The well known sliding genioplasty is sometimes selected by patients because they wish to avoid a submental scar from a chin implant. The incision location may not be the primary reason but may on the list of several motivations for choosing a bony chin augmentation procedure.While an intraoral incision avoids a scar it has its own potential disadvantages, which while hidden from view, does not mean they are irrelevant.
The location of the intraoral sliding genioplasty incision is on the lower lip side of the vestibule. It is a horizontal incision in which the surgical tendency is to make it moderately long for complete visibility of the bone which is to be cut. While the length of the incision may seem to have no clinical relevance since it is intraoral, that is not a completely accurate perception. The more the incision goes to the side the more likely it is going to cut through small terminal branches of the mental nerve which cross into the central lower lip. This will lead to greater numbness after the surgery, which although should fully resolve eventually, this is not assured outcome. In addition the longer incision is the longer it is going to take to heal.
An improved to incisional access to a sliding genioplasty is to use a much smaller central and perform the procedure through more of a tunnel approach. From the smaller central incision which goes through the central fat pad and its adjoining mentalis muscle long subperiosteal tunnels are made on each side. Retractors are used superiorly to protect the mental nerve which is almost never seen. A reciprocating saw with a long blade is then used to make the low angled long horizontal bone cuts from which the chin segment is downfractured.
Plate and screw fixation is done centrally and there is more than enough access and visibility to do so. With incisional closure the length of the incision stays inside that of the canine tooth are each side.
The small incision genioplasty works somewhat similarly as that of any implant placement. Fundamentally through a small incisional entrance a bigger operation is done through it which initially may seem impossible. Instead of an inplant it just happens to be cutting of the bone, moving it and plate fixation in a new position. The small incision disrupts less terminal branches of the mental nerve resulting in reduced numbness and more rapid healing of the incision.
Dr. Barry Eppley