The application of 3D-printed transparent facemask for facial scar management and its biomechanical rationale

Introduction: Deep facial burns leave conspicuous scar to the patients and affect their quality of life. Transparent facemask has been adopted for the prevention and treatment of facial hypertrophic scars for decades. Recently, with the advancement of 3D printing, the transparent facemask could facilitate the fitting of the facial contour. However, the effectiveness of the device and its biomechanical characteristics on pressure management of hypertrophic scar would need more objective evaluation. Method: A biomechanical model of the transparent 3D-printed facemask was established through finite element analysis. Ten patients with extensive deep facial burns within 6 months were recruited for clinical study using 3D-printed facemask designed according to biomechanical model, and the interface pressure was measured on each patient. The patients in the treatment group (n = 5) was provided with the 3D-printed transparent face mask soon after initial scar assessment, while the delayed treatment group (n = 5) began the treatment one month after the initial scar assessment. The scar assessment was performed one month post intervention for both groups. Results: The biomechanical modeling showed that the 3D, computer-generated facemask resulted in unbalanced pressure if design modifications were not incorporated to address these issues. The interface pressure between the facemask and patient's face was optimized through individualized design adjustments and the addition of silicone lining. After optimization of pressure through additional lining, the mean thickness and hardness of the scars of all 10 patients were decreased significantly after 1-month of intervention. In the delayed treatment group, the mean thickness of the scars was increased within the month without intervention, but it was also decreased after intervention. Conclusion: Facemask design and the silicone lining are important to ensure adequate compression pressure of 3D-printed transparent facemask. The intervention using the 3D-printed facemask appeared to show its efficacy to control the thickness and hardness of the facial hypertrophic scars.