Clinical and radiographic performance of delayed-immediate single-tooth implant placement associated with peri-implant bone defects. A 2-year prospective, controlled, randomized follow-up report

Objectives: The aim of the present study was to compare the delayed-immediate (Im) and the delayed (De) protocols for placement of single-tooth implants. Material and methods: After allocation to the Im and De groups by random, 46 patients were treated with a single-tooth implant with acid etched surfaces (Osseotite((R))) in the anterior or pre-molar region of the maxilla or the mandible on average 10 days (Im) or 3 months (De) following tooth extraction, respectively. Forty-one patients attended a follow-up visit 2 years after implant placement corresponding to 11/2 years of loading of the implant restorations. Peri-implant and prosthetic parameters were evaluated clinically and marginal bone levels measured on radiographs. Results: Three implants were lost, all before mounting of the crown. None of the implant restorations had failed after 11/2 years of function. Probing pocket depths were reduced by up to 1.4 mm on average from the time of loading to the 2-year follow-up and at that time, no significant difference between the Im and De groups was found (4.2 versus 4.1 mm). A statistically significant radiographic marginal bone loss had occurred in the Im group (mean=0.8 mm) as well as in the De group (mean=0.7 mm) in the follow-up period. However, a mean marginal bone level of approx. 1.5 mm in both groups measured from the implant-abutment junction was found to be acceptable. It was demonstrated that probing pocket depths and marginal bone levels after 11/2 years of loading of the implant-retained crowns were not influenced by the presence of peri-implant bone defects immediately after implant placement. Furthermore, no severe prosthodontic complications, such as screw loosening or porcelain fractures, arose in this study material. Conclusion: High success rates of single-tooth implants after 11/2 years of function were achieved using the delayed-immediate and delayed implant placement techniques.