If it's an emergency then yes. Dentistry has come a long way now. Your dentist needs approval from your gynecologist to take an x-ray. They will place a double lead shield to minimize secondary radiation (which is negligible to begin with). If antibiotics are needed your gynecologist will be consulted weather OK to prescribe those. If treatment is needed then safe or non-epinephrine containing anesthesia might be used. The procedure itself should be harmless.

Mam , please visit a good experienced endodontist.as you are going through pregnancy and already third trimester along ,so any invasive treatment can't be done.it requires a x-ray to evaluate the depth of caries ,but better to be avoided during pregnancy.so your endodontist will evaluate the situation and plan a treatment.if filling, you can safely go for it .But RCT involves use of antibiotics usually.but your endodontist still can go for Less or no antibiotics use.so better you go for a good endodontist