Cost and convenience. You can help make more affordable dental care for yourself by staying in-network. A dentist in-network has agreed to lower rates on services. That means you pay less even before your insurance pays for anything by getting a filling worked on at an in-network dentist than by going to an out-of-network one.
Also, some dental insurance plans don’t pay any benefits to out-of-network dentists at all, or pay less. Check your plan before you buy.
Finally, if you stay in-network, you often won’t have to deal with submitting claims yourself. The dental office and your insurance provider will handle that. If you are out-of-network, you may have to submit your own claims and wait to be reimbursed.