Table 1.

Qualitative Results, Log Reductions, and Corresponding P Values Obtained in the Study

Treatment	CFU*	Log Reduction†	Significance‡
Initial	55,214 ± 78,595
Post 1st endodontic Tx	7,193 ± 13,549	1.08 ± 0.39
Post 1st PDT	28,033 ± 3,885	0.74 ± 0.6
Total log redn 1st		1.83 ± 0.75	p = 2 × 10−5 vs endo
No. of sterile cultures	Endo = 0
	PDT = 2
Recolonization	24,280 ± 39,912
Post 2nd endodontic Tx	1,939 ± 4,217	1.14 ± 0.31
Post 2nd PDT	136 ± 345	1.61 ± 0.97	p = 2 × 10−3 vs 1st PDT
Total log redn 2nd		2.75 ± 1.04	p = 5 × 10−7 vs 2nd endo
Total log redn 1st + 2nd		3.19 ± 1.1	p = 6 × 10−5 vs 1stcombo
No. of sterile cultures	Endo = 0
	PDT = 5

^*Mean CFU values (± standard deviation) from 3 paper points from each of 20 teeth.

^†Mean log(10)(CFU before)/(CFU after) (± standard deviation) for each successive treatment.

^‡A two-tailed paired Student t test assuming unequal variance.