The GI, or digestive, tract extends from mouth to anus (see the image below). The division of the GI tract into upper and lower is a matter of some confusion and debate.
Dental PPO insurance plans, also known as dental preferred provider organizations or DPPOs, are a popular dental insurance option due to their flexibility in allowing insured members to choose dentists and dental specialists.
Cigna Dental also offers its own PPO network, which is the largest dental preferred provider organization in the United States. Cigna was formed in 1982 after the merger of two other health insurance companies.