Effect of photodynamic therapy in combination with various irrigation protocols on an endodontic multispecies biofilmex vivo

Interdisciplinary-Inspired Smart Antibacterial Materials and Their Biomedical Applications

The discovery of antibiotics has saved millions of lives, but the emergence of antibiotic-resistant bacteria has become another problem in modern medicine. To avoid or reduce the overuse of antibiotics in antibacterial treatments, stimuli-responsive materials, pathogen-targeting nanoparticles, immunogenic nano-toxoids, and biomimetic materials are being developed to make sterilization better and smarter than conventional therapies. The common goal of smart antibacterial materials (SAMs) is to increase the antibiotic efficacy or function via an antibacterial mechanism different from that of antibiotics in order to increase the antibacterial and biological properties while reducing the risk of drug resistance. The research and development of SAMs are increasingly interdisciplinary because new designs require the knowledge of different fields and input/collaboration from scientists in different fields. A good understanding of energy conversion in materials, physiological characteristics in cells and bacteria, and bactericidal structures and components in nature are expected to promote the development of SAMs. In this review, the importance of multidisciplinary insights for SAMs is emphasized, and the latest advances in SAMs are categorized and discussed according to the pertinent disciplines including materials science, physiology, and biomimicry.

The effects of antimicrobial photodynamic therapy (aPDT) with nanotechnology-applied curcumin and 450nm blue led irradiation on multi-species biofilms in root canals

This study aimed to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) utilizing nanotechnology-applied curcumin activated by blue LED (450 nm) on the elimination of microorganisms arranged in multispecies biofilms inside the root canals of extracted human teeth. Forty single-rooted human teeth were used; these were randomized into four experimental groups, each comprising 10 teeth: control group, no treatment; photosensitizer (PS) group, nanotechnology-applied curcumin alone; light group, blue LED used separately; and aPDT group, nanotechnology-applied curcumin activated by blue LED. To carry out the tests, the interiors of the root canals were inoculated with species of Candida albicans (ATCC 90029), Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922), and methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 43300), using a multispecies biofilm. After the incubation period, the canals were treated according to the experimental groups, with no treatment given in the control group. Studied inasmuch as the antimicrobial effectiveness of aPDT was concerned, it was observed that the greatest reduction in microbial counts using aPDTs was achieved against MRSA (mean reduction = 2.48 Log10 CFU/mL), followed by Escherichia coli (mean reduction = 1.72), and Enterococcus faecalis (mean reduction = 1.65); a reduction greater than 1.5 Log10 CFU/mL showed relevant effectiveness of aPDT against these microorganisms. Of note, aPDT has also shown considerable effectiveness against Candida albicans (mean reduction = 0.71), with a statistical difference in the reduction between the groups. aPDT was effective in reducing all microorganisms examined. The average reduction was greater than 1.5 Log10 in all microorganisms except for Candida albicans. HIGHLIGHTS: • aPDT was a viable treatment for root canals; • Nanotechnological curcumin aPDT was effective in reducing multispecies biofilm microorganisms; • aPDT technique showed efficacy under the worst microbiological conditions , such as mature multispecies biofilm; • Nanotechnological curcumin aPDT was able to reduce Gram positive, negative bacterial and yeasts in root canals.

Efficacy of photodynamic therapy in the treatment of oral candidiasis: a systematic review and meta-analysis

OBJECTIVE

To evaluate the clinical efficacy of photodynamic therapy (PDT) as an adjunct or alternative to traditional antifungal drugs in the treatment of oral candidiasis, and to provide evidence-based medical evidence for its use in the treatment of oral candidiasis.

METHODS

Computer combined with manual retrieval of China Academic Journals Full-text Database (CNKI), China Biomedical Literature Database (CBM), Chinese Science and Technology Journal Database (VIP), Wanfang Database, PubMed, Web of Science, Cochrane Library, Embase, Scopus retrieval for articles published before January 2023, basic information and required data were extracted according to the inclusion and exclusion criteria, and the Revman V5.4 software was used to conduct Meta-analysis of the included literature.

RESULTS

A total of 11 articles were included, 7 of which used nystatin as an antifungal drug, 2 of which were combined treatment of PDT and nystatin, 2 of the remaining 4 articles were treated with fluconazole, and 2 were treated with miconazole. Meta results showed that PDT was superior to nystatin in reducing the number of oral candida colonies in the palate of patients MD = -0.87, 95%CI = (-1.52,-0.23), P = 0.008, the difference was statistically significant, and the denture site MD = -1.03, 95%CI = (-2.21, -0.15), P = 0.09, the difference was not statistically significant; compared with the efficacy of fluconazole, RR = 1.01, 95%CI = (0.56,1.83), P = 0.96; compared with miconazole RR = 0.55, 95%CI = (0.38, 0.81), P = 0.002; PDT combined with nystatin RR = 1.27, 95%CI = (1.06, 1.52), P = 0.01; recurrence rate RR = 0.28, 95%CI = (0.09, 0.88), P = 0.03.

