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The change in the lateral parts of the body of the mandible
05-09-2009
These fractures tend to occur at the site of application of force, ie direct. The clinical manifestation of a unilateral fracture of the lower jaw of any location, including the lateral part of the body of the jaw, is largely predetermined by the direction of the plane of the fracture and its location relative to the median line: the farther from it is a fracture plane, the greater the displacement of bone fragments. Before talking about the nature of the displacement of fragments of the mandible in its turn, it should be recalled that represent the plane and axis. Of the normal anatomy is known that the median plane divides the human body into two symmetrical halves. Parallel to her are the sagittal plane, which divides the body into sections, arranged from right to left, ie on the right and left sides.
Perpendicular to the median plane in the vertical direction are the frontal plane, which define the segments that go from front to back, ie divide the body into front and rear parts.
Perpendicular to the median and frontal conducting horizontal plane, which define the segments that are located one above the other.
Through these planes can be axis: vertical, running from top to bottom, sagittal - front to back (longitudinal); front - from left to right (transverse). To simplify the perception and understanding of the material set forth below, we found it reasonable to determine the direction of the plane of the fracture of the body of the mandible terms «anteroposterior» or «posteroanterior». In this first part of the word means in terms of a point belonging to the alveolar part, and the second - a point belonging to the base (bottom) of the body of the mandible. Therefore, «anteroposterior» trend indicates that the fracture plane goes from the alveolar part of the downward and backward to the base of the body of the mandible; «posteroanterior» - of the alveolar part of the downward and anteriorly to the base of the body of the mandible. This terminology will be used mainly to characterize the oblique fractures of the body of the mandible. The plane of fracture may be deployed around the vertical axis: in the lingual side of (oral), when the compact disc from jaw lingual side is closer to the midline compared with the vestibular, and in the vestibular side (vestibular), when the compact disc to the vestibular side is closer to the average line compared with the lingual.
Clinical experience suggests that there may be at least three options for a plane (crack) fracture through the sagittal axis of the body of the mandible. The plane of fracture (crack) can take place vertically in relation to the body of the mandible, crossing the sagittal (longitudinal) axis of a right angle, ie fissure fracture of the alveolar part of the body and cause of the jaw is located on one vertical line. In this line of fracture external and internal cortical layers of the mandible on each of the fragments are on the same level, ie plane of fracture is not turned on the vertical axis (ris.4.2). This type of fracture is more often observed in the molars and premolars. The displacement of bone fragments in this case is significant. Less otlomok shifted inwards and upwards. There papulose papulose-contact teeth. Alveolar part tilted inwards (due to the traction jaw-hyoid muscle and force the prevalence of chewing muscles on the medial pterygium in moving the fulcrum in the temporomandibular joint). The base body of the mandible with the angle of a few deployed outwards. Greater otlomok under the influence attached to it the front group of muscles is shifted downward and toward the fracture (under the influence of the lateral, to a lesser extent the medial pterygium muscles and jaw-hyoid, anterior belly of the digastric and mentohyoid muscles on the opposite side).
Middle line, thus will be biased in the direction of fracture. The front teeth on a large group of fragments is not in contact, and molars and premolars have papulose-papulose contact. Possible rupture of the alveolar mucosa, as well as the lower lunoch-arms of the nerve, which is accompanied by numbness of the skin of the lower lip and chin on the side of the fracture. If the crack has a zigzag shape of the fracture, displacement of fragments may be less pronounced.
The latter, unlike the first fracture plane is rotated along the vertical axis of the vestibular, ie fracture line outside the compact layer of the jaw is closer to the midline, and internal (multilingual) - More / (ris.4.3). In this case, crack fracture is oblique direction from front to back and from outside to inside. Fragments will move so / the same as was described above. However, in addition to possible bias in the longitudinal direction (perednezaadnem) ie «Napolzanie» each other. This is accompanied by a narrowing of the dental arch, pushing the smaller-broke off outwards. Malocclusion is more pronounced. In the third variant, in contrast to the second fracture plane is tilted on the vertical axis in the lingual side (oral), ie has the opposite arrangement of cortical layers of the fracture lines: on the lingual side, it is closer to the midline, and from the vestibular - far from it (Fig.4.4). Gap has a fracture obliquity of the posterior part of body of the mandible anteriorly and medially. In this situation the displacement of bone fragments, tends to be significant. Fragments also shifted in the longitudinal direction towards each other. Smaller otlomok alveolar is significantly shifted to the lingual side, and the angle of the jaw and the base of the body - outwards. Mechanical obstacles to shift it to the lingual side of a shrinking jaw-hyoid muscle in this situation, practically no. Dental arch is also narrowed substantially disturbed bite throughout.
