Potential osseointegration of ceramic implants
Osseointegration is the process of biomechanically secure, infection-resistant bonding of living bone tissue to prosthetic implants, generally of commercially pure titanium metal. For aesthetic dental implants that must emerge through the host gingival tissue line, often the dark metallic appearance of the titanium metal is not aesthetically acceptable to the patient or to the restoring dental prosthodontic community. This investigation sought to demonstrate whether a sintered layer of titanium dioxide (TiO 2 ) over lithium disilicate (LS2) dental implant and/or abutments for placement at the gingival margins could functionally display osseointegrating properties while eliminating the problems of metallic “show through”. This methodology is based on two factors: first, the process of osseointegration is attributed to a superficial TiO 2 layer over commercially pure titanium implants, and second the advancement in dental ceramics, with improved aesthetic values have proved suitable dental restorative material, like lithium disilicate (LS2). Using a conventional dental furnace and two sources of titanium dioxide (TiO 2 ) material NIST (National Institue of Standards and Technology) standard Degussa P25 powder (P25) and titanium butoxide reagent (TNB), successful sintering processes were developed for providing the TiO 2 coatings on LS2 that were resistant to both abrasion and detachment, and slightly textured. Photocatalytic reduction of methylene blue solutions to clear leuco methylene blue solutions by TiO 2 -coated LS2 samples was used to quantitatively demonstrate the capability of these samples to reduce free radicals at the implant placement site in the bone, promoting probable osseointegration. TiO 2 -coated LS2 specimens were monitored spectrophotometrically while in UVA-irradiated methylene blue solutions and assessed by reflectance data from Spotmeter-measured red, green, and blue filters for uncoated control specimens and the coated alternatives. A significant white-approaching color shift for the coated specimens was noted. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) documented the presence of titania coatings over ceramic substrata, indicating good sintering of TiO 2 layers with the heat treatment. X-Ray Diffraction (XRD) showed the presence of a mixed matrix of anatase and rutile polymorphs of TiO 2 suggestive of photocatalytic activity better than for any single phase. Future work requires establishing the clinical function and longevity of such coated devices, along with the expected improvements in patient acceptance of this improved aesthetic approach. The white-approaching color shift by coating LS2 with titania will be compensated by differential choices of the starting LS2 ingot colors to match each recipient's adjacent dentition.