Electroconvulsive therapy is still used today in contemporary psychiatry for the management of patients with certain severe mental illnesses, to effectively reboot neurotransmitters in the brain. The analogy to shock treatment for a dental chair is surprisingly strong, since a chemical shock treatment of the waterlines of the dental chair is designed to, ideally, reboot the situation back to when the dental chair was brand-new, and the tubing was completely clear of any biofilms.
Agents used for shock treatment are designed to disrupt the EPS matrix of the biofilm, so that the biofilm fragments can be flushed from the waterline, leaving the tubing clean. Chemically, they are somewhat different to agents used to reduce the tenancy of organisms to overgrow during the normal operation of the dental chair, since these may only impair or reduce microbial overgrowth, but may not necessarily damage the structure of the biofilm. In some cases, products that are designed for continuous dosing have special formulations which allow them to be used for shock treatment (e.g. they may be used at a much higher concentration, and left in place for extended periods of time). Most commonly though, for a dental chair, a separate shock treatment agent will be used, which is compatible with the control blocks in the tubing of that dental chair, and this is left in for a prolonged period of time, for example, overnight, for dental chairs such as Belmont, Planmecca, Ritter, or Sirona.
Only a small number of brands of dental chair on the market have control blocks that are compatible with sodium hypochlorite. The indiscriminate use of sodium hypochlorite can easily cause significant corrosion to occur, as this material is extremely reactive to most pure metals as well as to many metal alloys. The general principle is to only use sodium hypochlorite when the manufacturer has explicitly stated that this is their recommended protocol. In other cases, use a purpose-built shock treatment agent (such as Dentisan Bioclear or Bilpron) that has broad compatibility with many brands of dental chairs.
Bioclear contains polyhexamethylene biguanide hydrochloride, also known as polyhexanide, which is a polymer that has a long history of use as a disinfectant and antiseptic extending back to the 1950s.  Its key mechanism of action is binding to and causing damage to bacterial cytoplasmic membranes, resulting in leakage of key components from the bacterial cytoplasmic fluid, and cell death.  This cationic biocide is used worldwide, including in wound dressings, and it has excellent antimicrobial activity, as well as good chemical stability and low toxicity. As a biocide it is superior to triclosan, octenidine, PVP-iodine and chlorhexidine, and is particularly useful in a situation where (as with waterline shock treatment) a prolonged exposure time can be provided.[3,4]