New assumptions concerning IPAs and cost of dental care.

Objectives: Previous studies suggest that fee-for-service (FFS) patients receive more treatment and at a greater cost than capitation patients. In this study treatment plans of dentists who are members of an independent practice association (IPA), a preferred provider organization (PPO), or who are paid their usual fee for service are compared.

Methods: A carefully selected and trained professional actor, with actual dental disease and recent radiographs, was sent to the offices of general practice dentists for an examination and treatment plan. To one group of dentists (n = 21) the patient said he was a member of a PPO plan served by that dentist, to a second group (n = 15) he said he was a member of an IPA plan served by that dentist, and to the third group (n = 19) he said he would pay by the traditional FFS method.

Results: IPA dentists recommended more restorations (mean = 9.60) than those in the PPO program (mean = 5.95) or those paid by the traditional FFS method (mean = 5.58). The anticipated mean cost to the patient was higher for the IPA dentists ($1,815.20) compared to the other two types (PPO = $1,186.24, FFS = $1,470.42).

Conclusions: The IPA models studied in this investigation permitted dentists to charge copayments for most treatments beyond basic services. This type of IPA might be similar to a fee-for-service model that provides practitioners with an incentive to do more rather than less treatment.