Randomized in vivo evaluation of photodynamic antimicrobial chemotherapy on deciduous carious dentin

Reduction of microorganisms in carious dentin by photodynamic therapy mediated by potassium iodide added to methylene blue and red laser

OBJECTIVE

To evaluate the effect of the association of potassium iodide to antimicrobial photodynamic therapy on human carious dentin produced with a microcosm biofilm model.

METHODS

A microcosm biofilm model was used to generate a caries lesion on human dentin. Pooled human saliva diluted with glycerol was used as an inoculum on specimens immersed on McBain artificial saliva enriched with 1 % sucrose (24 h at 37 °C in 5 % CO2). After refreshing culture media for 7 days, the dentin specimens were divided in 5 groups (3 specimens per group, in triplicate; n = 9): C (NaCl 0.9 %), CX (2 % chlorhexidine), PKI (0.01 % methylene blue photosensitizer+50 mM KI), L (laser at 15 J, 180 s, 22.7 J/cm2), and PKIL (methylene blue + KI + Laser). After the treatments, dentin was collected, and a 10-fold serial dilution was performed. The number of total microorganisms, total lactobacilli, total streptococci, and Streptococcus mutans was analyzed by microbial counts (CFU/mL). After normality and homoscedasticity analysis, the Welch's ANOVA and Dunnett's tests were used for CFU. All tests used a 5 % significance level.

RESULTS

CX and PKIL groups showed significant bacterial decontamination of dentin, compared to group C (p < 0.05) reaching reductions up to 3.8 log10 for CX for all microorganisms' groups and PKIL showed 0.93, 1.30, 1.45, and 1.22 log10 for total microorganisms, total lactobacilli, total streptococci, and S. mutans, respectively.

CONCLUSION

aPDT mediated by the association of KI and methylene blue with red laser reduced the viability of microorganisms from carious dentin and could be a promising option for cavity decontamination.

The effect of photodynamic therapy in controlling the oral biofilm: A comprehensive overview

Several resistance mechanisms are involved in dental caries, including oral biofilms. An accumulation of bacteria on the surface of teeth is called plaque. Periodontitis and gingivitis are caused by dental plaque. In this review article, we aimed to review the studies associated with the application of photodynamic therapy (PDT) to prevent and treat various microbial biofilm-caused oral diseases in recent decades. There are several studies published in PubMed that have described antimicrobial photodynamic therapy (APDT) effects on microorganisms. Several in vitro and in vivo studies have demonstrated the potential of APDT for treating endodontic, periodontal, and mucosal infections caused by bacteria as biofilms. Reactive oxygen species (ROS) are activated in the presence of oxygen by integrating a nontoxic photosensitizer (PS) with appropriate wavelength visible light. By causing irreversible damage to microorganisms, ROS induces some biological and photochemical events. Testing several wavelengths has been conducted to identify potential PS for APDT. A standard protocol is not yet available, and the current review summarizes findings from dental studies on APDT.

The efficacy of antimicrobial photodynamic therapy in the disinfection of coronal and radicular dentine of primary teeth: A systematic review and meta-analysis

BACKGROUND

Optimal endodontic disinfection by means of conventional root canal treatment of primary teeth remains a challenge. Recently, antimicrobial photodynamic therapy (aPDT) has been proposed as an adjunct to conventional endodontic treatment for microbial disinfection. The purpose of this review is to critically appraise and synthesize the currently-available evidence about the antimicrobial efficacy of aPDT (antimicrobial photodynamic therapy) when used as an adjunct to traditional root canal therapy.

MATERIALS AND METHODS

The focused question was ''In primary teeth needing root canal treatment (participants), is adjunct aPDT (intervention) more effective in disinfecting coronal and radicular dentine (outcomes) than root canal treatment alone (control)?'. The electronic research databases PubMED/Medline, ISI Web of Knowledge, Embase and CENTRAL (Cochrane Central Register of Controlled Trials) using relevant keyword phrases including 'antimicrobial photodynamic therapy', 'primary teeth', 'deciduous teeth', and 'endodontic treatment'. Original studies that described endodontic treatment of primary teeth or dentine using aPDT in comparison to conventional endodontic treatment were included. Case reports, reviews and other non-comparative studies were excluded. The literature search and quality assessment were carried out by two reviewers independently.

RESULTS

Ultimately, 9 studies were included in this review. Overall, majority of the studies concluded that adjunct aPDT improves the antimicrobial efficacy of conventional root canal therapy. However, several sources of bias were found in the studies.

CONCLUSION

Within the limitations of the studies, it is concluded that aPDT is a suitable adjunct to improve the disinfection of conventional root canal treatment. However, future studies should focus on the clinical outcomes, in relation to the reduction of microbial counts to ascertain the efficacy of aPDT in disinfection of primary dentine.

