hello and welcome to hcm forum,
thank you for writing in your query, as you stated that your canine is decayed, that surely gives an evidence that infection due to caries has now spread to the sorrounding tissue causing pain and swelling, i would recommend you to visit your dentist
so that he can prescribe you antibiotics and anti-inflammatory medication for a week, this will take care of the swelling as well as pain.
warm saline rinses won't help, use an antibacterial (betadine
) mouth wash(3-4 times/day) for as week.
also avoid hot food /drinks, do not apply hot compresses over the swelling,
i wish you good health, i hope i answered your query to your satisfaction,