Grafts and implants in nasal and chin augmentation. A rational approach to material selection.
Two major factors are involved in choosing augmentation materials: (1) the specific properties and limitations of the materials themselves (Table 2) and (2) the characteristics of the site for implantation. A wide variety of materials are currently available and these vary in density, ability to be sculpted, tissue reaction, resorption, migration, incidence of infection, extrusion rate, and ease of removal. Some of these characteristics are self-evident. For example, materials with high infection or extrusion rates (such as Silastic in nasal reconstruction) are clearly not useful in most instances. Likewise, materials that tend to migrate, such as tiny bits of cartilage, can lead to unacceptable results, but cartilage is such a generally good augmentation material in the nose that the measures to ensure stability are worth the additional time required for implantation. Resorption is a potential problem with all the biologic grafts and possibly with Supramid. Again, in certain situations in which alloplasts are unacceptable, such as infected areas, biologicals must be used and the consequences of resorption accepted. Density and ease of sculpting are often a matter of the surgeon's personal choice. As a general rule, bone is best replaced with firm materials and soft tissues are best augmented with soft materials. Should infection or rejection occur, the porous materials are much more difficult to remove; therefore, Silastic or a biological may be the best choice if there is any question about the presence of infection or possible future infection. The effect of the degree of tissue reaction is not well-understood. For example, Supramid elicits a marked tissue response but in general displays high compatibility with the tissues. Further investigation is needed to elucidate the role of tissue reactivity and porosity in the development of infection and extrusion. When choosing the implant material, the specific characteristics of the site for augmentation must be considered. A good example is the nose. Its mobility and thin soft-tissue coverage lead to extrusion of firm implants such as Silastic. By contrast, Silastic works well for chin augmentation. Also, consider present or future bacterial contamination in the area. This is especially important in nasal augmentation, where infection and extrusion can lead to unacceptable deformities. In general, nasal augmentation is best achieved in most circumstances by cartilage. If this is unavailable, then Supramid has a proven record for good tissue compatibility and resistance to infection. For the chin, Silastic (either rubber- or gel-filled prostheses) produces the most pleasing and long-lasting results.