CONCLUSIONS

PDT was effective in the treatment of oral candidiasis; PDT was more effective than nystatin for the treatment of denture stomatitis in the palate, while there was no significant difference between the two for the denture site; The efficacy of PDT for oral candidiasis was similar to that of fluconazole; PDT was less effective than miconazole for oral candidiasis; Compared with nystatin alone, the combination of PDT and nystatin is more effective in treating oral candidiasis with less risk of recurrence.

Antimicrobial photodynamic therapy against oral biofilm: influencing factors, mechanisms, and combined actions with other strategies

Oral biofilms are a prominent cause of a wide variety of oral infectious diseases which are still considered as growing public health problems worldwide. Oral biofilms harbor specific virulence factors that would aggravate the infectious process and present resistance to some traditional therapies. Antimicrobial photodynamic therapy (aPDT) has been proposed as a potential approach to eliminate oral biofilms via in situ-generated reactive oxygen species. Although numerous types of research have investigated the effectiveness of aPDT, few review articles have listed the antimicrobial mechanisms of aPDT on oral biofilms and new methods to improve the efficiency of aPDT. The review aims to summarize the virulence factors of oral biofilms, the progress of aPDT in various oral biofilm elimination, the mechanism mediated by aPDT, and combinatorial approaches of aPDT with other traditional agents.

Effectiveness of Different Final Irrigation Procedures on Enterococcus faecalis Infected Root Canals: An In Vitro Evaluation

This study aimed to evaluate the antibacterial effect of three final irrigation protocols and to compare their ability to remove the smear layer and debris from the root canal. Methods: Sixty-three single-rooted human teeth were inoculated with Enterococcus faecalis for 14 days. The teeth were divided into a positive control group (N = 3) and three treatment groups (N = 20) as follows: final irrigation with saline solution (control group), irrigation with 5.25% NaOCl ultrasonically activated with EndoUltra (EU), standard needle irrigation with Qmix 2in1 (Qx) and irrigation with 5.25% NaOCl activated using SiroLaser Blue (SB). The bacterial load was evaluated by analyzing the colony-forming units (CFU/mL). Selected specimens were split longitudinally and examined using scanning electron microscopy in order to determine the presence of a smear layer and debris. Statistical analyses were performed using one-way ANOVA and the Kruskal−Wallis rank-sum test. Results: Activation of NaOCl with EndoUltra or SiroLaser Blue was superior at reducing intracanal bacteria relative to standard needle irrigation with Qmix 2in1 solution (p < 0.05). Even though SiroLaser Blue showed the best results for removing the smear layer and debris, no significant differences were detected between the groups (p > 0.05). Conclusions: Final irrigation with 5.25% NaOCl ultrasonically activated using EndoUltra or SiroLaser Blue demonstrated a higher efficacy in bacterial reduction than standard needle irrigation with Qmix 2in1.

Investigating the Antibacterial Effect of Passive Ultrasonic Irrigation, Photodynamic Therapy and Their Combination on Root Canal Disinfection

Introduction: Enterococcus faecalis is a gram-positive, facultative anaerobic bacterium associated with persistent endodontic infections. Conventional disinfection methods may not completely eradicate the bacteria within the root canal system. Therefore, novel modalities have been suggested to optimize root canal disinfection. The aim of this study was to evaluate and compare the antibacterial effect of photodynamic therapy (PDT), passive ultrasonic irrigation (PUI) and their combination in addition to conventional endodontic irrigation against E. faecalis biofilms in root canals. Methods: Root canals of 50 single-rooted extracted human teeth were prepared and incubated with E. faecalis for 21 days. They were then divided into 4 treatment groups and a control group as follows: (1) NaOCl-Syringe irrigation with 2.5% NaOCl, (2) PUI-Passive ultrasonic irrigation with NaOCl, (3) NaOCl+PDT-Photodynamic therapy following syringe irrigation with NaOCl, (4) PUI+PDT, (5) Control-Syringe irrigation with saline. Colony-forming units were counted and bacterial reduction was calculated for each treatment group. Results: All treatments led to significant reductions in the bacterial load compared to the control group. PUI and PUI+PDT led to the complete elimination of the bacteria from the root canals. NaOCl and NaOCl+PDT treatments reduced the bacteria by 99.9% and 99.5% respectively. NaOCl+PDT was significantly less effective in reducing the bacteria compared to other treatment groups. There were no significant differences between the NaOCl, PUI, and PUI+PDT groups. Conclusion: Passive ultrasonic irrigation with or without the combination of Photodynamic therapy completely eradicated the bacteria. The use of PDT as an adjunction to NaOCl syringe irrigation and PUI did not enhance their antibacterial effect.