The role of the light source in antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (APDT) is a promising approach to fight the growing problem of antimicrobial resistance that threatens health care, food security and agriculture. APDT uses light to excite a light-activated chemical (photosensitiser), leading to the generation of reactive oxygen species (ROS). Many APDT studies confirm its efficacy in vitro and in vivo against bacteria, fungi, viruses and parasites. However, the development of the field is focused on exploring potential targets and developing new photosensitisers. The role of light, a crucial element for ROS production, has been neglected. What are the main parameters essential for effective photosensitiser activation? Does an optimal light radiant exposure exist? And finally, which light source is best? Many reports have described the promising antibacterial effects of APDT in vitro, however, its application in vivo, especially in clinical settings remains very limited. The restricted availability may partially be due to a lack of standard conditions or protocols, arising from the diversity of selected photosensitising agents (PS), variable testing conditions including light sources used for PS activation and methods of measuring anti-bacterial activity and their effectiveness in treating bacterial infections. We thus sought to systematically review and examine the evidence from existing studies on APDT associated with the light source used. We show how the reduction of pathogens depends on the light source applied, radiant exposure and irradiance of light used, and type of pathogen, and so critically appraise the current state of development of APDT and areas to be addressed in future studies. We anticipate that further standardisation of the experimental conditions will help the field advance, and suggest key optical and biological parameters that should be reported in all APDT studies. More in vivo and clinical studies are needed and are expected to be facilitated by advances in light sources, leading to APDT becoming a sustainable, alternative therapeutic option for bacterial and other microbial infections in the future.

Clinical applications of antimicrobial photodynamic therapy in dentistry

Given the emergence of resistant bacterial strains and novel microorganisms that globally threaten human life, moving toward new treatment modalities for microbial infections has become a priority more than ever. Antimicrobial photodynamic therapy (aPDT) has been introduced as a promising and non-invasive local and adjuvant treatment in several oral infectious diseases. Its efficacy for elimination of bacterial, fungal, and viral infections and key pathogens such as Streptococcus mutans, Porphyromonas gingivalis, Candida albicans, and Enterococcus faecalis have been investigated by many invitro and clinical studies. Researchers have also investigated methods of increasing the efficacy of such treatment modalities by amazing developments in the production of natural, nano based, and targeted photosensitizers. As clinical studies have an important role in paving the way towards evidence-based applications in oral infection treatment by this method, the current review aimed to provide an overall view of potential clinical applications in this field and summarize the data of available randomized controlled clinical studies conducted on the applications of aPDT in dentistry and investigate its future horizons in the dental practice. Four databases including PubMed (Medline), Web of Science, Scopus and Embase were searched up to September 2022 to retrieve related clinical studies. There are several clinical studies reporting aPDT as an effective adjunctive treatment modality capable of reducing pathogenic bacterial loads in periodontal and peri-implant, and persistent endodontic infections. Clinical evidence also reveals a therapeutic potential for aPDT in prevention and reduction of cariogenic organisms and treatment of infections with fungal or viral origins, however, the number of randomized clinical studies in these groups are much less. Altogether, various photosensitizers have been used and it is still not possible to recommend specific irradiation parameters due to heterogenicity among studies. Reaching effective clinical protocols and parameters of this treatment is difficult and requires further high quality randomized controlled trials focusing on specific PS and irradiation parameters that have shown to have clinical efficacy and are able to reduce pathogenic bacterial loads with sufficient follow-up periods.

[Potentialities of photoactivated disinfection in dentistry]

Infection control is an essential part of dental practice. Oral antiseptics should be highly effective against the most common oral pathogens without causing microbial resistance, biocompatible with the human tissues with no interaction with fillings materials. Photoactivated disinfection (PAD) is based on activation of photosensitizers - specific substances releasing active oxygen forms after absorption of the light. The active oxygen forms destroy bacterial cell structures without affecting human cells. The overwhelming majority of Russian and international researchers have reported high effectiveness of PAD in periodontics, implantology and endodontics, whereas the use of PAD in caries treatment and prevention is not so fully understood yet. Earlier studies have demonstrated high sensitivity of cariogenic bacteria to PAD, suggesting it as an additional minimally invasive caries therapy improving treatment effectiveness. PAD spares dental tissues without reduction in the effectiveness of disinfection. It is particularly important in treatment of deep carious lesions and disinfection of thin dentine layer near the pulp. Effectiveness of PAD in caries treatment has been demonstrated for both permanent and deciduous dentition. PAD doesn't affect bond strength to fillings, improves plasticity of dental pulp and dental hard tissues mineralization in children. Effective control of a wide range of bacteria without causing resistance makes PAD a prospective method of treatment and prevention of caries.

Efficacy of antiseptics and chemomechanical methods for dentin caries lesions: A systematic review with GRADE approach

Objectives

Selective caries removal aims to remove carious tissue in deep dentin lesions. However, a discussion stands on the value of antiseptics and chemomechanical adjuvant methods to reduce the bacterial load on residual caries lesions. This systematic review has addressed two main clinical questions to compare the antimicrobial efficacy of available methods using (1) antiseptic or (2) chemomechanical agents before restoring dentin carious lesions.

Methods

We included randomized and non-randomized controlled trials (RCTs/ NRCTs). We searched eight databases from inception to October 2021. Paired reviewers independently screened studies, extracted data, and assessed the risk of bias. The primary outcome was the reduction in the number of total bacterial in dentin, whereas secondary outcomes were reduction in the number of Lactobacillus and Streptococcus. We used the ratio of ratio of post-treatment to baseline means between two interventions in the logarithmic scale as a proper effect measure. Certainty of evidence was assessed with the Grading of Recommendations, Assessment, Development and Evaluation approach.

Results

We included 14 RCTs and 9 NRCTs, with nine interventions. Regardless the method, the number of bacteria at baseline was similar or exceeded that after the intervention, particularly in NRCTs. The evidence was inconclusive for most comparisons. Among antiseptic agents, chlorhexidine (CHX) resulted in an average of 1.14 times [95% confidence interval (CI): 1.08-1.21] more total bacterial than photodynamic therapy in RCTs. Among NRCTS, the natural agents resulted in five times more total bacterial than CHX (95% CI: 2-11). For chemomechanical methods, the control resulted in eight times (95% CI: 4-17) more total bacterial than Carisolv (SHAA).

