You can get Life for Teeth here - I use the spray and no, I don't brush their teeth (I know, shame on me). I originally got it because I bought a 3 year old that still had her baby teeth and her teeth were covered in tartar. I didn't want to rush into putting her under until I got her settled in and in good health. It definitely removed the tartar.
As far as how often you should have their teeth cleaned - The answer would be when they need it - if you see tartar build up this holds bacteria and can damage their heart, liver and kidneys. I have been using Life for Teeth on my other two, but they are just 1 year and 2 years, but so far not one speck of tartar and I don't use it every day like I'm suppose to, more like 2 or 3 times a week. I would use it just for the good breath, but I'm really hoping it will eliminate professional cleanings entirely (as it claims).
http://www.tobysnaturalpets.com/petz.htm
P.S. isoflurane or sevoflurane gas is always the safest form of anesthesia because very little is metabolized in the liver.