Long-term Reliability of Resin-bonded Attachments for Precision-Retained Removable Dental Protheses
Objectives: The purpose of this clinical study was to evaluate the outcome of resin-bonded attachments (RBAs) for precision-retained removable dental protheses (RDPs) with a clinical maintenance period of at least 2 years.
Methods: Ninety-seven patients (50 females and 47 males; mean age 63.7±10.1 years) with 162 RBAs (30 bonded to posterior teeth, 132 bonded to anterior teeth) were placed since December 1998 and then examined annually. Abutment teeth received a minimal invasive preparation, which included paralleled retention grooves, occlusal rests for posterior teeth and cingulum notches for anterior abutments. RBAs were cast in a cobalt-chromium alloy with a minimum thickness of 0.5 mm. The patrix was designed to contact the edentulous area like a pontic and to provide guidance for interproximal tooth brushes.
RBAs were adhesively luted with a luting composite resin (Panavia 21 Ex or Panavia V5, Kuraray, J) after rubberdam application. The following parameters were evaluated at baseline, and then annually: caries activity, plaque index, periodontal conditions and tooth vitality. Kaplan-Meier survival curves were used to account reasons of failure.
Results: The mean observation time of the RBAs until the last recall visit was 78.7±48.4 months (minimum 3.6 months, maximum 235.4 months). Twenty-nine RBAs placed in 23 patients debonded during the observation period (17.9%). Therefore, the ten-year survival rate according to Kaplan-Meier was 60.5% and dropped to 47.4% after 15 years of observation if debonding was considered as failure. If rebonded RBAs were regarded as surviving, the survival rate was 64.7% after 10 years and 60.0% after 15 years.
Conclusions: The use of RBAs for precision-retained removable dental protheses seems to be a promising long-term therapy alternative to conventionally retained RDPs. The survival rate and frequency of complications were comparable or even better to that of conventional crown-retained attachments for RDPs as reported in the current literature.