Bhai Rama Singh jee did not say anything about using the toothpaste or not. All he mentioned was that before sleeping if we clean our teeth with Black pepper and salt, our teeth and gums stay healthy for long time. At that time I noticed that he had beautiful teeth.
Regarding the use of toothpaste for Bibekis, I think it is okay to use it because the toothpaste is not eaten but used to clean our teeth. Its use is similar to that of soap used for the outer body. For this reason the dietary Bibek rules would not apply to it.
Having said that, it would be better to use Daatun but Daatun is not available in Canada and other Western countries. The use of Neem or Kikker Datun is very good for your teeth. This is my humble opinion.
Kulbir Singh
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