Antibacterial Effect of Red Laser Therapy on Enterococcus faecalis Using Different Photosensitizers: An In Vitro Study

Objective

To assess the antibacterial effect of red laser using different photosensitizers such as methylene blue and malachite green on monoradicular premolars contaminated with E. faecalis ATCC 29212.

Methods

This was an in vitro experimental study. Monoradicular premolars (44, 45, 34, and 35) were used, which were treated with ProTaper Next. After instrument change, irrigation, disinfection, and aspiration were performed with 2 ml of 4% NaOCl with a NaviTip 30°G needle (Ultradent, South Jordan, UT, USA). Group 1: RL + MB (red laser associated with methylene blue photosensitizer), group 2: RL + MG (red laser associated with malachite green photosensitizer), and group 3: control (no treatment). The E. faecalis strain was cultured on trypticase soy agar (TSB) (Difco, Detroit, MI, USA) and incubated at 37°C for 24 h. After the incubation period, colony-forming units (CFU/ml) of each group were counted using the plate count method. The ANOVA test was used with a significance level of p < 0.05.

Results

Group 1 had the lowest antibacterial contamination as it averaged only 530 ± 581.3 CFU/ml, while group 2 had the highest contamination with an average of 1990 ± 542.5 CFU/ml. Comparison revealed that there were statistically significant differences between the RL + MB and RL + MG groups (p < 0.001).

Conclusions

Group 1 had the best antimicrobial potential because it presented the lowest contamination in CFU/ml of E. faecalis compared to group 2 and group 3.

Influence of photodynamic therapy and intracanal medication on Martens hardness, elastic modulus and bond strength of glass-fiber posts to endodontically treated root dentin

BACKGROUND

The purpose of this in vitro study was to evaluate the influence of photodynamic therapy (PDT) with methylene blue photosensitizer (PS) and calcium hydroxide intracanal medication on Martens hardness (MH), elastic modulus (Eit) and adhesive bond strength of glass-fiber posts in different thirds of intraradicular dentin.

METHODS

Ninety-six bovine teeth were distributed into the following 6 experimental groups: a negative control irrigated with deionized water; a positive control irrigated with deionized water and filled with calcium hydroxide intracanal medication (Ca[OH]₂); Ca[OH]₂ + methylene blue 50 mg/L without activation; Ca[OH]₂ + methylene blue 100 mg/L without activation; Ca[OH]₂ + methylene blue 50 mg/L activated by red laser; and Ca[OH]₂ + methylene blue 100 mg/L activated by red laser (n = 16). MH and Eit were measured using an ultramicrodurometer under load action of 3 mN (n = 8). Adhesive bond strength was measured using the push-out test in a universal testing machine (n = 8), and representative samples underwent scanning electron microscopy. Data on MH, Eit, and bond strength were subjected to normality tests and analyzed by ANOVA and Tukey's test (α = 0.05).

RESULTS

Methylene blue PS, activated or not by red laser, associated with calcium hydroxide medication did not promote significant difference as compared to the control groups irrigated with deionized water, associated or not with the use of intracanal medication, regarding mechanical properties and bond strength (p > 0.05). Experimental groups showed no difference between the thirds regarding root canal depth (p > 0.05), except for the positive control group, in which the apical third showed higher Eit values than the middle third (p = 0.0324). There was a predominance of mixed failure in all experimental groups, excepted the red laser-activated group treated with the highest concentration of methylene blue, which showed predominance of adhesive failure.

CONCLUSIONS

PDT with methylene blue PS at 50 mg/L, associated with intracanal calcium hydroxide medication is a satisfactory alternative for endodontic treatment as there is no interference in the mechanical properties and bond strength among glass-fiber posts to intraradicular dentin at any depth of the root canal.

Antimicrobial action of photodynamic therapy on Enterococcus faecalis biofilm using curing light, curcumin and riboflavin

