Jaw Angle Implants
Q: Dr. Eppley, I am researching jaw angle implants and am seriously getting ready to choose a doctor. I consider you to be one of the top few in the nation, and have read your blog on how you’ve never experienced a tear with the masseter sling with jaw angle implants. However, is there still some roll up?
Another well respected doctor has told to me that no matter what there will be a bit of roll up, but did not clarify whether or not that implied no tearing.
A: To clarify the issue of the masseter muscle sling and its potential disruption, you first have to differentiate whether you are talking about width only jaw angle implants or vertical lengthening jaw angle implants. With width only jaw angle implants, it is not necessary to strip the tissues off of the lower border of the mandible. Thus there is little to no risk of any masseteric muscle sling disruption/roll up/retraction issues. With vertical lengthening jaw angle implants or total custom jaw angle implants, that is a completely different issue. By definition it is necessary to elevate the sling attachments off of the border of the mandible and the massteric pterygoid sling is disrupted. This is unavoidable. Whether there will be some muscle rollup depends on how much vertical jaw angle lengthening is created by the implant. If it is 5 to 7mms, for example, then the rollup will really be minimal. But if the vertical lengthening is 15 to 20mms, then it will be more significant. (more visibly noticeable) It is important to remember that the masseter muscle can not lengthen, that is a physical impossibility. So the longer the jaw angle is lengthened, the more the original position or even roll up of the muscle may be seen when biting down.
A complete tear or retraction of the masster muscle is a slightly different situation. For this to occur the entire attachments of the masseter muscle must be detached from the angle point forward to the mid-body of the mandible as well as high up onto the lateral ramus. The angle point attachments are quite significant and not easily dissected off of the bone. With aggressive degloving of the posterior and inferior mandibular borders (and I might add this is almost always done in sagittal split ramus osteotomies in orthognathic surgery) the risk of a more substantial masseter muscle retraction may be seen where the lower end of the muscle is seen up almost at the level of the earlobe when biting down.
Dr. Barry Eppley