Table 3.

Sum of the average number of congenitally missing tooth and tooth with short root according to the Parry–Romberg syndrome (PRS) severity index

PRS severity index	Patient	Congenitally missing tooth	Tooth with short root	Sum of congenitally missing tooth and tooth with short root
Mild	#1	0	0	0
	#4	0	0	0
	#8	2	1	3
	Mean	0.67 (n = 2/3)	0.33 (n = 1/3)	1.0 (n = 3/3)
Moderate	#3	3	1	4
	#5	2	6	8
	Mean	2.5 (n = 5/2)	3.5 (n = 7/2)	6.0 (n = 12/2)
Severe	#2	2	1	3
	#6	9	2	11
	#7	0	0	0
	#9	11	0	11
	#10	0	6	6
	Mean	4.4 (n = 22/5)	1.8 (n = 9/5)	6.2 (n = 31/5)

Mild, Total score < 140; Moderate, total score between 140 and 170; Severe, total score ≥ 180.