Immediate implant placement: treatment planning and surgical steps for successful outcome.

Placement of endosseous implants has made it possible to perform restorations in patients who are fully or partially edentulous (1, 2, 20, 21). Original protocols required the placement of implants into healed edentulous ridges. In 1989, Lazzara (44) placed implants at the time of tooth extraction. Immediate implants were augmented with barrier membranes to preserve ridge width and height and to decrease treatment time. Becker et al. (6, 9, 12) reported a 93.3% 5-year implant survival rate with clinically insignificant crestal alveolar bone loss for immediate implants that were augmented with barrier membranes. Over the past 16 years numerous studies have confirmed the reliability of implants placed at the time of tooth extraction (34, 67, 75, 76, 87, 88). Small osseous defects, which are frequently found adjacent to implants placed at the time of tooth extraction, can be grafted with autogenous bone obtained from edentulous ridges or other intraoral sites (6, 83). Clinicians have also used other materials and methods to augment edentulous ridges and small bony defects adjacent to dental implants, including demineralized freeze-dried bone and barrier membranes (33, 35, 49, 50, 60–62). The stability of implants can be determined using a resonance frequency analysis (51–53, 68, 69, 72, 79). This method requires the placement of an electronic transducer on the implant head or prosthetic abutment with a retaining screw, and the passing of a low-voltage current, which is undetectable to the patient, through the transducer. Resistance to the vibration of the transducer in the surrounding bone is digitally registered. The original resonance frequency measurements were recorded in hertz, but were later converted to implant stability quotient (ISQ) units. A recent study of immediate implants found a 2to 3-year cumulative survival rate of 97.8%, and a mean stability of all implants at the time of tooth extraction of 62.0 ± 9.8 ISQ and at 1 year of 64.0 ± 9.8 ISQ (13). Implants with ISQ values >50 are considered clinically stable. The initial stability was lower in the maxilla than in the mandible, while the 1-year stability measurements did not differ significantly between the jaws. However, sites that receive implants at the time of tooth extraction or within a short time after extraction may demonstrate a slight decrease in crestal bone width (10, 67). This paper will review the concept of placement of implants at the time of tooth extraction and describe the indications, limitations, and anatomic, prosthetic, and esthetic requirements for immediate implant placement. The notion of socket preservation for sites that might receive dental implants will be discussed. The idea of minimally invasive surgery and guided implant placement for implants placed at the time of extraction will also be introduced.