Recalcitrant bacteria play an important role of the persistence of periapical disease following root canal procedures, especially when they a part of a complex and stable biofilms that are found in the intricacies of the apical root canal anatomy. This is particularly true in cases that are deemed as a “failure in root canal treatment.” However, the literature is replete with confusion with regard to this concept of failure, as general terms, such as endodontic pathology or endodontic infection are used to denote factors implicated in the failure, without specifically identifying the issues of concern and their eradication, especially as they relate to the overall systemic health of the patient. Thus, attention for the cause of the failure immediately focuses on bacterial species without considering a vast array of potential causes. In doing so many studies tend to look at only one specific species as being the causative agent in the presence of the diagnosed failure (E. faecalis) and this bacterial species has been the focus of a wide range of investigative studies used for proof of concept. Is it possible that this focus has missed the bigger picture and potentially more virulent, invasive, and persistent species are involved? Have too many studies relied on short-term, single-bacterial biofilms, negating the very essence of the long-term interplay of multiple species within these colonies? This short communication will address this perspective, attempting to expand the investigative process for the presence and persistence of periapical disease and its impact on the host.

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Aim: The present study aimed to evaluate and compare the microcrack formation in apical root dentin as a result of root canal preparation with different nickel–titanium (NiTi) rotary systems. Materials and Methods: Sixty extracted mandibular premolar teeth with single canals were used. Apical 1 mm of roots was flattened perpendicular to the tooth axis. Forty-five teeth were prepared using ProTaper Next (PTN), ProTaper Gold (PTG), or TruNatomy files. Fifteen teeth were left unprepared as the negative control group. Images of apical surfaces of roots were obtained using a stereomicroscope at × 20 magnification. The presence of microcracks was noted with the help of the images. The data were analyzed with a Chi-square test using MiniTab 17 Statistical Software. Results: There was a statistically significant difference between the PTN and TruNatomy groups (P < 0.05). There was no statistically significant difference between the PTG group and other groups (P > 0.05). Conclusion: Whereas all rotary files created microcracks in the apical root dentin, TRN caused fewer microcracks than other NiTi rotary systems.

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Aim: The aim of this study was to compare the cleaning efficacy of three different rotary instrumentation systems in root canal preparation of primary anterior teeth. Materials and Methods: Thirty primary anterior teeth were freshly extracted and divided into three groups of ten teeth each. In Group I, root canals were instrumented with ProTaper, Group II with K3, and Group III with Hero 642 rotary file systems. After canal preparation, the teeth were sectioned longitudinally and visualized under standard error of the mean at coronal, middle, and apical thirds. Debris and smear layer removal efficacy was evaluated, and the data obtained were subjected to Kruskal–Wallis ANOVA test and Mann–Whitney U-test. Results: Statistically significant difference was noted in debris and smear layer scores at apical thirds (P < 0.05) between three groups with the highest efficacy for ProTaper followed by K3 and Hero 642 rotary systems. At coronal and middle thirds, K3 performed better than ProTaper file system. Conclusion: All the three groups showed decreased smear layer removal at the apical third. However, ProTaper and K3 rotary files showed significantly better cleaning efficacy at the apical third when compared to Hero 642 rotary files.

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Context: Microorganisms play an important role in the etiology of pulp and periapical diseases. For successful endodontic treatment, their control and elimination is important. The microorganisms may remain after root canal preparation intracanal medicament help in reducing remaining microorganism and can provide a favorable environment for periapical tissue repair. The increase in side effects and safety concerns of conventional medicaments has led to the recent popularity of herbal alternative medications. Aims: The purpose of this study was to investigate and compare the effectiveness of calcium hydroxide and Himalayan pink salt for the elimination of Enterococcus faecalis bacteria in extracted teeth samples. Materials and Method: Sixty extracted single-rooted human permanent teeth randomly divided into four groups. Group 1 − Control (n = 15); Group 2 − Ca (OH)₂ (n = 15), Group 3 − Himalayan Pink Salt (n = 15), and Group 4 − Ca (OH)₂ and Himalayan pink salt (n = 15). The intracanal medicaments were placed in teeth specimen infected with E. faecalis incubated in the anaerobic condition for 37°C. Dentine shavings were collected from the specimens at different time interval at the 1^st, 3^rd, and 5^th day and planted on agar plates. Colony-forming units (CFUs) were further be counted. Statistical Analysis Used: The data were statistically analyzed with the one-way analysis of variance, followed by Scheffe's multiple comparisons means to check the differences in CFU count between the groups (P < 0.05). Results: The present study showed that Himalayan pink salt exerted antibacterial activity in combination with calcium hydroxide.

