3D Printing for the Development of Palatal Defect Prosthetics

Data Acquisition

This study was conducted at the Veterans Affairs Palo Alto Health Care System (VAPAHCS) and was approved by the Stanford University Institutional Review Board (approval #28958, informed consent and patient contact excluded). A retrospective chart review was conducted on all patients with head and neck cancers who were treated at VAPAHCS from 2010 to 2022. Patients aged ≥ 18 years who had a palatomaxillary defect due to cancer treatment, had undergone a palatal resection, and who received treatment at any point from 2010 to 2022 were included in the review. CTs were not a specific inclusion criterion, though the quality of the scans was analyzed for eligible patients. Younger patients and those treated at VAPAHCS prior to 2010 were excluded.

There was no control group; all data was sourced from the US Department of Veterans Affairs (VA) imaging system database. Among the 3595 patients reviewed, 5 met inclusion criteria and the quality of their craniofacial anatomy CTs were analyzed. To maintain accurate craniofacial 3D modeling, CTs require a maximum of 1 mm slice thickness. Of the 5 patients who met the inclusion criteria, 4 were found to have variability in the quality of their CTs and severe defects not suitable for prosthetic reconstruction, which led to their exclusion from the study. One patient was investigated to demonstrate if making these prostheses was feasible. This patient was diagnosed with a malignant neoplasm of the hard palate, underwent a partial maxillectomy, and a palatal obturator was placed to cover the defect.

The primary data collected was patient identifiers as well as the gross anatomy and dimensions of the patients’ craniofacial anatomy, as seen in previous imaging research.²⁰ Before the imaging analysis, all personal health information was removed and the dataset was deidentified to ensure patient anonymity and noninvolvement.

CT Segmentation and 3D Printing

Using CTs of the patient’s craniofacial anatomy, we developed a model of the defects. This was achieved with deidentified CTs imported into the Food and Drug Administration (FDA)-approved computerized aid design (CAD) software, Materialise Mimics. The hard palate was segmented and isolated based off the presented scan and any holes in the image were filled using the CAD software. The model was subsequently mirrored in Materialise 3-matic to replicate an original anatomical hard palate prosthesis. The final product was converted into a 3D model and imported into Formlabs preform software to generate 3D printing supports and orient it for printing. The prosthetic was printed using FDA-approved Biocompatible Denture Base Resin by a Formlabs 3B+ printer at the Palo Alto VA Simulation Center. The 3D printed prosthesis was washed using Formlabs Form Wash 80% ethyl alcohol to remove excess resin and subsequently cured to harden the malleable resin. Supports were later removed, and the prosthesis was sanded.

The primary aim of this study was to investigate whether using CTs to create patient-specific prosthetic renderings for patients with head and neck cancer could be a feasible strategy. The CTs from the patient were successfully used to generate a 3D printed prosthesis, and the prosthesis matched the original craniofacial anatomy seen in the patient's imaging (Figure). These results demonstrate that high quality CTs can be used as a template for 3D printed prostheses for mild to moderate palatomaxillary defects.

3D Printing Costs

One liter of Denture Base Resin costs $299; prostheses use about 5 mL of resin. The average annual salary of a 3D printing technician in the United States is $42,717, or $20.54 per hour.²¹ For an experienced 3D printing technician, the time required to segment the hard palate and prepare it for 3D printing is 1 to 2 hours. The process may exceed 2 hours if the technician is presented with a lower quality CT or if the patient has a complex craniofacial anatomy.

The average time it takes to print a palatal prosthetic is 5 hours. An additional hour is needed for postprocessing, which includes washing and sanding. Therefore, the cost of the materials and labor for an average 3D printed prosthetic is about $150. A Formlabs 3B+ printer is competitively priced around $10,000. The cost for Materialise Mimics software varies, but is estimated at $16,000 at VAPAHCS. The prices for these 2 items are not included in our price estimation but should be taken into consideration.

Prosthodontist Process and Cost

The typical process of creating a palatal prosthesis by a prosthodontist begins by examining the patient, creating a stone model, then creating a wax model. Biocompatible materials are selected and processed into a mold that is trimmed and polished to the desired shape. This is followed by another patient visit to ensure the prosthesis fits properly. Follow-up care is also necessary for maintenance and comfort.

The average cost of a palatal prosthesis varies depending on the type needed (ie, metal implant, teeth replacement), the materials used, the region in which the patient is receiving care, and the complexity of the case. For complex and customizable options like those required for patients with cancer, the prostheses typically cost several thousands of dollars. The Healthcare Common Procedure Coding System code for a palatal lift prosthesis (D5955) lists prices ranging from $4000 to $8000 per prosthetic, not including the cost of the prosthodontist visits.^22,23