The effect of the smear layer on the penetration depth of three different root canal sealers into the dentinal tubules was examined in 64 recently extracted single-rooted teeth. After chemomechanical preparation, the samples were randomly divided in two equal groups. The smear layer remained intact in group A, whereas complete removal of the smear layer was performed in group B. Two roots from each group were used as controls. Ten roots from each group were obturated with laterally condensed gutta-percha points and sealers AH Plus, Apexit, and Roth 811, respectively. Examination in scanning electron microscope revealed that the smear layer obstructed all the sealers from penetrating dentinal tubules. In contrast, smear layer removal allowed the penetration of all sealers to occur to a varying depth. These findings suggest that smear layer plays an important role in sealer penetration into the dentinal tubules, as well as in the potential clinical implications.

MTA is a biocompatible material that stimulates periradicular tissue repair at the root-end situation; however, the nature of the newly formed tissues requires further elucidation.

Kokkas AB, Goulas A, Varsamidis K, Mirtsou V, Tziafas D.Irreversible but not reversible pulpitis is associated with up-regulation of tumour necrosis factor-alpha gene expression in human pulp.

No abstract

Intentional exposure of pulp to the environment of the buccal cavity usually results in inflammation of variable degree. The objective of this study was to test whether the analysis of TNF-α gene expression with RT-PCR can assist in the monitoring of such changes, in canine teeth. Pulp tissue from 24 teeth, from a total of 5 animals, was used. Exposure was effected by preparation of cervical cavities by a round bur and lasted for 2 (n = 8) or 7 (n = 8) days. Pulp from unopened teeth (n = 8) served as the control. TNF-α gene expression was practically undetected -with an RT-PCR method -in either exposed or unexposed pulp, under the conditions used which did allow the detection of TNF-α mRNA in a positive control of inflamed tissue.We conclude that analysis of TNF-α gene expression with conventional RT-PCR cannot be used as a marker of short-to-medium term pulp tissue changes accompanying intentional pulp exposure in canine teeth.