TABLE 1—
Regression Results of Significant Tooth Loss for Those Younger Than 65 Years and Those Aged 65 Years and Older: Behavioral Risk Factor Surveillance System, United States, 1999–2010
| Missing ≥ 6 Teeth, Aged < 65 Years (n = 1 127 140) |
Missing ≥ 6 Teeth, Aged ≥ 65 Years (n = 405 532) |
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| Variable | Equation 1,a b (SE) | Equation 2,b b (SE) | Equation 1,a b (SE) | Equation 2,b b (SE) |
| Rest of the United States | ||||
| Average in base year | 0.105** (0.0025) | 0.109** (0.0015) | 0.489** (0.0066) | 0.475** (0.0050) |
| Year trend | −0.002** (0.0002) | −0.002** (0.0002) | −0.009** (0.0006) | −0.007** (0.0005) |
| Mississippi Delta | ||||
| Additional tooth loss in base year relative to rest of the United States | 0.029* (0.0098) | 0.007 (0.0073) | 0.059* (0.0210) | 0.014 (0.0167) |
| Additional tooth loss in year trend relative to rest of the United States | 0.004** (0.0009) | 0.003** (0.0007) | 0.007** (0.0019) | 0.005* (0.0018) |
| Appalachia | ||||
| Additional tooth loss in base year relative to rest of the United States | 0.062** (0.0086) | 0.039** (0.0061) | 0.134** (0.0139) | 0.091** (0.0152) |
| Additional tooth loss in year trend relative to rest of the United States | 0.001 (0.0007) | −0.0003 (0.0006) | −0.0004 (0.0014) | −0.001 (0.0017) |
| R2 | 0.005 | 0.168 | 0.010 | 0.136 |
Note. Standard errors were robust, and observations were clustered at the county level. All results used complex sampling weights provided by the Behavioral Risk Factor Surveillance System.
Equation 1 data show the results of regressing the indicator variable for missing ≥ 6 teeth on indicator variables for being in Appalachia or the Mississippi Delta, a year trend, and an interaction between each region and the year trend. The base regressions show that for both age groups, Appalachia and the Mississippi Delta have significantly higher rates of significant tooth loss than the rest of the country in the base year. The year trend for the nation shows a decrease in the percentage with significant tooth loss, but this trend is much slower in the Mississippi Delta.
Equation 2 data show that a large portion of the base and trend differences are explained by the additional explanatory variables included. The control variables are demeaned, so the constants reflect the rate of tooth loss at the mean values for the explanatory variables.
*P < .01; **P < .001.