This study aims to compare the effects of Negative-Pressure Wound Therapy (NPWT) and wet-to-dry dressing on Stages 3 and 4 pressure injuries (PI), This study is a randomized controlled trial. A total of 30 patients with Stages 3 and 4 pressure injuries were included in the study. The patients were divided into two groups: NPWT group and the wet-to-dry dressing group. All patients received 3 rounds of treatment. Data were collected with a Patient Identification Form, Pressure Ulcer Scale for Healing (PUSH) Tool and the findings of the Three-Dimensional Wound Measurement (3DWM) device. We found that granulation tissue formation was more significant in the experimental group (p < .05), and that there was more significant wound shrinkage (p < .05) with a more significant decrease in the PUSH Tool scores (p < .05). The wounds were assessed with the tool and the 3DWM system. Device measurements were found to be correlated with PUSH Tool findings (p < .05). There was a significant correlation between device-measured granulation findings and PUSH Tool score results of the experimental group's third measurements (p < .05). We conclude that NPWT is an effective treatment method for pressure injuries, and 3DWM device is a useable wound assessment tool.