Antimicrobial peptide GH12 as root canal irrigant inhibits biofilm and virulence of Enterococcus faecalis. Li Y,Wang Y,Chen X,Jiang W,Jiang X,Zeng Y,Li X,Feng Z,Luo J,Zhang L International endodontic journal AIM:The objectives of this laboratory-based study were to investigate the effects of GH12 on Enterococcus faecalis biofilm and virulence. METHODOLOGY:Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of GH12 against E. faecalis were first determined. A time-kill assay was further conducted. The effects of GH12 on the expression of virulence and stress genes in E. faecalis were evaluated by RT-qPCR. Crystal violet stain was used to investigate the effects of GH12 on E. faecalis biofilm formation and 1-day-old biofilm. Finally, an ex vivo tooth model contaminated with E. faecalis was used to evaluate the antimicrobial activity of GH12 as an irrigant by CFU counting, SEM and CLSM. One-way anova and Tukey's multiple comparisons test were used to compare the differences amongst groups (α = 0.05). RESULTS:The MICs and MBCs of GH12 against E. faecalis were 8.0 ± 0.0 and 16.0 ± 0.0 mg L , respectively, and GH12 at 32.0 mg L reduced the bacterial numbers by more than 99.9% within 1 min. Various virulence genes (efaA, esp and gelE) and stress genes (dnaK, groEL, ctsR and clpPBCEX) in E. faecalis were significantly downregulated by GH12 at sub-MIC levels (P < 0.05). Additionally, both E. faecalis biofilm formation and the biomass of 1-day-old E. faecalis biofilm were significantly reduced by GH12 (P < 0.05). Elimination of E. faecalis in biofilms from root canal walls was achieved through irrigation with 64.0 mg L GH12 for 30 min. CLSM analysis revealed that GH12 at 64.0 mg L was most effective in eliminating bacteria within dentinal tubules (P < 0.05). CONCLUSION:In a laboratory setting, and when used as an irrigant, GH12 suppressed E. faecalis, downregulated specific virulence and stress-associated genes, eliminated intracanal E. faecalis protected by biofilms and killed bacteria in dentinal tubules. These results emphasize the need for preclinical and clinical studies to explore the potential of GH12 as an antimicrobial agent during root canal treatment. 10.1111/iej.13296

Novel root canal sealer with dimethylaminohexadecyl methacrylate, nano-silver and nano-calcium phosphate to kill bacteria inside root dentin and increase dentin hardness. Baras Bashayer H,Sun Jirun,Melo Mary Anne S,Tay Franklin R,Oates Thomas W,Zhang Ke,Weir Michael D,Xu Hockin H K Dental materials : official publication of the Academy of Dental Materials OBJECTIVES:Root canal re-infection and weakening of roots are two main challenges in endodontics. The objectives of the study were: (1) to develop a novel root canal sealer containing dimethylaminohexadecyl methacrylate (DMAHDM), nanoparticles of silver (NAg), and nanoparticles of amorphous calcium phosphate (NACP), and (2) to investigate the effects on the physical, anti-biofilm, remineralizing ions, and hardness of human dentin for the first time. METHODS:Methacrylate-resin dual-cured root canal sealer contained 5% DMAHDM, 0.15% NAg, and NACP at 10%, 20% and 30% mass fractions. The flow, film thickness, and Ca and P ions release were investigated. The effects of NACP on radicular dentin hardness after treatment with sodium hypochlorite (NaOCL) and ethylenediaminetetraacetic acid (EDTA) were assessed. Antibacterial properties were measured against Enterococcus faecalis (E. faecalis)-impregnated dentin blocks; colony-forming units (CFU) and live/dead assays were measured. RESULTS:Incorporating DMAHDM, NAg and NACP did not adversely influence the flow and film thickness properties. Sealer with 30% NACP neutralized the acid and increased the solution pH (p<0.05). Sealer containing 30% NACP regenerated dentin minerals lost due to NaOCL and EDTA treatment, and increased the dentin hardness to match that of sound dentin (p>0.1). Incorporating 5% DMAHDM and 0.15% NAg reduced biofilm CFU of E. faecalis-impregnated dentin blocks by nearly 3 logs when compared control group (p<0.05). SIGNIFICANCE:The novel therapeutic root canal sealer with triple bioactive agents of DMAHDM, NAg and NACP neutralized acid, raised the pH, regenerated dentin minerals, increased root dentin hardness, and reduced dentin-block-impregnated biofilm CFU by 3 logs. This new sealer with highly desirable antibacterial and remineralization properties are promising to increase the success rate of endodontic therapy and strengthen the tooth root structures. 10.1016/j.dental.2019.07.014