Conclusions

The certainty of the evidence was very low for all comparisons showing uncertainty whether one treatment could be more effective than another for dentin disinfection. So far, exclusively removing soft carious dentin would be enough to reduce the bacterial count.

Antimicrobial photodynamic therapy as an adjunctive treatment to ultrasound for the dentin caries-like lesion removal

OBJECTIVE

To evaluate in vitro the efficacy of ultrasound device to remove caries-like dentin and the curcumin-mediated antimicrobial photodynamic therapy (aPDT) to decontaminate the affected dentin.

METHODS

Bovine dentin specimens (n = 173) of 4 × 4 × 2 mm were first submitted to Knoop surface microhardness to standardize the specimens (29 ± 3 KHN). Artificial caries lesion was induced by Streptococcus mutans strain by biological model for 7 days. Infected dentin was removed (1 min) with the following techniques: dentin excavator, bur at low-speed rotation and ultrasound device. After that, aPDT application was performed using blue LED under 460 nm. Polarized light microscopy (PLM), removal rate (n = 10), cross-sectional microhardness (n = 10), colony forming units per milliliter (CFU) (n = 9) and confocal laser microscopy (CM) (n = 2) were performed. ANOVA with Welch correction, post-hoc Games-Howell and two-way ANOVA followed by Tukey's post-hoc tests were used.

RESULTS

PLM confirmed the caries lesion formation with a depth of ∼147.9 µm. Groups treated with ultrasound showed lower removal rate (p = 0.001). Regardless of the treatment, the microhardness values increased as function of depth (p ≤ 0.05). Carbide bur showed the highest microhardness value, followed by ultrasound and excavator. CFU and CM showed a significant reduction in S. mutans after aPDT application.

CONCLUSION

Ultrasound was efficient, since it removed infected dentin, preserving the affected dentin and aPDT can be used as a complementary therapy to decontaminate the affected dentin.

CLINICAL SIGNIFICANCE

Ultrasound device may help the clinician to remove dentin caries-like lesions since it is a conservative technique and provided the removal of infected dentin, preserving the affected dentin. aPDT application may be used as a complimentary technique to promote antibacterial effect and possibly minimize the risk of secondary caries.

Evaluation of composite restorations in primary molars subjected to selective caries removal associated with antimicrobial photodynamic therapy: A randomized controlled trial

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) has been used as an adjunct treatment of deep caries lesions; however, studies on the effects of aPDT on the longevity of restorations are still limited.

AIM

To evaluate the clinical performance of composite restorations in primary molars subjected to selective caries removal (SCR) associated with aPDT.

DESIGN

A randomized clinical trial was designed. Primary molars of patients (mean age 6.15 years) with deep caries lesions without signs and symptoms of pulpal involvement were selected. A total of 64 teeth were randomly divided into groups G1 (SCR, 32 teeth) and G2 (SCR + aPDT, 32 teeth) for treatment, restored with composite, and evaluated after a week (T₀ ), 6 months (T₁ ), and 12 months (T₂ ) according to the criteria of FDI. Groups were compared using the Rao-Scott chi-squared test and the logistic regression analysis for complex designs to account for multiple observations per subject (alpha = 0.05).

RESULTS

From all FDI criteria evaluated, the marginal adaptation for the SCR + aPDT group was significantly better in comparison with the SCR group at T0 and T2 in the logistic regression analysis (T0: OR = 0.151; 95% CI = 0.03-0.068, P = .015; and T2: OR = 0.201; 95% CI = 0.05-0.79, P = .022).

CONCLUSION

The marginal adaptation of primary molar resin restorations was positively affected by aPDT after 12 months of follow-up.

How can biophotonics help dentistry to avoid or minimize cross infection by SARS-CoV-2?

Biophotonics is defined as the combination of biology and photonics (the physical science of the light). It is a general term for all techniques that deal with the interaction between biological tissues/cells and photons (light). Biophotonics offers a great variety of techniques that can facilitate the early detection of diseases and promote innovative theragnostic approaches. As the COVID-19 infection can be transmitted due to the face-to-face communication, droplets and aerosol inhalation and the exposure to saliva, blood, and other body fluids, as well as the handling of sharp instruments, dental practices are at increased risk of infection. In this paper, a literature review was performed to explore the application of Biophotonics approaches in Dentistry focusing on the COVID-19 pandemic and how they can contribute to avoid or minimize the risks of infection in a dental setting. For this, search-related papers were retrieved from PubMED, Scielo, Google Schoolar, and American Dental Association and Centers for Disease Control and Prevention databases. The body of evidence currently available showed that Biophotonics approaches can reduce microorganism load, decontaminate surfaces, air, tissues, and minimize the generation of aerosol and virus spreading by minimally invasive, time-saving, and alternative techniques in general. However, each clinical situation must be individually evaluated regarding the benefits and drawbacks of these approaches, but always pursuing less-invasive and less aerosol-generating procedures, especially during the COVID-19 pandemic.

Effect of dental acid etchant-mediated photodynamic therapy on bacterial reduction and microshear bond strength of composite to dentin - An in vitro study

Objective:

The objective of this study was to assess the effect of dental acid etchant (DAE)-mediated photodynamic therapy on bacterial reduction and microshear bond strength of composite to dentin.

