Augmentation of the central midface generally refers to increasing the projection of the bony pyriform rim. This is the central maxillary bone that surrounds the large nasal cavity opening that lies underneath the external nose. It is most commonly referred to as the paranasal region. Its shape into the surrounding midface has either a flatter or concave contour depending upon the overall shape of the midface. As a result of its natural shape it is prone to being unprojected based on the natural growth of the midface.
Augmentation of a deficient paranasal region by implants has been done for over twenty years. It historically was largely performed in the Asian face, who are the most prone to such skeletal deficiencies, and was done with a solid silicone implant referred to as a Peripyriform implant. But today paranasal implants have evolved due to the broader base of patients who seek this type of midface augmentation and improved biomaterials and implant designs.
ePTFE implants provide the most contemporary approach to permanent paranasal augmentation. Made from expanded polytetrafluoroethylene (ePTFE) material, their design includes a medial arm connected to an outer larger implant base. The implants is designed to fit snug up underneath the nostrils. With this implant design projection is achieved to the central midface which will also decrease the depth of the nasolabial folds by the side of the nose.
The surgical technique for placement can be performed under local, IV sedation or general anesthesia. After intraoral infiltration with a local with epinephrine solution for hemostasis, bilateral high vestibular incisions under the upper lip and lateral to the pyriform aperture are made. There is no benefit to connecting these two incisions. that do not connect. It is important that these incisions are placed well above the gingivobuccal sulcus t ensure that an adequate inferior musculomucosal cuff of tissue persists for a competent wound closure. Wide subperiosteal dissection is done ensuring that the medial and lateral dissection done around the bony rim does not violate the nasal mucosa. Dissection is also carried around the pyriform aperture medial to but not crossing the anterior nasal spine.
ePTFE paranasal implants are a crescent shaped left-right pair and available in small, medium and large sizes in two different thicknesses. In selecting implant size thickness and surface area coverage are the two considerations. But the two rules to follow in paranasal augmentation are: 1) at least 5mms thickness is needed by most patients, and 2) the footprint of the implant should extend lateral enough to cover the canine fossa to avoid a bump-like external appearance.
ePTFE paranasal implants are easily customizable with a scalpel blade) to modify their thickness, edges or extent of the medial arms or main implant body. The lateral edges of the implant must particularly be smooth and have a tapered edge as it transitions to the bone. Such thinning of the lateral outer edges can be done by compression using a clamp. Once compressed the layered ePTFE material does not spring back out.
Once inserted and positioned the paranasal implant can be secured with sutures, screws or by placing perfusion holes through the implant for tissue ingrowth. Typically the limits of the pocket dissection and the tightness of the implant fit into it does not make firm fixation essential. If screws fixation is to the used a self-tapping 8mm screw is sufficient, one per side.After irrigating out with an antibacterial solution of choice a two layer musculomucosal closure is done over the implant.
ePTFE paranasal implants offer several improvements over previous materials and designs. ePTFE is a well known material that permits some tissue adherence…but not so significant that it makes implant removal difficult. Its crescent armed design allows for a better fit along the pyriform aperture. The ePTFE materials also allows for easy customization and modification through shaving and compression techniques.
Dr. Barry Eppley