Variable S group M group GM group S vs. M S vs. GM M vs. GM
Mean (SD) in mm P-value
Total
ΔHVC -2.13 (0.18) -0.58 (0.12) -0.31(0.05) < 0.0001a < 0.0001a 0.0117b
ΔHLC -2.06 (0.2) -0.52 (0.11) -0.43 (0.08) < 0.0001a < 0.0001a 0.201b
ΔRW -3.96 (0.87) -1.21 (0.69) -0.91 (0.53) < 0.0001a < 0.0001a 0.0342b
Premolar
ΔHVC -2.07 (0.6) -0.67 (1.12) -0.69 (0.79) < 0.0001a < 0.0001a 0.2588b
ΔHLC -2.34 (0.76) -0.58 (1.40) -0.52 (0.06) < 0.0001a < 0.0001a 0.2439b
ΔRW -3.51 (0,39) -0.58 (1.97) -0.47 (1.13) < 0.0001a < 0.0001a 0.0251b
Molar
ΔHVC -2.16 (0.03) -1.16 (0.08) -0.67 (0.07) < 0.0001a < 0.0001a < 0.0001a
ΔHLC -2.09 (0.73) -1.24 (0.48) -0.59 (0.26) < 0.0001a < 0.0001a < 0.0001a
ΔRW -4.27 (0.29) -1.21 (0.81) -0.75 (0.44) < 0.0001a < 0.0001a < 0.0001a

aStatistically significant at P ≤ 0.05 (Kruskal-Wallis test).
bStatistically significant at P > 0.05 (Kruskal-Wallis test).
SD = standard deviation; ΔRW = changes in ridge width, ΔHVC = changes in height of the vestibular crest, ΔHLC = changes in height of the lingual crest; S = spontaneous healing; M = porcine-derived collagen membrane alone; GM = porcine-derived graft material associated with collagen membrane.