The Canine and Premolar Area

Fractures behind the mental foramen can be sufficiently stabilized by only one plate. In this area there are two anatomical danger points. The apex of the canine is normally long and may lie close to the osteosynthesis line. Therefore, it is necessary to make sure that the drill holes are placed beside the apex and do not damage them. If this is not possible with a simple four-hole plate, a fourhole plate with bar should be used (Fig. 7.9). In most cases this allows the correct positioning of the drill holes. The nervus mentalis lies below the osteosynthesis line. It emerges from the mandible between the apices of the two premolars through the foramen mentale. If care is not taken, the mental nerve may be damaged by the application of the plate. It is therefore advantageous to place the concave section of the plate between the screw holes exactly over the exit point of the nerve (Fig. 7.10), or to bend the plate in an edgewise direction over the exit point. With a fracture situated at the mental foramen, a second plate below the nervus mentalis can be necessary if some torsional instability is detected on checking the osteosynthesis.