Is it permissible to fast for someone who has an unavoidable dental appointment during the daytime in Ramadan, with the possibility of receiving a local anesthetic injection and some calculus spray reaching the throat?

Dental treatment during Ramadan (definition) should be postponed until night for those who are able, to avoid complications that might lead to breaking the fast. There is no harm for those who are unable to postpone. The anesthetic injection does not invalidate the fast because it is neither food nor drink. If it is highly probable that particles of dental calculus reached the throat and were swallowed, then one must make up for that day, unless the person is sick and thus permitted to break the fast. However, if something unintentionally reaches the throat after taking precautions, it does not harm the fast.