The effect of platelet–rich plasma on clinical outcomes of the surgical treatment of periodontal intrabony defects: A systematic review and meta–analysis

Table 4 Univariate meta-regression analyses of potential sources of heterogeneity

Heterogeneity factor	Exp (β)	Std. err	t-value	P-value	95 % CI		Adjusted R ² (%)	I ² _res (%)
Heterogeneity factor	Exp (β)	Std. err	t-value	P-value	UL	LL	Adjusted R ² (%)	I ² _res (%)
Use of GTR	0.296	0.244	−4.990	0.001	−1.759	−0.673	100.00	7.48
Study design	0.476	0.366	−2.030	0.070	−1.557	0.072	38.36	55.39
Type of control
Allograft	2.461	0.570	1.580	0.149	−0.389	2.190	10.06	64.10
Synthetic	1.316	0.452	0.610	0.558	−0.747	1.296	10.06	64.10

Note: Xenograft dropped because of collinearity. Adjusted R² (%) = Proportion of between-study variance explained. I²res (%) = % of residual variation due to heterogeneity

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