Development And Evaluation Of Facial Prosthetic Adhesive

Facial prostheses can stay in place by the means of anatomic undercuts, mechanical means, adhesives or implants. Retention with implants or adhesives is commonly used in clinic. Implants are preferred for the ideal retention, but for the complicated and expensive operation or the patients can't accept implants for other reasons, the patients will have to rely on prosthetic adhesives. Retention with prosthetic adhesive is one of the most commonly used and useful techniques for its cheapness and convenience. Most of previous researches have been focused on investigation of the performance of commercial prosthetic adhesives; however, even no studies about prosthetic adhesive have been carried out domestically.Traditional facial prosthetic adhesives can be classified into two categories based on the components. Poly-acrylate adhesive is cheap and shows medial bond strength, however,with difficult removable adhesive residue left on skin. Silicone-based adhesive shows higher bond strength and leaves little residue on skin, but the organic solvent in it could be a potential irritation. Polysiloxane has perfect properties, such as physiological inaction, heat- resistantce and lower surface tension etc. Therefore the modification of poly-acrylate adhesive with organic siloxane has become one of the hot research topics. Most of the previous researches focused on paintings or adhesives for industrial application. The purpose of this study was to modify the poly-acrylate adhesive with organic siloxane, and make it have the advantages of both traditional adhesives to retain silicone prostheses with enough cohesive strength and appropriate bond strength and leaving little adhesive residue on skin.In this study, the best combination of materials was determined by using an orthogonal experimental design. A kind of poly-acrylate prosthetic adhesive (Non-modified Adhesive, NMA), and a kind of poly-acrylate prosthetic adhesive modified with organic siloxane (Facial Prosthesis-skin Adhesive, FPSA), were developed by using seed emulsion polymerization. The basic performances and biosafety of two newly produced prosthetic adhesives were evaluated. The biomechanical bond strengths of four prosthetic adhesives (Secure2 Adhesive, SA; B-200-R Regular, RE; NMA and FPSA) were compared; and the influence of water on these four adhesives were investigated further. At last clinic application of the adhesive FPSA was tried on some volunteers.The results showed that:1. Poly-acrylate PSA modified with organic siloxane was produced through semi-continuous emulsion polymerization.2. When taking addition of organic siloxane (2%), with combined emulsifiers (2%), combined initiators (0.6%) and functional monomers (1%), the polymerization procedure remained stable and the polymer emulsion showed good properties.3. The result of DSC showed the Tg of the modified emulsion was -45℃, which was appropriate for poly-acrylate emulsion PSA for skin application. FTIR showed organic siloxane had been grafted onto the acrylic polymer. Organic siloxane has improved the performances of acrylic polymer. TEM result showed the emulsion was homogeneous morphologically. The emulsion particles, about 350 nm in diameter, dispersed regularly. The core/shell structure was shown clearly.4. Biosafety evaluation of two newly produced facial prosthetic adhesives showed no serious irritation, which indicated that these two adhesives were safe to be used.5. Among the four facial prosthetic adhesives, SA had the highest bond strength with silicone elastomer and skin, followed by FPSA, in order, RE and NMA had the lowest.6. Observations of the failure mode showed that RE and NMA failed at the adhesive layer, with adhesive residue left on skin. When peeling off the prosthesis retained with prosthetic adhesives, tensile-shear force can be used to reduce adhesive residue on skin.7. The capacity for water-resistance from higher to lower was SA, FPSA, RE and NMA. Immersion in water didn't influence the behavior of silicone-based adhesive, but influenced that of the poly-acrylate adhesives. The capacity for water-resistance of the adhesive modified with organic siloxane was enhanced, but need to be improved further.8. Through clinic application on some volunteers, the prosthetic adhesive of FPSA showed enough bond strength and little irritation, with little residue left on skin, which indicates that this prosthetic adhesive can be used in clinic after further modification.