Table 2.

Color change and culture findings in lower chamber of NSP Group.

Unit*	Color¶	Day†	Positive culture‡	Leakage§
1	Yellow	4	Yes	Yes§
2	Red	5	No	No
3	Red	20	No	No
4	Orange	18	No	No
5	Orange	27	No	No
6	Orange	24	No	No
7	Yellow	5	Yes	Yes§
8	Yellow	19	Yes	Yes§
9	Orange	16	No	No
10	Orange	27	No	No
11	Red	17	No	No
12	Red	None	No	No
13	Red	17	No	No
14	Orange	19	No	No
15	Red	None	No	No
16	Red	None	No	No
17	Orange	16	No	No
18	Orange	18	No	No
19	Red	None	No	No
20	Red	None	No	No
21	Red	None	No	No

*Each unit consists of a dual-chamber model with an embedded root between the chambers.

^¶Color in the lower chamber after 30 days (Red: no change; yellow: acid; orange: weakly acidic).

^†Day when a color change was first observed in the lower chamber.

^‡Cultivable S. mutans from lower chamber sample after 30 days.

^§Evidence for bacterial penetration through root canal into lower chamber.