Young-Taeg Sul David H. Kwon Byung-Soo Kang Se-Jung Oh Carina Johansson Experimental evidence for interfacial biochemical bonding in osseointegrated titanium implants Authors’ affiliations: Young-Taeg Sul, David H. Kwon, Byung-Soo Kang, Department of Biomaterials, Institute for Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Sweden Young-Taeg Sul, Institute for Clinical Dental Research, Korea University, Seoul, Korea David H. Kwon, U.S. Army Advanced Education Program in General Dentistry, Fort Bragg, NC, USA Se-Jung Oh, Department of Physics and Astronomy, Seoul National University, Seoul, Korea Carina Johansson, Department of Prosthodontics/ Dental Materials Science, Institute of Odontology, Sahlgrenska Academy, University of Gothenburg, Sweden Corresponding author: Associate Professor Young-Taeg Sul Department of Biomaterials Institute for Clinical Sciences at Sahlgrenska Academy at University of Gothenburg Arvid Wallgrens Backe 20 Box 412, SE 413 46 Gothenburg, Sweden Tel.: +46 31 786 2969 Fax: +46 31 786 2941 e-mail: young-taeg.sul@biomaterials.gu.se Key words: biochemical bonding theory, bone and titanium implant interface, osseointegra- tion mechanism, surface chemistry and topography Abstract Objectives: (i) To identify and quantify an interfacial biochemical bond and the bonding strength of osseointegrated implants with bioactive titanium oxide chemistry, ATiOxB (A, metal cations; TiO x , titanium oxides/hydroxides; B, non-metal anions) and (ii) to provide quantitative evidence for the biochemical bond theory of osseointegration proposed by Sul et al. for description and explanation of why and how the implants with ATiO x B surface oxide chemistry may exhibit a significantly stronger bone response, in spite of the fact that the roughness values approached zero, or were equivalent to or significantly lower than those of the control implants. Materials and methods: We applied a newly developed biochemical bond measurement (BBM) method to model implant surfaces that were “perfectly” smooth nanotopography near-zero roughness as the constant parameter, and used the bioactive surface chemistry of titanium oxide, ATiO x B chemistry as a variable parameter in rabbit tibiae for 10 weeks. In this manner, we determined an interfacial biochemical bond and quantified its bonding strength. Results: The increase in biochemical bond strengths of the test implant relative to the control implant was determined to be 0.018 (±0.008) MPa (0.031 vs 0.021 MPa, n = 10) for tensile strength and 8.9 (±6.1) Ncm (33.0 vs 24.1 Ncm, n = 10) for removal torque. Tensile and removal torque show strong correlation in the Pearson test (r = 0.901, P  0.001). In addition, histomorphometric measurements including bone-to-metal-contact (BMC, P = 0.007), bone area and newly formed bone showed significant increases in the mean values for ATiO x B chemistry (P = 0.007, n = 10). Biochemical bond theory states that the surface oxide chemistry, ATiO x B must have more electrical and chemical molecular polarity that fractionally charges the surfaces denoted as d + and d  and leads to electrostatic and electrodynamic interactions with the bone healing cascade, eventually leading to the formation of biochemical bonding at the bone/implant interface. Conclusions: The present study has provided quantitative evidence for biochemical bond theory of osseointegration of implants with bioactive surface oxide chemistry, ATiO x B. The theory of biochemical bonds may provide a scientific rationale pertinent to recent emerging trends and technologies for surface chemistry modifications of implants. Research on biochemical bonds of osseointe- gration of metallic implants is a very difficult scientific challenge and is lacking in the lit- erature. Since the first introduction of osseo- integration by Bra ˚ nemark and his co-workers (Branemark et al. 1969) in 1969, osseointegra- tion has become a highly viable and predict- able treatment modality in modern implant dentistry. However, many unanswered ques- tions remain regarding in vivo osseointegra- tion mechanisms that regulate the bone response to the surface property variables from the micro to nano-scale. It is widely believed that osseointegration through bio- mechanical interlocking or interdigitation is established as the bone grows into surface irregularities over time and is stabilised by the dynamic regulation of bone modelling/ remodelling. A direct chemical bonding of bioactive glass-ceramic materials to bone and muscle was reported by Hench et al. in 1973 (Hench & Paschall 1973). However, such materials and their coatings are of limited use in load- bearing implants due to their poor mechani- cal properties (Hench 1998). Evidence for the chemical bonding theory of bioglasses and bioglass-ceramics was provided based on Date: Accepted 18 September 2011 To cite this article: Sul Y-TH. Kwon D, Kang B-S, Oh S-J, Johansson C. Experimental evidence for interfacial biochemical bonding in osseointegrated titanium implants. Clin. Oral Impl. Res. 00, 2011, 1–12 doi: 10.1111/j.1600-0501.2011.02355.x © 2011 John Wiley & Sons A/S 1