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Introduction: intracanal medicaments have an important role in disinfecting ofthe pulp space and in endodontic regenerative procedures. These medications comein close contact with the periradicular tissue, thus their degradation products must bebiocompatible with the periapical tissue. Otherwise, these medicaments will resultin intense inflammatory reaction. Aim of the study: The purpose of this in vitrostudy was to evaluate and compare the cytotoxicity of three intracanal medications;Neem oil, double antibiotic paste (DAP) and calcium hydroxide (Ca(OH)2).Materials and Methods: Immortalized human gingival fibroblast cells were retrievedfrom the cell bank and then cultured. Three different intracanal medications (Neemoil, DAP, Ca(OH)2) were added to the cultured cells. Cell viability was evaluatedusing 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) andApoptosis/necrosis assays. Statistical analysis was performed using One-way ANOVAand post-hoc Tukey test. Results: Ca(OH)2 recorded the highest significant cytotoxicityfollowed by Neem oil, then DAP which recorded the lowest significant cytotoxicity.Cytotoxicity of the three intracanal medicaments used were directly proportional totheir concentrations Conclusion: DAP could be better recommended as intracanalmedicament in regenerative endodontic procedures because of its biocompatibilitycompared to the other tested medications.

Purpose To evaluate the effect of different root canal irrigating regimens on the push-out bond strength of RealSeal root canal obturation system. Materials and methods 16 mm ± 1 of roots of 70 freshly extracted single rooted human teeth were obtained and divided randomly into seven groups (n = 10) according to irrigation regimens throughout root canal preparation and final rinse: 1(DW–DW), 2(NaOCl–NaOCl), 3(NaOCl–MTAD), 4(NaOCl–EDTA), 5(CHX–CHX), 6(CHX–MTAD), 7(CHX–EDTA). All root canals of all groups were prepared using K3 root canal preparation system up to size #40/0.06 taper and filled using RealSeal Root canal obturation system. Two-millimeter thick horizontal sections from the coronal, middle and apical thirds of each root were sliced for the push-out bond strength measurement. Results In cervical sections the highest push-out bond strength value was recorded for NaOCl–MTAD (4.074 ± 2.524) followed by CHX–MTAD (3.795 ± 1.935), CHX–EDTA (2.659 ± 0.587), NaOCl–EDTA (2.404 ± 1.166), CHX–CHX (1.905 ± 0.573), NaOCl–NaOCl (1.690 ± 0.427) and the least value was recorded for DW–DW (0.791 ± 0.381) with statistical significant difference between groups (P Conclusion Whenever root canal obturation using RealSeal is decided, it is preferred to use NaOCl solution throughout instrumentation in association with MTAD as a final irrigant after instrumentation to obtain a the highest push-out bond strength to root canal dentin specially at the coronal sections that showed higher bond strength than middle and apical sections.

Objective To compare smear layer removal after root canal final irrigation with 17% Ethylenediaminetetraacetic acid (EDTA), 10% citric acid (CA), Biopure MTAD, and 0.2% chitosan solutions. Materials and methods Fifty extracted maxillary central incisors were decoronated to a root length of 16 mm. They were cleaned and shaped using ProTaper system up to size F4 and 2.5% sodium hypochlorite (NaOCl) irrigation throughout instrumentation. The specimens were divided into 5 equal groups according to the final irrigation solution; group I: 17% EDTA, group II: 10% CA, group III: MTAD, group IV: 0.2% chitosan, group V (control): 2.5% NaOCl. Samples were split longitudinally and examined under scanning electron microscope for smear layer presence at coronal, middle and apical root canal levels. Results 0.2% chitosan solution has the lowest mean rank of smear layer scores at all tested root sections. The efficacy of MTAD in smear layer removal was better than that of 17% EDTA and 10% CA at the apical level. Coronal sections recorded the lowest mean ranks of smear layer score and the highest was found at the apical section. Conclusion Final irrigation with 0.2% chitosan solution was more efficient in smear layer removal. 17% EDTA, 10% CA, MTAD and 0.2% chitosan effectively but not completely remove the smear layer especially at the apical root levels.

Aim: To assess the effect of dentin powder (DB) and human serum albumin (HSA) as tissue inhibitors on the antibacterial activity of chitosan nanoparticles (CSnps) and chlorhexidine (CHX). Materials and methods: The antibacterial effect of CSnps and CHX in presence or absence of inhibitors was tested on planktonic Enterococcus faecalis OG1RF standard strain. Study groups were group 1: DB and CSnps, group 2: DB and CHX, group 3: HSA and CSnps, and group 4: HSA and CHX, group 5: CSnps suspension (positive control for groups 1, 3), group 6: CHX solution (positive control for groups 2, 4), and bacteria suspension as a negative control (group 7). The assigned medications were added to tissue inhibitors for an hour before bacterial suspension addition. After 1 min, 24, and 72 h of bacterial suspension addition a sample was taken. Bacterial culturing was done on brain heart infusion plates at 37°C. The plates were incubated for 24 h and were inspected for growth by naked eye and the colonies the number of surviving bacteria was calculated. Data were collected and the mean and SD of log10 colony forming units was calculated and statistically analyzed using one-way analysis of variance and pairwise comparison between groups was performed whenever significant difference was found. Level of significance was set at P value less than or equal to 0.05. Results: Group 3and group 7 were statistically significant than all tested groups at all times. Also, significant difference between group 4 versus group 2 and group 6 recording P value of 0.048 at 1 min. However, there was no significant difference between groups 1, 2, 4, 5, 6 at 24 and 72 h. Conclusions: HSA had significant inhibitory effect on antibacterial activity of CHX and CSnps than DB at 1 min. At 24 and 72 h, neither HSA nor DB had significant inhibitory effect on antibacterial activity of CHX while HSA had a significant effect on antibacterial activity of CSnps.

