This study evaluates the effects of three kinds of periodontal surgery using statistical analyses of histological and immunohistochemical indices. Dehiscence defects were made on roots of maxillary teeth in monkeys. Surgically exposed roots were untreated, etched with EDTA, or treated with Emdogain (R) after EDTA etching. Paraffin sections were stained with hematoxylin and eosin or immunostained for bone sialoprotein (BSP) or osteopontin (OPN) and analysed using several indices. The relative length of regenerated cementum and of BSP/OPN-immunoreactive lines on dentin defect showed no differences among the three groups. The attached regenerated cementum in the untreated group was shorter than in the etching groups. Regenerated cementum area was larger in the etching-Emdogain group than in the etching group. Thickness of immunolabeling on detached cementum was larger than that on attached cementum in all of the groups. These findings suggest that etching reinforces the attachment of regenerated cementum, and that BSP and OPN are associated with the attachment, where they exercise strong adhesion within a certain level of thickness.