3D Metrology-Based Comparison of Functional Casts Made With Conventional and 3D-Printed Custom Trays

3D Metrology-Based Comparison of Functional Casts Made With Conventional Custom Trays and 3D-Printed Custom Trays in Completely Edentulous Maxillary Patients

This study will compare the dimensional discrepancies of functional casts obtained using conventional custom trays and 3D-printed custom trays made from PET-G (Polyethylene Terephthalate Glycol) filament. Thirty completely edentulous maxillary patients treated in the Complete Denture Course at the School of Dentistry, University of São Paulo (FOUSP), will be evaluated. Anatomical casts will be obtained, digitized, and used to fabricate conventional or digitally designed and 3D-printed custom trays. Functional impressions will then be made with zinc-oxide eugenol impression paste, and the resulting functional casts will be fabricated in Type III gypsum. The casts will be digitized and compared using 3D metrology software. Measurements will be obtained at standardized anatomical regions, including the bilateral tuberosity regions, incisive papilla, palatine raphe, and four vestibular points.

Complete denture fabrication commonly relies on long-established conventional techniques. Custom trays are conventionally fabricated with chemically activated polymethyl methacrylate (PMMA) acrylic resin. Digital dentistry and additive manufacturing may provide alternative methods and materials for custom-tray fabrication, including PET-G (Polyethylene Terephthalate Glycol) filament.

In this study, functional casts obtained using conventional custom trays will be compared with functional casts obtained using digitally designed and 3D-printed custom trays. Anatomical casts will be made according to the anatomical impression technique fabricated in Type II gypsum, and digitized with an INEOS X5 bench scanner. The digital models will be processed in inLab software to remove undercuts and define the basal area outline.

For the conventional group, custom trays will be fabricated with chemically activated PMMA acrylic resin. For the printed group, custom trays will be digitally designed with a thickness of 3 mm and zero spacing, exported as STL files, and printed on an Adventurer 4 Pro printer using CREALITY CR-PETG thermoplastic filament, according to the manufacturer's parameters.

Functional impressions will be obtained using the technique recommended by the FOUSP Complete Denture Course and zinc-oxide eugenol impression paste. Functional casts will be fabricated in Type III gypsum, scanned, and exported as STL (Standard Triangle Language) files. The meshes will be compared in ZEISS Inspect software to quantify discrepancies between the test and reference meshes.

Inclusion Criteria

• Patients with stable systemic conditions.
• Completely edentulous maxillary patients.
• Residual ridges classified as normal according to Tamaki (1983).

Exclusion Criteria

• Recent tooth extraction, defined as extraction within the previous 6 months.
• High or severely resorbed residual ridges.