Volume changes and histological response to injected dextranomer/hyaluronic acid copolymer (Zuidex) and collagen (Contigen) in rats.

The objective of this study was to investigate the stability in terms of volume changes and local tissue reactions of dextranomer (Dx)/hyaluronic acid (HA) and collagen implants. A total of 57 rats were included in this study: the control group (nine rats), collagen-injected group (24 rats), and Dx/HA copolymer-injected group (24 rats). Under anesthesia, 0.35 ml of bulking agents was injected subcutaneously in the abdominal area. At 1, 6, and12 months, eight animals of the two implant groups and three animals of the control group were killed. The area of the injected material and surrounding tissue were carefully resected for histopathological examination. Mean volume changes in the Dx/HA copolymer group were 0.56 +/- 0.12, 0.43 +/- 0.08, and 0.28 +/- 0.02 ml at 1, 6, and 12 months, respectively. Mean volume changes in the collagen group were 0.25 +/- 0.03, 0.21 +/- 0.08, and 0.21 +/- 0.01 at 1, 6, and 12 months, respectively. The degree of tissue reaction and fibrosis are more pronounced in the Dx/HA copolymer group at each measurement period after injection.