Effects on wound healing of zinc oxide in a hydrocolloid dressing.

Background: Zinc oxide incorporated in gauze enhances healing of chronic wounds in humans and experimental pig wounds.

Objective: The purpose of this study was to examine the effects of zinc oxide added to a hydrocolloid dressing on the healing of surgical wounds in domestic pigs.

Methods: Forty partial-thickness wounds (2.2 x 2.2 cm and 400 microns deep) were treated with different zinc oxide concentrations, and epithelialization was evaluated morphometrically in a total of 320 histologic sections. Wound closure, bacterial growth, and inflammation were studied in eight full-thickness wounds (2.5 x 4.5 cm). The level of serum zinc was determined before and after treatment.

Results: In partial-thickness wounds, concentrations of zinc oxide at or below 1.0% (wt/wt) inhibited epithelialization, whereas no effect was observed at zinc oxide concentrations from 2% to 6%. In full-thickness wounds, zinc oxide (6%) reduced bacterial growth by about 2 log units and increased the inflammatory response in the granulation tissue, but had no effect on healing when compared with control (hydrocolloid alone). Serum zinc levels remained unchanged throughout the treatment period.

Conclusion: Apart from inhibiting bacterial growth, no additional beneficial effects on wound healing in nutritionally balanced pigs were found by supplementing a hydrocolloid dressing with zinc oxide.