It should be noted a possible feature of the X-ray pictures in such fractures. If the fracture plane coincides with the course of X-rays on the radiograph in lateral projection obtained a clear line of enlightenment (fracture line). If the plane of fracture and the rays do not coincide, formed two lines from the outer and inner compact layer of the jaw. This creates the impression that there was a fragment (comminuted fracture). Such «psevdooskolok» signed between the two semi-oval lines converging at the base of the mandible and on the crest of the alveolar part. A true piece of radiographs often presented in the shadow of a triangular shape, the lower side of which is the base body of the mandible.
In clinical practice, there are oblique fractures of the lateral part of the body of the mandible, when the plane (crack) fracture of the alveolar part is obliquely backward or, occasionally, towards the base of the body of the mandible. The plane skew the fracture may not be deployed around a vertical axis, and then the fracture line on the outer and inner compact layer of the jaws will be on the same level from the midline (ris.4.5). If the plane skew fracture deployed along the vertical axis vestibular, the outer compact layer of the jaw is located closer to the midline, and the inside - further. If the plane of fracture is deployed in a skew towards lingual (oral), the location of fracture lines, the compact layer is reversed compared to the previous: a lingual side - closer to the midline, and from the vestibular - further.
For the displacement of bone fragments in the vertical direction will be essential angle of the plane of fracture (anterior or posterior) in relation to the horizontal plane. If the plane of fracture has «anteroposterior» direction (see symbol), ie line fracture on the alveolar part is closer to the midline, and at the base of the jaw of the body - far from it, the displacement of smaller fragments up to be significant. If the plane of fracture is «posteroanterior» direction and the line of fracture to the alveolar part is backwards from the line of fracture based on the body of the mandible, the displacement of bone fragments in the vertical direction can not be, because the smaller otlomok, trying to move up, will prevent the displacement of more fragments down. Contiguous area of fracture jaw mutually held and not allow the muscles to move the fragments in the vertical direction.
When fractures of the lateral division of the body of the lower jaw line it often takes place in close proximity to the chin holes rarely - through him. In the latter case, perhaps expressed bleeding and reducing (lack of) pain sensitivity in the skin and mucous membrane of the lower lip.
At the turn of the localization of the patients have always complained of pain in the lower jaw on the side of the fracture, increasing when you open your mouth and chewing food. Less spontaneous pain are not available, but must appear in the functional load. If there was a displacement of bone fragments, patients indicate improper interdigitation, sometimes - to numb the skin of the lower lip and chin on the side of the fracture.
Mouth slightly opened, his chin a bit off from the midline in the direction of fracture. In the lower section of the buccal and Wharton on the side of the fracture is determined by swelling or swelling, or inflammatory infiltrate, which depends on the virulence of the microflora, immune status, period of treatment the patient for help. The skin in this area can be «bruise» (manifestation hematoma), or because it hyperemic developing purulent inflammation. On palpation the base of the body of the mandible bone is determined by the projection in the projection of premolars or canines, at least - the first or second molar. Symptom burden in the positive area previously identified bone protrusion.
Opening the mouth can not be fully due to the increasing pain. Chin there may deviate in the direction of fracture. From the vestibule, and in the sublingual area, respectively, small and large molars there is bleeding in the soft tissue. In the interdental spaces between the premolars and second premolars and first molars can be lacerated wound the mucous membrane of the gums. Percussion tooth located posterior to the fracture gap, usually painful. When you save the sensitivity of the skin of the lower lip and chin percussion of the tooth, located anterior to the fracture line, too painful because of the traumatic periodontitis and preserved innervation. Value of dentitions affected by many factors and described above. Symptom mobility fragments positive.
On radiographs of the mandible in lateral projection defined area of enlightenment (fracture line), respectively, lateral parts of her body, the displacement of bone fragments in the vertical plane, the ratio of the roots of teeth to fracture gap, the presence or absence of bone fragments, fracture and dislocation of the tooth root. X-rays performed in the direct projection, you can also see the displacement of bone fragments, but in the frontal plane.
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