Table 4.
Summary of five-category generalized fluorosis outcomes at the four dental exams. See Table 1 for definitions of each category.
| Tooth Type (Gamma statistic, p-value)* | Generalized Fluorosis Category | Age 9 (Permanent Teeth Only) (n = 282) | Age 13 (n = 282) | Age 17 (n = 282) | Age 23 (n = 282) |
|---|---|---|---|---|---|
| Early- Erupting (−0.38, < 0.0001) | No Fluorosis | 84 (29.8) | 127 (45.0) | 164 (58.2) | 173 (61.4) |
| Questionable** (not meeting Positive threshold) | 35 (12.4) | 73 (25.9) | 66 (23.4) | 63 (22.3) | |
| Any Positive | 46 (16.3) | 29 (10.3) | 18 (6.4) | 21 (7.5) | |
| Generalized Questionable** | 40 (14.2) | 41 (14.5) | 27 (9.6) | 21 (7.5) | |
| Generalized Positive | 77 (27.3) | 12 (4.3) | 7 (2.5) | 4 (1.4) | |
| Late-Erupting (−0.31, < 0.0001) | (n = 291) | (n = 291) | (n = 291) | ||
| No Fluorosis | – | 114 (39.2) | 167 (57.4) | 192 (66.0) | |
| Questionable** (not meeting Positive threshold) | – | 71 (24.4) | 59 (20.3) | 51 (17.5) | |
| Any Positive | – | 7 (2.4) | 8 (2.8) | 1 (0.3) | |
| Generalized Questionable** | – | 74 (25.4) | 48 (16.5) | 41 (14.1) | |
| Generalized Positive | – | 25 (8.6) | 9 (3.1) | 6 (2.1) | |
| Maxillary Incisors (−0.33, < 0.0001) | (Permanent Teeth Only) (n = 279) | (n = 279) | (n = 279) | (n = 279) | |
| No Fluorosis | 100 (35.8) | 141 (50.5) | 181 (64.9) | 192 (68.8) | |
| Questionable** (not meeting Positive threshold) | 28 (10.0) | 23 (8.2) | 16 (5.7) | 11 (3.9) | |
| Any Positive | 0 (0.0) | 1 (0.4) | 0 (0.0) | 0 (0.0) | |
| Generalized Questionable** | 64 (22.9) | 74 (26.5) | 55 (19.7) | 53 (19.0) | |
| Generalized Positive | 87 (31.2) | 40 (14.3) | 27 (9.7) | 23 (8.2) |
*
Gamma statistic for association between age and fluorosis severity. p-value was calculated under the assumption that the sample size was sufficiently large for (gamma statistic/asymptotic standard error) to approximately follow a standard normal distribution.
**
Note that the FRI's “questionable” category includes many zones with fluorosis affecting less than 50% of the zone, as well as some zones that do not have fluorosis.