Comparison of the left and right first molar inter-radicular alveolar bone volume. Estimated mean percentage difference of inter-radicular alveolar bone volume and bone volume fraction between the right and left upper first molars. There was a significant reduction in the tissue volume for the groups collagen (Col), EGF and NGF, while only EGF had a significant reduction in bone volume. Bone volume fractions were not altered significantly in any experimental group. Between-group assessment revealed a significant difference in the tissue volume between the sham group and the collagen and EGF groups. Error bars represent the standard error of the mean difference. *P < 0.05 and **P < 0.01.