The aim of this study was to assess the effect of antimicrobial photodynamic therapy (aPDT) with curcumin and riboflavin on three-week Enterococcus faecalis biofilm. At first the 15-mm root canals of 65 single rooted extracted human teeth (including maxillary incisors, mandibular and maxillary canines and mandibular premolars) were separated from the crown and were prepared with ProTaper instruments. After autoclave sterilisation, samples were inoculated with E. faecalis suspension, and incubated for three weeks. After ensuring biofilm formation by scanning electron microscopy (SEM) in two teeth, the remaining 63 teeth were randomly divided into seven groups (n = 9): aPDT + curcumin, aPDT + riboflavin, LED, curcumin, riboflavin, 5.25% NaOCl (positive control) and no intervention (negative control). For light source a LED unit with 390-480 nm wavelength (peak of 460 nm), power density of 1000 ± 100 mW cm^-2 and mean energy density of 60 J cm^-2 was used. The roots were horizontally sectioned into coronal, middle and apical thirds each with 5 mm thicknesses. Dentin chips with equal weight (1 ± 0.005 g) were collected from the root canal walls with Gates Glidden drills and were transferred into microtubes containing 1 mL of sterile saline and vortexed for 30 s. Next, 10 µL of the contents of each tube was serially diluted and eventually, 10 µL of each solution was cultured on BHI agar. The number of colony-forming units was determined. Data were analysed using the Kruskal-Wallis and Friedman tests. The colony reduction was not significantly different between NaOCl and either riboflavin + LED or Curcumin + LED. The 5.25% NaOCl group showed maximum reduction in colony count, compared with the negative control (P = 0.00). Groups with aPDT with Curcumin + LED (P = 0.005), and with riboflavin + LED (P = 0.011) showed significant reduction in colony count in all three canal thirds (P < 0.05) without any difference with one another. With significant reduction of E. faecalis colony count, aPDT with Curcumin and riboflavin can serve as an adjunct to routine root canal disinfection method.

Photodynamic Therapy in Endodontics: A Helpful Tool to Combat Antibiotic Resistance? A Literature Review

BACKGROUND

Antibiotic resistance has become a growing global problem where overprescription is a contributing factor for its development. In the endodontics field, complementary treatments, such as antimicrobial photodynamic therapy (aPDT), have been described to eliminate residual bacteria from the root canal space and reduce complications. The aim of this review is to describe the literature evidence up to now regarding the advantages, efficiency, and clinical outcomes of this therapy in endodontics as a possible tool to combat antibiotic resistance.

METHODS

A review of the literature from 2010 to 2021 was carried out using the PubMed and Web of Science databases. Two steps were taken: First, articles were compiled through the terms and MeSH terms "Photochesdmotherapy" and "endodontics." Then, a second search was conducted using "photodynamic therapy" and "antibiotic resistance" or "drug resistance, microbial."

RESULTS

A total of 51 articles were included for evaluation: 27 laboratory studies, 14 reviews, and 10 clinical studies. Laboratory studies show that aPDT achieves significant bacterial elimination, even against antibiotic-resistant species, and is also effective in biofilm disruption. Clinical studies suggest that aPDT can be considered a promising technique to reduce bacterial complications, and reviews about the issue confirm its advantages.

CONCLUSION

The benefits of aPDT in reducing complications due to its antibacterial effects means a possible decrease in systemic antibiotic prescription in endodontics. In addition, it could be an alternative to local intracanal antibiotic therapy, avoiding the appearance of possible antibiotic resistance, as no bacterial resistance with aPDT has been described to date.

Reduction of dual-species biofilm after sonic- or ultrasonic-activated irrigation protocols: A laboratory study

AIM

To evaluate the antibacterial effect of sonic- and ultrasonic-activated irrigation on bacterial reduction of a dual-species biofilm in root canals compared to nonactivated irrigation in a laboratory study.

METHODOLOGY

Two hundred and forty extracted human single-rooted maxillary anterior teeth were divided into two main groups (G, n = 120) according to the initial preparation size of the root canal (G1: size 25, 0.06 taper, G2: size 40, 0.06 taper). Root canals were inoculated with Enterococcus faecalis and Streptococcus oralis. After 5 days, G1 received combined instrumentation (up to size 40, 0.06 taper) and irrigation/activation, whereas G2 received solely irrigation/activation protocols. In both groups, irrigation was performed with sodium hypochlorite (NaOCl 1%) or physiological saline (NaCl 0.9%), using nonactivated syringe irrigation, sonic activation (2 x 30 s) or ultrasonic activation (2 x 30 s). Logarithmic reduction factors (LRFs) of colony-forming units were analysed separately for dentine-adherent and planktonic bacteria immediately after irrigation/activation protocols (time-point 1) or after 5 days of further incubation (time-point 2) by analysis of variance (anova) and post hoc tests (Tukey's HSD, t-test). The significance level was set at 0.05.

RESULTS

In G1 subgroups (combined instrumentation with irrigation/activation), LRFs were significantly affected by the applied irrigation solution (p < .0001), but not by the activation method (p > .05; anova). In G2 subgroups (solely irrigation/activation), both, irrigant solution and activation, significantly affected LRFs (p < .0001, anova). Sonic activation resulted in significantly higher LRFs than ultrasonic activation (p < .0001) which had significantly greater reductions than nonactivated irrigation (p < .05; Tukey's HSD). At T2, strong bacterial regrowth was observed in all groups; however, a significant bacterial reduction was detected for factors instrumentation, irrigant solution and activation (p < .0001; anova). Similar LRFs were found for dentine-adherent and planktonic bacterial cells in all groups (r = 0.91 at T1, r = 0.8 at T2).

