Neither syringe injection nor PUI methods were efficient in removing the inter-appointment root canal medicaments. Remnants of medicament were found in all experimental groups regardless of the vehicle used.

Finite element analysis (FEA) was used to investigate the influence of different post systems on the stress distribution of weakened teeth under oblique-load application. A maxillary central incisor root obtained from a sound tooth was weakened by partial removal of dentin inside the root canal. Seven two-dimensional numerical models, one from the sound tooth and six from the weakened root restored with composite resin and post systems were created as follows-ST: sound tooth; CPC: cast CuAl post and core; SSP: stainless steel post + composite core; GP: fiberglass + composite core; CP: carbon fiber + composite core; ZP: zirconium dioxide post + composite core; TP: titanium post + composite core. The numerical models were considered to be restored with a leucite-reinforced all-ceramic crown and received a 45º occlusal load (10 N) on the lingual surface. All the materials and structures were considered linear elastic, homogeneous, and isotropic, with the exception of fiberglass and carbon fiber posts which assumed orthotropic behavior. The numerical models were plotted and meshed with isoparametric elements, and the results were analyzed using von Mises and Sy stress criteria. When compared with the sound tooth, FEA revealed differences in stress distribution when post systems were used. Among the restored teeth, the use of CPC, SSP, ZP, and TP resulted in higher stress concentration in the post itself when compared to GP and CP. Therefore, results from the FEA images suggested that the use of non-metallic post systems could result in improved mechanical behavior for the weakened restored teeth.

MTA and Z-100 composite were biocompatible at 4 and 12 weeks in this experimental model.

The aim of this study was to determine the effect of ultrasonic vibration on the force necessary to remove pre-fabricated and anatomic and cast posts. Two hundred and forty teeth were divided into two groups. In group I, a 0.8-mm metallic pre-fabricated post, UnimetricMaillefer, was utilized; in group II, cast copper-aluminum alloy posts measuring 0.8, 1.0 and 1.2 mm in diameter were used. The root canals were prepared in three different diameters: 0.8, 1.0 and 1.2 mm, with a length of 10 mm. The posts were cemented with glass monomer cement resulting in 20 specimens for each subgroup. Half of the sample was submitted to ultrasonic vibration for 3 min, while the other half did not receive any vibration. The specimens were submitted to traction in a universal testing machine. The results were analyzed by non-parametric Mann-Whitney U, Wilcoxon and Kruskal-Wallis tests. The application of ultrasonic vibration significantly reduced the retention provided by the glass ionomer cement in the fixation of intracanal posts. The ultrasonic action was effective in both pre-fabricated and anatomic and cast posts. The effectiveness of the ultrasonic vibration was not related to the cementation line or the diameter of the post.

Hand instrumentation of the root canal was compared with ultrasonic instrumentation in 20 maxillary premolars with 2 root canals. The buccal and lingual canals were alternately instrumented by the 2 techniques until they had reached clinically ideal conditions for filling. After mechanical preparation, an attempt was made to evaluate root shape and the enlarging ability of the 2 techniques. For this purpose, a crosswise cut slice approximately 100 microns thick was cut off at the middle level of the root, which permitted comparative quantification of the instrumented area of the buccal and lingual canals. Crosscut serial sections of the remaining parts of the root were obtained for a systematic study of the entire extension of the root canal. It was concluded that the presence of debris inside the root canal depended more on the anatomical variation of the canal than on the technique used. No statistically significant differences in root canal area were evident at the middle third level of the root.

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