Effect of Dental Insurance Coverage and Payment Rates to Dentists on Use of Dental Care and Dental Health Outcomes Among Adults on Medicaid

Previous work has found that Medicaid beneficiaries are more likely to experience negative oral health outcomes (for example, dental pain and loss of teeth) compared with those not enrolled in Medicaid.  Some states but not others cover dental services for adult Medicaid beneficiaries.  Using data from the National Health Interview Survey (NHIS) 2000-2012, we estimate the effect of both dental insurance coverage and payment rates to dentists on the use of dental care (i.e., whether the individual has had a dental visit in the past six months or year) and dental health outcomes (i.e., whether the individual has lost all upper and lower teeth or reports experiencing oral pain within the past year). More detailed data on dental health outcomes from the National Health and Nutrition Examination Survey (NHANES) 2000-2012 will supplement our analysis. Dental insurance status for adults on Medicaid was ascertained via a web search and phone calls to states.  Payment rates to dentists for 2000-2012 were calculated using Medicaid Analytic Extract (MAX) data.   

Using the NHIS data, we employ a linear probability model to estimate the effect of state coverage of dental care and dental payment rates on the use of dental services for a sample of adults aged 21-64 on Medicaid and not Medicare controlling for socioeconomic characteristics and state and year fixed effects.  We will  also control for the Medicaid to private fee ratio for a comprehensive oral exam and the interaction of this variable with a dummy for whether Medicaid covers dental care for adults in that state and year.  Inclusion of state fixed effects serves to control for any correlation between state coverage of dental services or dental fee ratios and other unobserved attributes of states that may affect adults’ use of dental care.  In some models, we will also introduce a control group of adults with private health insurance coverage in order to separate the effect of Medicaid dental coverage and Medicaid fee ratios from other state-specific trends that may be correlated with the use of dental care.  

We estimate that only 47% of Medicaid beneficiaries had a yearly dental visit on average compared with 72% of privately insured individuals.  However, results from linear probability models indicate that     beneficiaries residing in states that provide adult dental services are 12.9 percentage points more likely to have seen a dentist within the past year, a 27% increase relative to the mean.   In addition to examining the effect of coverage on dental health outcomes, we plan to include dental fees as an independent variable in our future work in order to compare the size of the effect of the provision of dental benefits on use of dental care to the size of the effect of dental fees on use of care.

This analysis is the first to our knowledge to analyze how the combination of state coverage of dental services and relative Medicaid payment rates for adult dental services affects Medicaid beneficiary dental utilization and dental health.