A 4-YEAR CLINICAL-EVALUATION OF EXTENSIVE AMALGAM RESTORATIONS - DESCRIPTION OF THE FAILURES

The 4-year evaluation of a randomized controlled clinical trial to the functioning of Extensive Amalgam Restorations (EAR) is reported. In t his trial 300 EAR were made by three operators on molar teeth. Five di fferent auxiliary retention methods were used to retain these restorat ions. In the evaluation a differentiation in 'absolute' and 'relative' failures was made. After 4 years seven absolute failures (EAR dislodg ed or removed) were encountered (2%). When relative failures (endodont ic treatment or restoration at margin) arc also taken into account the number of failures increased to 31 (10%). Due to the low number of fa ilures, no significant influences from experimental variables (c.q. re tention method or operator) could be detected. It may be concluded tha t the results of this interim analysis of the clinical functioning of EAR are promising. It is thought that careful evaluation of cusp stren gth and reducing weak cusps diminishes clinical failure and as a resul t, it is not necessary to protect an EAR with a cast restoration in th e first 4 years of its clinical life.