Generally speaking, DHMO plans are more cost effective, while PPO dental plans offer greater flexibility. There's no way of saying that one plan is better than the other – it just comes down to which will meet your unique needs.
Why PPO is better than HMO?
HMOs don't offer coverage for care from out-of-network healthcare providers. The only exception is for true medical emergencies. With a PPO, you have the flexibility to visit providers outside of your network. However, visiting an out-of-network provider will include a higher fee and a separate deductible.