Effect of implant design on survival and success rates. A10-year prospective study of ITI® Dental Implants

Objectives: The aim of this 10-year study (observation time 8-15, mean: 10 years) was to compare the survival and success rates with 3 different implant designs of the ITI® Dental Implant System. Methods: In 89 patients treated for comprehensive dental care Hollow Screw(HS), Hollow Cylinder(HC) and Angulated Hollow Cylinder(AHC) type implants were placed depending on the available ridge width and prosthetic needs. Group A comprised 112 HS, group B 49 HC and group C 18 AHC implants. 1,5 and 10 years after surgical placement, clinical and radiographic parameters were assessed. The incidences of periimplantitis were noticed over the 10 years of maintenance. Success at 10 years was set at: PPD< 5mm, BOP-, bone loss < 0.2mm per year. Results: The survival rate for HS (112) was 95.4%, for HC (49) 85.7% and for AHC (18) 91.7% (Kaplan-Meier method, Wilcoxon test p<0.05). 90% of all the HS, 71% of the HC and 88% of the AHC did not present any incidence of periimplantitis over the 10 years (Kaplan-Meier method, Log-Rank and Wilcoxon tests p< 0.01). With the success criteria set a success rate for HS of 74%, for HC of 63% and for AHC of 61% was found. If the definition of success included PPD<6mm, success rates of 78%, 65% and 67% were found. Relying on purely clinical parameters: PPD<5mm and BOP-, the success rates increased to 90%, 76% and 89% respectively and with 6mm, even to 94%, 82% and 94% respectively. Conclusions: There was a significantly higher survival rate and also a significantly lower incidence of periimplantitis for screw versus cylinder type implants.Setting of thresholds for success criteria is crucial for reporting on success rates. This study was supported by the Clinical Research Foundation for the Promotion of Oral Health, Bern Switzerland and by the Papavramides Foundation, Universities of Athens, Greece and Bern, Switzerland.