CONCLUSIONS

In this laboratory study on extracted maxillary anterior teeth high-frequency sonic activation resulted in a greater bacterial reduction compared to ultrasonic activation in groups receiving solely irrigation/activation protocols; however, irrigation using NaOCl and ultrasonic activation also contributed significantly to bacterial reduction compared to the control groups.

Effect of photobiomodulation on post-operative symptoms in teeth with asymptomatic apical periodontitis treated with foraminal enlargement: A randomized clinical trial

AIM

To assess the efficacy of photobiomodulation in reducing post-operative symptoms and use of analgesics in teeth with asymptomatic apical periodontitis treated with foraminal enlargement in a single visit.

METHODOLOGY

This prospective double-blind, controlled, superiority, randomized clinical trial enrolled 70 patients requiring root canal treatment of one single-rooted tooth with asymptomatic apical periodontitis. The participants were randomized into one of the following two groups: 35 patients in the control group (C.G) - root canal treatment with foraminal enlargement, without any additional treatment and 35 patients in the photobiomodulation group (PBM.G) - root canal treatment with foraminal enlargement associated with photobiomodulation (antimicrobial photodynamic therapy and low-level laser therapy). The outcome variables were post-operative pain, tenderness, oedema and the use of analgesics. Pain intensity was measured using a visual analogue scale (recorded every day for 7 days, then the 14th and 30th days after root canal treatment). Facial oedema was assessed subjectively by two independent evaluators using photographs taken by one of the researchers at 48 h, 72 h and 7 days after the procedures. Data were tabulated and analysed using the Mann-Whitney U, Chi-Square, Fisher`s Exact, Student T and Ordinal Logistic Regression by Generalized Estimating Equations tests in SPSS software.

RESULTS

There were no significant differences in post-operative pain and tenderness between the groups at any observation period (p > .05). Photobiomodulation (beta = -0.77 / p = .01), time (beta = -0.23 / p < .01), and male gender (beta = -1.20 / p < .01) were associated with decreased post-operative pain. Only time (beta: -0.10; p < .01) and male gender (beta: -1.04; p < .01) were associated with decreased tenderness. For oedema and use of analgesics, there was no difference between the groups (p > .05).

CONCLUSIONS

Photobiomodulation had no significant effect on post-operative pain, tenderness, oedema and the use of analgesics after root canal treatment with foraminal enlargement, in single-rooted teeth treated in a single visit. Register of Clinical Trials: NCT03704857. Research Ethics Committee: no 2.353.996 / CAAE 74185417.9.0000.5626.

Root Caries Preventive Effect of Varnishes Containing Fluoride or Fluoride + Chlorhexidine/Cetylpyridinium Chloride In Vitro

Caries preventive varnishes containing only fluoride might differ from those containing a combination of fluoride and antimicrobial components in terms of mineralization properties and their impact on the cariogenic biofilm. We compared a fluoride and a fluoride + chlorhexidine (CHX)/cetylpyridinium chloride (CPC) varnish on root caries formation in vitro. One hundred bovine root dentin samples were allocated to five groups (n = 20/group): (1) 7700 ppm fluoride varnish (Fluorprotector S (F)), (2) experimental placebo varnish for F (F-P), (3) 1400 ppm fluoride + 0.3% CHX/0.5% CPC varnish (Cervitec F (CF)), (4) experimental placebo varnish for CF (CF-P), (5) untreated control. Cariogenic challenge was provided using a multi-station, continuous-culture 3-species (Streptococcus mutans (SM), Lactobacillus rhamnosus (LR), Actinomyces naeslundii (AN)) biofilm model for 10 days. Mineral loss (ΔZ) was evaluated using transversal microradiography and bacterial counts in the biofilm assessed as colony-forming units. Fluorescence in situ hybridization (FISH) and confocal microscopy were performed to assess the three-dimensional biofilm architecture. Mean ± SD (vol% × μm) ΔZ was significantly lower for F (9133 ± 758) and CF (9835 ± 1677) compared to control (11362 ± 919) (p < 0.05), without significant differences between F and CF. SM counts were significantly lower and LR counts significantly higher in F- and CF-biofilms compared to control. AN counts were significantly higher in the F-biofilms than in all other groups. According to FISH, SM and LR invaded dentinal tubules only in the control-group. In the CF-group, the basal biofilm layer did not contain SM and AN. Both F and CF varnishes had similar caries-preventive effects and a considerable impact on biofilm structure and composition.

Antibacterial activity, cytocompatibility and effect of Bio-C Temp bioceramic intracanal medicament on osteoblast biology

AIM

To analyse the antimicrobial and biological properties of a new bioceramic intracanal medicament (Bio-C Temp), and to compare it with two calcium hydroxide-based intracanal medicaments (Calen^® and UltraCal^® XS).

