Adhesive interface of a luting agent used for fiber post cementation.

AIM: The aim of this descriptive work was to observe and analize the images obtained with a scanning electron microscope (SEM) of the adhesive interface of a polymer-based cement (C) used for luting an organic fiber post (P) within its root preparation (R).  MATERIALS AND METHODS: The 26 human lower premolars used were randomly divided into the following groups: A (n=18) root canal treatment + P (Exacto #1 – Angelus, Brasil) + C (RelyX U200 – 3M ESPE, USA). B (n=2) Root canal treatment + P + IV (Reinforced Glass Ionomer – Fuji Plus –GC CORPORATION. TOKYO, JAPAN). C (n=2) root canal instrumentation without obturation. D (n=2) P without root canal treatment. And E (n=2) root canal treatment. Each specimen was then included embedded in epoxy resin and sectioned in 1mm-thick slices following its major axis starting from the center of  each piece, using a metallographic cutting machine (Isomet 1000, Buehler, Lake Buff, IL, USA) and diamond abrasive discs at low speed under water cooling (BUEHLER Diamond Wafering Blade Series 15 HC). Out of a total of 4 slices obtained from each piece, only the 2 central ones were used. The 52 slices underwent a chemical and mechanical treatment in order to demineralize and deproteinize the samples to be able to observe the adhesive interface with SEM. Photographs at pre-established marks were taken with 500x, 1000x and 2000x. RESULTS: 100% of the observed slices  (regardless of the technique) showed filamentous structures that went from the dentin- pre dentin union to the cement – dentin union with the following characteristics: hollow tubular section, variable length, cilindric shape following the direction of the dentin tubules and frequently sharp bends or fractures. CONCLUSION: It can be concluded that, according to our observations, the images obtained  of all groups showed filamentous structures that are were not composed, at least entirely, by resin cement. Further research is advisable in order to determine their real composition.