Purpose: The aim of this article was to review the current literature with regard to survival and success rates, along with the clinical procedures and outcomes associated with immediate and delayed implant placement.
Materials and methods: A MEDLINE search was conducted of studies published between 1990 and June 2003. Randomized and nonrandomized clinical trials, cohort studies, case-control studies, and case reports with a minimum of 10 cases were included. Studies reporting on success and survival rates were required to have follow-up periods of at least 12 months.
Results: Thirty-one articles were identified. Most were short-term reports and were not randomized with respect to timing of placement and augmentation methods used. All studies reported implant survival data; there were no reports on clinical success. Peri-implant defects had a high potential for healing by regeneration of bone, irrespective of healing protocol and bone augmentation method. Sites with horizontal defects (HD) of 2 mm or less healed by spontaneous bone fill when implants with rough surfaces were used. In the presence of HDs larger than 2 mm, or when socket walls were damaged, concomitant augmentation procedures with barrier membranes and bone grafts were required. Delayed implant placement allowed for resolution of local infection and an increase in the area and volume of soft tissue for flap adaptation. However, these advantages were diminished by simultaneous buccolingual ridge resorption and increased requirements for tissue augmentation.
Discussion: Immediate and delayed immediate implants appear to be predictable treatment modalities, with survival rates comparable to implants in healed ridges. Relatively few long-term studies were found. Successful clinical outcomes in terms of bone fill of the peri-implant defect were well established. However, there was a paucity of data on long-term success as measured by peri-implant tissue health, prosthesis stability, and esthetic outcomes.
Conclusions: Short-term survival rates and clinical outcomes of immediate and delayed implants were similar and were comparable to those of implants placed in healed alveolar ridges.