Bacteria debridement efficacy of two sonic root canal irrigant activation systems.

OBJECTIVE: To evaluate the bacteria debridement efficacy of two generations of sonic root canal irrigant activation systems: EndoActivator (Dentsply Sirona), the first generation, and SmartLite Pro EndoActivator, the second generation. METHODS: Instrumented, autoclaved, single-rooted human premolars were inoculated with Enterococcus faecalis (ATCC-29212) for 21 days. The bacteria biofilm-containing teeth were randomly divided into 5 groups (N=8): Group 1: Syringe-side-vented needle (S-N) delivery of saline for 1 min; Group 2: S-N delivery of 2% NaOCl for 1 min; Group 3: S-N delivery of 2% NaOCl for 5 min; Group 4: EndoActivator activation of 2% NaOCl for 1 min; Group 5: SmartLite Pro EndoActivator activation of 2% NaOCl for 1 min. The teeth were evaluated for bacterial reduction using CFU counts, and the percentages of dead bacteria within the dentinal tubules using confocal laser scanning microscopy. RESULTS: Activation of NaOCl with EndoActivator or SmartLite Pro EndoActivator significantly reduced the overall intracanal bacterial load, compared with S-N irrigant delivery (P<0.05), with no significant difference between the two agitation devices (P>0.05). Nevertheless, S-N delivery of 2% NaOCl for 5 min produced better bacteria debridement than either sonic agitation system. Different degrees of bacteria kill were identified in the coronal-middle portions and apical portion of the canal space. CONCLUSION: Delivery time of NaOCl affects the efficacy of bacteria disinfection. Activation for 1 min with the EndoActivator or SmartLite Pro EndoActivator demonstrated comparable canal wall biofilm and intracanal bacteria reduction efficacy when 2% NaOCl was used as irrigant for disinfecting E. faecalis in single-rooted teeth. CLINICAL SIGNIFICANCE: Although the sonic root canal irrigant activation devices investigated do not completely eliminate live bacteria biofilms from the canal space, they help reduce bacteria load during irrigant activation.

Effect of airborne-particle abrasion on 3-dimensional surface roughness and characteristic failure load of fiber-reinforced posts.

STATEMENT OF PROBLEM: Debonding is the most common complication of fiber-reinforced posts (FRPs). Airborne-particle abrasion (APA) has been suggested to increase resin cement adhesion to the surface of FRPs. However, which abrasion protocol is the most favorable is unclear. PURPOSE: The purpose of this in vitro study was to compare the surface roughness and characteristic failure load of three FRP systems following different APA protocols. MATERIAL AND METHODS: A total of 150 posts from 3 manufacturers (glass FRP, quartz FRP, and zirconia-enriched glass FRP) were randomly assigned to different surface treatments (NT: no treatment-control; E0: cleaned with 96% ethanol solution; E2: APA for 2 seconds/mm2-ethanol cleaned, E5: APA for 5 seconds/mm2-ethanol cleaned; and E10: APA for 10 seconds/mm2-ethanol cleaned) forming 15 groups in total. APA was performed with 50-µm aluminum oxide. Each post was observed under a 3-dimensional (3D) laser microscope, and average 3D surface roughness (Sa) was measured. Failure was induced with a universal testing machine. Two specimens per group were evaluated under the same microscope to evaluate failure patterns. Surface roughness data were analyzed with the Welch ANOVA (α=.05), followed by the post hoc Games-Howell test. Failure load differences were determined by 2-parameter Weibull statistics and likelihood ratio contour plots (95% confidence bounds). RESULTS: Statistically significant differences were found in the mean surface roughness among the groups (Welch ANOVA, P<.001). APA resulted in a significant surface roughness increase in all tested post systems. No surface roughness difference was found between surface treatments E2, E5, and E10 in any tested post systems. Weibull statistics and likelihood contour plots revealed a significant decrease in the characteristic failure load for glass FRP after surface treatment E2 (88.7 N) compared with the control (95.3 N). Quartz FRP showed a significant decrease in the characteristic failure load after surface treatment E5 (103.6 N) compared with the control (108.9 N). Zirconia-enriched glass FRP showed no significant decrease in the characteristic failure load after any of the tested surface treatments. Qualitative morphological changes and failure pattern differences were observed among the tested post systems after the different surface treatments. CONCLUSIONS: APA significantly increased surface roughness in all post systems. APA effects on characteristic failure load were dependent on the material used.