Good thinking! I too would go with this. I’m assuming the OP has counted day of arrival as day one? If do nothing the 500 baht per day overstay fine is normally waived for the first day. However, passport would still be stamped in red as ‘overstay’.
First time I went to a dentist in Thailand I went to my local general dentist. The lady told me my options were either extraction or root canal, post and crown. I opted for root canal, post and crown. As she didn’t do them she referred me to her friend, a specialist dentist in the next larger town. He took a look and decided he could do a filling by lowering the tooth. He stated if it breaks again we can always do a root canal, post and crown then. Unfortunately, a couple of years later the same tooth broke again. The specialist dentist told me there wasn’t enough remaining to save it and a general dentist at the same surgery extracted it. Could have been just bad luck but maybe a root canal, post and crown at the time would have saved it for longer? Since then I have had two crowns fitted at the same surgery. Cost for filling 1,200 baht, extraction was only a few hundred baht. Crown (without root canal) 8,000 baht each. Cost of crowns vary depending upon type of tooth and, of course, the material of the crown selected. My dentist gave me a leaflet about implants which can be done two months after extraction. Korean; 37,000 baht and German 40,000 baht. I haven’t had any root canals or implants.
There are general and specialist dentists. For extractions and fillings a general dentist will do. In addition to High Street dental surgeries, your local community government hospital will have a dental department. For root canals, crowns and more you need a specialist. Prices are lower than private dentistry in United Kingdom.