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Aims: To compare the smear layer removal efficacy of 17% ethylenediaminetetraacetic acid (EDTA), 0.2% Chitosan nanoparticles, and QMIX 2 in 1 at apical third of root canal system, using Endovac system (Kerr, Switzerland) irrigation system and analyzed with the scanning electron microscope (SEM). Materials and Methods: Forty-five extracted mandibular single-rooted premolar noncarious human teeth were selected. The samples were randomly divided into three groups: Group 1: Irrigated with 1 ml of 17% EDTA, Group 2: With 0.2% Chitosan nanoparticles, and Group 3: With QMix2in1 (Dentsply Sirona, USA); 15 teeth in each group as final irrigant. The root canals were sequentially cleaned and shaped till 0.30 mm/0.09 taper and were irrigated with 1 ml of 5% sodium hypochlorite and 1 ml of 0.9% saline, after introducing each file into the canal. Endovac system (Kerr, Switzerland) system was used as delivering unit for all irrigation solutions with separate syringes. The tooth samples were sectioned and analyzed under SEM. The data obtained were analyzed using the Chi–square test. Results: All three irrigation solution in Group 1, Group 2, and Group 3 removed smear layer. Group 3 showed a significant difference in smear layer removal from the root canal system than Group 1 and Group 2. Conclusions: The final irrigation with QMix2in1 (Dentsply Sirona, USA) solution aids in better smear layer removal at the apical third of the root canal system, using Endovac system (Kerr, Switzerland) irrigation system.

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Objective: The objective of the study is to evaluate and compare the cyclic fatigue resistance of ProTaper Gold (PTG, Dentsply Tulsa Dental Specialties Inc., USA), Dia-X (DX, Diadent Group International, Europe), and ZenFlex (ZF, Kerr Corporation, USA) nickel–titanium (NiTi) rotary files in simulated curved canals with two different angles of curvature. Materials and Methods: A total of 60 new NiTi files (n = 20) with triangular cross-section, 21-mm length and size #20 PTG, DX, and ZF were used for cyclic fatigue testing. A stainless steel block having simulated canals with two different angles of curvature (60° and 90°) was used. 10 files for each curvature were used. The number of cycles to fracture and the fracture length of the fragment were recorded. The data were statistically analyzed using one-way ANOVA followed by Post hoc Tukey's test. Results: Statistically significant difference was found between all the three groups (P < 0.05). The PTG files showed greater resistance to cyclic fatigue in both the curvature angles of 60° and 90° followed by DX and ZF. In addition, the length of fracture fragment was insignificant in all the three instruments tested (P > 0.05). Conclusions: The PTG showed greater resistance to cyclic fatigue than DX and ZF instruments in both the apical curvatures.

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Aim: This study aims to determine the setting time and flow of a novel root canal sealer material with nanoparticle incorporated cyanoacrylate. Materials and Methods: To determine the setting time, sealer materials were mixed and packed into the stainless-steel ring molds of specific dimensions that are placed on a glass plate. The whole assembly was stored at 37°C, >95%relative humidity for at least 1 h. To measure the setting time, the needle of a custom-made Gilmore apparatus was adjusted vertically onto the surface of the sealer. To determine the flow, a volume of 0.05 ml mixed sealer was dropped on a glass plate. At 3 min after the onset of mixing, a second glass plate of 20 g weight was placed on the sealer and a 100 g weight was added to make a total mass of 120 g. The 120 g weight was unloaded after 10 min from the start of mixing. The minimum and maximum diameters of the sealer discs were measured by a digital caliper with a resolution of 0.01 mm. Results: Nanoparticle-modified cyanoacrylate cement has an initial setting time of 40 min and a final setting time of 75 min. Whereas the initial setting time for the AH Plus sealer is 238 min and the final setting time 480 min. The formulated nanoparticle incorporated cyanoacrylate sealer has a flow of 23.5 mm which is within the acceptable limits of ISO specification. Conclusion: The nanoparticle incorporated cyanoacrylate sealer has better setting time and flows within the limit of the American Dental Association specification.

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Aim: The aim of this study is to determine the antimicrobial efficacy of aqueous and ethanol extracts of Euclea divinorum Hiern against some root canal microorganisms compared to conventional root canal irrigants. Settings and Design: An in vitro laboratory study at the University of Nairobi. Materials and Methods: E. divinorum branches were collected, dried, and ground into coarse powder. The aqueous filtrates were lipolyzed while the ethanol filtrates were reduced under vacuum and oven-dried into powder. Growth inhibition of cell cultures from pure strains of Enterococcus faecalis (ATCC® 29212™), Streptococcus mutans (ATCC ®25175™), Staphylococcus aureus (ATCC® 25923™), Fusobacterium nucleatum (ATCC®25586™), Lactobacillus acidophilus (ATCC® 4356™), and Candida albicans (ATCC® 24433™) by the extracts were determined using tenfold liquid microdilution incubated for 24 and 48 h at 37°C. Cytotoxicity of the extracts was compared to those of 5.25% sodium hypochlorite, 2% chlorhexidine gluconate, and 17% ethylenediaminetetraacetic acid (EDTA). The one-way analysis of variance and Tukey's HSD test were used to test for differences between the mean growth inhibition of the extracts and the controls. Results: Fifty mg/ml ethanol extract had the highest growth inhibition at 99% ±3.04, 95% confidence interval (CI) (9.24, 100.755) against F. nucleatum followed by S. aureus at 97.22% ±3.77, 95% CI (95.04, 99.39) for 48 h incubation. S. mutans, L. acidophilus, and C. albicans showed resistance to the cytotoxic effects of the plant extracts. The mean growth inhibitions of 50 mg/ml ethanol extract against E. faecalis, and S. aureus were similar to those of 5.25% sodium hypochlorite and 17% EDTA for 24 h incubation while being higher against F. nucleatum at P < 0.01(Tukey's HSD). Conclusion: Fifty mg/ml E. divinorum extracts showed growth inhibition against E. faecalis, S. aureus, and F. nucleatum which was similar to the efficacy of 5.25% sodium hypochlorite. S. mutans, L. acidophilus, and C. albicans showed resistance to the cytotoxic effects of the extracts.

