What makes your bristle?

The stiffness of a toothbrush bristle is proportional to …

1. The modulus of the material,
2. The cube of its length,
3. The 4^th power of its diameter.

Given that we would choose a soft material to use as a lap, why is dental advice ‘Use a soft toothbrush’?

Sam

Possibly so that you don't lap away your even softer gums.

A hard brush will cause gum damage.

Ian S C

I use hard cast iron for laps so the softer job is lapped to conform with the shape of the lap.

Soft tooth brush bristles bend to conform to the uneven shapes and crevices of hard teeth. Stiff bristles would skate right over top of gaps between teeth.

Who sits around thinks about this stuff anyway?

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My dentist tells me that a good electric toothbrush will not damage the gum, it actually does them some good, toughens them up and makes them lees liable to infection apparently.

Hopper said "Who sits around thinks about this stuff anyway?"

An old fuddy duddies like me who makes swarf no more, wondering how can he stir these clever blokes with stuff of little consequence.

It's not working

I had hoped for the last lap!

Sam

I use a hard one 😬 Soft one does not do it for me. My gums are so far receded which is just how it is. My teeth do not rattle 😂

Bri

Sop far no one has been given the brush off!

Old toothbrushes are handy for cleaning taps after use, or threads in screw on chucks (Like Heinecken, they can reach the parts that paint brushes cannot! )

For our some of far flung overseas readers, Heinecken is a lager sold in UK.

I'll leave now!

Howard

Or for browny points with the misses, they are great for getting the crud off the back of diamonds in rings. Just dont let her catch you using hers to do it.

Well, she could hardly expect you to clean her jewellery with a brush that's been inside a 4-jaw chuck full of swarf and cutting-fluid!

Pedant alert.

Isn't it inversely proportional to the cube of its length?

Neil

Absolutely Neil,

I stand corrected ...

The softness of a toothbrush bristle is proportional to …

1. The modulus of the material,
2. The cube of its length,
3. The 4^th power of its diameter.

Sam ... a not so alert pedant.

Sort of on topic and the extraordinary knowledge base on this forum will, I'm sure, solve a mystery for me!

I have two Oral B rechargeable toothbrushes - one for the downstairs and one for the upstairs bathroom. I use one in the morning after my shower and one upstairs at night before bed. Useage is essentially similar, similar toothpaste, similar cleaning time, both carefully dried after use and replaced in charger. After a couple of days use, the upstairs on its base starts to collect a hardening blob of toofh paste between the brush handle and the base, the downstairs one remains consistently clean. I have just cleaned the upstairs unit for the third time in a year and it's driving me crackers!! Why the difference and, given that both are cleaned and dried after use, where is the toothpaste residue coming from????? Other than overtime by the workshop gremlin, I have no idea!!

rgds

Bill

An upstairs gremlin perhaps, Bill?

Sam

Any chance of a photograph?

Bill,

Sight unseen, I suspect there's a sealing problem, and that a toothpaste slurry is working its way down the inside of the unit. Can you dismantle it without difficulty?

Sam

Bill, assuming this is consistent between brush head changes, then it will be temperature and humidity difference. On one brush the residual paste is drying out on the head and shank, to be washed off at next use, on the other it is running all the way down and collecting in the gap before it dries out.

The unpleasant smell bothers me, and I have clearly spent too much time thinking about it 😁

Altitude.

Thank you all. Sam, quite right, of course ..." better than a thousand words", so -

Downstairs

and

whereas, Upstairs -

and

... toothpaste, by the way, similar for both. Just doesn't make sense to me!

rgds

Bill

Swap the two entire units between upstairs and dowstairs and see if prolem moves to. That way you know if problem is the unit or the environs or the toothpaste.

Could be temp or humidity.

Edited By Hopper on 08/04/2019 12:37:30