On possibly bioactive CP titanium implant surfaces

Abstract

Background Osseointegrated titanium implants are routinely used in clinical dentistry. Although the overallclinical results are good, there are situations when an improved implant healing is desirable, for instance incompromised bone or in order to decrease healing time. Six factors are proposed to affect titanium implantosseintegration, where one is surface quality. Attempts to optimize surface quality of titanium implants withrespect to topography and biochemistry and to prepare possibly bioactive surfaces demonstrate promisingresults, yet there is a need for further investigations.Aim The aim of the thesis was to investigate the significance of surface orientation for bone tissue response invivo and, furthermore, to investigate possibly bioactive titanium implant surfaces in vitro and in vivo.Material and Methods The thesis is based on five experimental studies, where 12 differently modified CPtitanium implant surfaces were investigated.Topography and chemistry were characterized by Laser Scanning Profilometry, Optical Interferometry, ScanningElectron Microscope and X-ray Photoelectron Spectroscopy, respectively.In vivo bone responses were evaluated histomorphometrically and mechanically in a rabbit model (Study I, II).In vitro cell response were investigated in human primary monocyte (Study III, IV) and osteoblast (Study V) cellculture models, while calcium phosphate nucleation (CaP) capacity of the surfaces were investigated in simulatedbody fluids (SBF) (Study V).Results In Study I titanium implants prepared with isotropic and anisotropic surfaces with similar roughnessdemonstrated similar bone response in vivo after 3 months of implantation.In Study II the non-bioactive (anodized) and possibly bioactive (alkali-heat treated) titanium implants with andwithout covalently immobilized protein coatings (blood plasma) demonstrated similar bone response in vivo after 1month of implantation.In Study III the non-bioactive (anodized) and possibly bioactive (anodized/Mg) titanium surfaces demonstratedincreased inflammatory cell attachment, yet a similar early inflammatory cell response in vitro compared to theturned and blasted control surfaces.In Study IV the protein coatings influenced the early inflammatory response in vitro; however, cells on immobilizedcatalase surfaces, not fibrinogen, demonstrated the strongest inflammatory response.In Study V the possibly bioactive surfaces (alkali-heat treated, anodized/Mg, fluoride and nano HA coated), gaverise to an earlier CaP formation than the blasted control surfaces. Furthermore, the SBF treated (72 hours) alkaliheattreated fluoride and anodized/Mg surfaces demonstrated similar or decreased bone cell response, while theSBF treated blasted and nano HA surfaces increased bone cell response compared to the blasted controls.Conclusion Within the limits of the studies of the present thesis, surface orientation had no effect on boneresponse in vivo. Furthermore, possibly bioactive surfaces did not significantly increase bone response in vivo,while possibly bioactive/oxide modified and, in particular, bioactive/covalently immobilized proteins influencedearly inflammatory cell response in vitro.