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.
The surface roughness of dental restorative materials has a crucial effect on the health of dental and periodontal tissues as well as for the longevity of restorations. In this study we tested a glass ionomer restorative cement, two nanohybrid resin composites, a flowable resin composite and a silorane-based composite. Twenty cylindrical specimens of each material were prepared, cured, polished and instrumented with a sonic scaler (Alegra ST ZE-55 RM W&H, Austria). The mean surface roughness was recorded using a profilometer (SJ-201, Mitutoyo, Japan) at three stages: before scaling, after scaling and after re-polishing. Additional specimens were analyzed by scanning electron microscopy and back-scattered imaging. Data were examined statistically by analysis of variance (ANOVA) and post-hoc tests at a level of significance of P < 0.05. The profilometric measurements and the SEM evaluation showed that, in most of the materials tested, the surface roughness was significantly increased after sonic instrumentation. After re-polishing the specimens, the roughness values were decreased. Periodontal scaling should include polishing of restorations in order to overcome alterations in surface roughness.
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