Quittintime: Toothpaste (!!)

Toothpaste Abrasiveness

I was exceedingly annoyed a while ago, over at Taunton, when someone asked a question about using toothpaste as a finishing compound (for violins as I recall). There was a general pig-pile from a lot of folks who ought have known better, and for some time I have been mumbling under my breath about it.

Toothpastes ARE abrasive. Here is a chart showing relative abrasivity: http://www.oxyfreshww.com/oral_health/articles/abrasivityindex.asp

And from http://www.australianprescriber.com/magazines/vol17no2/toothpaste.htm: ?For efficient tooth cleaning, the dentifrice requires a degree of abrasiveness. The common abrasives used include dicalcium phosphate dihydrate, insoluble sodium metaphosphate, calcium pyrophosphate, calcium carbonate, alumina trihydrate, magnesium trisilicate and, more recently, silica gels. These abrasives have a hardness ranging between that of dentine and a value below that of enamel in order to be safe but effective stain removers. Nevertheless, cervical tooth abrasion can occur, creating wedge-shaped notches usually near the gingival margin. In severe cases, pulpal pathosis and periapical lesions may result. However, factors other than toothpaste abrasivity play the major role in cervical abrasion e.g. injudicious toothbrushing with a hard-bristle toothbrush and excessive pressure.?

All of these are used as abrasives in other uses, but for toothpaste the grind is exceedingly fine to prevent excessive tooth wear. The abrasivity is measured using a test for tooth wear and not with standard abrasive tests used in woodworking and the like. ?The abrasive properties of a dentifrice are measured in a standard test called the Relative Dentin Abrasivity (RDA) Test, which is conducted by accredited facilities. The abrasivity of the dentifrices are recorded as RDA values and used by all toothpaste manufacturers. The higher the RDA value the more abrasive the dentifrice. In this test, baking soda alone scores a 7, and the ARM & HAMMER? products ranging from 10-117, all within accepted levels of abrasivity and typically below most other toothpastes.? (http://myoralcare.com/questions/)

This test actually makes sense, as we are interested on the effect upon teeth, not upon some arbitrary grit and hardness level.

But to the initial question: You certainly CAN use toothpaste for polishing out fine scratches. And the formulation that makes it a little sticky is also very useful for keeping it onto the part where you are working. Try it on something some time. Rub toothpaste and a little water in a small area where there are small scratches and see if it doesn?t tend to smooth things out.