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Photodynamic therapy (PDT) is a treatment modality that was initiated in 1900; however, it was not until the last decade that PDT regained attention for its several favourable features during the treatment of microbial infections in endodontics. Recently, several papers advocated its use for root canal treatment. The concept of photodynamic inactivation requires microbial exposure to either exogenous or endogenous photosensitizer molecules, followed by visible light energy, typically wavelengths in the red/near‐infrared region that cause the excitation of the photosensitizers resulting in the production of singlet oxygen and other reactive oxygen species that react with intracellular components and consequently produce cell inactivation and death. Recently, PDT has been suggested as a promising effective adjunct to standard antimicrobial intracanal cleaning and shaping for the treatment of periapical lesions. Current publications tested PDT in terms of bacterial load reduction in vivo, in vitro and ex vivo, showing promising results. The purpose of this article was to review the existing literature on PDT in the endodontic field regarding its mechanism of action, photosensitizers and light sources, limitations and clinical procedures. Although positive results have been demonstrated in vitro, there are considerably fewer in vivo investigations. In conclusion, more in vivo studies are needed on the use of antimicrobial PDT in root canal treatment. [ABSTRACT FROM AUTHOR]

Aim: To investigate whether a minimally invasive basic root canal preparation technique has an influence on root canal cleanliness in extracted mandibular molar teeth. Methodology: A total of 80 root canals (40 mesio‐buccal and 40 mesio‐lingual) from 40 mandibular molars were included. The teeth were divided equally into four different experimental groups depending on the subsequently root canal preparation technique: Group 1: a basic preparation was performed up to size 20,.04 taper; Group 2: a basic preparation was performed up to size 2,.06 taper; Group 3: a basic preparation was performed up to size 25,.04 taper; and Group 4: a basic preparation was performed up to size 25,.06 taper. After the use of each instrument, each root canal was irrigated with 2.5 mL of 6% sodium hypochlorite for 30 s. Then, 1 mL NaOCl was activated for 20 s using an EDDY sonic tip. Final irrigation was performed using a total of 5 mL of 17% EDTA solution. The roots were then split longitudinally and all root canal thirds were observed through scanning electron microscopy (SEM) to evaluate the presence of superficial debris and smear layer using a scoring system. Data were statistically analysed using the Kruskal–Wallis and Bonferroni tests with a level of significance set at P < 0.05. Results: In all groups, there was significantly more residual debris and smear layer in the apical third (P < 0.05), with no differences between the middle and coronal thirds (P > 0.05). For both the parameters analysed, there was no difference amongst the groups in the middle and coronal thirds (P > 0.05), whilst in the apical third significantly less debris and smear layer was found in specimens from groups 3 and 4 than for groups 1 and 2 (P < 0.05). Conclusion: All basic root canal preparation techniques were associated with less debris and smear layer on the canal walls in the middle and coronal thirds, without differences among them. Even though debris and smear layer were always present in the apical third, an apical size of 25 resulted in significantly cleaner canals walls compared to a size 20. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To compare the cyclic fatigue resistance and bending properties of R‐Pilot and WaveOne Gold (WOG) Glider files, at intracanal temperature (35°C). Methodology: Forty R‐Pilot and 40 WOG Glider files were subjected to a cyclic fatigue resistance test (n = 20), calculating the time to fracture (TTF) in an artificial stainless steel canal. The length of the fractured file tips (FL) was also measured. The fracture surface of fragments was examined with a scanning electron microscope, and the cross‐sectional area of the fractured surfaces was measured. Flexibility of the tested files (n = 20) was determined using 45° bending test. Data were analysed statistically using the Mann–Whitney U‐test at 5% significance level. Results: Time to fracture was significantly higher in the R‐Pilot group compared to the WOG Glider (P < 0.05). There was no significant difference between groups for fracture length. The bending resistance of R‐Pilot files was significantly greater than WOG Glider files (P < 0.05). Conclusions: A significant greater cyclic fatigue resistance was observed for R‐Pilot files compared to WOG Glider instruments, although the bending resistance of WOG Glider files was lower. [ABSTRACT FROM AUTHOR]

Aim To evaluate the cyclic fatigue of Mtwo Ni-Ti rotary instruments after controlled clinical use in molar teeth. Methodology Twenty Mtwo instruments of each size were selected and divided into two groups: group A consisted of 10 new instruments (control group); group B consisted of 10 used instruments. Each instrument in group B was used to clean and shape 10 root canals of molar teeth in patients. Cyclic fatigue testing of instruments was performed in tapered artificial canals with a 5-mm radius of curvature and a 60° angle of curvature. In all 140, instruments were rotated until fracture and the number of cycles to failure was recorded. Data were analysed using one-way ANOVA, Tukey's HSD test and independent sample t-test to determine any statistical difference; the significance was determined at the 95% confidence level. Results A reduction of cycles to failure between new (group A) and used (group B) instruments was apparent. A statistically significant difference (P < 0.05) was noted between instruments of groups A and B in all sizes with the exception of size 40, 0.04 taper. Conclusions Clinical use significantly reduced cyclic fatigue resistance of Mtwo rotary instruments when compared with an unused control group. However, all the instruments had minimal instrument fatigue when discarded after controlled clinical use. [ABSTRACT FROM AUTHOR]