X-ray of the maxillofacial region (dental X-ray)

Traditional methods of X-ray examination are still used predominantly in dental practice. Radiography is the method of choice. X-ray examination of the maxillofacial area is rarely performed: in some cases of trauma, to determine the localization of foreign bodies, and for angio- and sialography. However, transillumination is usually combined with X-ray examination.

Depending on the location of the X-ray film in relation to the teeth, intra- and extraoral X-ray methods are distinguished. Intraoral dental X-rays can be taken on any X-ray diagnostic device, but special dental devices are best suited for these purposes.

For intraoral radiography, a packaged or specially cut (3x4 cm) film is used, packed in light-proof standard packages. The film is pressed in the area being examined with a finger (contact images), held with special film holders (interproximal images, "parallel beam radiography") or with closed teeth (bite images, occlusal).

When taking dental X-rays, the patient sits with the back of his head resting on the headrest, the midsagittal plane is vertical and perpendicular to the floor of the room. In the case of taking X-rays of the upper teeth, the head is positioned so that the imaginary line connecting the external auditory opening with the base of the nose is parallel to the floor of the room. When taking X-rays of the lower jaw teeth, the imaginary line running from the external auditory opening to the corner of the mouth should be parallel to the floor of the room.

Intraoral contact (periapical) radiography

Taking into account the shape of the alveolar processes and the peculiarities of the arrangement of teeth in them, it is necessary to follow certain rules to obtain an undistorted image. The isometry rule, or the bisector rule, was proposed by Cieszynski in 1906: the central beam is directed to the apex of the root of the tooth being examined perpendicular to the bisector of the angle formed by the axis of the tooth and the film. As the angle of the tube inclination increases, the length of the tooth decreases; as it decreases, it increases. To facilitate taking pictures, a tilt scale is applied to the tube.

In order to obtain a separate image of the teeth, the central beam of X-rays must pass perpendicular to the tangent (tangent rule) drawn to the arc, at the location of the tooth being examined. The central beam of rays is directed to the apices of the roots of the teeth being examined: on the upper jaw they are projected onto an imaginary line running from the tragus of the ear to the base of the nose, on the lower jaw they are located 0.5 cm above the lower edge of the bone.

Intraoral bitewing radiography

Bitewing radiographs are taken when it is necessary to take intraoral contact images (increased gag reflex, trismus in children), when it is necessary to examine the alveolar process and hard palate, to assess the condition of the cortical plates of the lower jaw and the floor of the oral cavity. Bitewing radiographs are used to examine all the teeth of the upper jaw and the anterior lower teeth. When taking images, it is necessary to observe the above rules of isometry and tangent.

Interproximal radiographs

The film is held with a film holder or with a piece of thick paper attached to the film wrapper and clamped between the closed teeth. The central beam is directed perpendicular to the crowns and the film. The radiograph shows an undistorted image of the marginal sections of the alveolar processes (interdental septa), crowns of the upper and lower teeth, which is essential for assessing the effectiveness of periodontal disease treatment. The technique makes it possible to produce identical images in dynamics. When radiographing all sections, 3-4 images are taken.

Shooting with "parallel beams" ("long-focus radiography") is carried out using a powerful X-ray tube with a localizer tube 35-40 cm long. In the oral cavity, the film is held by a film holder or special rollers made of porous materials parallel to the long axis of the tooth. Due to the large focal length, there is no distortion of the image of the marginal sections and teeth in the image. The technique makes it possible to obtain identical images, which are used in periodontology.

Extraoral radiographs

Extraoral radiographs make it possible to assess the condition of the upper and lower jaws, temporomandibular joints, and facial bones that are not displayed or are only partially visible on intraoral images. Since the image of teeth and surrounding structures is less structural, extraoral images are used to assess them only in cases where it is impossible to perform intraoral radiographs (increased gag reflex, trismus, etc.).

In 1966-1969, Yu I Vorobiev and M. V. Kotelnikov developed a method for obtaining extraoral radiographs in oblique contact and tangential projections using a dental apparatus. When radiographing the frontal sections of the jaws, the first oblique contact projection is used. The cassette with the film and intensifying screens is pressed against the superciliary arch on the side being examined, flattening the tip of the nose and shifting it. The head is turned toward the side of the examination by approximately 60°. The central beam of X-rays is directed perpendicular to the film through the sternocleidomastoid muscle at the level of the angle of the lower jaw.

When X-raying the molar and premolar area (second oblique contact projection), the cassette is pressed against the zygomatic bone on the side being examined. The central beam is directed perpendicular to the film below the lower edge of the lower jaw to the area of the second premolar.

When examining the angle and branch of the mandible (third oblique contact projection), the midsagittal plane is parallel to the plane of the cassette pressed against the zygomatic bone on the side being examined. The central bundle is directed perpendicular to the film onto the upper part of the branch.

Extraoral contact radiography makes it possible to assess the condition of the teeth, the marginal parts of the alveolar processes, the periapical areas, the relationship of the roots of premolars and molars with the maxillary sinus and mandibular canal.

In terms of information content, the technique is not inferior to intraoral contact radiographs.

Radiography in oblique tangential projections is used to assess the condition of the vestibular regions, primarily the upper jaw.

The patient sits in the dental chair, the head rests on the headrest. The central beam of rays is directed tangentially to the area being examined, perpendicular to the film cassette and intensifying screens. Depending on which area is being displayed on the contour (central, lateral incisor, canine, premolars, molars), 5 tangential projections are distinguished.

The chin-nasal projection is used to examine the maxilla, maxillary sinuses, nasal cavity, frontal bone, orbit, zygomatic bones and zygomatic arches.

On radiographs of the facial skull in the frontal-nasal projection, the upper and lower jaws are visible, and the bones of the base of the skull and cervical vertebrae are projected onto them.

X-ray of the body and branch of the lower jaw in lateral projection is performed on a dental X-ray diagnostic device.

An anterior axial skull radiograph is used to evaluate the walls of the maxillary sinus, including the posterior sinus, nasal cavity, zygomatic bones and arches; it shows the mandible in axial projection.

In the most common method of radiography of the temporomandibular joint on a dental apparatus, the central beam of X-rays is directed through the semilunar notch of the opposite side (according to Parma). The tube is brought as close as possible to the semilunar notch of the healthy side, thereby providing magnification and clarity of the image, which facilitates the analysis of the radiographic picture of the joint on the examined side. Radiographs of each joint are taken with the mouth closed and open.

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