Bleaching trays are thin, custom-fitted, flexible trays made from thermoplastic materials (e.g., ethylene-vinyl acetate [EVA] or polyvinyl chloride [PVC]) designed to hold bleaching gel against teeth for whitening. Unlike restorations like zirconia crowns (700–1,200 MPa), E-max veneers (360–500 MPa), or dentures, bleaching trays are non-restorative, focusing on esthetic enhancement. They are less complex to design than crowns or dentures but require precision for fit and comfort to ensure effective whitening and patient compliance.
Advantages of Bleaching Tray Design
- Esthetics: Enhances tooth shade (e.g., A3 to A1), complementing E-max/zirconia veneer goals; DSD optimizes patient satisfaction.
- Non-Invasive: No tooth preparation, unlike crowns (0.4–1.5 mm) or Co-Cr partial dentures (rest seats).
- Comfort: Soft, thin material is more comfortable than rigid acrylic dentures or Co-Cr frameworks.
- Digital Workflow: CAD/CAM ensures precise fit, similar to temporary crowns or E-max workflows.
- Patient Compliance: Easy to use at home, with DSD-guided previews increasing acceptance.
CAD Design
- Software: Import scans into CAD software (e.g., exocad, 3Shape Dental System, or dedicated tray modules like 3Shape Splint Studio).
- Tray Design:
- Thickness: Design a 0.5–1.0 mm thick tray (typically 0.035–0.040 inches) for flexibility and comfort, thinner than acrylic denture bases (2–3 mm) or flexible dentures (1–1.5 mm).
- Coverage: Extend tray margins 1–2 mm beyond the gingival margin to cover teeth fully but avoid tissue irritation.
- Reservoirs: Add 0.5–1.0 mm reservoirs (small spaces) on the facial surfaces of teeth (especially anteriors) to hold bleaching gel, ensuring even application.
- Margins: Create scalloped margins following the gingival contour for a snug fit and to minimize gel leakage.
- Retention: Ensure a tight fit to teeth without undercuts to allow easy insertion/removal.
- Parameters:
- Material: Specify soft thermoplastic (e.g., EVA, PVC, or polyurethane) for vacuum/pressure forming.
- Esthetics: Use DSD to confirm anterior tooth coverage aligns with smile design.
- Comfort: Smooth edges to prevent tissue trauma.
Occlusion: Minimal consideration, as trays are thin and worn without opposing contact (typically at night).
