title: Primary stability of turned and acid-etched screw-type implants: a removal torque and histomorphometric study in rabbits.
abstract: OBJECTIVE
  This study evaluated the effect of primary stability on the osseointegration of turned and acid-etched screw implants in a rabbit model.
  
  
  METHODS
  One pair of turned and acid-etched implants (3.75 in diameter, 5.5 mm long) was placed in each tibia of 15 rabbits. In the right tibial metaphysis the implants were inserted according to a standard surgical protocol. In the left tibia, the osteotomy sites were enlarged using a sequence of drills, and 2 implants were placed with reduction of primary stability. Animals were sacrificed 9 weeks after surgery. Histomorphometric and removal torque analyses were performed to evaluate bone-implant contact and strength of osseointegration.
  
  
  RESULTS
  Surface texture had a significant effect on percentage of bone-implant contact (P = .001). Acid-etched implants with high primary stability showed the highest percentage of bone-implant contact (77%), followed by acid-etched implants with low primary stability (61%), turned implants with low primary stability (56%), and turned implants with high primary stability (46%). For removal torque, acid-etched implants had higher peak mean values than turned implant groups (P < .001). Reduction of primary stability was not significant to either percentage of bone-implant contact (P = .645) or removal torque values (P = .214).
  
  
  CONCLUSIONS
  Acid-etched implants had higher bone response and implant fixation than turned implants, regardless of primary stability.
authors.affiliation: Department of Prosthodontics, Lutheran University of Brazil, Canoas, RS, Brazil. edu2f@terra.com.br
authors.forename: Eduardo de Lima
authors.initials: Ede L
authors.lastname: Fernandes
authors.forename: Ieda Levenzon
authors.initials: IL
authors.lastname: Unikowski
authors.forename: Eduardo Rolim
authors.initials: ER
authors.lastname: Teixeira
authors.forename: Nilza Pereira
authors.initials: NP
authors.lastname: da Costa
authors.forename: Rosemary Sadami
authors.initials: RS
authors.lastname: Shinkai
mesh_terms: D000134:Acid Etching, Dental; D000704:Analysis of Variance; D000818:Animals; D001863:Bone Screws; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D020878:Device Removal; D005260:Female; D008422:Materials Testing; D016348:Osseointegration / Q000502:physiology*; D011817:Rabbits; D013499:Surface Properties; D013977:Tibia / Q000601:surgery; D019415:Torque
chemical_list: D015921:Dental Implants