Classification of the mandibular fractures.

By Dr. Vishaal Bhat on Friday 30 November 2007 with 0 comments

For a practical use, fractures of the lower jaw can be divided into the following classes:

Fractures of the alveolar ridge

Most often, a fracture appears at the front section. There are usually more fracture lines that descend through the teeth sockets vertically, and a horizontal line divides the ridge from the body at the apex area. Dislocation by an impact appears at the direction towards the tongue. Simple reposition is possible under a good anesthesia, however, teeth roots sometimes prevent from placing a bone fragment into its proper position. Affection of the alveolar ridge is often associated with damages of the teeth.

Fractures of the mandible toothed section

At the middle part of the jawbone, fractures usually do not run perfectly vertically along the symphysis, but rather sideways. In cases of double-sided fractures at the canine teeth area, a fragment of the chin may be pulled backwards by tension of the front depressors. Support of the tongue is thus damaged, causing the tongue to get stuck in the throat followed by suffocation.

Lateral fractures result either from a direct impact at a place of its effect or on the other side of the jawbone by transferring its force there. Muscle tension is ultimate for dislocation of fragments. In general, a short fragment is pulled upwards, especially when the dental arch is shortened on the affected side and an interdigitation of antagonists is not present. Lateral fractures use to be double, i.e. on both sides of the jawbone. Although the presence of teeth at this part of the lower jaw may cause complications (teeth damage or its presence at fracture line), these fractures can be cured easily and successfully by conservative means, i.e. by a firm intermaxillary fixation for 4 weeks.

Fractures behind rows of teeth

At the teethless distal sections (a retained third molar is often placed here), the bone’s thickness is reduced and its fracture can occur after hitting with a fist (on the left side after a blow of a right-handed person who stands opposite to a victim). If a fracture line runs below the attachments of the strong masseter which encompasses both fragments, a dislocation is not apparent. However, if pulling upwards prevails and if there is a retained tooth present at the fracture line, surgical treatment including the tooth extraction followed by osteosynthesis, is the only correct way of treatment.

Fractures of mandibular rami are less common. Most often they arise from a direct impact. Dislocation is usually not significant, these fractures do not require surgical treatment, and an intermaxillar fixation is sufficient for healing.

Fractures of the articular process

These indirect fractures appear frequently. The lower jawbone is very thin at its neck area which can be regarded as a kind of protective mechanism. This part prevents by its breakage the joint head from penetration into the middle cranial space. A direct fracture of the joint process can result for instance from a gunshot wound. These fractures can be either extracapsular or intracapsular. A fracture with no significant dislocation should be treated by resting for 3 weeks followed by rehabilitation of the mouth opening. Luxation fractures belong to those rare injuries of the articular process that require surgical repositioning and fixation.

Fractures of the muscular process

These fractures are very rare injuries. If the coronoid process under the zygomatic arch blocks opening of mouth, it should be removed from intra-oral access. No fixation of fractures is required, however, an immediate rehabilitation of mouth opening is necessary.

Fractures of a edentulous or sparsely toothed jawbone

After reposition of fragments, it is not possible to make any immobilization with dental splints or intermaxillar fixation. Fixation with the aid of resin occlusal humps, interconnected inside the mouth and reinforced from the outside by “headstall” bandages, is rather symbolical than functional. For this reason, this kind of fractures is often treated surgically, currently using mini-splints or functionally stabilizing bone splints and screws.

Defective fractures

Are characterized by a bone loss during a gunshot wounding or an explosion. Reconstruction is made by a combined treatment including the transfer of a bone transplant and fixation of the fracture (autotransplants from the illiac crest or a rib).

Category: Oro-Maxillo Facial Surgery Notes



Post a Comment