dental care for 12 year old chihuahua?

i have 3 chihuahua . one just passed away last sunday of leaking heart valve. i m so sad. now i have 2 left they both 12 years old and they are very little. i didn't know how important dental care is for dog so i never take them to the dentist. now i want to take my other 2 chihuahua to go clean up their teeth but i m so afraid my chihuahua can't handle it because i think the dentist might take some of their teeth out. i m so scared please help me should i take them to the dentist or just brush their teeth at home? their teeth are very yellow and smell.
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If their hearts can take the anesthesia, it is best to take out any loose, rotten teeth.
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