Antibacterial effect of silver nanoparticles mixed with calcium hydroxide or chlorhexidine on multispecies biofilms.

The purpose is to evaluate the antibacterial effects of the silver nanoparticles (AgNPs) (Nanografi, METU Teknokent, Ankara, Turkey) mixed with calcium hydroxide (Ca(OH)2) (Ultracal XS, Ultradent, St Louis, US) or chlorhexidine gel (CHX) (Gluco-Chex, Cerkamed, Stalowa Wola, Poland) against a multispecies biofilm, by confocal laser scanning microscopy (CLSM) and culture-based analysis. Dentine blocks were inoculated with Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii for 1 week. Infected dentine blocks were randomly divided into groups according to medication; saline solution (SS), Ca(OH)2, Ca(OH)2 + AgNP, 2%CHX gel and 2%CHX gel + AgNP and time of application: 1 and 7 days (all groups, n = 5). Bacterial samples were collected before and after medication to quantify the bacterial load. Biofilm elimination was quantitatively analyzed by Live/Dead BacLight Bacterial Viability staining and CLSM. The addition of AgNPs to Ca(OH)2 increased the effectiveness of medicament in terms of bacterial reduction in both application times (1 and 7 days) (p < 0.05: ANOVA, Tukey's test) according to culture-based analysis. The CLSM images revealed that mixture of AgNP with CHX killed significantly more bacteria when compared with all other medicaments at 1- and 7-day application times (p < 0.05 and p > 0.05, respectively: Kruskal-Wallis, Dunn post hoc tests). The efficacy of Ca(OH)2 mixed with AgNPs was superior to Ca(OH)2 used alone in both application times (p < 0.05) according to CLSM analysis. The present study put forth the potential use of AgNPs mixed with Ca(OH)2 or CHX on multispecies (Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus and Actinomyces naeslundii) biofilm in 1 and 7day application periods.

A comparison of the efficacy of conventional and new retreatment instruments to remove gutta-percha in curved root canals: an ex vivo study.

AIM: To compare the efficacy of conventional and new retreatment instruments when removing gutta-percha root fillings in curved root canals. METHODOLOGY: A total of 56 curved molar roots were instrumented with ProFile instruments and filled using system B and Obtura II. The root fillings were removed with manual K-files and Hedström files (Dentsply Maillefer), ProFile (Dentsply Maillefer), R-Endo (Micro-Mega) or ProTaper Universal retreatment files (Dentsply Maillefer). Eucalyptol was used as a solvent with all techniques. Bucco-lingual and proximal radiographs of the roots were exposed and the percentage area of the remaining material was calculated by dividing the area of remaining filling material by the area of canal wall. Data were statistically analysed with Kruskal-Wallis and Mann-Whitney U tests (P = 0.05). RESULTS: None of the techniques completely removed the root filling materials. No significant differences were found amongst the coronal, middle and apical thirds in both radiographic projections (P > 0.05). In the bucco-lingual direction, the remaining filling material was significantly less following manual instrumentation than R-Endo and ProTaper instrumentation (P < 0.05). In the proximal view, it was significantly less following manual and ProFile instrumentation than R-Endo (P < 0.05). Complete removal of filling material occurred only in three specimens (with manual instruments). Manual instruments were significantly faster than R-Endo and ProFile (P < 0.05). More procedural errors (five fractured instruments and two perforation) were noted when using ProTaper (P < 0.05). CONCLUSIONS: In this laboratory study in curved molar roots, ProTaper Retreatment and R-Endo instruments were less effective in removing filling material from canal walls than manual and ProFile instruments.

Evaluation of the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals through the glucose penetration model.

OBJECTIVE: To compare the sealing ability of gutta-percha and thermoplastic synthetic polymer-based systems along the root canals using a recently introduced glucose penetration model. STUDY DESIGN: Premolars (n = 156) instrumented to an apical size of .06/40 were divided into 12 experimental and 2 control groups. The root canals were filled with either gutta-percha (groups 1-6) or Resilon (groups 7-12) core materials combined with AH Plus (groups 1, 4, 7, 0), Ketac Endo (groups 1, 5, 8, 11), or Epiphany (groups 2, 6, 9, 12), using cold lateral compaction (groups 1-3, 7-9) or System B with Obtura II (groups 4-6, 10-12). The leaked glucose concentration was measured spectrophotometrically at 1, 8, 15, 22, and 30 days. Percentage leaking of each group was also calculated. Data were recorded as mmol/L and statistically analyzed with Kruskal-Wallis and Mann-Whitney U tests (P = .05). RESULTS: Throughout the experimental period Resilon/Ketac-Endo/cold lateral compaction (group 8) showed the highest mean cumulative glucose penetration (mmol/L) (17.27 +/- 10.32), whereas Resilon/AH Plus/cold lateral compaction (group 7) had the least (3.36 +/- 4.65) (P < .05). At the 30(th) day, the least leaking percentage was observed in gutta-percha, Epiphany/cold lateral compaction (group 3). Glucose penetration was affected by the obturation technique in some groups. Ketac-Endo either with gutta-percha (group 2) or Resilon (group 8) indicated significantly less glucose penetration in warm technique, whereas gutta-percha/Epiphany (group 3) had significantly less glucose penetration in cold technique (P < .05). CONCLUSIONS: All material/technique combinations allowed glucose penetration. Gutta-percha/AH Plus combinations allowed similar patterns of glucose penetration to Resilon/Epiphany combinations.