Table 2.

Histopathological changes of hepatic cells in rats exposure to different concentrations of fluoride

Groups		Portal inflammation	Lytic necrosis	Knodell scorea	Interpretation
15 days	Control	0	0	0	No inflammation
	0.5 ppm	0	0	0	No inflammation
	5 ppm	1	1	2	Minimal inflammation
	20 ppm	1	1	2	Minimal inflammation
30 days	Control	0	0	0	No inflammation
	0.5 ppm	0	1	1	Minimal inflammation
	5 ppm	1	1	2	Minimal inflammation
	20 ppm	1	3	4	Minimal inflammation
60 days	Control	0	0	0	No inflammation
	0.5 ppm	1	3	4	Minimal inflammation
	5 ppm	3	3	6	Mild inflammation
	20 ppm	3	3	6	Mild inflammation
Portal inflammation: 0, no portal inflammation, 1, mild (sprinkling of inflammatory cells in < 1/3 of portal tracts), 3, moderate (increased inflammatory cells in 1/3–2/3 of portal tracts), 4, marked (dense packing of inflammatory cells in > 2/3 of portal tracts).				Necrosis: 0, none, 1, mild (acidophilic bodies, ballooning degeneration, and/ or scattered foci of hepatocellular necrosis in < 1/3 of lobules or nodules) 3, moderate (involvement of 1/3–2/3 of lobules or nodules) 4, marked (involvement of > 2/3 of lobules or nodules)

0 = no inflammation, 1–4 = minimal inflammation, 5–8 = mild inflammation, 9–12 = moderate inflammation and 13–18 = marked inflammation

^aKnodell HAI score is the combined scores for periportal necrosis, intralobular necrosis, portal inflammation, and fibrosis to yield a possible range of 0–22. As used in clinical trials, the first three categories are often totaled to give a necroinflammatory score (0–18), while the fibrosis score (0–4) is reported separately