Influence of implant geometry and osteotomy design on early bone healing: A pre-clinical in vivo study

To analyze the early stages of osseointegration around implants with different geometry following installation in sites using different osteotomy protocols.

Two types of implants were installed using regular or modified (reduced diameter) osteotomy protocols in mandibular premolar/molar regions following tooth extraction in six dogs. Three implant site categories were created: Reference (A implant and regular osteotomy), Test-1 (B implant and regular osteotomy), and Test-2 (B implant and modified osteotomy). Implant installation procedures were repeated after 4 and 6 weeks. The insertion torque (ITQ) was measured during implant installation and resonance frequency analysis providing implant stability quotient (ISQ) values was performed following implant installation and once every week during the course of the study. Biopsies were obtained immediately after the 3rd installation procedure and prepared for histological analysis.

The modified osteotomy protocol created a higher insertion torque (ITQ). The analysis also revealed a correlation between insertion torque at implant installation and radiographic bone loss after 6 weeks of healing. The decline in ISQ values during healing was more pronounced at Test-2 than other sites. While the degree of bone-to-implant contact (BIC%) in the marginal area was similar in test and reference sites at 6 weeks of healing, Test-2 implants presented with a significantly higher BIC% in the mid and apical areas than Test-1 implants.

It is suggested that placement of implants in undersized osteotomy sites will result in an increased remodeling of the cortical bone during the early healing process.