[Clinical and radiologic follow-up of coronal restoration with a standard radicular retainer].

The purpose of this study was to assess clinically and radiographically at mid-term the anchoring of custom posts in flat and curved roots. The results were compared to those of a similar study done in vitro (Brustlein-Rathle et al. 1988). 342 root canals from 143 premolars and molars were treated with standardized procedures by undergraduate students at the "Section de Médecine dentaire" of the University of Geneva. The results, which corroborated the above-mentioned in vitro observations, confirmed that the endodontic preparation as well as the canal widening for the post insertion straightens and thins the canal walls in 60% of the round and curved roots and in 25% of the flat and curved roots, also named root at risk. The study also demonstrated the difficulties of estimating and visualizing radiographically the weakening and possible cracks within the root wall because of radicular and osseous radiographic superimposition.