Materials and Methods:

Eighty permanent third molars after sample preparation were exposed to a cariogenic challenge with Streptococcus mutans. After incubation, specimens were randomly divided into four groups (n = 20): Group I – DAE, Group II – low-level laser (LLL), Group III – diode laser + methylene blue (MB + L), and Group IV – diode laser + DAE (DAE + L). Half of the specimens from each group were selected for bacterial reduction assessment and the other half for microshear bond strength. All the samples for assessment of bacterial reduction (before and after intervention) were seeded onto the surface of mitis-salivarius-bacitracin medium. After incubation, the viable bacterial count was determined in colony-forming unit/mL. For microshear bond strength assessment, samples were subjected to various treatment modalities and then bonding and debonding procedure was performed for blocks of composite and values were recorded.

Results:

Significant reductions in S. mutans were observed in all the groups – Group I (DAE) 68.50%, Group II (LLL) 55.90%, Group III (MB + L) 88.60%, and Group IV (DAE + L) 87% with comparable bacterial reduction between Group III (MB + L) and Group IV (DAE + L). Furthermore, a significant difference in bond strength values was seen in Group III (MB + L) 10.99 MPa and Group IV (DAE + L) 17.99 MPa whereas an insignificant difference was found between Group I (DAE) 20.74 MPa, Group II (LLL) 18.27 MPa, and Group IV (DAE + L).

Conclusion:

DAE caused a comparable reduction in bacterial count to MB-assisted PDT and also there was no adverse effect on bond strength values. PDT can be performed while acid etchant containing MB dye is being applied in the cavity, thus reducing operative time and enhancing cavity disinfection.

Efficacy of antimicrobial photodynamic therapy (aPDT) in reducing cariogenic bacteria in primary deciduous dentine

AIM

The aim is to systematically review the efficacy of aPDT in minimizing cariogenic bacteria in primary dentine when compared to tooth preparation and endodontic debridement.

MATERIALS AND METHODS

The focused question was: Is aPDT (intervention) effective in minimizing the cariogenic bacteria (outcome) in deciduous dentine (participants) after caries removal when compared to before aPDT or mechanical caries removal alone (controls). The keywords that were used were: 'antimicrobial photodynamic therapy', 'dentine', 'primary teeth' and 'deciduous teeth' in different combinations. Following the exclusion of the irrelevant studies, eight (seven clinical studies and one in vitro study) studies were included in the review. The data from each study was extracted and the quality of each article was assessed.

RESULTS

In four out of the eight studies, aPDT with methylene blue or toluidine blue had improved the efficacy of microbial reduction in deciduous dentine when compared to conventional root canal treatment or caries removal. In four studies, no significant improvement in microbial reduction was observed following aPDT compared to caries removal or endodontic debridement without aPDT. Four studies received an overall quality grading of 'medium', three studies were assessed as having a 'low' quality and only one study received an overall grading of 'high' quality.

CONCLUSION

Within the limitations of this review, aPDT may improve the anti-bacterial efficacy of restorative and endodontic procedures in deciduous teeth. However, due to lack of long-term clinical trials and robust study designs, the efficacy of aPDT in minimizing cariogenic bacteria in deciduous dentine is debatable.

Antimicrobial photodynamic therapy mediated by methylene blue coupled to β-cyclodextrin reduces early colonizing microorganisms from the oral biofilm

OBJECTIVE

To test the effect of antimicrobial photodynamic therapy (A-PDT) on the oral biofilm formed with early colonizing microorganisms, using the photosensitizer methylene blue coupled with β-cyclodextrin nanoparticles and red light sources laser or LED (λ =660 nm).

METHODS

The groups were divided into (n = 3, in triplicate): C (negative control, 0.9 % NaCl), CX (positive control, 0.2 % chlorhexidine), P (Photosensitizer/Nanoparticle), L (Laser), LED (light-emitting diode), LP (Laser + Photosensitizer/Nanoparticle) and LEDP (LED + Photosensitizer/Nanoparticle). A multispecies biofilm composed ofS. gordonii, S. oralis, S. mitis, and S. sanguinis was grown in microplates containing BHI supplemented with 1% sucrose (w/v) for 24 h. Light irradiations were applied with a laser at 9 J for 90 s (320 J/cm²), or with LED, at 8.1 J for 90 s (8.1 J/cm²). The microbial reduction was assessed by counting viable biofilm microorganisms in selective culture media, before and after the treatments. Data normality was assessed by the Shapiro-Wilk test, and the results were submitted to Kruskal-Wallis analysis, followed by Dunn's test, with a significance level of 5%.

RESULTS

The groups LP and LEDP were able to significantly reduce the biofilm microorganism counts by as much as 4 log₁₀ times compared to the negative control group (p < 0.05) and did not statistically differ from the positive control group (CX) (p > 0.05).

CONCLUSION

The A-PDT mediated by encapsulated β-cyclodextrin methylene blue irradiated by Laser or LED was effective in the microbial reduction of multispecies biofilm composed of early colonizing microorganisms.

