'Abdullah bin Mas'ud Allah be pleased with him narrated that the Messenger of Allah (PBUH) said:
“Those who exaggerate [in their devotions, behaviour, or speech] have destroyed themselves.”
[Muslim, Ch.14, On Moderation in Devotions, Hadeeth 144]
These are people who exaggerate in their practice of religion and their affairs of life. Moderation is encouraged. And people should practise religion and live life according to their ability and capacity.
People should be moderate in their behaviour and speech. And not preach hatred and violence. Our practices and interpretations of Islam should not be severe and extreme to burden Muslims and deter potential ones from joining in the faith.
But that is not say we should compromise our faith. And be liberal with it.
Using toothpaste whilst fasting is makruh & disliked. One may use a scented miswak, a plain brush &a tongue scraper instead.
Also a person who is a musāfir (traveller) before Dawn may omit the fast of that day. If journey begins in day, can't miss fast.