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


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).


CONCLUSIONS
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.
Department of Periodontology, Peking University School and Hospital of Stomatology, Beijing, China.|Department of Oral Implantology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.|Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China.
Baoxin
B
Huang
Department of Periodontology, Peking University School and Hospital of Stomatology, Beijing, China.
Huanxin
H
Meng
Department of Periodontology, Peking University School and Hospital of Stomatology, Beijing, China.
Weidong
W
Zhu
Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA.|School of Chemical Engineering, Oklahoma State University, Stillwater, OK, USA.
Lukasz
L
Witek
Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA.
Nick
N
Tovar
Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA.|Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, NY, USA.
Paulo G
PG
Coelho
D000818:Animals; D016723:Bone Remodeling / Q000502:physiology*; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D004285:Dogs; D020007:Implants, Experimental; D008334:Mandible; D013499:Surface Properties; D014945:Wound Healing / Q000502:physiology
D015921:Dental Implants
animal study; biologic width; crestal bone resorption; implant-abutment interface; subcrestal placement