title: Differences in crestal bone-to-implant contact following an under-drilling compared to an over-drilling protocol. A study in the rabbit tibia.
abstract: OBJECTIVE
  The objective of this study is to compare bone-to-implant contact (BIC) between implants inserted at high torque due to under-drilling of the crestal bone to those inserted at low torque due to over-drilling of the crestal bone.
  
  
  METHODS
  Forty implants with diameters of 3.75 mm (group A) or 3.55 mm (group B) were inserted in the proximal tibiae of NZW rabbits in two separate surgeries on day 0 or 21. Osteotomy of the crestal bone was finalized with a 3.65-mm drill. In group A, implants were inserted at torque ≥35 Ncm (under-drilling) and in group B with torque <10 Ncm (over-drilling). Implants and their surrounding bone were retrieved on day 42, thus creating 3- and 6-week observation periods, processed for non-decalcified histology and stained with toluidine blue. Crestal BIC (c-BIC) and total BIC (t-BIC) were measured. Wilcoxon test was used to evaluate differences between groups.
  
  
  RESULTS
  Three weeks post-surgery, the mean c-BIC in group A was 16.3 ± 3.3 vs 31.5 ± 3.4 % in group B (P < 0.05). At 6 weeks, a similar trend was observed (group A: 28.7 ± 3.6 %; group B: 38.4 ± 4.9 %) (P > 0.05). No differences in t-BIC were noted at 3 weeks and at 6 weeks between the groups.
  
  
  CONCLUSIONS
  Insertion of implants with an over-drilling protocol of the crestal aspect of the osteotomy resulted in increased short-term crestal bone-to-implant contact.
  
  
  CONCLUSIONS
  Insertion of implants with a high torque following an under-drilling protocol, commonly used for immediate loading, may reduce crestal bone-to-implant contact at early healing stages.
authors.affiliation: Department of Periodontology and Dental Implantology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. omerco2@gmail.com.
authors.forename: Omer
authors.initials: O
authors.lastname: Cohen
authors.affiliation: Department of Oral Rehabilitation, School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Zeev
authors.initials: Z
authors.lastname: Ormianer
authors.affiliation: Department of Periodontology and Dental Implantology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Haim
authors.initials: H
authors.lastname: Tal
authors.affiliation: Department of Oral and Maxillo-facial Plastic Surgery, University of Cologne, Cologne, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rothamel
authors.affiliation: Department of Oral Biology, School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Miron
authors.initials: M
authors.lastname: Weinreb
authors.affiliation: Department of Periodontology and Dental Implantology, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Ofer
authors.initials: O
authors.lastname: Moses
mesh_terms: D000818:Animals; D015921:Dental Implants; D057893:Immediate Dental Implant Loading / Q000379:methods*; D020007:Implants, Experimental; D008297:Male; D016348:Osseointegration; D010027:Osteotomy; D011817:Rabbits; D013977:Tibia / Q000601:surgery*; D019415:Torque
chemical_list: D015921:Dental Implants
keywords: BIC; Implants; Insertion; Over-drilling; Torque; Under-drilling