PROGNOSTIC VARIABLES ASSOCIATED WITH IMPLANT FAILURE - A RETROSPECTIVE EFFECTIVENESS STUDY

The purpose of this study was to determine implant survival rates by m eans of life table analyses for a cohort of patients not part of a pro spective efficacy trial and treated by practitioners at varying experi ence levels. Prognostic variables associated with implant failure were identified by means of proportional hazards models and advanced stati stical methods that account for patient effects. Ninety-nine consecuti ve patients treated from 1987 to 1991 with follow-up to 1994 were incl uded in this retrospective study. A total of 384 dental implants (79.7 % Branemark, 19.3% IMZ plasma-sprayed, 1% IMZ hydroxyapatite-coated) w ere placed and subsequently supported 108 prostheses. Survival and pro portional hazards modeling were used to generate Kaplan-Meier survival curves and to identify variables associated with implant failure. Sur vey data analysis was used to adjust for any patient effects for varia bles identified as significant through the proportional hazards models . Thirty-four implants failed over the follow-up period (median follow -up time 3.6 years), resulting in an overall failure rate of 8.9%. Sev enteen of 99 patients experienced an implant failure. When prosthesis type was excluded from the modeling process, survey data analysis iden tified posterior location and an implant width of less than 4.0 mm as being associated with implant failure (all P < .05).