"Therefore the fact that you wear the top retainer makes absolutely no difference for the bottom teeth." — That assumes that no bottom retainer is worn. So the question still stands, if one uses a lower retainer, can the wire be removed?. (I know from personal experience that it can, but can't say it's true in general.)

"decreasing the heart rate" — it doesn't so much slow it as it does prevent it from increasing. I take bisoprolol, and recently started bicycling again after getting a stent. First I asked my doctor what the maximum heart rate for me would be and his response was "don't worry about it". It turns out that even on relatively long hilly rides, my pulse is almost always between 105 and 120 bpm. I have lots of energy, but little power. When my body produces adrenaline to get me up the hills (previously 150 bpm) the beta blockers inhibit it and I ascend very slowly (but don't get out of breath).

@anongoodnurse says "I didn't bold the quotes to emphasize pain relief, you did.". — Correct. But can you show me where one should bold the quotes to emphasize where the literature mentions physical damage? That's what I was looking for and failing to find.

@anongoodnurse says "The most effective treatment is to urinate on the affected area". Suppose someone would rather put up with the pain rather than go through the embarrassing treatment, and then two days later learns that not urinating on it also results in amputation; wouldn't it be remiss not to have mentioned this significant fact when suggesting how to relieve the pain?

@anongoodnurse asks "Does that make the statement, "Urine is a pain reliever." true?". Of course not. Did I ever claim that NTG is a pain reliever? What's upsetting you so much is the popular literature itself, not anything I said.

"Nitroglycerin is not a pain killer or pain medication." — All the popular literature disagrees with that statement. (Note that I'm not claiming it is correct or that you are wrong.) See my update.