The short answer is no if you are paying the premium yourself. If your employer is paying the majority of the premium then of course dental insurance is worth it.
If you are self-employed, have individual coverage, or are on Medicare, it rarely makes sense to purchase such coverage in my opinion.
Annual dental benefits range between $1000-$3000, with the vast majority of plans offering $1000 per year in maximum benefit. Why spend $600 or more a year in premium for an individual policy with a $1000 maximum benefit each year? In most cases you will do just as well financially by asking your dentist for a cash discount.
Two cleanings a year should cost no more than $300 out of pocket, with no insurance. Would you spend $600 in premium for $300 in value? What about the years when major dental work is required, such as a crown or bridge? Your dental plan likely will cover 50% of the cost up to the $1000 maximum benefit. Fillings and root canals are usually covered at 80%, up to the $1000 maximum benefit. The catch is that you likely are not covered for major dental work the first year because there is a waiting period before such coverage begins. Adding the one year of premium you paid during the waiting period to the out of pocket costs associated with a crown or bridge, it quickly becomes apparent that most dental insurance plans simply are not worth it.
Other drawbacks:
What if your dentist is not in-network? You will pay the out of network costs, or, if an HMO type dental plan, your claims will not be covered. You will likely have to submit the claims yourself if out of network.
Medicare does not include dental coverage. If you have an HSA (Health Savings Account) pay dental expenses through this account.
Tip:
If you still would like to have dental coverage if for no other reason than peace of mind, contact your dentist and ask which plans they prefer, and accept.