Polyacrylic Acid with Methylene Blue Dye as a Sensitizing Agent for Photodynamic Therapy to Reduce Streptococcus mutans in Dentinal Caries

Objective: To evaluate 11.5% polyacrylic acid (PA) containing 0.3% methylene blue (MB) dye as a photosensitizer for photodynamic therapy (PDT) of carious dentin. Methods: One hundred twenty molars were selected and the dentin was exposed for cariogenic challenge, where the molars were placed in brain heart infusion medium containing a standard strain of Streptococcus mutans (ATCC). Samples were randomly divided into eight groups (n = 15): S: saline, PA, MB: MB 0.3%, PA+MB: PA containing 0.3% MB + LLL: irradiation with low-level laser, PDT (MB): MB 0.3% + laser, PDT (PA): PA + laser, and PDT (PA+MB): PA containing 0.3% MB + laser. Carious dentin was collected before and after exposure to S. mutans. All samples of carious dentin were homogenized, diluted, and seeded in mitis salivarius bacitracin medium, and the cultures were incubated at 37°C for 15 days in anaerobic jars. The Wilcoxon test was used for analysis. Results: The percent microbial reduction achieved with each treatment was as follows: PDT (MB), 53.62%; PDT (PA+MB), 50.47%; PDT (PA), 46.73%; PA, 38.51%; MB, 19.75%; PA+MB, 17.18%; LLL, 12.83%; S, 5.99%. The greatest reductions in S. mutans growth occurred with PDT (MB), PDT (PA+MB), and PDT (PA) when compared to the S group (p = 0.0002, 0.0023, and 0.0232, respectively). Conclusions: PA containing 0.3% MB can be used as a photosensitizer for PDT to reduce S. mutans burden in carious dentin.

Light Energy Dose and Photosensitizer Concentration Are Determinants of Effective Photo-Killing against Caries-Related Biofilms

Caries-related biofilms and associated complications are significant threats in dentistry, especially when biofilms grow over dental restorations. The inhibition of cariogenic biofilm associated with the onset of carious lesions is crucial for preventing disease recurrence after treatment. This in vitro study defined optimized parameters for using a photosensitizer, toluidine blue O (TBO), activated via a red light-emitting diode (LED)-based wireless device to control the growth of cariogenic biofilms. The effect of TBO concentrations (50, 100, 150, and 200 μg/mL) exposed to light or incubated in the dark was investigated in successive cytotoxicity assays. Then, a mature Streptococcus mutans biofilm model under sucrose challenge was treated with different TBO concentrations (50, 100, and 150 μg/mL), different light energy doses (36, 108, and 180 J/cm²), and different incubation times before irradiation (1, 3, and 5 min). The untreated biofilm, irradiation with no TBO, and TBO incubation with no activation represented the controls. After treatments, biofilms were analyzed via S. mutans colony-forming units (CFUs) and live/dead assay. The percentage of cell viability was within the normal range compared to the control when 50 and 100 μg/mL of TBO were used. Increasing the TBO concentration and energy dose was associated with biofilm inhibition (p < 0.001), while increasing incubation time did not contribute to bacterial elimination (p > 0.05). Irradiating the S. mutans biofilm via 100 μg/mL of TBO and ≈180 J/cm² energy dose resulted in ≈3-log reduction and a higher amount of dead/compromised S. mutans colonies in live/dead assay compared to the control (p < 0.001). The light energy dose and TBO concentration optimized the bacterial elimination of S. mutans biofilms. These results provide a perspective on the determining parameters for highly effective photo-killing of caries-related biofilms and display the limitations imposed by the toxicity of the antibacterial photodynamic therapy’s chemical components. Future studies should support investigations on new approaches to improve or overcome the constraints of opportunities offered by photodynamic inactivation of caries-related biofilms.

The Impact of Photosensitizer Selection on Bactericidal Efficacy Of PDT against Cariogenic Biofilms: A Systematic Review and Meta-Analysis

BACKGROUND

There are investigations on multiple photosensitizers for modulation of caries-related biofilms using PDT. However, much controversy remains about recommended parameters mostly on the selection of an efficient photosensitizer.

OBJECTIVE

The study performed a systematic review to identify the answer to the following question: What photosensitizers present high bactericidal efficacy against cariogenic biofilms?

METHODS

Systematic review with meta-analyses were carried out for English language articles from October to December 2019 (PRISMA standards) using MEDLINE, Scopus, Biomed Central, EMBASE, LILACS, and Web of Science. Information on study design, biofilm model, photosensitizer, light source, energy delivery, the incubation time for photosensitizer, and bacterial reduction outcomes were recorded. We performed two meta-analyses to compare bacterial reduction, data was expressed by (1) base 10 Logarithm values and (2) Log reduction RESULTS: After the eligibility criteria were applied (PEDro scale), the selected studies showed that toluidine Blue Ortho (TBO) and methylene blue (MBO) (5-min incubation time and 5-min irradiation) demonstrated better bacterial reduction outcomes. For the data expressed by Log TBO, MBO, curcumin, and Photogem® presented a significant bacterial decrease in comparison to the control (p = 0.042). For the data represented by Log reduction, the bacterial reduction toward S.mutans was not significant for any photosensitizer (p = 0.679).

CONCLUSION

The lack of methodological standardization among the studies still hinders the establishment of photosensitizer and bactericidal efficiency. TBO, MBO, curcumin, and photogem generate greater PDT-based bacterial reduction on caries-related bacteria.. Further clinical studies are necessary in order to obtain conclusive results.

Laser-Assisted aPDT Protocols in Randomized Controlled Clinical Trials in Dentistry: A Systematic Review

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) has been proposed as an effective alternative method for the adjunctive treatment of all classes of oral infections. The multifactorial nature of its mechanism of action correlates with various influencing factors, involving parameters concerning both the photosensitizer and the light delivery system. This study aims to critically evaluate the recorded parameters of aPDT applications that use lasers as the light source in randomized clinical trials in dentistry.

METHODS

PubMed and Cochrane search engines were used to identify human clinical trials of aPDT therapy in dentistry. After applying specific keywords, additional filters, inclusion and exclusion criteria, the initial number of 7744 articles was reduced to 38.

