Table 1 Electrolyzed water used in the human dental setting

1

Kim J., et al. 2017 [17]

RCT

To evaluate the effectiveness of electrolyzed hydrogen water against oral Streptococci biolfims.

6 healthy adults with at least 20 teeth.

Oral rinse with electrolyzed Hydrogen water (H-water): dissolved hydrogen, 1.5 ppm; oxidation-reduction potential, − 600 mV ~ − 700 mV. Patients rinsed 3 times dayly with the test intervention for 2 weeks, then after pausing for 1 week, proceeded with tap water oral rinses for two weeks.

Tap water oral rinse

Mean ± SD of Streptococci CFU in saliva

After one week, four of the six participants showed significantly lower streptococcal CFU after gargling with H-water than after gargling with tap water (*p < 0.05, **p < 0.01). For all 18 trials data, The CFU values were also significantly lower when oral rinse was performed with H-water (p < 0.005).

Oral rinse with electrolyzed water would be helpful in diminishing oral Streptococci related to caries.

2

Valdez-Gonzales C., et al. 2013 [18]

RCT

To evaluate the effectiveness of OPW in reducing bacterial loading as an irrigating solution in necrotic pulpectomized primary teeth.

40 child patients between 3 to 8 years with at least 1 necrotic teeth needing canal treatment.

Canal irrigation with oxidative potential water (OPW):+ 1100 mV, pH and ORP greater than 2.7.

Canal irrigation with 1% NaOCl

Number of CFU/mL on teeth with canal before and after irrigation.

In the pre-irrigation samples corresponding to the OPW group, a median of 1.65 × 10⁹ CFU/mL (range, 9 × 10⁸–2.1 × 10⁹) with a mean of 1.63 × 10⁹  ±  4.18 × 10⁸ CFU/mL was obtained. In the same experimental group for post-irrigation samples, a median of 0 CFU/mL (range 0–5 × 10⁸), with a mean of 5 × 10⁷ ±  1.53 ×  10⁸ CFU/mL, was obtained. The difference  between the bacterial  load after irrigation with OPW was statistically significant (P < 0.0001). Comparative analysis showed no statistically significant difference between 1% NaOCl and OPW (P = 0.1519).

Electrolyzed water could be a feasible alternative for irrigating after pulpectomy of necrotic primary teeth.

3

Gulabivala K., et al. 2004 [22]

In vitro

To test the effectiveness of electrochemically activated aqueous solutions in the debridement of E. faecalis biofilms in root canals of extracted teeth.

198 extracted human single-rooted teeth.

Canal irrigation with electrochemically activated water: Neutral anolyte (NA) (pH 6.5), acidic anolyte (AA) (pH 3.0), or catholyte (C) (pH 11.5).

Solutions with and without ultrasonication. PBS, NaOCl (3%)

Remaining CFU/mL

The NA, NA (U), C alternated with NA and the AA (U) groups all had significantly (α = 0.05) lower CFU counts compared with PBS controls.

There was a significant difference between the C/NA groups with and without ultrasonication but not between other combinations. NA (U) and AA (U) were the most effective test solutions but NaOCl (3%) gave by far the highest bacterial kills.

4

Marais JT, Williams WP. 2001 [23]

In vitro

To evaluate the antimicrobial effectiveness of ECA on a selected group of anaerobic bacteria in root canals of extracted human teeth.

60 caries-free, single-rooted, adult maxillary anterior human teeth were collected from the extraction clinic, intracanal Irrigated for 5 min with one of the four different irrigation solutions.

Electro-chemically activated water (ECA): pH 7.0 or pH 9.0.

Distilled water, Sodium hypochlorite (3.5% concentration).

Mean (SD) of CFU/mL of P. intermedia, P. gingivalis, E. faecalis, and A. actinomycetemcomitans.

ECA groups showed fewer numbers of colony formation 693 (253), 525 (418) respectively. This reduction however, did not approach the negative (zero) values as recorded for NaOCl and in fact are closer to those values obtained for the control group (group A).

The use of ECA caused a reduction in the number of anaerobic bacteria within the root canal system, but this was not statistically significant (P > 0.05) when compared to sodium hypochlorite.

5

Zan R., et al. 2016 [24]

In vitro

To evaluate and compare the antibacterial efficacy of SPO on E. faecalis biofilms in human root canals at different irrigation times.

126 extracted human mandibular premolar teeth with a single canal.

Canal irrigation with super-oxidized water (SPO) for different periods of time.

Canal irrigation with 0.9% NaCL, 5.25% NaOCl for 2 minutes.

CFU/mL E. faecalis.

There were statistically significant differences between negative control and all groups (P < 0.05). Although positive control showed no statistically significant difference when compared with SPO groups.

Super-oxidized water had a highly antibacterial effect against E. faecalis biofilms in root canals. Moreover, super-oxidized water indicated a remarkable and similar bactericidal effect to that of traditional NaOCl against E. faecalis biofilms.

6

Hope CK., et al. 2010 [25]

In vitro

To elucidate the importance of the biofilm modality of growth of E. faecalis with respect to its recalcitrance during endodontic irrigation.

8 extracted human single teeth.

Super-oxidised water (SOXH2O), pH 5–6.5, components: Sodium chloride (0.42%w/v), hypochlorous acid (0.022%w/v) and sodium chlorate (0.002%w/v).

1% NaOCl and PBS.

Mean log CFU/mL of E. faecalis.

Remaining mean log CFU of E.faecalis from SOXH2 irrigated teeth was greater than 1% NaOCl (4.66 vs 3.36), without statistical significance (P = 0.177).

Biofilms of E. faecalis were susceptible to concentrations of irrigant that proved ineffective in the tooth model.