Complete Healing of a Large Cystic Lesion Following Root Canal Treatment with Concurrent Surgical Drainage: A Case Report with 14-Year Follow-Up. Cho Yong-Sik,Jung Il-Young Journal of endodontics We describe complete healing of an extensive cystic lesion by using a conservative approach: root canal treatment with concurrent surgical drainage. A silicone Foley catheter drain was modified into a surgical drainage stent, which was then used for 4 weeks. Disinfection of the root canal was achieved by the use of hand files and irrigation with 5.25% NaOCl for a minimum of 30 minutes. The irrigant changes were performed at 5-minute intervals, and no intracanal dressing was used. At subsequent follow-up examinations, cone-beam computed tomography and periapical radiographs confirmed that complete healing had occurred around the periapical and lateral areas of affected teeth. This case report indicates the potential for healing of large cystic lesions by nonsurgical root canal treatment. 10.1016/j.joen.2018.12.008

Investigation of an Improved Side-Vented Needle and Corresponding Irrigation Strategy for Root Canal Therapy with CFD Method. Liu Lei,Shen Chenlu,Ye Weijia,Yao Hua,Peng Qiao,Cui Yongdong,Khoo Boo Cheong Computer methods and programs in biomedicine BACKGROUND AND OBJECTIVE:This research aimed to present an improved side-vented needle and explore its availability as well as the corresponding irrigation strategy. METHODS:A CFD model was used to simulate the irrigant flow in a simplified prepared round root canal with an apical delta respectively with different needles for irrigation. The needle types include flat end-tip needle, original side-vented needle, and improved side-vented needle. Different insertion depths and inlet velocities were contrastively studied, as well as the gap size between the bulb at the end tip of the improved side-vented needle and the root canal. The study includes a total of 13 schemes. Velocity, pressure, and shear stress in the root canal were measured to contrast the internal flow-field details and irrigation efficiencies between different schemes. RESULTS:Poor irrigation replacement appeared in the schemes without enough needle insertion no matter which kind of needle has been used, though relatively lower pressure emerged at the apical foramen. On the contrary, deepening needle insertion not only brings better irrigant replacement but also higher apical foramen pressure. The original side-vented needle tends to make lower pressure at the apical foramen and simultaneously worse irrigant replacement as compared to the flat end-tip needle. The fluid entering the apical anatomy part deceases a lot as the original side-vented needle was replaced by the improved one. The scheme using the improved side-vented needle with gap size ratio and inlet velocity respectively equaling 5.0% and 5.50m/s can be considered the best one. CONCLUSIONS:The improved side-vented needle can ensure acceptable irrigant replacement performance without leading to a high-pressure level at the apical foramen. The gap between the bulb and the wall of the root canal is very crucial for the pressure at the apical. The ideal irrigation strategy is ensuring the gap equals zero. However, it is a little hard to realize during the whole procedure of the root canal preparation except the final step. Consequently, another strategy that keeping the value of gap size ratio as small as possible such as less than 15% and simultaneously ensuring lower-velocity coming fluid, is necessary in the non-final irrigation. 10.1016/j.cmpb.2020.105547