a fracture, if a fracture is not diagnosed on radiographs, repeated pictures are taken after 2-3 days. Due to osteoporosis and bone resorption at the ends of fragments, the fracture line becomes wider and better defined on the roentgenogram.

Due to the violation of the integrity of the bone beams, the fracture line is defined as a band of enlightenment with fuzzy contours. Most clearly, the fracture line is visible if there is a violation of the integrity of the cortical bone (cortical plates of the jaw or hole).

The image of the fracture line in the photograph changes depending on the projection conditions of the study. In the case of the passage of the central ray parallel to the plane of the fracture, a strip or thinning line of bone tissue is visible in the picture. With a fracture of the lingual and buccal cortical plates of the lower jaw at different levels, two fracture lines, forming an oval and simulating a comminuted fracture, are visible in the picture. The performance of panoramic tomograms in these cases resolves diagnostic difficulties.

With longitudinal displacement with the occurrence of fragments due to their superposition, the fracture zone looks like a strip-shaped seal region. In complex cases of diagnosis of fractures, computed tomography can significantly help.

Fractures of the lower jaw

Anatomical features of the structure of the lower jaw predetermine the preferred localization of fractures: at the level of the canine, along the middle line (respectively, the intermaxillary suture), in the region of the angle and neck of the muscular process.

Among the factors influencing the displacement of fragments (the direction of the acting force, the mass of the fragment itself), the greatest importance is the pull of the muscles attached to the fragments.

Displacement with the occurrence of fragments occurs with transverse and oblique fractures in the region of the jaw branch, double fractures of the jaw body, fractures of the cervix of the condylar process. In 40% of cases double, in 4,5-6% - triple fractures are observed.

In case of traumatic injuries of the lower jaw, the following approach to X-ray examination is recommended:

1. all patients perform a direct review frontal-nasal radiograph, which makes it possible to identify multiple fractures of other bones (zygomatic arches, covering skull bones), some of which are clinically pronounced indistinct and sometimes are a random radiographic finding. Due to projection distortion, the magnitude of diastosis in these pictures is greater than in reality;
2. in order to get an idea of the condition of the alveolar part, the cortical plates of the holes and teeth in the fracture region produce intraoral contact radiographs. If this is not possible, extraoral x-rays are made in oblique contact projections. In each specific case, the choice of technique is determined by the localization of the fracture;
3. For the examination of the anterior sections of the jaw produce a direct panoramic radiography;
4. at fractures of the body, angle and branch of the jaw, orthopantomograms or lateral radiographs are performed;
5. at fractures of the condylar process produce orthopantomograms, lateral radiographs of the body and the branches of the lower jaw. In case of head fractures and high neck fractures, tomograms or zonograms of the temporomandibular joint are required in the lateral projection with an open mouth.

In early childhood, subperiosteal fractures predominate in the type of a green branch, mixing of fragments is rarely observed. In children aged 3 to 9 years, the weakest point in trauma is the cervix of the condylar process. The fracture of the cervix (a trauma only the cervix or in combination with injuries of other departments) accounts for 30% of all fractures of the lower jaw.

Fractures of the upper jaw

Fractures of the upper jaw are often combined with damage to other bones of the facial skull and sometimes the base of the skull. Taking into account the "lines of weakness" Lefort identified three types of fractures, which are rarely observed in pure form. Upper fracture (type Lefort III) - the fracture line passes through the nasal and teary bones, the bottom of the orbit in the direction of the pterygoid process of the base bone, fractures the malar bone with the upper jaw and nasal bones from the base of the skull. The middle fracture (type Lefort II) - the plane of the fracture goes through the nasal, tearing bones, the bottom of the orbit, the maxillary-cheek seam, there is a fracture of the upper jaw from the base of the skull and zygomatic bone. With the lower fracture (type Lefort I), the plane of the fracture passes through the alveolar processes (fracture of the alveolar process), maxillary tubercles and lower parts of the pterygoid processes of the base bone. With these fractures, the alveolar bone is displaced from the teeth and the bite is broken. An indirect radiographic evidence of a fracture is a reduction in the pneumatization of the maxillary sinus due to hemorrhages and a violation of the integrity of one of its walls. Fractures of the middle zone of the face can cause traumatic sinusitis. Hemorrhages and swelling of the soft tissues of the cheeks on the survey radiograph simulate a picture of the dimming of the maxillary sinus. In differential diagnosis, orthopantomography, tomography and zonography are helpful, preferably in the upright position of the patient. When the whole body of the jaw is broken and air gets into soft tissues, emphysema with a typical radiographic pattern occurs.

In view of the comparatively fast connective tissue fixation of fragments, even when they are displaced, severe deformations and functional disturbances occur, for the elimination of which complex reconstructive operations are required. This necessitates the recognition of traumatic injuries in the shortest possible time for repositioning the fragments.

In case of traumatic injuries of the upper jaw, the following pictures are taken:

1. chin-nasal radiograph;
2. a semi-axial or axial radiograph;
3. lateral radiograph of the skull;
4. orthopantomogram;
5. for the study of the frontal sections of the jaw - a direct panoramic radiograph;
6. for evaluation of the condition of the alveolar process and teeth in the fracture zone - intraoral contact radiographs, X-ray photographs of the solid palate, vnutrice, extraoral contact radiographs in an oblique projection.

