Antimicrobial residual effects of irrigation regimens with maleic acid in infected root canals

Table 1 Irrigation protocols. E. faecalis counts counts before and after instrumentation (mean ± standard deviation)

Final irrigating solutions	Short-term		Long-term				Paired comparison **
	CFUs × 10 ³ of *E. faecalis*		Grown samples at 60 days
	Before instrumentation *	After instrumentation	Number and % of grown samples		Minimum	Maximum
Group 1: 2.5% NaOCl	88 ± 69.07	0	12	100	3	20	a
Group 2: 7% MA	106 ± 135.6	0	11	91.7	5	>60	b
Group 3: 7% MA + 0.2% CTR	119 ± 156.1	0	7	58.3	5	>60	b,c
Group 4: 7% MA + 2% CHX	119.4 ± 154.5	0	5	41.7	24	>60	c,d
Group 5: 7% MA + 0.2% CTR +2% CHX	93.1 ± 84.1	0	4	33.3	9	>60	c,d
Control group: 0.9% Saline solution⁺	88 ± 69.07	0.004 ± 0.007	-		-	-	-

Number of grownsamples at 60 days. Median of the day of regrowth. n = 12 per group.
NaOCl: sodium hypochlorite. MA: maleic acid; CTR: cetrimide; CHX: chlorhexidine.
⁺No long-term analysis was performed because all samples grew on first day.
*Before instrumentation there was the same E. faecalis level in all groups determined by an ANOVA test previously subjecting data to a Poisson normalization transformation: √(basal data + 3/8) (p = 0.978).
**The same letter shows differences that were not statistically significant determined by the Log-Rank test (statistical significance level was set at p< 0.05). p values of pair by pair comparisons: group 1 vs group 2: p = 0.015, group 1 vs group 3: p = 0.010, group 1 vs group 4: p< 0.001, group 1 vs group 5, p< 0.001, group 2 vs group 3: p = 0.247, group 2 vs group 4: p = 0.005, group 2 vs group 5: p = 0.005, group 3 vs group 4: p = 0.193, group 3 vs group 5: p = 0.157, group 4 vs group 5: p = 0.928.

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