We learn from this Hadith that the Prophet (PBUH) liked to clean his teeth with Miswak (a softened stick used as tooth brush for cleaning the teeth) with every Salat, but he did not made it obligatory for the reason that it would be inconvenient for his followers. It shows that he was extremely affectionate and kind to his Ummah.
This Hadith also shows that using Miswak is an admirable act. Every Muslim should make it a routine to use it as frequently as possible especially before performing prayers.