Use of 5-mm-diameter implants: Periotest (R) values related to a clinical and radiographic evaluation

A modified design of the original Branemark implant consisting of a cp. Tit anium 5.0-mm-diameter self-tapping implant threaded up to the marginal plat form has been proposed for specific indications. From February 1992 to Nove mber 1995, a total of 185 machined screw implants (Nobel Biocare, Gothenbur g, Sweden) were installed in 45 patients to withstand 58 prostheses. Of the se, 91 were 3.75-mm diameter and 94 were 5.0-mm wide. Most of the implants were placed in type B and C bone quantity and type 2 and 3 bone quality. A retrospective evaluation with regard to indications, marginal bone remodell ing, Periotest(R) values (PTv) and survival rate is presented. PTv and radi ographic measurements were made at abutment connection and repeated 3, 6 an d 12 months later and thereafter every year. The follow-up ranged from 16 t o 55 months (mean 32.9 months) post-loading. Three patients with 8 5.0-mm i mplants dropped-out of the study at different stages. Out of the wide impla nts, 1 was expelled during the healing period; 3 were found mobile at the a butment connection; 1 lost its osseointegration suddenly after 2 years of f unction; 4 belonging to 1 patient did not meet the success criteria due to continuous marginal bone loss. The cumulative success rate of 5.0-mm implan ts (CSR) after 1 year of function was 97.2% for upper jaws and 88.4% in man dibles, whereas the CSR in maxilla after 48 months was 97.2% and 83.4% in m andibles. The obtained PTv from 5.0-mm-wide fixtures in maxilla and mandibl es were respectively 1.1 and 0.6 units lower than those obtained PTv for 3. 75-mm-diameter implants in the same patients. The hypothesis that there are differences in the damping capacity of the bone surrounding a 5.0-mm-wide implant compared to the 3.75-mm-diameter implant is supported by the PTV re sults.