Nowadays toothpaste tubes come with a flat top so that they can stand upside down at the sink. The upside is that the paste has enough time between brushings to flow slowly down and you never have to squeeze or shake the tube to get at the last few drops. The downside is that those last few drops come quite suddenly.

A transparent longitudinal strip along the tube would allow you to monitor the filling status of the tube and procure a replacement just in time.

For the high-tech geeks this could also be done with a small electronic scale, but you would have to know the exact weight of the empty tube (which could be printed on it) to adjust the scale to the zero/empty point. And your wife's toothpaste tube would need another setting or another scale. So I'd prefer the low-tech solution.
-- Toto Anders, Dec 15 2015

Finally... http://www.packagin...othpaste-clear-tube
[2 fries shy of a happy meal, Dec 15 2015]

//enough time between brushings to flow slowly down//
You must have really runny toothpaste. Mine doesn't flow down at all; much precision squeezing is required.
-- neutrinos_shadow, Dec 15 2015


A lot of toothpaste now comes in dispenser pumps, reflecting the need to technologize everything to the point where the packaging costs more than the product. These pumps usually have a window in the side so you can see how much is left.
-- MaxwellBuchanan, Dec 15 2015


Or, you could put a drop of different coloured toothpaste to come out last as a 'just about out' indicator.
-- AusCan531, Dec 15 2015


// ... fooling the owner into thinking it’s not squashed and depleted. Squash the air out as it gets used. //

My brand uses a rather sturdy and elastic plastic tube which resumes its original shape after squashing. They won't give you any clues, I assume.
-- Toto Anders, Dec 16 2015


// the other obvious option is to write an app //

You saved my day.

To increase accuracy, especially in the winter season when elevenses and cholocate cookies tend to increase the brushing frequency, the toothbrush would need a bluetooth sender to notify the app whenever it is removed from the holder for more than 30 seconds. Or an accelerometer which notes when the brush is in use. Which could also warn you against directional mistakes in applying the brush (side to side cost me some gum until my dentist recommended up and down).
-- Toto Anders, Dec 16 2015


Perhaps have a pressure-sensitive pad which the tube of toothpaste rests on when not in use. The weight of the tube would be fed back into the system.
-- pocmloc, Dec 16 2015


Or just keep a spare tube in the cupboard.
-- MaxwellBuchanan, Dec 16 2015


I'm trying to allocate my resources more efficiently than keeping spare this and spare that. I mean, who has a second car in the garage only for the case that the first one breaks down? Or spare glasses? They get lost or broken before they come into use. And the spare toothpaste tube will be forgotten and rotting in the dark recesses of the cupboard while I'm sitting on the pavement in front of the chemist's trying to beg a few cents for a new tube of toothpaste - only because I spent all my resources on spares.
-- Toto Anders, Dec 16 2015


//who has a second car in the garage only for the case that the first one breaks down?//

Who doesn't?
-- MaxwellBuchanan, Dec 16 2015


I think he means a drivable car, not a hulk you are cannibalizing for parts.
-- bungston, Dec 17 2015



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