METHODOLOGY

The direct contact and the crystal violet tests were performed to assess the antimicrobial activity of intracanal medicaments against Enterococcus faecalis. The cytocompatibility and the effect of the medication on the biology of the human osteoblast-like cell line (Saos-2) were evaluated with methylthiazole tetrazolium (MTT), neutral red, alkaline phosphatase activity and mineralization (alizarin red) assays. The data were analysed using one-way anova and Tukey's tests, two-way anova and Bonferroni's tests, or Kruskal-Wallis and Dunn's tests (α = 0.05).

RESULTS

Bio-C Temp had significantly less antibacterial activity and biofilm biomass reduction than the other intracanal medicaments (P < 0.05). There was no difference in the viability of Saos-2 exposed to the various intracanal medicaments, except regarding the 1 : 2 dilution, when the Bio-C Temp group had significantly lower cell viability than the UltraCal^® XS and Calen^® groups (P < 0.05). Bio-C Temp induced significantly greater ALP activity than the other intracanal medicaments (P < 0.05) at day 1. Calen^® induced significantly greater deposition of mineralized nodules than the other intracanal medicaments (P < 0.05), and no difference was observed between Bio-C Temp and UltraCal^® XS (P > 0.05).

CONCLUSIONS

Bio-C Temp had similar cytocompatibility at higher dilutions, and higher or similar induction of ALP activity and deposition of mineralized nodules in comparison with Calen® and UltraCal® XS. However, it had significantly less antibacterial and antibiofilm activity than Calen® and UltraCal® XS.

Comparison of Antibacterial Effects of Photodynamic Therapy and an Irrigation Activation System on Root Canals Infected With Enterococcus faecalis: An In Vitro Study

Introduction: Enterococcus faecalis is a resistant bacterium which is the most abundant species in infected root canals. Photodynamic therapy (PDT) is a method for killing the bacteria with active Oxygen radicals generated in a photosensitizer when exposed to centralized light. Furthermore, as a new method of canal disinfection, a variety of irrigation activation systems have been introduced, one of which is GentleFile (GF) with rotary movements and spiral effects for antibacterial action. This study aimed to compare the effectiveness of the two mentioned methods when used with and without Sodium Hypochlorite in eliminating E. faecalis from infected root canals. Methods: Fifty-eight uniradicular teeth were randomly divided into 4 experimental groups of 14. Two specimens were selected for later scanning electron microscopy in order to screen the procedure steps. In each experimental group, 10 samples were selected to be treated with GF or PDT; 3 of them were selected as positive controls and the other one sample was chosen as a negative control. Experimental groups were as follows: (1) Irrigation activation system, (2) Irrigation activation system + sodium hypochlorite, (3) PDT, and (4) PDT+ sodium hypochlorite. The specimens were then cultured for a bacterial colony count. Results: The decrease in the bacterial count after the treatment with the irrigation activation system was 99.8% (P =0.011) and when the system was used with sodium hypochlorite, it was 100% (P =0.001). The antibacterial effect of PDT was 90.08% (P =0.011) and it was 99.7% when PDT was combined with sodium hypochlorite (P =0.011). Conclusion: All four methods can be administered as complementary methods in root canal disinfection. According to the results of disinfection in the experimental groups of current study it is concluded that integration of new technologies such as activation irrigation system or PDT in Combination with NaOCl ameliorates disinfection of root canal and can provide several advantages in the endodontic outcome.

Pretreatment of Root Canal with Photodynamic Therapy Facilitates Adhesion, Viability and Differentiation of Stem Cells of the Apical Papilla

This study was to test the hypothesis that root canal pretreated with photodynamic therapy (PDT) would promote stem cells from the apical papilla (SCAP) adhesion, proliferation and differentiation without affecting smear layer removal and microhardness of root canal. Standardized root canals were randomized into four groups (n = 30/group): (1) sodium hypochlorite(NaOCl) group, (2) NaOCl + ethylene diaminetetraacetic acid (EDTA) group, (3) NaOCl + PDT group, (4) NaOCl + EDTA + PDT group. After treatments, smear layer removal and microhardness of root canal were evaluated. SCAP with hydroxyapatite-based scaffolds were seeded into root canals for 7 days. SCAP adhesion was observed by scanning electron microscope (SEM), and viable cells were calculated by CellTiter-Glo Luminescent kit. Platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) expression of SCAP were evaluated by Quantitative Reverse Transcriptase-Polymerase Chain Reaction. There was no significant difference in the smear layer removal and microhardness of root dentin between the groups with and without PDT treatment (P > 0.05). SCAP with elongated cytoplasmic processes and cell-cell contact were observed on the dentin surfaces treated with PDT. Elevated cell viability, PDGF and VEGF expression were found in root canal treated with PDT (P < 0.05). Under the experimental conditions, PDT could provide positive microenvironment for SCAP growth.

