A Four-Year Survival Rate Multicenter Prospective Clinical Study on 377 Implants: Correlations Between Implant Insertion Torque, Diameter, and Bone Quality
The purpose of this study was to evaluate the survival rate and incidence of prosthetic complications in 377 implants with a double octagon connection. Furthermore, the correlations among implant dimensions (diameter and length), bone quality, and insertion torque were investigated. A 4-year multicenter prospective clinical study was designed to evaluate the survival rate of 377 dental implants inserted in 189 patients between January 2004 and April 2010. After an average follow-up of 46 months, the implant survival rate was 99.7%, and the incidence of complication was 0.53%. Moreover, insertion torque was statistically related in a significant way to implant diameter. The connection system seemed to reduce the risk that the prosthetic component screw would loosen. Within the limits of this study, it was observed that a wider diameter corresponded to a higher implant primary stability. Implant length did not seem to be critical in obtaining higher primary stability.
Figure 1. Double octagon connection. Figure 2. Radiograph taken 2 years after surgery. Note the correct seating of the prostheses and the absence of fracture lines in the screw or abutment.
Figure 3. Histogram position on 377 patients. Figure 4. Pie chart showing distribution of the implant usage according to the prosthetic rehabilitations: 192 implants were inserted to support a fixed bridge (blue area), 156 implants replaced a single tooth that was missing for a minimum of 60 days (green area), 18 implants were placed in postextraction sockets (purple area), 15 implants received a temporary prosthesis after immediate loading protocols (yellow area), and 11 implants were used in full-arch rehabilitation (red area). Figure 5. Pie chart showing bone graft distribution: 5 patients (blue area) were treated with autogenous bone grafts, 21 (green area) using a mixture of autogenous and heterologous bone graft, and 91 (yellow area) using deprotenized bovine bone mineral only, all of them in association with collagen resorbable membranes. Figure 6. Scatterplot showing torque-diameter correlation. (diameter [dp4]: 1 = 3.8 mm; 2 = 4.3 mm; 3 = 4.8 mm; 4 = 5.5 mm). Figure 7. Scatterplot showing correlations between torque and bone quality.
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