OMG, I just had this issue this week. I went for a cleaning on Monday last week and I was informed that a cracked tooth from my sports days was starting to form a cavity. The repair had started to come loose and decay was setting in. I had never had a cavity in my life so this was terrifying for me. I had 5% of my tooth drilled and a filling. It was not pleasant. Especially the needle to freeze my mouth. Thankfully, the bill was covered by my dental insurance through work. I go to the dentist because I must not because I want to.