The effect of different titanium and hydroxyapatite-coated dental implant surfaces on phenotypic expression of human bone-derived cells Christine Knabe, 1,2 Cameron Rolfe Howlett, 2 Falk Klar, 3 Hala Zreiqat 2 1 Department of Experimental Dentistry, University Hospital Benjamin Franklin, Free University of Berlin, Assmannshauser Str. 4-6, 14197 Berlin, FRG 2 Department of Pathology, School of Medical Sciences, Faculty of Medicine, UNSW, Sydney, NSW 2052, Australia 3 Friadent Dentsply Inc., Steinzeugstr., 68229 Mannheim, Germany Received 11 March 2004; accepted 7 June 2004 Published online 5 August 2004 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jbm.a.30130 ABSTRACT Roughened titanium (Ti) surfaces have been widely used for dental implants. In recent years, there has been the tendency to replace Ti plasma-sprayed surfaces by sandblasted and acid-etched surfaces in order to enhance osseous apposition. Another approach has been the utiliza- tion of hydroxyapatite (HA)-coated implants. This study examines the effect of two roughened Ti dental implant surfaces on the osteoblastic phenotype of human bone– derived cells (HBDC) and compares this behavior to that for cells on an HA-coated surface. Test materials were an acid- etched and sandblasted Ti surface (Ti-DPS), a porous Ti plasma-sprayed coating (Ti-TPS), and a plasma-sprayed po- rous HA coating (HA). Smooth Ti machined surfaces served as control (Ti-ma). HBDC were grown on the substrata for 3, 7, 14, and 21 days, counted and probed for various bone- related mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase, and bone sialoprotein). All dental implant surfaces significantly af- fected cellular growth and the temporal expression of an array of bone-related genes and proteins. HA-coated Ti had the most effect on osteoblastic differentiation inducing a greater expression of an array of osteogenic markers than recorded for cells grown on Ti-DPS and Ti-TPS, thus sug- gesting that the HA-coated surface may possess a higher potency to enhance osteogenesis. Furthermore, Ti-DPS sur- faces induced greater osteoblast proliferation and differen- tiation than Ti-TPS. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 98 –107, 2004 Keywords: dental implants; human bone-derived cells; cell- biomaterial interactions; in situ hybridization; immunocyto- chemistry INTRODUCTION In recent years, the utilization of endosseous im- plants for the rehabilitation of completely or partially edentulous patients has become a standard treatment modality in dentistry. 1 Over the past two decades, numerous prospective long-term studies have docu- mented a high efficacy and predictability of osseointe- grated implants. 1–7 Titanium is widely used as dental implant material, because direct contact occurs be- tween bone and the implant surface. 8 –14 Preferably, roughened surfaces like the titanium plasma-sprayed (TPS) surfaces have been used as the endosseous area of dental implants in order to increase the total surface area available for osseous apposition. 12,15 In recent years, there has been the tendency to replace titanium plasma-sprayed surfaces by sandblasted and acid- etched surfaces in order to accelerate osseointegra- tion. 1,10,11,15–17 Surface topography plays a critical role in the inter- action of dental implants with adjacent tissues. 10 –12 Many of the most important steps in the peri-implant healing cascade are profoundly influenced by implant surface microtopography. 10 In vitro studies have shown that microroughened sandblasted and/or acid- etched surfaces enhance platelet activation and aggre- gation and fibrin retention. 10,11,18 As a result, a migra- tory pathway for the differentiating osteogenic cells to reach the implant surface is provided. 11,18 Further- more, these microroughened surfaces enhance osteo- Correspondence to: C. Knabe, Department of Experimen- tal Dentistry, University Hospital Benjamin Franklin, Free University of Berlin, Assmannshauser Str. 4-6, D-14197 Berlin, Germany; e-mail: Christine.Knabe@medizin.fu- berlin.de Contract grant sponsor: German Research Foundation; contract grant number: DFG KN 377/2-1 Contract grant sponsor: Australian National Health and Medical Research Council © 2004 Wiley Periodicals, Inc.