Table 3.

Mean Change in Periodontal Status During the Study

Periodontal Measures*	Control Group	Treatment Group	P
Mean change in probing depth (mm)	728 (0.23±0.017)	689 (0.03±0.018)	†
Alabama	223 (0.28±0.030)	199 (0.04±0.032)	<.001
North Carolina	250 (0.34±0.028)	240 (0.25±0.029)	.022
Texas	255 (0.07±0.027)	250 (–0.20±0.027)	<.001
Mean change in percentage of sites with probing depth at least 4 mm	728 (7.81±0.559)	689 (1.40±0.574)	‡
Alabama	223 (12.08±1.049)	199 (4.35±1.1108)	<.001
North Carolina	250 (10.61±0.905)	240 (7.79±0.923)	.030
Texas	255 (1.32±0.751)	250 (–7.10±0.758)	<.001
Mean change in percentage change with probing depth at least 5 mm	728 (2.35±0.392)	689 (–1.80±0.403)	§
Alabama	223 (0.14± 0.875)	199 (–6.13±0.926)	<.001
North Carolina	250 (5.29±0.584)	240 (3.07±0.896)	.008
Texas	255 (1.40±0.494)	250 (–3.03±0.499)	<.001
Mean change in attachment level	728 (–0.01±0.019)	689 (–0.10±0.020)	.002
Mean change in percentage bleeding on probing	728 (4.48±0.936)	689 (–7.85±0.963)	<.001

Data are number (mean±standard deviation) unless otherwise specified.

^*Negative numbers indicate improvement.

^†Significant interaction effect between treatment and clinic (P=.005).

^‡Significant interaction effect between treatment and clinic (P=.003).

^§Significant interaction effect between treatment and clinic (P=.011).