Eliminating Candida albicans for endodontic treatment purposes during the SARS-CoV-2 pandemic

Due to the specific structure of the spike proteins of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), the virus has a high potential for mutation. Also, it is a challenge for current vaccines to provide satisfactory protection against the virus. Therefore, preventing the virus from spreading during a pandemic is a priority. Dental procedures, as a risk factor, can generate dental aerosol and spread the virus. As a result, all treatments that generate dental aerosol should be reduced or avoided unless they are absolutely necessary. Furthermore, eradicating microorganisms from the root canal can be considered a priority for a successful treatment. Candida albicans (C. albicans) is the most common fungus that causes endodontic treatment failure.^1,2 This brief letter focuses on the topic of C. albicans eradication for endodontic treatment purposes.

C. albicans is a diploid, Gram-positive fungus attaching to teeth dentin and colonizing in dentinal walls of root canals. As a result, it penetrates into dentinal tubules and is implicated in cases of persistent or refractory root canal infections. The fungus could remain in dental tubules despite intracanal medicament (i.e., calcium hydroxide) or conventional irrigation solutions. Long-term successful root canal treatment is attributed in eliminating microorganisms from infected root canals. Hence, it is crucial to use appropriate disinfecting methods, including irrigations and materials for root canal therapy to eliminate C. albicans.^2,3

In the clinical study, Horlenko et al. investigated the anti-microbiological efficacy of two techniques for eliminating microorganisms from infected root canals in 64 patients with chronic apical periodontitis. The infected root canals of 34 patients (36 teeth) were used as the main group and treated using the ultrasonic method and multicomponent antimicrobial gel. The gel included metronidazole benzoate, chlorhexidine diacetate 2%, and hydrocortisone acetate. Only 2% chlorhexidine gel was applied in the canals of 30 patients (35 teeth), i.e., the control group. In the main group, the results showed that C. albicans decreased from 23.5% to 5.6% before and after treatment, respectively. In comparison, the fungus population decreased from 25.3% to 16.1% in the control group before and after the treatment, respectively. Also, the success rate of the treatment was 86% and 63% in the main and control groups, respectively. Thus, the combination of the ultrasonic method (for penetrating gel into dentinal tubules) and multicomponent antimicrobial gel is recommended for eradicating microorganisms from infected root canals.⁴

In another study, Mustafa et al. assessed the efficacy of antimicrobial photodynamic therapy, mechanical instrumentation, and combining both methods to remove microorganisms in 60 teeth with C-shaped canals. The results demonstrated that combining antimicrobial photodynamic therapy using a 600 nm diode laser with mechanical instrumentation is more effective in reducing microorganisms (i.e., C. albicans and bacterium), particularly in root canal curvature.⁵

In addition, Yasini et al. investigated the efficacy of nano-curcumin as a sonodynamic antimicrobial chemotherapy in reducing the biofilm of C. albicans and another microorganism from infected root canals of 80 extracted teeth. The study reported that combining ultrasonic waves and nano-curcumin is more effective than other methods. Thus, applying the novel combination method (curcumin and ultrasonic) is recommended to eliminate C. albicans from infected root canals.⁶

To eliminate C. albicans from infected root canals, Reddy et al. compared the antifungal effectiveness of Octenisept 100% with other solutions (i.e., 17% EDTA + 5.25% NaOCl, 17% EDTA + 5.25% NaOCl + 1% clotrimazole, and phosphate buffer saline) based on 80 extracted teeth (40 teeth from young individuals between 12 and 25 years and the other 40 teeth from elderly people above 60 years). The results showed that Octenisept has the highest antifungal effect against C. albicans. Octenisept also showed better antifungal effect on dental samples in the younger population than in the older population. Thus, using 2 mL of Octenisept for 1 min can be useful to eradicate C. albicans from infected root canals.⁷

The effectiveness of the antimicrobial activity of alpha-mangostin against endodontic pathogens in a multi-species bacterial-fungal biofilm model was evaluated. The results showed that the novel 0.2% alpha-mangostin can inhibit the metabolic activity of bacterial-fungal biofilms, including C. albicans, and has the potential for endodontic therapy.⁸

Furthermore, Alexidine digluconate has fungicidal effect and can inhibit the biofilm formation of diverse fungi. This chemical compound has also demonstrated longer-lasting antimicrobial activity than chlorhexidine. Even when combined with NaOCl, no precipitation or side effects have been reported for Alexidine. Thus, it is recommended as more effective and safer for endodontic irrigating solutions, particularly in the case of C. albicans.²

To eradicate C. albicans, Kerlikowski et al. investigated the effect of cold atmospheric pressure plasma on C. albicans in root canals using mono and combination methods with other irrigation solutions (NaOCl, chlorhexidine, and octenidine). The researchers applied the cold atmospheric-pressure plasma jet kINPen 08 with argon gas flow at 5 slm and an admixture of 1% oxygen (Plasma/O₂). Based on 150 extracted teeth, the results indicated that Plasma/O₂ reduced the highest log10 CFU of C. albicans at 6 and 12 min of treatment times. Plasma/O2 alone provided the best antiseptic properties compared to the other groups. Accordingly, it is suggested for the eradication of C. albicans during root canal therapy.⁹

Moradi Eslami et al. evaluated the efficacy of Ca(OH)₂, triple antibiotic paste (i.e., ciprofloxacin, minocycline, and metronidazole), toluidine blue, light emitting diode (630 nm LED exposure), diode laser (940 nm), and photodynamic therapy (1 mg/mL toluidine blue + 630 nm LED exposure) in eradicating microorganisms from 84 teeth. The three experimental groups including photodynamic therapy, light emitting diode, and triple antibiotic paste showed satisfactory results in eradicating C. albicans and another microbial biofilm. Overall, the triple antibiotic paste showed better results in decreasing the biofilm thickness of microorganisms.³

As root-filling materials, epoxy resin-based sealers (e.g., AH Plus) exhibited satisfactory results against C. albicans.¹⁰ Due to the ability of C. albicans to form biofilms, invade dentinal tubules, and resist common irrigation solutions, eradication of C. albicans from infected root canals is a challenging issue, particularly during the pandemic. Therefore, clinicians should consider the possibility of C. albicans in the case of retreatment or apical periodontitis.² Based on the information provided in this brief letter, the eradication of C. albicans requires additional treatment strategies: 1) using combined methods (e.g., ultrasonic technique + antimicrobial gel (metronidazole benzoate, chlorhexidine diacetate 2%, and hydrocortisone acetate), photodynamic therapy (600 nm diode laser) + mechanical instrumentation, and novel curcumin + ultrasonic), 2) endodontic disinfectants (e.g., Octenisept, alpha-mangostin, and Alexidine), 3) Plasma/O2, 4) triple antibiotic paste (i.e., ciprofloxacin, minocycline, and metronidazole), and 5) AH Plus as root filling martial. Hence, appropriate treatment methods are essential in optimizing endodontic therapy, especially during the COVID-19 pandemic.