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Background: Biomechanical preparation of the root canal system is one of the most crucial steps of endodontic treatment. Intracanal debris is invariably extruded during biomechanical preparation which causes inflammation of periradicular tissues leading to flare-up. Aim: The aim of the study is to evaluate and compare the amount of apical extrusion of debris using Neoendo Flex, Pro-HS, and Mani Silk rotary files during root canal preparation. Materials and Methods: Sixty premolars with straight, single root canals were selected for the study. After access opening and working length determination, the samples were randomly divided into four groups according to file system used for root canal preparation: Group I – Neoendo Flex (n = 15), Group II – Pro-HS (n = 15), Group III – Mani Silk (n = 15), and Group IV – No instrumentation (n = 15). The debris collected after biomechanical preparation was quantitatively determined using a precision balance. The data obtained were statistically analyzed using ANOVA and post hoc Dunnett's test. Results: Minimum debris extrusion was seen with Neoendo Flex files and maximum debris extrusion was seen with Pro-HS files but the difference was not statistically significant (P > 0.05). Conclusions: Within the limitations of our in vitro study, it can be concluded that all Nickel– Titanium (NiTi) file systems studied caused apical extrusion of debris. Neoendo flex extruded least amount of debris apically compared to Mani Silk and Pro-HS files. Design features of a file primarily influence the amount of extruded debris.

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Aim: The aim of this study was to evaluate the accuracy of the apex locator in the presence of different irrigating solutions. Materials and Methods: Thirty humans, single canal mandibular premolars were decoronated, and canal orifices were flared with Gates-Glidden drills. Working length (Gold standard [GS]) was measured under ×3.5 magnification by inserting a size 10 K file until the tip became visible and deducting 0.5 mm from this length. Teeth were embedded in an alginate mass. Electronic apex locator (EAL) measurements were made with Propex II, while different irrigants were placed in the root canals with 30G needle and groups were made based on the type of irrigating solution used i.e., Group I (3% NaOCl), Group II (5% NaOCl), Group III (2% Chlorhexidine), and Group IV (17% ethylenediaminetetraacetic acid). Statistical analysis was performed. Results: Statistically insignificant differences were observed between the GS and EAL lengths among all the groups. There were significant differences (P < 0.05) only between Group III as compared to Group II and Group I. Conclusion: EAL can be used to accurately measure the working length, even in the presence of irrigating solutions. Of the irrigating solutions tested, least effect on the accuracy of EAL was seen with 2% chlorhexidine and the highest effect was seen with 5% NaOCl.

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Background: The rationale of endodontic treatment is to eradicate the infection and prevent the microorganisms from infecting or re-infecting the root canal system (RCS). Gram-negative anaerobic rods, Gram-positive anaerobic cocci, Gram-positive anaerobic, and facultative rods are most commonly isolated from the RCS. Herbal compounds can be used as a promising alternative to conventional calcium hydroxide. The current study aimed to compare and evaluate the antimicrobial effect of four different intracanal medicaments against Enterococcus faecalis. Aim: The objective of the current study is to compare and evaluate the antimicrobial effect of a new herbal intracanal medicament compared with the other four agents against E. faecalis. Materials and Methods: A total of 100 single-rooted teeth were selected, root canal preparation was performed using a standardized protocol, inoculated E. faecalis, which were further divided into five groups each according to intracanal medicaments used. Group 1: Calcium Hydroxide-16 mg/ml of distilled water (n = 20), Group 2: Diclofenac–400 mg/ml of distilled water (n = 20), Group 3: Ibuprofen–400 mg/ml of distilled water (n = 20), Group 4: Omeprazole–2 mg/ml of distilled water (n = 20), and Group 5: Oregano essential oil–25 μg/ml of distilled water (n = 20). The antimicrobial assessment was performed on the 7^th day, and dentine samples were collected to determine the number of colony-forming units. One-way analysis of variance and post hoc Tukey test was performed. Results: Group 1 (calcium hydroxide) showed a statistically significant reduction of E. faecalis (P < 0.05), followed by group 5 (Oregano essential oil extract). Conclusion: Calcium hydroxide showed a beneficial reduction of E. faecalis when compared to other tested agents.

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