RESULTS

Almost one-half of the articles presented incomplete parameters, whilst the others had different protocols, even with the same photosensitizer and for the same field of application.

CONCLUSIONS

No safe recommendation for aPDT protocols can be extrapolated for clinical use. Further research investigations should be performed with clear protocols, so that standardization for their potential dental applications can be achieved.

Biofilm Inactivation using Photodynamic Therapy in Dentistry: a review of literature

Introduction: Photodynamic therapy (PDT) is a therapy involving light and a photosensitising chemical substance, used in conjunction with molecular oxygen in order to elicit cell death (photo-toxicity) and thus ability to kill microbial cells, including bacteria, fungi and viruses. Photodynamic therapy is an alternative method of biofilm disruption and it is considered a new way of microorganism inactivation. It is also an additional procedure to reduce the infection rate in patients, caused by the increasing antimicrobials resistance of bacteria. The aim of this literature review was to evaluate the specific effects and the antibacterial effectiveness of photodynamic therapy using different types of photosensitizers (Erythrosine, Rose Bengal, Toluidine blue, Methylene blue, Ozone, Riboflavin, Curcumin, Chlorhexidine, SAPYR) and a visible light of a specific wavelength for each photosensitizer and to reveal the applications of PDT in periodontics, endodontics, prosthodontics and dental caries. Methods: A research of literature was performed in an attempt to find all the articles published on this topic in the last 10 years. The articles was searched by using a certain combination of different keywords (photodynamic therapy ) and (diode laser ) and (teeth) in PubMed database. Results: A total number of 83 articles were found. After applying inclusion and exclusion criteria, 35 articles were taken into consideration for our study and among them 4 were a manuscript, 3 was a review of literature, 1 was an in vivo evaluation and 27 were in vitro studies. Conclusion: Considering that none of the disinfection methods can completely remove the biofilm, PDT is a therapeutic tool complementary to conventional disinfection, with great applicability in dentistry. PDT showed significantly efficacy in reduction of biofilms. Exposure to light in the presence of a photosensitizing chemical substance helps in the reduction of microbes and the protocols could be recommended for clinical usage, but only together with ‘classic ‘ disinfection.

Effects of Rose Bengal- and Methylene Blue-Mediated Potassium Iodide-Potentiated Photodynamic Therapy on Enterococcus faecalis: A Comparative Study

BACKGROUND AND OBJECTIVES

This study was performed to compare the use of methylene blue (MB) and rose bengal (RB) in antimicrobial photodynamic therapy (PDT) targeting Enterococcus faecalis (E. faecalis) bacteria in planktonic and biofilm forms with potassium iodide (KI) potentiation.

STUDY DESIGN/MATERIALS AND METHODS

E. faecalis bacteria in planktonic form were exposed to antimicrobial PDT protocols activating MB and RB, with or without KI potentiation, following laser irradiation with different exposure times, 60 mW/cm² laser power, and different photosensitizer agent (PS)/potentiator concentrations to observe relationships among the variables. Two continuous-wave diode lasers were used for irradiation (red light: λ = 660 nm and green light: λ = 565 nm). The pre-irradiation time was 10 minutes. The vitality of E. faecalis biofilm was assessed by confocal laser scanning microscopy, and the morphology was determined by scanning electron microscopy. The effects on the proliferation of stem cells from the apical papilla (SCAPs) were analyzed by cell counting kit-8 assay. The staining effect of antimicrobial PDT on dentin slices was investigated. Statistical analysis using a one-way analysis of variance was done.

RESULTS

KI-potentiated RB and MB antimicrobial PDT both effectively eradicated E. faecalis bacteria in planktonic and biofilm forms. The minimum bactericidal concentrations of PSs (±100 mM KI) were obtained through PDT on planktonic E. faecalis, and the optimal light parameters were 60 mW/cm² , 6 J/cm² for 100 seconds. KI-potentiated PDT effectively strengthened the ability to inhibit E. faecalis biofilm with 86.50 ± 5.78% for MB (P = 0.0015 < 0.01) and 91.50 ± 1.75% for RB (P = 0.0418 < 0.05) of bactericidal rate, with less toxicity for SCAPs (P < 0.001) and less staining. KI could reduce the staining induced by antimicrobial PDT on dentin slices.

CONCLUSION

A combination of KI and antimicrobial PDT may be a useful alternative to conventional disinfection methods in endodontic treatment. MB and RB antimicrobial PDT at much lower concentrations with KI could hopefully achieve disinfection effects comparable with those of 1.5% NaClO while causing few adverse effects on SCAPs. KI helps to avoid staining problems associated with high concentrations of photosensitizer agents. Lasers Surg. Med. © 2020 Wiley Periodicals, LLC.

Model for Taking Care of Patients with Early Childhood Caries during the SARS-Cov-2 Pandemic

Pending the availability of vaccines to contain the SARS-CoV-2 pandemic, the current solution is "social distancing" with a reduction of dental treatments to those assessed as urgent and emergency cases. These treatments also involve Early Childhood Caries (ECC) due to the fact that this disease affects preschool children (a vulnerable population) and, in addition, shows a propensity to evolve into more serious complications (dental pain, infections). A narrative review was carried out to support a protocol for treating ECC with efficacious and safe (in terms of SARS-CoV-2 transmission) procedures. Protocol involves criteria for patients' selection remotely (telemedicine), and well-detailed criteria/equipment and hygiene procedures to combat against SARS-CoV-2 transmission. Moreover, the protocol proposes innovative caries treatments, named Minimally Invasive Treatments (MITs), well known in pedodontics for their high level of children's acceptance during dental care. MITs allow for caries removal (particularly in primary teeth) without any high-speed rotating instrument cooled with nebulized air-water spray (with high risk of virus environmental diffusion), usually adopted during traditional treatments. For evaluating MITs effectiveness in caries management, only Systematic Review and Randomized Controlled Trials (RCTs) were included in our study, without any risk of bias assessment. The indications proposed in this protocol could support clinicians for the temporary management of ECC until the SARS-CoV-2 pandemic ends.

