Brushing Teeth on Shabbas

Question

I recently saw a “glatt kosher Shabbos toothbrush” advertised. Is it permitted to use it on Shabbos with water? Even if it is technically permitted to use it on Shabbos, is there an issue of uvdin dechol to brush one’s teeth with a toothbrush on Shabbos?

Thank you.

Beracha

Rav Azriel Auerbach 

There are a number of melachos involved with brushing one’s teeth on Shabbos. From what I have heard, these kosher toothbrushes deal with meleches sechitah, i.e., the water in between the bristles. Even though the plastic bristles do not absorb water, nonetheless, if the bristles are packed tightly together, then removing the water is sechitah. 

How can one determine if one’s kosher toothbrush is really kosher? The rule is that the bristles are close enough together that if one turns the toothbrush upside down and the water remains in between the bristles, the water is considered halachically absorbed, and then it is forbidden to brush one’s teeth with such a toothbrush, for it would constitute meleches sechitah on Shabbos. The same rule would apply to a brush used for cleaning dishes.

I would like to add that even if the toothbrush is “glatt kosher,” there are two issues that one cannot kasher. Firstly, it is forbidden to use toothpaste on Shabbos, for spreading a thin layer of paste across one’s teeth and gums is included in meleches memarei’ach. Secondly, if one suffers from bleeding gums, brushing one’s teeth on Shabbos will most likely aggravate his condition and cause bleeding. It would be forbidden for him to brush his teeth on Shabbos.

As far as uvdin dechol is concerned, since this particular toothbrush is set aside specifically for Shabbos use, its usage would not be considered uvdin dechol.