No, I'm not talking about a root canal. Yes calcium hydroxide has been used as a disinfectant in root canals, but there is a movement to use it as a completely hypyallergenic disinfectant product before fillings (that are not root canals), and it makes the tooth pulp re-harden itself.
Also, I'm talking about PURE calcium hydroxide, NOT the products that are "mostly" calcium hydroxide but have toxic stuff added, like Dycal <- this is NOT what I mean.