Effect of multi-adhesive layering on retention of extraoral maxillofacial silicone prostheses in vivo

Statement of problem. Loss of retention of maxillofacial prostheses often makes the margin visible or the prosthesis dislodge. Using several medical adhesives in combination may improve retention. Purpose. The purpose of this study was to investigate the effect of single- and multi-adhesive layering of 2 adhesives on the retention of maxillofacial silicone elastomer strips adhered to the skin of human forearms using a peel test. Material and methods. Power analysis from a previous study and a pilot trial specified at least 20 subjects. Eight Silastic Adhesive A/MDX4-4210 silicone rubber strips (N=240) were applied in a predetermined random order to the left and right ventral forearms of 30 IRB-approved human subjects. Skin-Prep Protective Dressing was applied. Secure Medical Adhesive (SMA) and Epithane-3 (E3) adhesive were used alone or as SMA/E3 or E3/SMA sandwiches (from skin to prosthesis) to adhere strips. Strips were peeled 6 hours later in a universal testing machine at 10 cm/min and data reported in N/m. Paired t tests were used to evaluate left and right arm differences. A Friedman test for nonparametric correlated data with within-subject design was performed, determining differences between both adhesives singly and in combination (cx=.05). Results. Tests of left-right differences were insignificant (P=0.43), so the data from both arms were combined. Many strips with E3 did not adhere before testing and were counted as 0 adhesion. Median peel strengths (and 25th and 75th percentiles) in N/m were: SMA = 76.1 (47.1-107), E3 = 6.75 (0.0-25.9), SMA/E3 = 107 (78.0-132), and E3/SMA= 19.6 (6.99-42.4). All 4 variables were significantly different (P < .0005). Conclusion. The multi-adhesive combination of SMA/E3 had the highest adhesion, followed, in order, by SMA alone, E3/ SMA, and E3 alone. Both E3 groups left a difficult-to-remove residue on the skin. SMA/E3 left a halo-like residue on the skin at the periphery of the strips from the E3 leaking around the SMA. SMA remained adherent to the prosthetic material.