Wikipedia:Reference desk/Archives/Science/2019 September 13

= September 13 =

Sprayed concrete lining
Can sprayed concrete lining be used for tunneling any type of ground including sand for example? How do you prevent collapse of excavation between excavating and spraying suck? 82.132.186.180 (talk) 08:13, 13 September 2019 (UTC)


 * You'd need some type of temporary structure to hold back the sand until the concrete sets. Another concern is that getting concrete to set in such an environment may be difficult. Massive fans would be needed to bring in fresh air, and maintaining the desired temperature may also be difficult. SinisterLefty (talk) 08:36, 13 September 2019 (UTC)
 * See Tunnel construction. Some tunnel boring machines have pressurised compartments at the front end, allowing them to be used in difficult conditions below the water table. Unstable wet soil can be temporarily stabilised by freezing. DroneB (talk) 11:47, 13 September 2019 (UTC)


 * Yes, see Shotcrete for one system. Stabilisation at the tunnelling face itself is done by some development of the tunnelling shield invented two hundred years ago by Brunel. Freezing is sometimes used, but probably not in sand (wet sand isn't common, as it would either be washed out already, or else it's only a shallow marine deposit and so would be easier to tunnel by the cut and cover approach.). Andy Dingley (talk) 13:33, 13 September 2019 (UTC)

Root canal treatment by vacuum suction
Is it theoretically possible to do root canal treatment by vacuum suction (specifically canal cleaning), without local anesthesia? Not a medical advice. 212.180.235.46 (talk) 18:21, 13 September 2019 (UTC)
 * That's kind of two questions. Do you want them tied together, or answered separately? --OuroborosCobra (talk) 18:31, 13 September 2019 (UTC)
 * Complete cleaning of infected pulp requires skilled use of Endodontic files and reamers (or a rotary file) or decay will continue. Alternatives such as lasers or vacuum suction have not been proven adequate. It is theoretically possible to operate without anesthesia but a patient would surely prefer medication such as Diazepam to reduce pain and anxiety in dentistry. DroneB (talk) 19:07, 13 September 2019 (UTC)


 * Diazepam is not a pain reliever. Local anesthesia is used. AboutFace 22 (talk) 21:40, 13 September 2019 (UTC)
 * Sedation is more commonly used than anaesthesia. Also the anaesthesia for root canal treatment is quite complicated, so generally not preferred.
 * Suction wouldn't work for root canal work. The tissue to be removed is not only the necrotic (so easily removed) but also some (currently) healthy tissue which can't be preserved (that's pretty much the definition). So it can't be removed easily by mere suction.  Also the canal will need work to smooth it out, so that the mechanical obturation put in place afterwards will be reliable. Andy Dingley (talk) 23:19, 13 September 2019 (UTC)
 * Unless you're torturing someone, either local or general anesthesia is necessary regardless of what tools are used. Root canal treatment involves opening the tooth and removing the pulp, which contains nerves. This is excruciatingly painful if the pain is not blocked. Toothache is often caused by inflammation of this pulp. --47.146.63.87 (talk) 05:56, 14 September 2019 (UTC)

I watched my wife have a root canal without anesthesia, this was her choice, did not flinch. — Preceding unsigned comment added by 81.131.40.58 (talk) 12:49, 16 September 2019 (UTC)


 * That would be because the nerve was already dead (unless she is incredibly brave and can mentally block out pain). I found the process unpleasant even with a local anaesthetic.   Dbfirs  13:35, 16 September 2019 (UTC)
 * Are you sure you're not conflating local and general anesthesia? Local anesthesia is when the dentist injects anesthetic around the nerve going to the tooth. This is done for fillings and other procedures. General anesthesia is inducing a coma. (As long as we're trading war stories, I had my impacted wisdom teeth removed with just local anesthesia and nitrous oxide. Didn't feel any pain even though they were nice and deep in the jaw, and one tooth had to be broken to be removed. The unpleasant part was the pain following the procedure. The co-codamol I was prescribed did nothing, so I spent the next few days swapping ice packs and guzzling ibuprofen.) --47.146.63.87 (talk) 23:15, 16 September 2019 (UTC)