It depends on what type of plan you buy or is offered to you by your employer. I worked with dental insurance companies for six years. There are Aetna plans that are awful and Aetna plans that are great, and the same goes for Blue Cross.
What you want to look for is the yearly maximum per person (this ranges from $1000 per year to unlimited coverage), the deductible, if any (from $0 to $100 per person, normally), and what percentage of which procedures is covered (a typical breakdown might be 100% of preventative work, 80% of restorative, and 50% of crowns, but this can vary greatly).
Also, a DMO/HMO plan (most popular are Cigna DMO and Aetna DMO) is not as good as a PPO, dental-health-wise. You will end up being required to see specific dentists and those dentists tend to be stingy with referrals. With a PPO plan, you will have network dentists who they would prefer you to see (and who you will pay less to see), but you usually don't need a referral to a specialist, and you can go out-of-network if you are willing to pay a higher percentage of the work. With a POS plan, the premiums will usually be lower, but you will pay more for your care. What you choose depends on whether you simply require a cleaning twice per year, or if you have extensive work to be done.
Good luck! If you have questions about particular breakdowns or companies, feel free to DM me, though my information and experience is about 7 years old... I haven't worked in the field since my son was a baby.