Authors' response

We appreciate your interest in our study and agree with your concern about the possible toxicity of the quaternary ammonium compound. We have tested [2 (Methacryloyloxy)ethyl] trimethylammonium chloride (MADQUAT), which is a polymerizable quaternary ammonium compound that can, therefore, be covalently bound to the resulting polymer matrix.1 There is always the concern of incomplete polymerization and leaching of the unpolymerized compound into the oral cavity, but so far, no detectable release of ammonium-based monomer that might be toxic to mammalian cells has been reported.

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