Influence of different drilling preparation on cortical bone: A biomechanical, histological, and micro‐CT study on sheep

• Published in: Clinical oral implants research 2018-07, Vol.29 (7), p.707-715
• Main Authors: Stocchero, Michele, Toia, Marco, Jinno, Yohei, Cecchinato, Francesca, Becktor, Jonas P., Naito, Yoshihito, Halldin, Anders, Jimbo, Ryo
• Format: Article
• Language: English
• Subjects: Animals; Biomechanical Phenomena; Biomechanics; Bone density; Bone healing; Bone implants; Bone Remodeling; bone remodeling/regeneration; Computed tomography; Cortical bone; Cortical Bone - anatomy & histology; Cortical Bone - diagnostic imaging; Cortical Bone - surgery; dental implant(s); Dental Implantation, Endosseous - methods; Dental implants; Dentistry; Drilling; Female; Histology; Implantation; Mandible; Mandible - anatomy & histology; Mandible - diagnostic imaging; Mandible - surgery; Osseointegration; osteotomy; Rank tests; regeneration; Sheep; Torque; X-Ray Microtomography
• ISSN: 0905-7161; 1600-0501; 1600-0501
• DOI: 10.1111/clr.13262

Objective The aim of this study was to investigate the extent of cortical bone remodeling between two different drilling protocols by means of histomorphometric, µ‐CT, and biomechanical analyses. Material and methods A total of 48 implants were inserted into the mandible of six sheep following two drilling protocols: Group A (Test, n = 24), undersized preparation; Group B (Control, n = 24), non‐undersized preparation. The animals were euthanatized to obtain 5 and 10 weeks of implantation time. Removal torque (RTQ) was measured on 12 implants of each group and the peri‐implant bone was µ‐CT scanned. Bone volume density (BV/TV) was calculated in pre‐determined cylindrical volumes, up to 1.5 mm from implant surface. Non‐decalcified histology was prepared on the remaining 12 implants from each group, where total bone‐to‐implant contact (totBIC) and newly‐formed BIC (newBIC) was measured. Bone Area Fraction Occupancy (BAFO) was determined in pre‐determined areas up to 1.5 mm from implant surface. Paired sample t test or Wilcoxon signed‐rank test was used to investigate differences between the groups. Results Group A presented significantly increased RTQ value at 5 weeks, while no difference was observed at 10 weeks. Group B presented increased BV/TV value at 5 weeks. Both groups showed comparable values for totBIC at both time‐points. However, Group A presented significantly lower newBIC at 5 weeks. Higher BAFO was observed in Group B at 5 weeks. Conclusions Implants inserted into undersized sites has an increased biomechanical performance, but provoked major remodeling of the cortical bone during the early healing period compared to non‐undersized preparations. After 10 weeks, no difference was observed.