[Risk factors for three-unit bonded bridges]

Statistical methods of survival-analysis were applied to investigate the effects of anatomical factors and clinical procedures which determine the "life-time" of 3-unit adhesive bridges. Their influences were analyzed until the first loss of retention after insertion. Besides the therapist effect, increased mobility and macromechanical preparation of the abutments could be identified as significant variables. Bridges bonded to one non-mobile and one hypermobile abutment tooth were found to be especially threatened. Extensive macromechanical preparation of the hard tissues reduces the hazard of debonding remarkably; this effect may be replaced by improved retentive mechanism of retainers.