Clustering Phenomena in Implant Dentistry: 7-year Retrospective Follow-up

Clustering Phenomena in Implant Dentistry: 7-year Retrospective Follow-up
A.J. ZORTEA JR, R.S. MAGINI, G.S. COURA, C.F. FERREIRA, J.N. FREIRE, and K.N. CASTRO, Universidade Federal De Santa Catarina, Florian??polis, Brazil
2003
IADR
Objectives: The objectives of this study were to detect the global rate of failures of 401 Steri-Oss Implants (Nobel Biocare,USA) inserted in 135 patients, between 1993 and 2000, and then estimate the ǃ?clustering phenomenaǃ? in these clinical situation. Material and Methods: It were obtained clinical and radiographic signs from 135 patients, that had received 401 osseointegrated implants, without strict protocol of clinical investigations. These patients were male and female, white, yellow and black, from different social groups and classes, with aging from 16 to 80. The success/ failure criteria utilized was the proposed criteria of ALBREKTSSON et al.(1986), and chi-square tests were applied, for determining the failure risk for an implant; the implant was taken as unit, assuming independence among implants from the same subject. Results: The general failure rate was 9.2%. It wasn't found significant statistical differences between male (47 inserted/6 failed) and female (88 inserted/ 6 failed). Results showed the probability of failures increase with aging, but when chi-square test was applied, it was shown that age was not a deterministic factor for failure. In 82 (60.7%) from 135 patients it was inserted more than one implant, and it was possible to observe that 6 patients lost 24 implants (64.9%), from 37 failed implants, demonstrating the ǃ?clustering phenomenaǃ?. Conclusions: Despite the increased probability of failures with aging, it was demonstrated that age wasn't a deterministic factor for failure. An interesting observation was the consistent presence of several failed implants in the same patient, with few patients accounted for most of the failures. This has been described in the literature as the ǃ?cluster phenomenonǃ? or the ǃ? clustering effectǃ?, and might indicate that some genetic or systemic factors can influence the outcomes in implant therapy. The general failure rate found was 9.2%, similar to some findings in the literature.