title: Nanostructures and hydrophilicity influence osseointegration: a biomechanical study in the rabbit tibia.
abstract: OBJECTIVE
  Implant surface properties have long been identified as an important factor to promote osseointegration. The importance of nanostructures and hydrophilicity has recently been discussed. The aim of this study was to investigate how nanostructures and wettability influence osseointegration and to identify whether the wettability, the nanostructure or both in combination play the key role in improved osseointegration.
  
  
  METHODS
  Twenty-six adult rabbits each received two Ti grade 4 discs in each tibia. Four different types of surface modifications with different wettability and nanostructures were prepared: hydrophobic without nanostructures (SLA), with nanostructures (SLAnano); hydrophilic with two different nanostructure densities (low density: pmodSLA, high density: SLActive). All four groups were intended to have similar chemistry and microroughness. The surfaces were evaluated with contact angle measurements, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and interferometry. After 4 and 8 weeks healing time, pull-out tests were performed.
  
  
  RESULTS
  SLA and SLAnano were hydrophobic, whereas SLActive and pmodSLA were super-hydrophilic. No nanostructures were present on the SLA surface, but the three other surface modifications clearly showed the presence of nanostructures, although more sparsely distributed on pmodSLA. The hydrophobic samples showed higher carbon contamination levels compared with the hydrophilic samples. After 4 weeks healing time, SLActive implants showed the highest pull-out values, with significantly higher pull-out force than SLA and SLAnano. After 8 weeks, the SLActive implants had the highest pull-out force, significantly higher than SLAnano and SLA.
  
  
  CONCLUSIONS
  The strongest bone response was achieved with a combination of wettability and the presence of nanostructures (SLActive).
authors.affiliation: Department of Prosthodontics, Faculty of Odontology, Malmö University, Malmö, Sweden.
authors.forename: Ann
authors.initials: A
authors.lastname: Wennerberg
authors.forename: Ryo
authors.initials: R
authors.lastname: Jimbo
authors.forename: Stefan
authors.initials: S
authors.lastname: Stübinger
authors.forename: Marcel
authors.initials: M
authors.lastname: Obrecht
authors.forename: Michel
authors.initials: M
authors.lastname: Dard
authors.forename: Simon
authors.initials: S
authors.lastname: Berner
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015921:Dental Implants; D057927:Hydrophobic and Hydrophilic Interactions; D020007:Implants, Experimental; D007368:Interferometry; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures; D016348:Osseointegration; D056951:Photoelectron Spectroscopy; D011817:Rabbits; D013499:Surface Properties; D013977:Tibia / Q000601:surgery*
chemical_list: D015921:Dental Implants
keywords: bone healing; hydrophilicity; hydrophobicity; implants; nanostructures