Yes, no and maybe
Some insurance plans cover immediate dentures at the benefit level they allow for major services and prosthetics. There may be a deductible and copay with the amount determined by the insurance contract. Some plans do not cover major services at all. Since extractions are necessary for the placement of an immediate denture, the benefits for the extractions would be deducted from the benefits available for the denture. Therefore, depending on the number and complexity of the extractions there may be limited benefits left for the denture services.
Also, a reline of the immediate denture is often necessary, and this service may only be covered after a certain period of time, not necessarily when you and your dentist feel it is indicated. Benefits may or may not be available due to annual maximums and plan restrictions.
As with many dental services when you have a dental plan, it is often best to predetermine treatment for an estimate of your out-of-pocket costs.