Comminuted fractures involve multiple fracture lines in the mandibular body resulting in multiple fragments of bone. The bone is often shattered in the area of fracture, with fracture lines running in three dimensions.
Many clinicians consider comminuted fractures synonymous with multifragmentary fractures.
The alveolar process and teeth are commonly involved in comminuted fractures. Often, fragments containing teeth have to be removed as they have no mucosal connection.
Comminution often results in nonviable bone fragments and thus in a bone defect of variable size.
Routine diagnosis of this type of fracture should include x-rays taken in two planes at 90° to each other; the minimum requirement is a PA view and a panoramic view.
CT or digital volume tomography (DVT) imaging is extremely useful in cases of comminuted fractures.
The advantage of CT scanning is that the small fragments and bone shattering can be identified as can the displacement of the major fragments. This example depicts a combination of large and small separated bone pieces within the comminution area.
PA view of the same case.
Basal triangle (wedge) fracture
Mandibular body fractures with basal triangle represent a special severity grade. This type of fracture can be classified at the lower end of the scale of complex fractures.
Panoramic x-ray displaying bilateral mandibular fracture in the midbody on the left and the angle on the left. Both fractures show a fragmentation with a basal triangle (wedge).
3-D reconstruction of a case with a basal triangle fracture …
… in the posterior body region.
Representative slice of a sagittal CT scan series of the same patient.
Mechanism of the injury
This more severe type of mandibular body fractures most often results from heavy impact during physical altercation or from traffic accidents.
Basal triangle fractures In the particular case of basal triangle fractures, the vector of impact has a diagonal superior–inferior direction causing compressive forces at the lower mandibular border leading to a blowout of a bony triangle. The base of the bony triangle lies along the lower mandibular border and its apex reaches the alveolar process in this particular fracture mechanism.