Cluster assignments and multivariate analysis in implant dentistry

Cluster assignments and multivariate analysis in implant dentistry
A.J. ZORTEA, Jr., R.S. MAGINI, S.F.T. FREITAS, M.C.M. CALVO, G.S. COURA, and K.N. CASTRO, Universidade Federal de Santa Catarina, Londrina, Parana, Brazil
March 2004
Clinical Implant Studies
Objectives: The aim of this study was to detect the global rate of failures of 401 Steri-Oss Implants(Nobel Biocare,USA), inserted in 135 patients, between 1993 and 2000, estimate the "clustering Phenomena", and to identify, in a statistically valid manner, the main clarifying factors associated with dental implant failure. 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, 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. An factorial analysis multivaried was applied to identify the main clarifying factors associated with dental implant success or failure; an Ascending Hierarchic Classification was carried through to identify groups with similar characteristics. The 135 patients were described from: sex, age, tobacco use and other buccal habits, occupation, civil state, medicine use, presence of diabetes and other chronic illnesses. These variables were associated to some of the characteristics techniques of the implantations, as design, implant surface characteristics, localization, prosthesis, load, timing of placement, implant lenght, implant diameter, immediate implants, sinus grafting, bone grafting and number of implants. Results: The general failure rate was 9.2%. It was possible to cluster 4 groups, defined mainly for the number of implantations, degree of success, region of the implantation, health status, civil state, occupation and age. The proposal of formation of these groups was to detect individual aspects that allow to formulate prognostics for dental implantations and suggest an approach to sucess prediction. Conclusions: The general failure rate found was 9.2%; the techniques variables had greater importance that the individual variables in the outcome of the implants.