Influence of placement depth on bone remodeling around tapered internal connection implants: a histologic study in dogs

Objectives To evaluate the influence of implant‐abutment interface ( IAI ) placement depth on bone remodeling around implants with two different types of tapered internal IAI : screwed‐in ( SI ) and tapped‐in ( TI ) connections in dogs. Materials and methods Eight weeks post mandibular tooth extraction in six beagle dogs, two SI implants (OsseoSpeed ™ , Astra Tech, DENTSPLY ) and two TI implants (Integra‐ CP ™ , Bicon LLC ) were placed in one side of the mandible. The four experimental groups were as follows: (i) SI ‐placed equicrestally ( SIC ); (ii) TI ‐placed equicrestally ( TIC ); (iii) SI ‐placed 1.5 mm subcrestally ( SIS ); and (iv) TI ‐placed 1.5 mm subcrestally ( TIS ). Healing abutments were connected 12 weeks after implant placement. Sixteen weeks later, the dogs were sacrificed and histomorphometric analysis was performed. Histometrical outcomes were evaluated using a nonparametric Brunner–Langer model. Results Mean distance from the IAI to first bone‐implant contact (IAI‐ fBIC ) was 0.88 mm (median: 0.77; SD: 0.54) for SIC group, 1.23 mm (median: 1.22; SD: 0.66) for TIC group, 0.41 mm (median: 0.31; SD: 0.36) for SIS group, and 0.41 mm (median: 0.26; SD: 0.45) for TIS group. Subcrestal groups showed lower IAI‐ fBIC compared with equicrestal groups ( P  <   0.001). Connective tissue presented similar measurements regardless of the IAI placement depth and IAI type ( P  >   0.05), but the epithelium length and peri‐implant soft tissue length in subcrestal groups were significant larger than that in the equicrestal groups ( P  <   0.001 and P  =   0.004, respectively). Conclusion Subcrestal implant placement with tapered internal IAI is beneficial for bone contact with the implant neck, and concurrently, it may not increase the soft tissue inflammation around IAI .