Table 4.

Different multiple linear regression models for PD reduction

Independent factors included	Variables	B	Coef	P
Baseline factors	Adjusted R2 = 0.576
	Age	−0.05	−0.13	0.006
	DBD depth at BL	−0.07	−0.07	NS
	PD at BL	0.85	0.78	0.000
Baseline factors + hard tissue variation	Adjusted R2 = 0.618
	Age	−0.01	−0.03	NS
	DBD depth at BL	−0.33	−0.30	0.000
	PD at BL	0.86	0.79	0.000
	aDBD depth reduction	0.49	0.33	0.000
Baseline factors + soft tissue variation	Adjusted R2 = 0.798
	Age	−0.07	−0.19	0.000
	DBD depth at BL	0.37	0.34	0.000
	PD at BL	0.20	0.19	0.000
	# Difference between PD reduction and DBD depth reduction	0.73	0.73	0.000

DBD Distal intra-bony defect, RMS Retromolar space. “NS” denotes “no significant difference”

Note: ^aThe DBD depth was regarded to be a factor related hard-tissue variation. #The difference between PD reduction and reduction in DBD depth was regarded to be a factor related to soft-tissue variation