Introduction The aim of this study is to compare the debridement efficacy of the EndoVac irrigation system versus needle irrigation with different irrigant solutions using scanning electron microscope. Materials and methods Eighty human freshly extracted single rooted teeth with fully developed, single root canals were collected. The teeth were divided randomly into two equal main groups according to the method of irrigation system used: group A, EndoVac system; and group B, needle irrigation. Each group was further subdivided into four equal subgroups according to the type of irrigant solution used: subgroup 1; sodium hypochlorite (NaOCl), subgroup 2; EDTA, subgroup 3; mixture of tetracycline, acid and detergent (MTAD), subgroup 4; saline. The canals were instrumented to a master apical file size #40/0.02 taper. Roots were split longitudinally in a buccolingual direction and examined under scanning electron microscope. Result At all tested root canal levels, group A recorded lower mean rank of score percentage compared to group B with statistical significant difference between them (P = 0.001 and 0.039 at the middle and the apical root level, respectively), while there was no statistical significant difference between both groups (P = 0.053) at the coronal root level. Conclusion The debridement efficacy of NaOCl only, NaOCl+EDTA, NaOCl+MTAD or even saline increased when using EndoVac system rather than conventional needles especially in the apical third.

Purpose To compare the cleaning efficacy of root canal walls after using two Nickel–Titanium (Ni–Ti) rotary files (Flexmaster and Mtwo) and one hand Ni–Ti file (Ni–Ti flex-K) when associated with different final irrigation regimens (SmearClear, 17% ethylene diamine tetra acetic acid (EDTA) and sodium hypochlorite). Materials and methods Ninety extracted human premolars with similar range of canal curvature (21–39°) were selected. After crown removal and working length determination, roots were divided into three equal groups according to root canal instrumentation: Group I and Group II were prepared using Flexmaster, Mtwo Ni–Ti rotary systems respectively where Group III was prepared using hand NiTi flex-K files. Each group was further subdivided into three equal subgroups according to root canal final irrigation; subgroup A: SmearClear, subgroup B: 17% EDTA and subgroup C: NaOCl. Roots were then splitted longitudinally and processed for scanning electron microscopic (SEM) examination to evaluate and score the root canal cleanliness. Results Final root canal irrigation using either SmearClear or 17% EDTA had significantly better cleaning efficiency than that of NaOCl in all tested groups. Ni–Ti hand files had significantly less cleaning efficacy than that of rotary systems except in subgroup C using NaOCl.

Objective To compare the antimicrobial effect of different irrigation solutions against Enterococcus faecalis (E. faecalis) and Streptococcus mutans (S. mutans) planktonic microorganisms and dual-species biofilm within the root canal. Materials and methods Forty three extracted human single-rooted teeth (18–25 years old) were selected and decoronated. The root canals were prepared to a master apical size 40 using hand K-files with distilled water irrigation. Roots were sterilized, microbial suspension of mixed culture of the tested microorganisms were inoculated into canals and incubated for 48 h. Three randomly chosen teeth were used to check up root infection, the remaining forty infected root canals were divided equally into 4 groups according to the irrigant solutions used. Group A: sterile distilled water; Group B: 5.25% Sodium Hypochlorite (NaOCl); Group C: 2% Chlorhexidine (CHX); Group D: 200 mg/mL N-Acetylcysteine (NAC) solution. Finally, the canals were washed with saline. The first microbiological sampling for planktonic bacteria was taken from root canal lumen and the number of CFU of tested organisms was counted. Each root canal was then split longitudinally, and a 4-mm-long mid-part of one half was cut, sterilized and inoculated with the mixed microbial suspension for 48 h. Specimens of each group were immersed in 5 ml of tested irrigation solution for 5 min. The proportions of dead bacterial cells in the biofilm were assessed by CLSM. Results Both planktonic bacteria were more sensitive to NAC solution recording significantly the lowest mean CFU values. S. mutans was statistically more sensitive to NaOCl irrigation compared to E. faecalis. CLSM showed significantly more proportion of dead cells in dual-species biofilm when NAC irrigation solution was used. Conclusion NAC solution can be considered as a potential alternative irrigation solution in root canal infections because of its antimicrobial efficacy against both S. mutans and E. faecalis planktonic bacteria and dual-species biofilm.