Ridge alterations after implant placement in fresh extraction sockets or in healed crests: An experimental in vivo investigation.

ABSTRACT

OBJECTIVES: To study the early and late bone healing around implants placed according to a flapless immediate (test) or flapped delayed (control) implant surgical protocol. MATERIALS AND METHODS: In eight beagle dogs, immediate and delayed implants were placed. Test and control implants were randomly assigned, and horizontal and vertical bone remodelling, as well as bone-to-implant contact (BIC), were assessed with histology at 2 and 8 weeks. Teeth were used as negative controls. RESULTS: Similar results were attained in the two groups when the vertical resorption of the buccal bone crest was evaluated (approximately 0.5 mm). On the other hand, a marked horizontal buccal bone resorption was observed. Immediate implants attained a thinner buccal bone crest as compared to the delayed implant and the tooth. De novo bone formation on the implant surface appeared to be more pronounced at delayed sites at 2 weeks, whereas at 8 weeks, no difference in BIC was observed. CONCLUSIONS: Ridge alterations occurred at both implant placement protocols, with similar limited amounts of vertical buccal bone reduction and a pronounced horizontal bone reduction. The process of horizontal bone remodelling differed between the two surgical protocols.