Socket-shield technique: the influence of the length of the remaining buccal segment of healthy tooth structure on peri-implant bone and socket preservation. A study in dogs

Objective: The aim of this study was to evaluate the influence of the location and length of root pieces on buccal peri-implant bone width and socket preservation in socket shield technique. Material and methods: Forty-eight dental implants (24 narrow and 24 regular platform internal hex implants) were placed in six dogs. The clinical crowns of teeth P2, P3, P4 and M1 were detached horizontally and removed from the underlying roots. Then the mesial root of each tooth was extracted and the distal root was degraded using a high-speed hand-piece with round bur, creating a concave shell of dentin cementum and periodontal ligament (PDL) connected to the buccal aspect of the socket. Remaining root fragments of different lengths were created: coronal (1/3); middle and coronal (2/3); full length (3/3). These were positioned all around the bone crest. Implants were placed at the center of the root sockets, 1–3 mm deeper than the original root apex. RFA and histological evaluations were made at 4 and 12 weeks. Data underwent statistical analysis (p < 0.05). Results: All 48 implants osseointegrated satisfactorily. On both buccal and lingual sides, the coronal (1/3) radicular fragment was attached to the buccal bone plate by physiologic periodontal ligament with less crestal bone resorption compared with middle (2/3) and whole root (3/3) groups for narrow and standard implants. Conclusions: Within the limitations of this study, the results demonstrate that a small piece of root in the coronal part of the alveolus can protect the buccal, mesial and distal bone crest following the immediate placement of NeO narrow or NeO Standard Internal Hex implants. The thickness of peri-implant bone and the remaining root fragment together will provide a total thickness of >2 mm.