title: The effect of hydrothermal spark discharge anodization in the early integration of implants in sheep sinuses.
abstract: OBJECTIVE
  Spark discharge anodic oxidation forms a porous oxide film on titanium implant surfaces, which may increase surface roughness and enhance early osseointegration. This study aimed to clinically and histomorphometric compare commercially-available sandblasted (RBM) implants, treated with hydrothermal anodization and placed into an animal maxillary sinus model.
  
  
  METHODS
  Thirty 3.75 mm × 8.5 mm threaded titanium implants were placed into the maxillary sinuses of 10 sheep via an external approach, with three test groups and 10 implants per group: right side, Control = CP-titanium with RBM surface, Test group 1 = CP-titanium with RBM + anodized surface; left side, Test group 2 = Ti-6Al-7Nb with RBM + anodized surface. Schneiderian membranes were elevated but not bone grafted. Resonant frequency analysis (RFA) was measured at surgery. Animals were sacrificed after 1 month unloaded healing. Resin-embedded undemineralized ground-sections were digitised, and mean bone-implant contact (% BIC) was measured bilaterally for the best-three consecutive threads.
  
  
  RESULTS
  Seven of 30 implants showed signs of failure. RFA was low at placement but did not differ between the groups (group mean ISQ values ranged from 23 to 35; χ(2)  = 0.37). RFA was not repeated at sacrifice due to implant instability. Histomorphometric analysis showed % BIC was highest for control (34.8 ± 15.7), followed by Test 1 (29.6 ± 18.1) and Test 2 implants (23.3 ± 22.7), but this difference was not statistically significant (χ(2)  = 0.3).
  
  
  CONCLUSIONS
  Early integration of RBM implants placed into thin maxillary sinus walls was not enhanced by hydrothermal anodization of implant surfaces. This may be related to the initial low stability of the implants and the relatively short healing period. However, non-anodized RBM surfaces showed promising results, with % BIC values comparable to the best estimates of other studies using sinus grafting. Whether the modification of the implant surfaces through anodization with simultaneous sinus grafting would promote enhanced early osseointegration, is a subject of future research.
authors.affiliation: Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand.
authors.forename: Warwick J
authors.initials: WJ
authors.lastname: Duncan
authors.affiliation: Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand.
authors.forename: Jennifer H A
authors.initials: JH
authors.lastname: Gay
authors.affiliation: Department of Dental Biomaterials and Institute of Biodegradable Materials, Institute of Oral Bioscience and BK21 Plus Project, School of Dentistry, Chonbuk National University, Jeonju, South Korea.
authors.forename: Min-Ho
authors.initials: MH
authors.lastname: Lee
authors.affiliation: Department of Dental Biomaterials and Institute of Biodegradable Materials, Institute of Oral Bioscience and BK21 Plus Project, School of Dentistry, Chonbuk National University, Jeonju, South Korea.
authors.forename: Tae-Sung
authors.initials: TS
authors.lastname: Bae
authors.affiliation: Department of New Drug Discovery and Development, Chungnam National University, Daejeon, South Korea.
authors.forename: Sook-Jeong
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand.
authors.forename: Carolina
authors.initials: C
authors.lastname: Loch
mesh_terms: D000818:Animals; D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D055664:Electrochemical Techniques; D020007:Implants, Experimental; D008443:Maxillary Sinus / Q000601:surgery*; D023421:Models, Animal; D016348:Osseointegration; D034561:Sheep, Domestic; D013499:Surface Properties; D014025:Titanium
chemical_list: D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D014025:Titanium
keywords: biomaterials; bone implant interactions; sinus floor elevation; surface chemistry