The Effect of Topical Corticosteroid Time of Application on Fibroblast and Type III Collagen Expression in Oryctolagus cuniculus with Deep Dermal Burn Wound (As an Indicator for the Best Time to Start Topical Corticosteroid Application in Preventing Hypertrophic Scar)

Background: Hypertrophic scar is an abnormal scar that causes physical deteriorations, psychological problems, and aesthetic issues. An excessive number of fibroblasts and collagen III expressions are histopathology indicators for the hypertrophic scar. The role of topical corticosteroids in suppressing inflammation and hypergranulation had widely demonstrated in previous studies. However, there is no study related to the application of topical corticosteroids as prevention of hypertrophic scars from burn wound found. Hence, this study aimed to examine the evidence of the effects of corticosteroid topical in decreasing the number of fibroblasts and type III collagen expression and the best time to start its application in preventing hypertrophic scars. Methods: This randomized experimental post-test only study involved 54 deep dermal burn wounds on the ventral ear of female Oryctolagus cuniculus that distributed into three groups based on the healing phases. Each group consisted of treatments and controls. Corticosteroid topical application on the first treatment group (inflammatory phase group), the second group (proliferation phase group), and the third group (remodelling phase group) was started on day 3, on day 10, and day 21, respectively. Specimens taken on day 35. Haematoxylin-Eosin and Immunohistochemically staining performed to measure the number of fibroblasts and type III collagen and to observe the epithelization and inflammation process. Results: The number of fibroblasts significantly decreased in the second treatment group (p =0.001) and followed by the first group (p = 0.016), but no significant decrease found in the third group (p = 0.430). The type III collagen decreased significantly in the second treatment group (p = 0.000) and followed by the third group (p = 0.019), but no significant decrease found in the first group. There was no statistically different number of fibroblast and type III collagen discovered between the controls. Complete epithelization found in all groups. Also, no ongoing inflammation found in all groups.  Conclusion : Topical corticosteroids on deep dermal burn wound revealed to be effective in reducing the number of fibroblasts and type III collagen with no healing disruption. The proliferation phase found to be the best time to start the application of topical corticosteroids.