Photoinhibition of Streptococcus mutans Biofilm-Induced Lesions in Human Dentin by Violet-Blue Light

This in vitro study determined the effectiveness of violet-blue light on Streptococcus mutans (UA159) biofilm induced dentinal lesions. Biofilm was formed on human dentin specimens in a 96-well microtiter plate and incubated for 13 h in the presence of tryptic soy broth (TSB) or TSB supplemented with 1% sucrose (TSBS). Violet-blue light (405 nm) from quantitative light-induced fluorescence (QLF^TM) was used to irradiate the biofilm. Supernatant liquid was removed, and the biofilm was irradiated continuously with QLF for 5 min twice daily with an interval of 6 h for 5 d, except with one treatment on the final day. Colony forming units (CFU) of the treated biofilm, changes in fluorescence (∆F; QLF-Digital Biluminator^TM), lesion depth (L), and integrated mineral loss (∆Z; both transverse microradiography) were quantified at the end of the fifth day. Statistical analysis used analysis of variance (ANOVA), testing at a 5% significance level. In the violet-blue light irradiated groups, there was a significant reduction (p < 0.05) of bacterial viability (CFU) of S. mutans with TSB and TSBS. Violet-blue light irradiation resulted in the reduction of ∆F and L of the dentinal surface with TSBS. These results indicate that violet-blue light has the capacity to reduce S. mutans cell numbers.

Influence of antimicrobial photodynamic therapy in carious lesion. Randomized split-mouth clinical trial in primary molars

BACKGROUND

The literature presents many studies regarding photodynamic antimicrobial therapy (aPDT). However, the great variety of protocols to be used can directly influence its effectiveness in reducing microorganisms. The aim of this randomized split-mouth clinical study was to evaluate the effect of aPDT in the reduction of Streptococcus mutans and their effect on restorations performed.

METHODS

Twenty children between 6 and 8 years old with active caries and dentin cavitation, located on the occlusal surface of homologous primary molars were included. The selective removal of carious tissue was performed in both molars, than one was subsequently restored and the other received aPDT treatment on the affected dentin with low intensity laser (InGaAlP) associated to 0.005% methylene blue photosensitizer before restoration. Dentin collections were performed only in the tooth submitted to aPDT in three moments: before and after selective caries removal and after application of aPDT. The restorations were analyzed after polishing and after 6 months using United States Public Health Service (USPHS) method. Data were analyzed using ANOVA with repeated measures and Bonferroni post-hoc test with a significance level of 5%.

RESULTS

There was a significant reduction on the amount of microorganisms after selective caries removal (p = 0.04) and also after the application of aPDT (p = 0.01). The reduction of S. mutans CFU was of 76.4% after caries removal, but associated with aPDT was 92.6%. After 6 months of clinical evaluation, no difference between groups was found for retention, marginal adaptation, color, marginal discoloration, and secondary caries.

CONCLUSIONS

aPDT can be used as an additional treatment against cariogenic microorganisms after selective caries removal without compromising composite resin restorations.

Photodynamic inactivation of Candida ssp. on denture stomatitis. A clinical trial involving palatal mucosa and prosthesis disinfection

Denture stomatitis (DS) is the most common oral fungal infection in denture wearers. Photodynamic inactivation (PDI) has been showing to be an effective technique in vivo against fungi, including fungal infections in the oral cavity. The disinfection of both oral mucosa and denture may represent a real advantage in terms of fungus control. This clinical study was designed to explore methylene blue (MB)-mediated PDI on oral mucosa and prosthesis of patients with DS. Subjects with DS were divided into two groups. One group received treatment based on the use of oral miconazole gel 2% (MIC). The other group received treatment by PDI using MB at 450 μg/mL and a diode laser (λ = 660 nm) with 100 mW and fluence of 28 J/cm². Clinical outcome was evaluated regarding the degree of oral mucosa erythema and microbiological reduction of Candida spp. located in both palatal mucosa and prosthesis. Our results showed that PDI was significantly more effective than MIC in ameliorating inflammation after 15 days. Following 30 days, no statistically significant differences were observed between groups. Regarding the fungal burden, although the MIC group has presented more pronounced inactivation than PDI for both mucosa and prosthesis, no statistically significant differences were detected between them. This clinical study suggests that PDI can reduce fungal load and decrease the inflammation degree in patients with Candida-associated denture stomatitis.

An experimental study for rapid detection and quantification of endodontic microbiota following photo-activated disinfection via new multiplex real-time PCR assay

BACKGROUND

The infected root canal system harbors one of the highest accumulations of polymicrobial infections. Since the eradication of endopathogenic microbiota is a major goal in endodontic infection therapy, photo-activated disinfection (PAD) can be used as an alternative therapeutic method in endodontic treatment. Compared to cultivation-based approaches, molecular techniques are more reliable for identifying microbial agents associated with endodontic infections. The purpose of this study was to evaluate the ability of designed multiplex real-time PCR protocol for the rapid detection and quantification of six common microorganisms involved in endodontic infection before and after the PAD.