7

Ezure M., et al. 1996 [translated from Japanese] [19]

RCT

To evaluate the effect of oral hygiene with Water-spray-type Oral Washing Unit and Aqua Oxidizing Water on experimental gingivitis.

15 males with clinically healthy gingiva discontinuing or not oral cleaning.

Oral irrigation with aqua oxidizing water (AOW) three times a day during 30 s.

Discontinuation of all oral cleaning, and oral washing with sterile distilled water.

The change of the plaque index (P1I), the gingival index (GI), and gingival crevicular fluid (GCF volume), bacteria flora, halitosis for 1 and 2 weeks.

Changes in P1I showed significant reduction in the negative control group and test group in comparision with the controls (p < 0.05, p < 0.01). The time course of changes in GCF volume showed significant changes compared to the negative control group and the test group(p < 0.05, p < 0.01). Based on the results above, a plaque-controlling effect due to the use of the AOW was recognized, and an effect on bacterial flora due to use of AOW as the oral washing agent was observed.

The use of aqua oxidizing water for irrigation is useful in exerting a plaque-controlling effect and a gingivitis-preventing effect.

8

Ruqshan Anjum MG., et al. 2015 [26]

In vitro

To determine the antimicrobial efficacy of chlorhexidine, Oxum, Ozonated water in root canals infected by E. faecalis.

40 extracted single-rooted human teeth.

Canal irrigation with super oxidized water, (Neutral pH), components: Hypochlorous acid, Sodium hypochlorite, Chlorine dioxide, Ozone, Hydrogen peroxide, and Sodium chloride.

2% chlorhexidine, Ozonated water and NaCl.

CFU/mL of E. faecalis.

CFU of E. faecalis decreased in the pre-test when treated with CHX followed by super-oxidized water, ozonated water and saline.

Chlorhexidine significantly reduced the number of E. faecalis followed by super-oxidized water and ozonated water.

9

Chaudhari H., et al. 2019 [20]

RCT

To compare the superoxide solution with povidone-iodine by means of clinical parameters and microbiologically by CFU.

20 sites with chronic periodontitis (PD ≥ 5 mm) (ten sites per group). All patients received SRP.

Superoxide solution.

Povidone-iodine.

Mean/SD of Probing pocket depth (PPD) and sulcus bleeding index (SBI). CFU/mL.

The mean PPD at baseline and 30 days was observed to be 1.716 ± 0.351 and 0.683 ± 0.274, respectively, for EWA and 1.700 ± 0.380 and 1.0 ± 0.00, respectively, for control. The mean gingival sulcus bleeding scores at baseline and 30 days were observed to be 1.726 ± 0.351 and 0.603 ± 0.274, respectively, for EW and 1.700 ± 0.380 and 1.25 ± 0.00, respectively, for control. There was a statistically significant reduction in CFU in EW after 1 month as compared to control.

Superoxidized water irrigation as an adjunct to SRP proved to be effective in the treatment of periodontitis, without any side effects.

10

Ito K., et al.; 1996 [21]

RCT

To compare the effects of Acid Water with placebo treatment on the ultrastructure of early plaque formed on dentine specimens attached to retainers in the human oral cavity.

24 dentine specimens from 12 freshly extracted healthy human teeth placed in retainers. The retainers were placed in 6 healthy participants.

Acid water (AW): pH < 2.7, ORP > 1100 mV, active oxygen and Chlorine.

2% chlorhexidine, saline.

Morphology and developmental condition of plaque deposits. Thickness of plaque formed in mm.

On AW treatment, the plaque consist of coccoid forms and and short rods, the plaque is not well developed. The thickness of plaque accumulation was moderate (8.80 mm). On CHX treatment, plaque developed was fairly and was composed mainly cocci, very few short rods and filaments were hardly evident. There wasn’t statistically significant difference between AW and CHX (p < 0.001).

Washing with AW has almost the same potential for inhibition of plaque formation as washing with CHX without producing any side-effects. Therefore, there is a possible use for AW as an anti-plaque.

11

Lata S., et al. 2016 [27]

In vitro

To compare and evaluate the antimicrobial effectiveness of ECA, 1% hypochlorite, and 3% hypochlorite when tested against the standard strain of E. faecalis.

48 extracted human permanent maxillary central incisors of patients between the age group 40 to 60 years irrigated with different solutions for 5 minutes.

Electro-chemically Activated (ECA) water.

1% an 3% sodium hypochlorite, distilled water.

Mean (μL)/SD CFU and Mean (nm)/SD CFU of E. faecalis, before and after irrigation.

Differences between CFU values between groups was found to be not statistically significant. There was a statistically significant difference between the optical density values among sodium hypochlorite, and EW.

The antibacterial efficacy of ECA water was found to be comparable with sodium hypochlorite solution against E. faecalis.

12

Hope CK., et al. 2010 [25]

In vitro

To validate an extracted tooth model of endodontic irrigation.

Twelve extracted, single rooted teeth.

Super-oxidised water (SOXH₂O).

PBS, 1% NaOCl, 2% CHX.

The number of viable bacteria recovered, mean (Log₁₀ CFU) E. faecalis.

The number of viable bacteria recovered from the teeth following irrigation with the PBS control was 3.329 (log₁₀ cfu), whilst the antimicrobial irrigants 1% NaOCl, 2% CHX and SOXH2O yielded 0.552, 1.441 and 1.577 (log₁₀ cfu) respectively. However, only the difference between PBS and 1% NaOCl was statistically significant.

The extracted tooth model is a useful method for evaluating the effectiveness of antimicrobial endodontic irrigants. In these preliminary experiments, the most effective irrigant was 1% NaOCl.