The results suggest that a single overloading event causing ductile fracture of ProTaper instruments is the most common fracture mechanism encountered under the clinical conditions.

CLINICAL TECHNIQUE: It is generally accepted that the success of root-canal treatment is mainly dependent on the proper cleaning, shaping and hermetic obturation of root canals. Obturation of the root canal is of importance as 60% of endodontic failures are attributable to incomplete obliteration of the root-canal system. The clinical application of many obturation techniques used today demands the preservation of the natural apical construction or the preparation of an artificial equivalent during chemo-mechanical preparation. However, in clinical practice there are cases where the apical foramen is wide because of over-instrumentation, root-end resection during periradicular surgery, root resorption or because the apex of the root is incompletely formed. Thus the preparation of an artificial apical stop is very difficult to achieve. It is a common experience that performing usual gutta-percha condensation techniques in such canals often results in overfilling and therefore special obturation techniques are needed. Some clinical cases of teeth with wide apical foramen treated by a special obturation method are presented in this paper. In this method the end point of the primary gutta-percha cone is elasticized with a heated instrument and inserted into the root canal to record the internal morphology of the apical portion.

Aims: to evaluate the effect of different endodontic sealers on the coronal discoloration of the tooth part. Materials and methods: Forty intact human upper incisors and canines free of caries, restorations and coronal discoloration were used in the study. Black rectangular pieces of adhesive tape, with a round opening of 3 mm in diameter was cut to match the size of colorimeter window, the tape was applied to the middle third of the buccul surface of the tooth to facilitate a means of enamel surface standardization for analysis and was further secured to the teeth crowns with cyanoacrylate glue. A colorimeter (Microcolor, Data Station, DeLange, Braive instruments, Leige, Belgium) according to the CIE-L*a*b* color system was used to evaluate the color of enamel in the coronal part before and after instrumentation and obturation of the teeth, employing a repeated measures design (n=5) per sample. Results: There was no statistically significant difference among the levels of time of different materials (p = 0.095). Sealapex was presented significant differences against control group. Conclusion: The selection of endodontic sealers should be based mainly on other criteria (setting time, microleakage and toxicity) and no on the potent ional staining.