MATERIALS AND METHODS

Samples were taken from the root canals of 50 patients with primary and secondary/persistent endodontic infections using sterile paper points. PAD with toluidine blue O (TBO) plus diode laser was performed on root canals. Resampling was then performed, and the samples were transferred to transport medium. Then, six target microorganisms were detected using multiplex real-time PCR before and after the PAD.

RESULTS

Veillonella parvula was found using multiplex real-time PCR to have the highest frequency among samples collected before the PAD (29.4%), followed by Porphyromonas gingivalis (23.1%), Aggregatibacter actinomycetemcomitans (13.6%), Actinomyces naeslundii (13.0%), Enterococcus faecalis (11.5%), and Lactobacillus rhamnosus (9.4%). After TBO-mediated PAD, P. gingivalis strains, the most resistance microorganisms, were recovered in 41.7% of the samples using molecular approach (P > 0.05).

CONCLUSION

As the results shown, multiplex real-time PCR as an accurate detection approach with high-throughput and TBO-mediated PAD as an efficient antimicrobial strategy due to the significant reduction of the endopathogenic count can be used for detection and treatment of microbiota involved in infected root canals, respectively.

Evaluation of photosensitizer penetration into sound and decayed dentin: A photoacoustic spectroscopy study

BACKGROUND

Photodynamic therapy (PDT) may have topical indications. In those cases it is important for a topical photosensitizer to penetrate into the tissue to which it has been applied. This study aimed to compare the penetration of two different concentrations of erythrosine into intact and in vitro decayed dentin samples.

METHODS

This in vitro study evaluated erythrosine (0.3 and 5%) penetration into sound (intact) and decayed dentin. A total of 11 dentin discs were prepared and divided into two equal halves, in order to keep one half sound while the other half was submitted to sterilization and an in vitro demineralization model for 5 days. Before erythrosine application, the organic and inorganic composition of all samples was evaluated by Fourier Transform Raman spectroscopy, and after erythrosine application for 30 min, the penetration depth was determined by Photoacoustic spectroscopy technique.

RESULTS

The results indicated that 0.3% erythrosine showed a higher penetration depth into sound dentin (p = 0.002); and 5% erythrosine higher penetration into decayed dentin (p < 0.001). However considering clinical parameters, no statistically significant difference was found between any of the conditions tested.

CONCLUSIONS

Erythrosine demonstrated ability to penetrate into dentin, irrespective of sound or decayed condition. Photoacoustic spectroscopy can be considered a method for estimating the penetration into hard tissues, and in conjunction with Raman spectroscopy, these are effective methods for evaluating the spectral response of dentin. Considering that erythrosine is capable of penetrating into decayed dentin, clinical trials are needed to test the effectiveness of this photosensitizer in Photodynamic therapy and Antimicrobial Photodynamic therapy.

Antimicrobial photodynamic therapy as an adjunct for treatment of deep carious lesions-A systematic review

For deep carious lesions, a more conservative treatment modality ("selective caries removal") has been proposed, where only the heavily contaminated dentine is removed. In this regard, effective adjuncts for cavity disinfection such as the antimicrobial photodynamic therapy (aPDT) can be valuable clinically prior to definitive restoration. Therefore, the aim of this study was to systematically assess clinical studies on the effectiveness of aPDT as a supplementary tool in the treatment of deep caries lesions. Searches were performed in four databases (PubMed, EMBASE, ISI Web of Science, ClinicalTrials.gov) from 1st January, 2011 until 21st June, 2016 for search terms relevant to the observed parameters, pathological condition, intervention and anatomic entity. The pooled information was evaluated according to PRISMA guidelines. At first, 1651 articles were recovered, of which 1249 full-text articles were evaluated, 270 articles thereof were reviewed for eligibility and finally 6 articles met all inclusion criteria. The aPDT protocols involved Methylene Blue, Toluidine Blue and aluminium-chloride-phthalocyanine as photosensitizers and diode lasers, light-emitting diodes and halogen light-sources. The data from five reports, utilizing both culture-dependent and -independent methods, disclosed significant reduction of cariogenic bacterial load after mechanical caries removal with adjunct aPDT. As these studies exhibit some methodological limitations, e.g. lack of positive controls, this systematic review can support the application of aPDT to a limited extent only in terms of reducing the microbial load in deep carious lesions before restorative treatment.

Effect of the antimicrobial photodynamic therapy on microorganism reduction in deep caries lesions: a systematic review and meta-analysis

This study aimed to perform a systematic review to assess the effectiveness of antimicrobial photodynamic therapy (aPDT) in the reduction of microorganisms in deep carious lesions. An electronic search was conducted in Pubmed, Web of Science, Scopus, Lilacs, and Cochrane Library, followed by a manual search. The MeSH terms, MeSH synonyms, related terms, and free terms were used in the search. As eligibility criteria, only clinical studies were included. Initially, 227 articles were identified in the electronic search, and 152 studies remained after analysis and exclusion of the duplicated studies; 6 remained after application of the eligibility criteria; and 3 additional studies were found in the manual search. After access to the full articles, three were excluded, leaving six for evaluation by the criteria of the Cochrane Collaboration’s tool for assessing risk of bias. Of these, five had some risk of punctuated bias. All results from the selected studies showed a significant reduction of microorganisms in deep carious lesions for both primary and permanent teeth. The meta-analysis demonstrated a significant reduction in microorganism counts in all analyses (p<0.00001). Based on these findings, there is scientific evidence emphasizing the effectiveness of aPDT in reducing microorganisms in deep carious lesions.