When you need to fasten something semi-permanently to wood, a lag screw is an excellent choice. But using it incorrectly can be a disaster, so make sure you have the right materials for the job before starting.
Lag screws are larger than other fasteners, such as wood or sheet metal screws. They have sharp cutting threads and a shoulder below the head (in longer lengths). Unlike other types of fasteners, which come with multiple heads, lag screws are only available with hex heads, meaning that they can be driven in only one way—with a nut driver or ratchet.
To install a lag screw, first make sure the materials are properly aligned and use clamps to keep them in place. Then, drill a hole with a bit that is slightly smaller than the bolt’s diameter. Be careful not to drill too deep, since the head of a lag screw can break off in softer materials like wood.
If the holes are drilled correctly, you can then insert and tighten the bolt. Be sure to use a hex wrench or ratcheting socket wrench when tightening, as overtightening could cause the bolt to snap inside the material.
The lag screw technique provides good interfragmentary compression in displaced mandibular fractures, and restores premorbid anatomic alignment. This is particularly true for oblique fractures, where it is important to ensure that the screws are placed perpendicular to the fracture line. This fixation also offers excellent stability and occlusion. Lag screw