While there is frequent debate about the need for screw fixation for facial implants, there really is no debate on their use when it comes to jaw angle implants. The jaw angle region is a difficult area to create an adequate subperiosteal pocket and the strong effects of masseter muscle contraction make for a high risk of implant displacement.
The traditional placement of screws in the jaw angle region is often done through an intraoral approach. While successful for many mandibular ramus surgeries, it is often not so in jaw angle implants. The need to get the implant adequately far back over the ramus leaves little implant material to be accessed for an intraoral screw fixation approach. The angulation is too severe using self-tapping screws to get adequate engagement through the implant into the bone. Often when trying to do so the implant is brought forward out of position so that the screws can be placed. While this may secure the implant to the bone it also loses the desired aesthetic effect.
As a result I have long used a percutaneous technique where the screw can be placed in a perpendicular orientation to the implant. This is especially useful in using self-self-tapping screws as getting them started into the bone requires the placement of some pressure on the screwdriver. This enables the screw tip to get started cutting into the bone. The use of a percutaneous technique also allows for a much greater diversity of placement locations through the jaw angle implant. The very small skin incision externally heals with an imperceptible scar.
With using the percutaneous screw fixation technique it requires a good assistant who can load the screw into the driver once inside the mouth. This can be challenging for some and there is an easy way to get around the screw loading part of the process. Place the screws into the desired location on the implants before they are placed into position. This then eliminates the screw loading step and makes the technique faster and potentially less frustrating.
One of the keys in screw preplacement into the implant is to recognize that it is going to be in the upper part of the implant where the material thickness is thinner. Self-tapping screws, whether they be 1.5 or 2.0mms, do not come in lengths greater than 7mms.
Dr. Barry Eppley