The penetration effect of ultrasound and Er:YAG laser irrigation activation techniques on dentine of infected human root canals / 口腔疾病防治

Objective@#This ex vivo study evaluated the effect of ultrasound and Er:YAG laser irrigation activation techniques on the penetration of sodium hypochlorite solution into infected human root canal dentin, providing a reference for clinical infection control of infected root canals.@*Methods @#Thirty-six cases of infected root canals were collected and randomly divided into three groups according to the irrigation technique: 12 cases in the conventional syringe irrigation (CSI) group, 12 cases in the passive ultrasonic irrigation (PUI) group, 12 cases in the Er:YAG laser and photon-induced photoacoustic streaming (PIPS) group and 36 cases of clean root canals (12 cases in the CSI group, 12 cases in the PUI group, 12 cases in the PIPS group). All of the selected root canals were straight root canals of posterior teeth. After standardizing the root length, all canals were subjected to instrumentation and dynamic irrigation. 2% methylene blue solution was used to visualize the penetration of the irrigant. EXAKT cutting and grinding equipment was used to take transverse sections of 100-150 μm at the coronal, middle and apical thirds of the root canals. The data (maximum penetration depth, average penetration depth, and penetration percentage) were observed under a light microscope to evaluate the effect of dye penetration. @*Results @# With the three irrigation techniques, the maximum penetration depth, average penetration depth and penetration percentage of the infected root canals were significantly lower than those of clean root canals in the full length of the root canal (P<0.05). The penetration percentage, average penetration depth and maximum penetration depth of the PIPS group were significantly higher than those of the CSI group in the coronal, middle and apical thirds of the infected root canal, respectively (P<0.05). There was no significant difference in the maximum penetration depth, average penetration depth or penetration percentage between the PUI and CSI groups (P>0.05). There was also no significant difference in the maximum penetration depth, average penetration depth or penetration percentage between the PIPS and PUI groups (P>0.05). @*Conclusion @# The dentine permeability of infected root canals was weaker than that of clean root canals. Er:YAG laser-assisted irrigation activation technology could significantly improve the penetration of sodium hypochlorite solution into infected dentin, but passive ultrasonic irrigation did not significantly improve the penetration.

Research progress on the effect of new disinfection methods on the clearance of Enterococcus faecalis in the root canal / 口腔疾病防治

@#Enterococcus faecalis has been confirmed to be closely related to dental pulp and periapical disease in recent years. Enterococcus faecalis is one of the important bacteria causing persistent or secondary root canal infection and root canal treatment failure. Traditional root canal disinfection drugs such as sodium hypochlorite, chlorhexidine and calcium hydroxide can not completely remove Enterococcus faecalis in the root canal because of the concentration limitation of the drug and the complexity of the root canal system. Therefore, how to effectively resist the Enterococcus faecalis infection in the root canal has become one of the important research directions in the treatment of periodontal pulp periapical disease. In recent years, some new antimicrobial agents and disinfection methods have emerged due to the drug resistance and pathogenicity of Enterococcus faecalis, such as laser, photodynamic, ultrasonic irrigation and ozone therapy. Their combination with traditional root canal irrigation drugs can significantly enhance the ability of traditional drugs to remove Enterococcus faecalis in the root canal. In addition, the emergence of new disinfection methods such as chlorine dioxide, nano-magnesia, superoxidized water and N-acetylcysteine have been shown to have a unique killing effect on Enterococcus faecalis in root canals. At present, most of the new disinfection methods described above are in the in vitro experimental stage, and their stimulation and damage to normal tissue still lack relevant clinical data support; thus, these outcomes need to be further studied.

Culture-dependent approaches to explore the prevalence of root canal pathogens from endodontic infections

Abstract: Endodontic infections are considered to be caused by the presence of various microorganisms within the root canal system. Recognition of this microbiota contributes to the successful treatment of infected root canals. This study investigated the microorganisms associated with primary and secondary endodontic infections via culture methods, biochemical tests, and molecular approaches in an Iranian population. Microbial specimens were collected from 36 patients with primary endodontic infection and 14 patients with a history of root canal therapy. Advanced microbiological culture techniques were used to isolate microbiota; subsequently, biochemical tests and 16S ribosomal RNA gene sequencing were performed to identify the microorganisms. Within the total 218 cultivable isolates, Veillonella parvula (20.6%) was found to occur with the highest frequency in primary endodontic infection, followed by Porphyromonas gingivalis (14.1%), and Aggregatibacter actinomycetemcomitans (9.2%). Enterococcus faecalis (36.6%) was the most predominant microorganism in secondary endodontic infections, followed by Candida albicans, Propionibacterium acnes, and V. parvula with frequencies of 20%, 2%, and 2%, respectively. It was concluded that V. parvula and E. faecalis was most frequently found in primary and secondary endodontic infections, respectively.

