Many people have work-sponsored or personal dental insurance plans that run from January 1-December 31. Your insurance benefits give you a set dollar amount for that entire year (e.g. $1500). If you don't come to the dentist for a whole year, by the time January (2020) rolls around again, you have lost (but paid for!) the entire amount of insurance coverage for 2019 and cannot get it back. Even if its just for a check-up and cleaning, make sure to maximize the benefits that you have paid for!