Effect of final irrigation protocols on the fracture resistance of roots with varying dentine thickness.

This study evaluated the effects of 9% etidronic acid (HEBP) and 17% ethylenediaminetetraacetic acid (EDTA) used either with conventional syringe irrigation (CSI) or passive ultrasonic irrigation (PUI) on the fracture resistance of roots with different dentine thickness. The root canals of 120 extracted teeth were widened, leaving dentinal walls with different thicknesses of either 0.75 mm, 1.50 mm, or 2.25 mm with 40 teeth in each group. Within each of these groups, four subgroups (n = 10) were formed according to the final irrigation regimens applied: 2.5% NaOCl-17% EDTA with CSI; 2.5% NaOCl-17% EDTA with PUI; 2.5% NaOCl + 9% HEBP with CSI; 2.5% NaOCl + 9% HEBP with PUI. The irrigated root canals were obturated with AH Plus sealer and gutta-percha cones. A compressive vertical loading was applied to the samples and the force at fracture was recorded. Data were statistically analysed using a multiple linear regression analysis. The most influencing factor for the fracture strength of roots was the remaining dentine thickness, followed by the irrigation method, and then the irrigation solution. The samples irrigated using PUI were statistically significantly more resistant to fracture than those using CSI (mean difference = 116.3 N; 95% CI = [53.9, 178.6] N). The application of HEBP was associated with higher resistance to fracture than the application of EDTA (mean difference = 71.0 N; 95% CI = [8.6, 133.3] N).

Preparation of natural indicator incorporated media and its logical use as a colorimetric biosensor for rapid and sensitive detection of Methicillin-resistant Staphylococcus aureus.

Herein, we report a rational design in preparation of natural indicator incorporated media used as a rapid, selective, sensitive and economic colorimetric biosensor for detection of Methicillin-resistant Staphylococcus aureus (MRSA). Anthocyanins obtained from red cabbage (Brassica oleracea) extract (RCE) are major components and acted as pH responsive indicators in the RCE media. The RCE media was tested for eight gram-positive, four gram-negative bacterial and one model fungal pathogens. We experimentally revealed how salt concentration and antibiotic (cefoxitin) in the RCE media influence the growth of pathogens and especially MRSA. Benefiting pH dependent color change function of anthocyanins is indispensable point of the RCE media in sensing of MRSA growth. The potential MRSA colorimetric sensing mechanism of anthocyanins relies on both protonation and decrease in electron density on structures of anthocyanins by acidic organic volatile compounds produced during growth of MRSA. The protonated anthocyanins with low electron density changed original purple color of the RCE media to pink color. We demonstrated that detection of MRSA was achieved by spectrophotometrically (one single cell) and visually with naked eyes (100 cells) in 2nd hrs and 6th hrs of incubation, respectively. We optimized concentrations of cefoxitin (from 1 µg/mL to 20 µg/mL) against MRSA and Methicillin-sensitive Staphylococcus aureus (MSSA) bacterial cell (3 McFarland) suspensions, then growth of MRSA was visually and clearly detected in the presence of 4 µg/mL cefoxitin between 90 min and 3 h. We persistently offer that the proposed RCE media can be a well alternative to currently used phenotypic methods in clinics owing to its much rapid, sensitive, selective and economic properties.

Effect of Root Canal Disinfection with a Diode Laser on Postoperative Pain After Endodontic Retreatment.

Objective: The aim of this randomized clinical trial was to evaluate the influence of root canal disinfection with a 940-nm diode laser on the intensity of pain after endodontic retreatment. Background data: Microorganisms are the most common causes of tooth pain. Therefore, clinical studies are needed to explore the effect of disinfection techniques on postoperative pain. Methods: Eighty-four patients scheduled for endodontic retreatment were allocated to two groups in a 1:1 ratio (n = 42 each). After root canal filling removal and chemomechanical procedures, the root canals were disinfected with a 940-nm diode laser in one group [laser disinfection (LD) group]. In the other group, a mock application of laser was made with the power off [pseudo-laser disinfection (PLD) group]. All retreatment procedures were completed in a single visit. The patients assessed their pain levels at 24, 48, and 72 h after retreatment using a numeric rating scale. The number of analgesic pills used during this period was also recorded. The collected data were statistically analyzed using Mann-Whitney U and Wilcoxon tests. Results: Postoperative pain on the first 2 days was significantly lesser in the LD group than in the PLD group (p < 0.05), and the difference became insignificant on the third day (p > 0.05). Moreover, analgesic intake over 3 days and pain on percussion on the fourth day were significantly lesser in the LD group than in the PLD group (p < 0.05). Conclusions: Elimination of microorganisms from root canals is important for preventing postoperative complications. Our findings suggest that diode LD can reduce postoperative pain and provide comfort after endodontic retreatment. This study is registered in www.ClinicalTrials.gov database with the identifier number NCT03584880.

Comparative Safety of Needle, EndoActivator, and Laser-Activated Irrigation in Overinstrumented Root Canals.

OBJECTIVE: To evaluate the safety of sodium hypochlorite (NaOCl) irrigation using three different techniques during the final rinse in overinstrumented root canals. BACKGROUND DATA: The effect of irrigant activation on irrigant extrusion from overinstrumented root canals is still unclear. METHODS: A total of 30 single-rooted teeth were decoronated. The working lengths were determined and the roots were divided into two groups of 15 teeth each: group 1, instrumentation 0.5 mm short of the apical foramen and group 2, instrumentation 0.5 mm beyond the apical foramen (overinstrumented). Needle irrigation (NI), sonic irrigation with EndoActivator (EAI), and laser-activated irrigation (LAI) were used for the final rinse in each group; each root underwent the three irrigation procedures in a randomized crossover manner. A modified container-foam model was used to collect apically extruded NaOCl. The weight of the extruded NaOCl was calculated by subtracting the initial weights of the containers from their final weights. All data were statistically analyzed. RESULTS: The amount of NaOCl extrusion was similar with all three irrigation systems in group 1. In group 2, the amount of extruded NaOCl was significantly greater with EAI than with NI and LAI. EAI and LAI caused significantly greater extrusion in group 2 than in group 1. CONCLUSIONS: EAI, NI, and LAI are equally safe for irrigating canals with intact apices. However, the risk of irrigant extrusion can increase in overinstrumented canals, with EAI associated with a greater risk compared with NI and LAI.