Table 2. Percentage of roots (n) for each score, according to a histological analysis performed by different clinical conditions and after different protocols of endodontic treatment.

Quantitative histological parameters	Scores	Clinical conditions and treatments
		Healthy Tooth	Untreated Periapical Lesion	Single Session	EGCG-based paste	Calcium hydroxide-based paste
Tissue disorganization	Absent	100	0	0	80	85
	Mild	0	0	0	20	15
	Moderate	0	0	30	0	0
	Severe	0	100	70	0	0
	Statistical analysis	b	a	a	b	b
Inflammatory Infiltrate	Absent	100	0	0	80	90
	Mild	0	0	0	20	10
	Moderate	0	0	30	0	0
	Severe	0	100	70	0	0
	Statistical analysis	b	a	a	b	b
Expression of MMP-2	Absent	0	0	0	0	0
	Mild	100	0	0	85	80
	Moderate	0	0	40	15	20
	Severe	0	100	60	0	0
	Statistical analysis	b	a	a	b	b
Expression of MMP-9	Absent	0	0	0	0	0
	Mild	90	0	0	80	85
	Moderate	10	0	30	20	15
	Severe	0	100	70	0	0
	Statistical analysis	b	a	a	b	b