Aetna Dental Aetna is Columbia's dental provider for the PPO plan and the Dental Maintenance Organization (DMO) plan. PPO: 800-773-9326 Search Aetna Network Dentists(Log in, register or continue as a guest and Select Plan: Aetna Dental Direct PPO/PDN) Search Columbia University Dentists (Columbia Preferred Dental Network)(Log in, register or continue as a guest) DMO: 800-773-9326 Search Aetna DMO Dentists(Log in, register or continue as a guest)