Maas et al.17 pointed out that the clinical efficacy of implant material over the long term is dependent on the stability of the material to chemical degradation such as by hydrolysis and other oxidation-reduction reactions, as well as physiologic cellular activity directed against the material. The porosity of the implant materials plays an important role in host tissue ingrowth and subsequent stability. In addition, such factors as thin skin overlying the implant, scarring of the tissue bed, and the architecture facilitating stabilization of the implant play crucial roles in determining the longevity of the clinical result.17
Porous implants have a greater risk of immediate infection, as there is increased surface area for adherence of bacteria. However, porous implants have fewer late-stage infections, as the incorporation of host tissue into the implant pores allows access to the site for immune response mediators.19
The great majority of alloplastic implants commonly used in nasal reconstruction are polymeric materials.
Silicone implants have long been used to correct significant dorsal deformities. Tissue reaction to solid silicone implants is characterized by a moderate fibrous tissue capsule without tissue ingrowth.20 When a silicone implant is placed in the nasal dorsum, it is subject to trauma and mobilization. Although these implants have been used in large numbers with excellent results, they are subject to moderate to intense ongoing inflammation, seroma formation, and extrusion. Extrusion rates for silicone implants have been reported as high as 10% for dorsal implants and 50% for columellar implants.21,22
Expanded porous polyterrafluoroethylene (e-PTFE) is commonly used for nasal augmentation.24,25 The 30-^m pore size allows for limited tissue ingrowth. Although the implant is soft, resulting in a natural feel, it provides excellent support over the dorsum and can be used for tip grafts and even in the columel-lar area. The implant is easily contoured and comes in a variety of thicknesses, making it very applicable to a variety of contouring problems.
I consider e-PTFE the implant of choice for reconstructing moderate to large dorsal defects. This implant has the advantage of being readily available. It also reduces operative time, as no second surgical site is needed to harvest a graft. The implant is easily contoured and very well tolerated by patients. When stacked autologous cartilage implants are used over the nasal dorsum, grafts can become dislodged, and irregularities result when sunglasses or reading glasses are worn. This problem is less likely with the solid alloplastic implant.
I have found that the implant can be easily placed through an internasal incision with the aid of chromic guide sutures affixed to a Keith needle to assist in properly positioning the implants. The implant is first soaked in antibiotic solution before being placed; prophylactic antibiotics are recommended. When such implants are used, it may be appropriate to consider prescribing prophylactic antibiotics for patients who undergo dental work, in order to minimize the possibility of bacteria seeding the implant.
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