Brushing the teeth not only helps one look better and feel healthier, but also it pleases God. The religious leaders of Islam emphasized on this fact and suggested their followers to brush their teeth too.
According to Prophet Muhammad, “If you brush your teeth before saying your prayers, that prayer is better than seventy five prayers one says without brushing his teeth.”
In the Mesbah Al-Shari’a book, Imam Sadegh quoted from Prophet Muhammad, “Brushing the teeth not only cleans the mouth, but also pleases God.”
One of the things that Prophet Muhammad never forgot to do was brushing his teeth.
If you think about it, you will find out that brushing the teeth has many different advantages.
Still, a sane person knows that brushing teeth is a physical act and improves the health in one’s body only and in order to purify the soul too, they need to pray to God, to worship Him, and to ask Him to forgive the sins they have committed.
Prophet Muhammad said that brushing the teeth was like a means that awakened the souls; teeth are made clear and white with the aim of chewing the food and helping the digestion, but they become dirty and damaged by chewing the food.
source : http://www.tebyan.net