There is no definitive answer to this question. Each person with dental insurance must make this choice for themselves.
PPO dental insurance allows you to go in or out of network. Often going out of network affords you the opportunity to be exposed to a far greater number of dentists. Many dentists do not need to participate in these plans since patients continue to utilize their practices due to the respect they have for their dental skills.
If you have a PPO plan you may want to consider using an out of network dentist, since even though you may experience greater out of pocket contributions, you may benefit in the long run and will be seeing a dentist truly of your own choice.