A NEW ADHESIVE BONDING MATERIAL FOR THE CEMENTATION OF IMPLANTABLE DEVICES IN OTOLOGIC SURGERY

Background: Presently, there are no U.S. Food and Drug Administration (FDA)-approved adhesive bone cements for the surgical fixation of pros thetic materials in the middle ear, A promising new cement, 4-META/MMA -TBB opaque resin, has shown remarkable adhesive propel-ties as a bone cement in viva. The cement is composed of 4-methacryloyloxyethyl trim ellitate anhydride (4-META) and methyl methacrylate (MMA) as monomers and tri-n-butyl borane (TBB) as an initiator. Methods: An electromagne tic semiimplantable hearing device presently under development was imp lanted into the middle ear of six cats using 4-META/MMA-TBB resin to c ement a titanium-encased magnet to the incus, The animals were subsequ ently killed (at a mean of 9.6 months) to assess the temporal bones an d specifically the magnet-incus complex in each animal. Results: The t itanium-encapsulated magnet was firmly adherent to all incuses without any failure of the cement-bone interface. Histopathologic examination of the implanted temporal bones demonstrated lack of middle ear infla mmation. Transmission electron microscopy of the incuses demonstrated a unique ''hybrid layer'' in the bone-side subsurface of the bone-ceme nt interface that elucidates the mechanism of interfacial adhesion. Co nclusions: Our investigation highlights the special biomechanical prop erties as well as the biocompatibility of 4-META/MMA-TBB resin that ma ke it an attractive bone-bonding agent for use in otologic surgery, in cluding its potential usefulness during ossicular reconstruction.