Sir, with regards to the letter by Whyatt et al. on sodium hypochlorite (NaClO) and paediatric patients,1 they stated: ‘Anecdotally, clinicians typically err on the side of caution for paediatric patients…' Also: ‘However, the evidence base to support this is limited and there is a lack of a protocol for endodontic treatment in teeth with immature apices.' AAE states ‘the most commonly used antimicrobial irrigant is NaOCl, an oxidizing agent that releases chlorine in the form of hypochlorous acid (HOCl)…'2 This statement already mentions HOCl. The letter did not offer clinicians alternatives to HClO, which is worrying considering the literature available.3,4,5

HClO is obtained by the electrolysis of saline mixed with distilled water, demonstrating antimicrobial potential and low cytotoxicity.3 In addition, HClO has proinflammatory and anti-inflammatory properties, regulating cytokines and growth factors.5 Higher HOCl concentrations (500 ppm) provide significantly higher antibacterial effect, and no cytotoxicity.4

The negative effects of NaOCl on dentine have been proven.3,4,6,7,8,9 Higher concentrations increase its deleterious effects. Additionally, 5.25% NaOCl significantly reduces flexural resistance of dentine, compared to a 0.5% NaOCl solution - 5.25% NaOCl greatly reduced 34.1% of tooth fracture strength, with degradation of the intratubular wall leading to enlarged dentinal tubules and the loss of intertubular dentine.9

Deciduous teeth with immature apices will show even more fragile walls, with greater impact in tubules and this will obviously affect longevity. Inflammatory reactions in children would also be a matter of concern. Exposing their tissues to an irritating solution makes no sense at all. Therefore, alternatives to NaOCl are available and have proven their efficacy. The use of HOCl is one of these alternatives and its use should be considered.