Augmentation of the midface is a variable term and concept. This could mean a wide range of augmenting the convexities and concavities that make up the central third of the face. Traditionally midface augmentation meant cheek implants. And although there are various styles of cheek implants this means increasing the convexity of the zygomatic major bone only. (aka cheekbone) Other now commonly augmented midface areas are the infraorbital rims with tear trough implants and the base of the nose (pyriform aperture) with premaxillary and paranasal implants.
When midface augmentation is requested today it is often implies a more comprehensive approach employing multiple types of midface implants put together. While this does provide a more comprehensive midface augmentation than either one alone it still represents ‘spot’ augmentation rather than impacting the entire midface bone surface.
To cover most or all of the midface bone for increased horizontal augmentation it takes a custom implant design to do so. It would not be rare to see a patient with indwelling cheek and pyriform aperture implants in a primary effort to ‘pull the midface forward’. This is seen in patients with generalized lack of midface projection often associated with increased midface width.
In designing a custom midface implant it will cover the entire midface out to just the side of the cheek just below the lateral orbital rim. It is important to add no width to the face so not having any width beyond a vertical line dropped down from the posterior edge of the lateral orbital rim is important.
The dimensions of most custom midface implants over the greatest convexity (anterior cheek) and greatest concavity (paranasal region) is usually not greater than 5 or 7mms. But to keep proper shape to the midface it should have less projection over the central maxilla and moderate projection along the infraorbital rims.
All most all custom midface implants can be placed through an intraoral approach. To do so the opening for the infraorbital nerve must be split superiorly to allow the implant to pass around it to be properly positioned. It is also important that the opening made for the nerve to pass through is big enough to prevent postoperative nerve impingement/compression.
During placement, besides getting the implant around the infraorbital nerves, it is also important in making the intraoral incision to leave a good cuff of musculomucosal tissue above the mucogingival junction. (lower end of the incision) This ensures that there will be a competent two-layer closure over the implant. It is also important during the subperiosteal dissection that it goes to the medial edge of the pyriform aperture bone and around the anterior nasal spine…but without creating a nasal mucosal disruption which would increase the risk of postoperative infection.
Augmenting the complete bony surface of the midface creates the most complete method of midface augmentation. It most closely represents what the natural bone shape would look like if it had developed with more projection with the exception of the lower end dentoalveolar structures. It is akin to what a LeFort III advancement osteotomy would create if one did not need any occlusal change.
Dr. Barry Eppley