Cold plasma: a good Enterococcus faecalis inhibitor â€“ an in vitro tooth root canal pilot study

doi:10.15406/jdhodt.2022.13.00561

Journal of

eISSN: 2373-4345

Dental Health, Oral Disorders & Therapy

Short Communication Volume 13 Issue 1

Cold plasma: a good Enterococcus faecalis inhibitor â€“ an in vitro tooth root canal pilot study

Rufo Figueroa- Banda,¹ Luis Ponce- Soto,² Gustavo Obando- Pereda²

Verify Captcha

Regret for the inconvenience: we are taking measures to prevent fraudulent form submissions by extractors and page crawlers. Please type the correct Captcha word to see email ID.

¹Dentistry School of Universidad Catolica de Santa Maria, Peru
²Proteomics, pain and inflammation laboratory of Universidad Catolica de Santa Maria, Peru

Correspondence: Gustavo Obando Pereda, Proteomics, pain and inflammation laboratory of Universidad Catolica de Santa Maria, Arequipa, Peru

Received: December 12, 2021 | Published: January 21, 2022

Citation: Figueroa-Banda R, Ponce-Soto L, Obando-Pereda G. Cold plasma: a good Enterococcus faecalis inhibitor â€“ an in vitro tooth root canal pilot study. J Dent Health Oral Disord Ther. 2022;13(1):1-2. DOI: 10.15406/jdhodt.2022.13.00561

Download PDF

Abstract

Tooth root canals with endodontic treatment can be reinfected because the continued presence of Enterococcus faecalis biofilm. Many techniques of has been proposed to eliminated this bacteria, however, these techniques no offer the fully elimination of the E. faecalis. In this pilot study cold plasma was effective in the fully inhibition of E. faecalis biofilm in infected tooth root canals.

Keywords: E. faecalis, disinfection, cold plasma

Introduction

The main of endodontic treatment is to eliminate total microbial biofilm inside of the root canal system to prevent a reinfection.¹ Traditional and modern treatments as mechanical debridement, chemicals and physics irrigation employing sodium hypochlorite, chlorhexidine, laser irradiation and ultrasound, perform a good microbial removing but not a complete elimination thus being able to reinfect the tooth canal system.² Persistent endodontic infection are frequently cause by Enterococcus faecalis who has the capacity to live in dentinal tubules forming a mature biofilms capable to resist any antibiotic and resist the host immune defenses.³ The elimination of E. faecalis from root canal systems can be make using many strategies as the use mainly calcium hydroxide (Ca[OH]2) as intracanal medication.^3,4 However, some studies showed than E. faecalis still in the root canals more than 10 days of treatment provoking a future reinfection of the root canal systems.⁵ Atmospheric pressure plasma technologies have been used in various applications such disinfection, sterilization mainly.⁶ In dental application is use in dental whitening a disinfection of dental materials.⁷ In this manner, the main of the study is investigate the capacity of cold plasma in the inhibition of E. faecalis biofilm.

Materials and methods

Root canal samples

Thirty single rooted extracted human teeth were cleaned and stored in 0.1% thymol solution at 4°C before the procedures. The tooth were decoronated below the cementoenamel junction to obtain a standard length of 10 mm.⁸ All tooth specimens were prepared with nickel-titanium hand files up to size #40 in a step-back manner. The canals were irrigated with 5.25% sodium hypochlorite (NaOCl), the smear layer was cleaned using 20% EDTA for 5 minutes and an ultrasonic bath of 5.25% NaOCl for 5 minutes.⁸ After that, root apical foramens were sealed with composite resin. Finally, the root samples were sterilized in an autoclave for 15 minutes at 121°C at 1 atmosphere pressure.⁹

Bacterial culture and root canal infection

ATCC of E. faecalis (29212) was cultured in brain-heart infusion (BHI) broth under at 37°C in aerobic condition. The experimental bacterial concentration was adjusted to 1.5 x 108 colony-forming units (CFU)/mL as measured by spectrophotometer. 100 uL of E. faecalis inoculum were placed into the root canal and using a sterile dental wax the coronal portion was sealed. The samples were place in sterile 10 mL centrifuge tubes with 3 mL of BHI and were incubated for 21 days at aerobic conditions. After that, the samples were washed three times with sterile water until the cold plasma treatment.⁹

Cold plasma device

The cold plasma device was built as described by Pan.⁹ Briefly, one Teflon tube, a 1-mΩ resistor, and an outer cooper foil surrounding the Teflon tube connected to a high-voltage (18 kv). Premixed argon (98%) and oxygen (2%) passed into the teflon tube at a flow rate of 5L/min. The plasma is generated inside the tube by the high-voltage electrodes.

Disinfection of the root canal

Twenty-five specimens were used to verify the effectiveness of cold plasma against the E. faecalis biofilm in root canal system. The tooth were divide in 5 groups of 5 teeth. Group 1 was used as negative control, groups 2 – 4 were treated by cold plasma for 2, 5 and 10 minutes, respectively (Figure N°1). Group 5 (positive group) were treated using NaOCl irrigation. After that, root canal was washed with sterile water and sterile paper points were inserted into the canal to retire the bacterial. The paper points were places into sterile tubes with BHI for 7 days in aerobic conditions at 37°C to observe microbial growth.⁹

Figure 1 Photograph of cold plasma jet during in vitro tooth root canal.

Statistical analysis

Analysis was performed using Anova One-way post hoc Tukey, and a P value < 0.05 was considered significant.

Results

The results of this experiment (Figure N°2) showed that NaOCl canal treatment (positive group) do not have a statistical difference in compare with 2 minutes cold plasma treatment (p = 0.622). Cold plasma treatment at 5 and 10 minutes, showed the total inhibition of E. faecalis growth in the root system canals. Negative control showed a high E. faecalis presence in compare with the other experimental groups (p < 0.0001).

Figure 2 Cold plasma jet in 5 and 10 minutes showed a total inhibition of E. faecalis growth in compare with other treatments.

Discussion

Reinfection of the root canal system after the endodontics procedures can be explain by the presence of E. faecalis (mainly) in the dentinal tubules that in time can be activate and avoid the immune system response provoking a fully reinfection needs a retreatment or total tooth retire.^3-5 Many techniques for tooth disinfection have been proposed such ultrasonic, laser, and chemicals, however, the literature report that these techniques some times are functional and other do not.^1,2

Cold plasma technology has been used for many proposed since disinfection of alimentary to medical device.⁹ In this way many reports in dental sciences have been used this technology to disinfection of wounds and other application.⁷ The study showed great effects in disinfection of E. faecalis in root canal systems. Application of cold plasma in the root canal over 5 minutes obtain a total disinfection of E. faecalis. These results are in concordance with previously studies that encounter total disinfection of other bacteria include E. faecalis from root canal systems.^9-11

Microbial inactivation by cold plasma is produce by the vibration of O₂ and N₂ molecules producing the reactive oxygen and nitrogen species¹² that provoke a damage by oxidation of microbial cell membrane, proteins and DNA strands.¹³ In this manner the cold plasma technology can be used has a disinfection therapy in dental endodontic procedures.