Assessment of the Ability of Different Cleaning Protocols to Remove Eugenol-based Endodontic Sealer from the Root Dentin.

AIM: The aim of this study is to assess three protocols for removing a eugenol-based filling endodontic sealer from root dentin and the bond strength of fiberglass posts luted with resin cement. MATERIALS AND METHODS: Sixty single-rooted bovine teeth were prepared and filled with the Endofill endodontic sealer and gutta-percha cones. After 7 days, 9 mm of the filling was removed and divided into five groups (n = 12) according to the cleaning protocol: G1 (negative control), unfilled; G2 (positive control), saline solution; G3, 95% alcohol; G4, amyl acetate; and G5, Largo bur. The canals were hybridized and fiberglass posts were luted with resin cement. They were cross-sectioned in slices of 1 mm and subjected to the push-out test. The other samples were sectioned longitudinally and visualized in a scanning electron microscope (SEM), and the existing chemical elements were quantified by energy dispersive spectroscopy (EDS). The statistical analysis used variance analysis (ANOVA)-one way and Fisher's test, at a 5% significance level. RESULTS: The 95% alcohol was more effective for cleaning the canal, resulting in a clean dentinal surface and bond strength statistically similar to the negative control. The Largo bur was also statistically similar to the negative control, with only a few debris impregnated on the wall. Amyl acetate showed more sealer residues on the canal walls, with a consequent lower bond strength value than the other groups, only higher than the positive control. CONCLUSION: The 95% alcohol and Largo burs may be used after removing the canal filling, so that the bond strength is improved when using the eugenol-based sealer.

Cytotoxicity of different concentrations of glycolic acid and its effects on root dentin microhardness - An in vitro study.

The aim of the study was to evaluate the cytotoxicity of different glycolic acid concentrations (GA) and its effects on dentinal microhardness. Cytotoxicity was evaluated after inoculation of test irrigants in the lymphocyte primary culture for 3 min. The tested substances were distilled water(DW); 17% EDTA; QMix; 10% GA; 17% GA; and 25% GA. Counting of total, live and dead cells was performed, obtaining the average percentage of dead cells of each group. For microhardness evaluation, 60 root dentin samples were divided into the same tested groups (n = 10) and immersed in test irrigants for 3 min. Dentin microhardness was evaluated by Vicker test. Specific statistical analysis was made in both tests. Results showed significant lower cytotoxicity for QMix and 10% GA (P < 0.05). Moreover, all test irrigants presented similar values of microhardness than the control group (P > 0.05). In conclusion, lower GA concentration can be an alternative for final irrigation on endodontics.

Effectiveness of calcium and sodium hypochlorite in association with reciprocating instrumentation on decontamination of root canals infected with Enterococcus faecalis.

The aim of this study was to evaluate the antimicrobial activity of sodium and calcium hypochlorite utilising reciprocating instrumentation. Sixty root canals were inoculated with E. faecalis for 14 days. Samples were divided into six groups according to decontamination protocol: G1: no treatment, G2: distilled water, G3: 2.5% sodium hypochlorite, G4: 2.5% calcium hypochlorite, G5: 5.25% sodium hypochlorite and G6: 5.25% calcium hypochlorite. Instrumentation was performed with Wave One reciprocating system (Dentsply Sirona Endodontics, York, PA, USA) in groups G2 to G6. Colony-forming units (CFUs) counting was performed and the data were subjected to Anova and Tukey (α  =  0.05). Group 1 and 2 showed the highest mean contamination, with a significant difference between them (P < 0.05). Groups 3, 4, 5 and 6 showed the lowest contamination means with no significant difference between them (P < 0.05). Sodium and calcium hypochlorite, in association with reciprocating instrumentation, can be an effective decontamination protocol in root canals infected with E. faecalis.

Effect of different protocols of eugenol removal on the bond strength between the fibre post and root dentin.

The aim of this study was to evaluate the bond strength between the fibre post and root dentin after different cleaning protocols to remove eugenol from dentin. The residues and elemental composition of dentin were analysed using SEM and EDS. Bovine incisor roots were obturated with eugenol-based sealer. The post space was prepared, and the roots were divided into the following groups according to the cleaning protocol: unfilled (negative control), saline solution (positive control), 70% ethanol, acetone and 70% isopropyl alcohol. The fibre posts were cemented and push-out test realised. Chemical analysis of the dentin was performed using SEM and EDS. The bond strength values were analysed by anova/Fisher's and were as follows: negative control (7.30 ± 2.77) = 70% ethanol (6.64 ± 2.91) = 70% isopropyl alcohol (5.01 ± 3.15) = acetone (4.42 ± 1.53) >positive control (1.29 ± 0.56). It was concluded that 70% ethanol may be a good cleaning protocol to remove eugenol from dentin.