The dynamics of closure following excisional mid-palatal mucoperiosteal wound in a rat model.

The aim of the present study was to assess macroscopically the time-related dimensional pattern of excisional palatal mucoperiosteal wound closure in rats, concomitantly with microscopic analysis of the density of inflammatory infiltrate and myofibroblasts. Excisional palatal wounds, 4.2 mm in diameter, were made in twenty-one 2-month-old male Wistar rats. The total area and anteroposterior/laterolateral dimensions of the wounds were measured macroscopically at 1, 2, and 3 weeks post-operatively. In addition, histomorphometry was used for assessment of the intensity of inflammation and density of myofibroblasts in the wound area. A significant decrease was found in the total area and anteroposterior but not the laterolateral dimension of the wounds during the 2nd week. These changes were less prominent in the 3rd week. Three weeks post-operatively, the density of inflammatory infiltrate remained high in the central part of the wound concomitant with a significant increase in the number of myofibroblasts. We concluded that the second week was the most significant in wound closure, with wound contraction first occurring in an anteroposterior plane followed by the laterolateral plane. The increased inflammatory reaction and changes in the density of myofibroblasts may explain the macroscopic decrease in wound dimensions in a time-related manner. These findings emphasize the importance of the amount of soft tissue left at surgery, and suggest that the most appropriate time for the use of healing promoters would be the second post-operative week.