An Insight into Advanced Approaches for Photosensitizer Optimization in Endodontics-A Critical Review

Apical periodontitis is a biofilm-mediated disease; therefore, an antimicrobial approach is essential to cure or prevent its development. In the quest for efficient strategies to achieve this objective, antimicrobial photodynamic therapy (aPDT) has emerged as an alternative to classical endodontic irrigation solutions and antibiotics. The aim of the present critical review is to summarize the available evidence on photosensitizers (PSs) which has been confirmed in numerous studies from diverse areas combined with several antimicrobial strategies, as well as emerging options in order to optimize their properties and effects that might be translational and useful in the near future in basic endodontic research. Published data notably support the need for continuing the search for an ideal endodontic photosensitizer, that is, one which acts as an excellent antimicrobial agent without causing toxicity to the human host cells or presenting the risk of tooth discoloration. The current literature on experimental studies mainly relies on assessment of mixed disinfection protocols, combining approaches which are already available with aPDT as an adjunct therapy. In this review, several approaches concerning aPDT efficiency are appraised, such as the use of bacteriophages, biopolymers, drug and light delivery systems, efflux pump inhibitors, negative pressure systems, and peptides. The authors also analyzed their combination with other approaches for aPDT improvement, such as sonodynamic therapy. All of the aforementioned techniques have already been tested, and we highlight the biological challenges of each formulation, predicting that the collected information may encourage the development of other effective photoactive materials, in addition to being useful in endodontic basic research. Moreover, special attention is dedicated to studies on detailed conditions, aPDT features with a focus on PS enhancer strategies, and the respective final antimicrobial outcomes. From all the mentioned approaches, the two which are most widely discussed and which show the most promising outcomes for endodontic purposes are drug delivery systems (with strong development in nanoparticles) and PS solubilizers.

Microbiota of periodontal pockets and root canals in induced experimental periodontal disease in dogs

AIM

To investigate the relationship between the microbiota of periodontal pockets (PP) and root canals (RC) in dogs submitted to experimental periodontal disease (ExPD).

METHODS

ExPD was induced by combining cotton and wire ligatures. After 125 days, microbiological samples were collected from PP and RC. Strains isolated from 19 teeth were submitted to DNA extraction, 16S rRNA gene amplification and gene sequencing. Pearson's χ² - and Fisher's exact tests and McNemar's test were used when appropriate.

RESULTS

The number of species in PP was greater than in RC, with prevalence of obligate anaerobes and Gram-negative bacteria. In the PP predominated Fusobacterium necrophorum, Porphyromonas gingivalis, Prevotella loescheii, Campylobacter gracilis and Veillonella parvula. In the RC samples, 9 had microbial growth, with predominance of the following genera: Staphylococcus, Streptococcus and Neisseria. Eight genera were common to both sites in the same tooth. PP presented a greater number of species than the RC. No significant difference was observed in the species found in PP and RC in the same tooth.

CONCLUSION

Microbial composition of the RC could be modulated by the presence of periodontal disease, especially in cases of severe periodontal destruction. RC microbiota was less complex and diverse than the PP.

Non-Invasive Photodynamic Therapy against -Periodontitis-causing Bacteria

Periodontitis is initiated by causative bacteria in the gingival sulcus. However, as the lesion is often deep and out of circulation system and biofilm is frequently formed on the bacteria cluster, use of antibacterial agents has been limited and the invasive method such as curettage is thought as an only treatment. Here we designed non-invasive photodynamic therapy (PDT), with the ointment which leads a photosensitizer deliverable into gingival sulcus. We assessed whether 650 nm light-emitting-diode (LED) penetrates the 3-mm soft tissue and effectively activates a photosensitizer toluidine-blue-O (TBO) through the thickness to remove Porphyromonas gingivalis and Fusobacterium nucleatum species. The oral ointment formulation was optimized to efficiently deliver the photosensitizer into gingival sulcus and its efficacy of PDT was evaluated in in vitro and in vivo models. Four weeks of TBO-formulation mediated-PDT treatment significantly attenuated periodontitis-induced alveolar bone loss and inflammatory cytokines production in rats. These results confirm that a 650 nm LED indeed penetrates the gingiva and activates our TBO formulation which is sufficiently delivered to, and retained within, the gingival sulcus; thus, it effectively kills the bacteria that reside around the gingival sulcus. Collectively, TBO-mediated PDT using LED irradiation has potential as a safe adjunctive procedure for periodontitis treatment.

Photodynamic therapy in endodontics

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.

