The effects of healing abutments of different size and anatomic shape placed immediately in extraction sockets on peri-implant hard and soft tissues. A pilot study in foxhound dogs.

OBJECTIVES: The aim of this animal study was to compare the effects of narrow, concave-straight and wide anatomic healing abutments on changes to soft tissues and crestal bone levels around implants immediately placed into extraction sockets in foxhound dogs.

MATERIALS AND METHODS: Forty-eight titanium implants (Bredent Medical GMBH, Germany) of the same dimensions were placed in six foxhound dogs. They were divided into two groups (n = 24): test (implants with anatomic abutment) and control (implants with concave-straight abutment). The implants were inserted randomly in the post extraction sockets of P2 , P3 , P4, and M1 bilaterally in six dogs. After eight and twelve weeks, the animals were sacrificed and samples extracted containing the implants and the surrounding soft and hard tissues. Soft tissue and crestal bone loss (CBL) were evaluated by histology and histomorphometry.

RESULTS: All implants were clinically and histologically osseointegrated. Healing patterns were examined microscopically at eight and twelve weeks. After eight and twelve weeks, for hard tissues, the distance from the implant shoulder to the first bone-to-implant contact (IS-C) was higher for control group in the lingual aspect with statistical significance (P < 0.05). For soft tissues (STL), the distance from the top of the peri-implant mucosa to the apical portion of the junction epithelium (PM-Je) was significantly less on the lingual aspect in the test group (with wider abutment) at eight and twelve weeks (P < 0.05). The distance from the top of the apical portion of the junction epithelium to the first bone-to-implant contact (Je-C) was significantly higher in the test group (wider abutment) in the lingual aspect at eight and twelve weeks (P < 0.05). There was no connective tissue contact with any abutment surface.

CONCLUSIONS: Within the limitations of this animal study, anatomic healing abutments protect soft and hard tissues and reduce crestal bone resorption compared with concave-straight healing abutments.