Bactericidal effects and smear layer removal of Er∶YAG-laser radiation against Enterococcus faecalis in root canals / 中南大学学报(医学版)

Objective:To evaluate the cleaning ability of Er∶YAG laser against Enterococcus faecalis in root canals.Methods:The single-rooted human teeth were sterilized and inoculated with Enterococcusfaecalis and were randomly assigned into 2 groups.A group of teeth was irrigated with saline during root canal preparation while another group with NaClO.After mechanical preparation,the two groups were randomly divided into 3 subgroups according to the different treatments:Samples,laser radiation,and calcium hydroxide intracanal medication for 7 days.Bactericical effects were compared among groups.Root canal walls and dental tubules were observed under scanning electron microscope.Results:Er∶YAG laser was the most efficient way for anti-bacteria among the groups (P＜0.05),but there was no significant difference between the 2 laser groups (P＞0.05).Meanwhile the smear laser was efficiently removed by laser compared with other treatments,and the laser could open the dentinal tubules.Conclusion:Er∶YAG laser can be effectively used for root canal disinfection without NaClO and Ca(OH)2.

Establishment of an in-vitro root canal-apical complex model / 重庆医学

Objective To establish an in-vitro root canal-apical complex model for studying the mechanisms of the infected root canal to apical periodontitis and periapical biofilm .Methods Single rooted premolar extracted for orthodontic ,was sealed in sterile vial containing LB solid medium ,and the culture medium covered apical thirds .Totally 25 root canal-apical complex models were prepared .Five models were randomly selected for the bacteria detection in periapical by PCR at 1st day .The remained 20 models were randomly subjected to a control group(n=10) and experimental group(n=10) .Extracted teeth were opened in experimental group and control group with no treatment .All models were exposed in air .At 21st day ,bacteria were detected through PCR in root canal and apical;endotoxin content in apical was assayed by chromogenic end-point limulus test .Results In apical ,bacteria was not found in all groups ,but not for the experimental group .The mean endotoxin content was (8 .913 ± 0 .614)EU/mL in control group and (10 .525 ± 0 .981)EU/mL in experimental group .The endotoxin content was increased significantly in experimental group ,when compared with control group(P<0 .01) .Conclusion Root canal-apical complex was established in vitro through this method .Bac-teria was not easy to reach the apical when the infected root canal was not disturbed .Bacteria in the infected root canal caused apical periodontitis through the secretion of virulence factors such as endotoxin .

Clinical effect of combined nickel-titanium instruments and ultrasonic technique and warm vertical technique used in one-visit endodontic treatment for infected root canals / 中国基层医药

Objective To evaluate the effect of one-visit endodontic treatment for infected root canals with combination of nickel-titanium instruments and ultrasonic technique and warm vertical technique.Methods According to treatment,90 teeth were randomly divided into experimental and control groups.Two groups were used nickel titarlium root canal preparation.Experimental group:51 teeth for ultrasonic root canal irrigation,and warm vertical technique was employed to fill the root canal.Control group:39 teeth for rinse syringes,and warm vertical technique was employed to fill the root canal.Washing fluid was 2％ sodium hypochlorite.The root canal filling was observed after a week and one year of postoperative pain response.Results A week later,two groups of post-operative pain showed that there was significant difference in responses (x2 =15.525,P ＜ 0.05).One year later,the two groups showed no significant difference in efficacy(x2 =0.085,P ＞ 0.05).Conclusion The combination of nickel-titanium instruments and ultrasonic irrigation technique and warm vertical obturation,for the treatment of infected root canals was a method to complete the root canal filling,could reduce both the number of patients subsquent visits and the postoperative pain response,while it could improve the quality of root canal filling.

Apical prepration size in infected root canals / 대한치과보존학회지

The final preparation (MAF) size in infected root canals is still controversial. Nonetheless, recent studies demonstrated that larger apical preparation sizes produces a greater reduction in remaining bacteria and dentinal debris as compared to smaller apical preparation sizes. Therefore, clinicians should be practiced with treatment strategies guided by evidence-based information, especially in infected/failed root canals.

A preliminary study of improving the System B root canal filling technique / 实用口腔医学杂志

Objective:To combine the cold lateral condensation with System B root canal filling techniques in order to increase the amount of gutta-percha to fit different canal that could improve percentage of gutta-percha-filled area(PGFA)and decrease the probability of apical extrusion. Methods: Two groups of extracted human canines (total 80) were prepared by modified double-flared technique and filled with gutta-percha by System B technique and the combined technique respectively. The overfilling samples were collected. A horizontal section was cut 1.5 mm from the apical foramen of each tooth. The cross-sectional area of the canal and the gutta-percha was measured using an image-analysis program. The PGFA was then calculated. Results:Overfilling rate in the combined technique group was significantly lower than that of the control group (P

Disinfecting effects of a new polyantibiotic paste on infected root canal / 实用口腔医学杂志

0.05). Conclusion: MCM may be useful in root canal therapy to disinfect the infected root canal.