Comparison of final disinfection protocols using antimicrobial photodynamic therapy and different irrigants after single-file reciprocating instrumentation against intracanal bacterial biofilm - An in vitro study

BACKGROUND

The aim of the study was to compare the efficacy of antimicrobial photodynamic therapy (aPDT) with irrigation protocols that include sodium hypochlorite (NaOCl), ethylenediaminotetraacetic acid (EDTA) or QMiX (combined irrigant: EDTA, chlorhexidine, detergent) solution after single-file reciprocating root canal instrumentation.

METHODS

The study sample included 68 extracted mandibular human single canal teeth. The canals were inoculated with bacterial suspension made of wild strain of Enterococcus faecalis. After 17 days of incubation, the samples were assigned to experimental groups according to the final disinfection protocol and a control group. The root canals in all groups were, firstly, instrumented with Wave One Gold reciprocating system. Then the canals were disinfected as follows: Group 1. 2.5% NaOCl and EDTA followed by the application of the aPDT; Group 2. 2.5% NaOCl, EDTA and 2.5% NaOCl; Group 3. 2.5% NaOCl and QMIX solution; Group 4. 2.5% NaOCl and EDTA. In the control group, the canals were irrigated with saline solution. Microbiological samples were collected at baseline, after single-file instrumentation and after the final disinfection protocols. The samples were plated onto Mitis Salivarius agar plates for incubation. The colony forming units (CFUs) were counted, and the final number was determined based on the dilution factor.

RESULTS

Reciprocating single-file instrumentation reduced CFUs significantly in all groups (p<0.05). No significant difference between Group 1 and Group 2 was observed (p=0.178). Irrigation with the QMiX was more efficient than the aPDT (p=0.02).

CONCLUSIONS

The aPDT used after irrigation with NaOCl and EDTA demonstrated similar antimicrobial efficacy as conventional irrigation with NaOCl.

Effect of DNase Treatment on Adhesion and Early Biofilm Formation of Enterococcus Faecalis

Objective

Extracellular DNA (eDNA) has been shown to be important for biofilm stability of the endodontic pathogen Enterococcus faecalis. In this study, we hypothesized that treatment with DNase prevents adhesion and disperses young E. faecalis biofilms in 96-well plates and root canals of extracted teeth.

Methods

E. faecalis eDNA in 96-well plates was visualized with TOTO-1®. The effect of DNase treatment was assessed in 96-well plates and in extracted single-rooted premolars (n=37) using a two-phase crossover design. E. faecalis was treated with DNase (50 Kunitz/mL) or heat-inactivated DNase for 1 h during adhesion or after 24 h of biofilm formation. In 96-well plates, adhering cells were quantified using confocal microscopy and digital image analysis. In root canals, the number of adhering cells was determined in dentine samples based on colony forming unit counts. Data from the 96-well plate were analyzed using one-tailed t-tests, and data from extracted teeth were analyzed using mixed-effect Poisson regressions.

Results

eDNA was present in wells colonized by E. faecalis after 1 h of adhesion and 24 h of biofilm formation; it was removed by DNase treatment, as evidenced by TOTO®-1 staining. DNase treatment reduced the area covered by cells in 96-well plates after 1 h (P<0.05), but not after 24 h (P=0.96). No significant differences in the number of adhering cells were observed in extracted teeth after 1 (P=0.14) and 24 h (P=0.98).

Conclusion

DNase treatment does not disperse endodontic E. faecalis biofilms. The sole use of DNase as an anti-biofilm agent in root canal treatments is not recommendable.

Light Activated Disinfection in Root Canal Treatment-A Focused Review

Light activated disinfection (LAD) is a strategy for optimizing root canal disinfection by using a highly-selective, targeted killing of bacteria using a combination of photosensitizers and light. Over the past decade, numerous in vitro and clinical studies have been performed to demonstrate the effectiveness of this mode of root canal disinfection. While most studies offer an important understanding of the effectiveness of LAD on monospecies biofilms, few have offered credence to the fact that infections of the root canal system are mediated by polymicrobial biofilms. Hence, it is imperative to understand the effect of LAD on polymicrobial biofilms both in terms of microbial killing and the changes in the biofilm architecture. The aim of this review was to systematically review the literature to evaluate the effect of LAD on dual and multispecies biofilms and demonstrate the antibiofilm effect of LAD. Two databases (PubMed and Scopus) were searched to identify eligible studies using a combination of key words. These studies were reviewed to draw conclusions on the effect of LAD on dual and multi species biofilm and the antibiofilm effect of LAD. It was found that LAD alone may be unable to eradicate dual and multispecies biofilms, but it may enhance the effect of conventional canal debridement strategies. Novel formulations of photosensitizers with nanoparticles showed the potential to inhibit biofilm formation and/or disrupt the biofilm architecture.