title: Evaluation of bone substitutes for treatment of peri-implant bone defects: biomechanical, histological, and immunohistochemical analyses in the rabbit tibia.
abstract: OBJECTIVE
  We sought to evaluate the effectiveness of bone substitutes in circumferential peri-implant defects created in the rabbit tibia.
  
  
  METHODS
  Thirty rabbits received 45 implants in their left and right tibia. A circumferential bone defect (6.1 mm in diameter/4 mm depth) was created in each rabbit tibia using a trephine bur. A dental implant (4.1 mm × 8.5 mm) was installed after the creation of the defect, providing a 2-mm gap. The bone defect gaps between the implant and the bone were randomly filled according to the following groups: blood clot (CO), particulate Bio-Oss(®) (BI), and Bio-Oss(®) Collagen (BC). Ten animals were euthanized after periods of 15, 30, and 60 days. Biomechanical analysis by means of the removal torque of the implants, as well as histologic and immunohistochemical analyses for protein expression of osteocalcin (OC), Runx2, OPG, RANKL, and TRAP were evaluated.
  
  
  RESULTS
  For biomechanics, BC showed a better biological response (61.00±15.28 Ncm) than CO (31.60±14.38 Ncm) at 30 days. Immunohistochemical analysis showed significantly different OC expression in CO and BC at 15 days, and also between the CO and BI groups, and between the CO and BC groups at 60 days. After 15 days, Runx2 expression was significantly different in the BI group compared to the CO and BC groups. RANKL expression was significantly different in the BI and CO groups and between the BI and BC groups at 15 days, and also between the BI and CO groups at 60 days. OPG expression was significantly higher at 60 days postoperatively in the BI group than the CO group.
  
  
  CONCLUSIONS
  Collectively, our data indicate that, compared to CO and BI, BC offered better bone healing, which was characterized by greater RUNX2, OC, and OPG immunolabeling, and required greater reversal torque for implant removal. Indeed, along with BI, BC presents promising biomechanical and biological properties supporting its possible use in osteoconductive grafts for filling peri-implant gaps.
authors.affiliation: Department of Oral and Maxillofacial Surgery and Implantology, Sagrado Coracao University - USC, Bauru, SP, Brazil .
authors.forename: Pâmela Letícia
authors.identifier: 0000-0003-1734-4187
authors.initials: PL
authors.lastname: Dos Santos
authors.affiliation: Department of Diagnosis and Surgery, Sao Paulo State University - UNESP School of Dentistry at Araraquara, Araraquara, SP, Brazil .
authors.forename: Rafael Scaf
authors.identifier: 0000-0003-1110-6233
authors.initials: RS
authors.lastname: de Molon
authors.affiliation: Department of Health Sciences, Implantology Post Graduation Course, University Center of Araraquara - UNIARA Dental School, SP, Brazil .
authors.forename: Thallita Pereira
authors.identifier: 0000-0002-2464-8181
authors.initials: TP
authors.lastname: Queiroz
authors.affiliation: Department of Basic Sciences, Sao Paulo State University - UNESP School of Dentistry at Araçatuba, Araçatuba, SP, Brazil .
authors.forename: Roberta
authors.identifier: 0000-0002-6773-6966
authors.initials: R
authors.lastname: Okamoto
authors.affiliation: Department of Health Sciences, Implantology Post Graduation Course, University Center of Araraquara - UNIARA Dental School, SP, Brazil .
authors.forename: Ana Paula
authors.identifier: 0000-0001-7386-1280
authors.initials: AP
authors.lastname: de Souza Faloni
authors.affiliation: Department of Oral and Maxillofacial Surgery and Implantology, Sagrado Coracao University - USC, Bauru, SP, Brazil .
authors.forename: Jéssica Lemos
authors.identifier: 0000-0001-7113-2017
authors.initials: JL
authors.lastname: Gulinelli
authors.affiliation: Department of Surgery and Integrated Clinic, Sao Paulo State University - UNESP School of Dentistry at Araçatuba, Araçatuba, SP, Brazil .
authors.forename: Eloá Rodrigues
authors.identifier: 0000-0001-8016-6737
authors.initials: ER
authors.lastname: Luvizuto
authors.affiliation: Department of Surgery and Integrated Clinic, Sao Paulo State University - UNESP School of Dentistry at Araçatuba, Araçatuba, SP, Brazil .
authors.forename: Idelmo Rangel
authors.identifier: 0000-0001-8892-781X
authors.initials: IR
authors.lastname: Garcia
keywords: Bone substitutes; Bone transplantation; Dental implantation; Osseointegration; Rabbits