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Additive Manufacturing: A Comparative Analysis of Dimensional Accuracy and Skin Texture Reproduction of Auricular
Alexey Unkovskiy1, Sebastian Spintzyk2, Detlef Axmann1
1Department of Prosthodontics, Tüebingen University Hospital, Tübingen, Baden-Württemberg, Germany.
This study compared three additive manufacturing methods—fused deposition modeling (FDM), selective laser sintering (SLS), and stereolithography (SL)—to determine which is best for creating auricular prostheses replicas. The researchers measured 23 subjects' ears and created digital models using 3D scanning. These models were then used to fabricate 53 prostheses using the three methods. The study found that FDM produced the most accurate replicas in terms of size and skin texture. While all methods remained within clinically acceptable error ranges, FDM was superior. The researchers also found that digital modeling and postprocessing had a greater impact on accuracy than the manufacturing method itself. The findings suggest that FDM is a reliable option for auricular prostheses fabrication.
Area of Science:
- Maxillofacial prosthetics within biomedical engineering
- Additive manufacturing in clinical applications
Background:
Digital fabrication techniques have gained traction in maxillofacial prosthetics. Traditional methods rely on manual modeling, which introduces variability. Computer-aided design and additive manufacturing offer alternatives. Prior research has shown that 3D scanning and CAD can produce accurate digital models. However, the reproducibility of these models in physical form remains uncertain. No prior work had resolved how different additive manufacturing methods affect dimensional accuracy. This gap motivated a study comparing FDM, SLS, and SL. The goal was to determine which method best preserves anatomical features. The study focused on auricular prostheses due to their complex geometry.
Purpose Of The Study:
The aim was to compare additive manufacturing methods for auricular prosthesis replicas. Specifically, the study sought to identify which method best maintains dimensional accuracy and skin texture. The motivation stemmed from the need for consistent, reproducible prostheses in clinical settings. The researchers proposed that digital workflows could reduce variability in prosthetic fabrication. The challenge lies in translating digital models into physical replicas with high fidelity. The study focused on three methods: FDM, SLS, and SL. Each method was tested on 23 subjects' auricles. The goal was to determine which method best preserves anatomical landmarks.
Main Methods:
The study involved measuring auricles of 23 subjects using a structured light scanner. These scans were converted into 3D CAD datasets. The datasets were postprocessed and used to fabricate 53 APRs using FDM, SLS, and SL. Each APR was compared to the original in vivo and CAD datasets. Landmark distances were measured in all groups to assess dimensional accuracy. A matched pairs method was used to compare mean values. Surface texture was evaluated using stereomicroscopy and profilometry. The study focused on skin detail reproduction and measurement error.
Main Results:
FDM showed the lowest mean dimensional differences at 0.43% compared to in vivo measurements. SLS followed at 0.54%, and SL at 0.59%. When compared to CAD datasets, FDM had a 0.20% difference, SL at 0.36%, and SLS at 0.39%. All values remained below the clinical relevance threshold of 1.5%. The measurement error across all groups ranged from 0.20 to 0.28 mm. The helix protrusion proved difficult to measure accurately. Skin texture reproduction was feasible for details exceeding 0.192 mm in depth. FDM demonstrated superior skin surface reproduction among the methods tested.
Conclusions:
The authors propose that FDM offers the best dimensional accuracy and skin texture reproduction for auricular prostheses. They suggest that digital acquisition and CAD postprocessing have a greater impact on outcomes than the additive manufacturing method itself. None of the tested methods exceeded the clinical relevance threshold for dimensional differences. The study highlights the importance of digital workflows in prosthetic fabrication. The findings suggest that FDM is preferable for auricular prosthesis replicas. However, all methods showed limitations in skin texture reproduction. The results support the use of digital workflows in maxillofacial prosthetics. The authors emphasize the need for further research on digital modeling techniques.
Frequently Asked Questions
Fused deposition modeling (FDM) demonstrated the lowest mean dimensional differences at 0.43% compared to in vivo measurements.
The authors propose that digital acquisition and CAD postprocessing have a greater impact on outcomes than the additive manufacturing method itself.
The anthropometrical approach showed drawbacks in measuring the protrusion of the ear's helix, indicating limitations in the measurement protocol.
Skin texture was qualitatively assessed using stereomicroscopy and profilometry to determine the level of skin detail reproduction.
The threshold of clinical relevance was set at 1.5%, and none of the tested methods exceeded this value.
The authors suggest that digital acquisition and CAD postprocessing play a more important role in outcomes than the additive manufacturing method used.
