CATEGORY 74 AUSTRALASIAN DENTIST CLINICAL TDS ClTemp Vol pH 180 mg/L 7 mg/L 20°C 140 mL 6.7 Legend. TDS: Total dissolved solids; Cl- (Chloride) Time Cw O3 TOC Cw H2 Ca O3 (min) (mg/L) (ppm) (ppm) (ppm) 2.5 2.7±0.19 4.3±0.18 NT NT 5 4.8±0.31 6.3±0.35 1±0.1 0 7.5 5.5±0.23 8.5±0.32. NT 0 Legend. Cw O3 ( Ozonated water concentration), TOC (Total oxidants concentration), Cw H2 (Dissolved molecular hydrogen concentration), CaO3 (Ambient air ozone gas concentration), ppm (parts per million), NT (Not Tested). Table 1 Water characteristics Table 2 Ozonated water, TOC, H2 and ambient ozone gas concentrations the concentration of other oxidants (i.e., hydrogen peroxide, hydroxylradicals, hypochlorous acid, hypochlorite) which canoxidize iodide to iodine. Dissolved molecular hydrogen concentration was measured with a hydrogen sensor (Trustlex ENH-2000, Osaka, Japan). Ambient ozone gas levels in air were monitored with a portable gas detector (PortaSens II, Analytical Technology Inc., USA) at 5 cm from the EOG during device activation. The direct EOG tumbler has a preset working time of 2.5 min (One cycle). Tests were performed at 1,2and 3 consecutive cycles, 2.5 – 5 – 7.5 min operating time, respectively. Ozonated water tests were repeatedfive times, total oxidants and dissolved molecular hydrogen were analyzed by duplicate. Ambientozone gas levels were monitored at 5- and 7.5-minoperation time. Values are expressed as (X) ± SD. Results The EOG device operates at a constant current and the voltage is auto-adjusted according to water electrical conductivity. The lower the water conductivity or total dissolved solids (TDS), the higher is the operating voltage. This feature will ensure that the water electrolysis performance is stable within a large TDS range (50 – 400 mg/L). The concentration range of ozonated water, TOC, H2, and ambient ozone gas, are depicted in (Table 2). It is noteworthy to mention that the evolved gas bubbles by water electrolysis have a sub-micron size, and the resulting increase of the gas/liquid contact area enhances gas dissolution into water. Another factor which can also contribute to dissolution rate and usage efficiency is the residency time of then an obubbles inside water before total off-gassing, around 1 minute for the tested EOG device (Figure 3). Discussion Ozonated water concentration range in ozone therapy, especially in dentistry, can be classified as low (1-3 mg/L), medium (4-8 mg/L) and high (10-25+ mg/L) (Sabbah et al., 2018). In severely infected clinical cases, high range ozonated water concentration is first used and then reduced to medium/low according to the healing phase progression. In cases where there is a need for multiple applications of ozonated water, it would be more convenient for both dentists and patients to apply ozonated water at home, especially when low/ medium concentrations are advisable. The tested direct EOG device produces a low to medium ozonated water concentration range (2 – 5.5 mg/L), while the total oxidants concentration (TOC) range is 4 – 8.5 ppm (Table 2). Since the monitor used for dissolved ozone concentration measurement is highly specific to ozone, the higher TOC values correspond to reactive oxygen species generated by ozone decomposition in water and are measured by non-ozone specific methods. For safety reasons, maximum allowable ozone gas levels in ambient air is ≤ 0.070 ppm for an 8-hour period (EPAUnited States Environmental Protection Agency). At 5- and 7.5-min continuous operation, ozone gas was not detected at 5 cm from the device. Ozonated water is mostly known for its antimicrobial and disinfection property and has the lowest CT factor (Concentration x Time) among common oxidants used in various fields (Gomes et al., 2019, Azim et al., 2020, Romanovski et al.,2020, Epelle et al., 2023). Dentists routinely prescribe oral antiseptics or over-the-counter mouthwash solutions (i.e., Chlorhexidine, triclosan, povidone-iodine, benzydamine‑hydrochloride, essential oils, chlorine dioxide, hydrogen peroxide) for preventive/ therapeutic oral care regimen, or after professional in-office interventions. The most reported side effects of oral antiseptics and mouthwash solutions are teeth staining, burning sensation, taste alteration, mucosaldesquamation and ulcers. Some formulations havefood allergens which might trigger allergic reactions (Tartaglia et al., 2019, Coimbra et al., 2023). Ozonated water at 1.2 – 20 mg/L showed no cytotoxic effects on human oral epithelial cells and gingival fibroblasts, while chlorhexidine, hydrogenperoxide 3% and sodium hypochlorite 0.2% showedcytotoxic effects. Mouthwash solutions cytotoxiceffects on primary human gingival fibrob lasts were highest with chlorhexidine, followed by benzydamine-HCl and essential oils (Huth et al.,2006, Mon et al., 2019, Alpaslan et al., 2021). Several studies reported that ozonated water with a concentration range of 2-16 mg/L had no cytotoxic effects, induced increase of cellular metabolism, intracellular ATP, growth factors release, and contributed to cells proliferation and acceleration of wound healing (Ebensberger et al., 2002, Kuroda etal., 2015, Borges et al., 2017, Küçük et al., 2021,Leon et al., 2022). Ozonated water at 0.5 mg/L had the same local hemostatic effect as 4 mg/L and is as effective as liquid thrombin in decreasing bleeding time (Sakai et al., 2014). All these beneficial properties as antimicrobial, anti-inflammatory, wound healing acceleration, absence of cytotoxicity and undesirable side effects, make ozonated water highly indicated for home oralcare. Home oral care – general guidelines The treating dentist usually plans a customized preventive – therapeutic home oral care according to patient’s risk factors. Long term daily use of mouthwash might decrease nitric oxidebioavailability by affecting the oral microflora and might cause blood pressure elevation (Joshipura etal., 2020). Taking into consideration the potential long-term effect on normal oral microbiota, general preventive guidelines are here presented and should not be considered as specific protocols. Caries and periodontal diseases Dental plaque biofilm is a key risk factor in caries and periodontal diseases which affect many people worldwide (Marsh, 2006, Frencken et al., 2017). Figure 3 (a) Electrolysis cell visible; clear water; (b) Gas nanobubbles; opaque water.
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