Fracture of the zygoma

The most common fractures of the temporal process of the malar bone, which separates from both the temporal bone and the body of the zygomatic, with the fragment blending inside and out.

When a zygomatic bone trauma often occurs, the displacement of its body to the inside, the introduction of the upper jaw, hemorrhage in the maxillary sinus.

To localize the fracture and determine the displacement of the fragments, an x-ray of the skull is performed in the axial projection. The target tangential radiography of this area is quite informative: the cassette with the film is placed below the angle of the jaw, the central ray is directed from the top downwards along the tangent to the zygomatic arc perpendicular to the film.

Fracture fracture

Fracture fracture occurs as a result of metaplasia of blood clots in the peri-mandibular soft tissues (parostal callus), due to the reaction of the endosteum, lining the medullary spaces (endosteal callus) and periosteal reaction (periosteal callus).

Approximately 35 days after the injury, the osteoid tissue becomes calcified and becomes bone. On the roentgenogram, ossified periosteal stratifications are most often defined as a linear shadow along the edge of the lower jaw. Although the restoration of the structure of bone tissue in the zone of the fracture line ends in 3-4 months, the fracture line in the pictures is visible for 5-8 months. The orientation of the bone trabeculae in the plane of the fracture differs from the predominantly horizontal direction of the main bone trabeculae in a nearby spongy bone substance.

Degradation of small fragments lasts 2-3 months. Fracture fracture in the head and neck of the condylar process occurs more quickly (within 3 to 4 months the fracture line is not determined;).

Complications of fracture fusion

One of the most common complications of jaw fractures is traumatic osteomyelitis. Complications also include the formation of a false joint (pseudoarthrosis) along the line of fracture with a persistent violation of bone continuity, as a result of which the appearance of mobility uncharacteristic for this department is possible. The formation of a false joint can be caused by incorrect juxtaposition and fixation of fragments, the interposition of soft tissue between them, the severity of trauma (loss of a significant part of the bone, soft tissue crushing), and the violation of blood supply to bone fragments.

The detection of abnormal bone mobility during clinical investigation makes it possible to diagnose a false joint. However, pathological mobility may be absent in connection with the fixation of fragments by fibrous tissue. In these cases, the most informative X-ray study in two mutually perpendicular projections, sometimes in combination with a tomography.

On the roentgenogram of the false joint, there is no bone marrow connecting the fragments, the ends of the fragments are rounded and smoothed, sometimes covered with a cortical plate. The space between the fragments, filled with connective tissue, is called the joint slit. Depending on the severity of the processes of bone formation and the shape of fragments, atrophic and hypertrophic false joints are distinguished.

Dislocation of the lower jaw

In connection with topographic features of the structure of the temporomandibular joint, anterior dislocations often occur. The cause of the dislocation is injury or excessively wide opening of the mouth, in particular when performing medical manipulations. Dislocations are complete and incomplete (subluxation), unilateral and bilateral.

The purpose of the radiographic study is to determine whether dislocation is combined with a fractured condylar process. For diagnosis of dislocation, radiographs of Parma or tomograms are performed. On the tomogram in the lateral projection, the articular cavity is revealed, the condylar procession head is located anterior to the articular tubercle in the metamorphosis fossa.

Dislocations in other directions (behind, outside and inside) are rare and, as a rule, are accompanied by fractures of the condylar process and the temporal bone.

Dislocations and fractures of teeth

Dislocations and fractures of the teeth occur with acute trauma and removal of the tooth or root. Chronic trauma of teeth occurs during abnormalities of the occlusion and after incorrect orthopedic interventions.

When a dislocation occurs, a break in the periodontal tissue and a change in the position of the tooth in the hole (partial or complete dislocation). In the case of displacement of the tooth from the hole on the roentgenogram, the periodontal gap at the apex and the deformation of the gap are noted. Dislocations of the teeth most often occur in the anterior section of the upper jaw. When the dislocation is punctured with destruction of the cortical plate of the socket, the periodontal gap in the periapical region is absent. Impacted dislocations of infant teeth may be accompanied by damage to the corresponding primordia of permanent teeth with a violation of their formation and death. When a temporary tooth injury without damage to the pulp, root dissolution occurs within the usual time.

The fracture line may be located transversely or obliquely in any part of the root and neck, between the neck and the middle of the root; between the middle of the root and the tip; there are also longitudinal fractures of the root and crown.

With fractures and dislocations of the teeth, an x-ray examination can establish whether there is a fracture of the cortical plate and the alveolar process.

The fracture is rare. On the roentgenogram in these cases, the muff-shaped thickening of the tooth is determined, the image of the fracture line disappears as a result of the formation of dentin.

With the preservation of the pulp in the analysis of repeated shots, attention is paid to the presence or absence of replacement dentin in the tooth cavity and canals, the state of fragments of the roots, the periodontal gap and the cortical plate of the socket.

The pulp of the permanent tooth, lost during the trauma, is removed and the channels of the fragments are sealed, which can be fastened with a pin. If the crown is defective, tabs are used on the pin, the length and depth of insertion is determined taking into account the size of the root. On repeated radiographs, the condition of the periodontal fissure and the cortical plate of the socket is assessed.