In clinical practice, the quality and fit of your final prosthetics depend heavily on the foundation, and that begins with a well-crafted special tray and bite block. While labs often handle these, there’s growing interest among clinicians, particularly dental nurses and therapists, in getting hands-on with tray fabrication. Whether you’re a CDT looking to refine your process or a dentist/nurse wanting to enhance chairside skills, this guide offers practical insights into using light-cure materials effectively.
Why Use Light-Cure Material for Special Trays?
Light-cure materials offer several advantages: they’re quick to work with, relatively easy to handle, and can be fabricated chairside with minimal mess—perfect for those with limited lab access. They’re also particularly well-suited for cases involving flabby ridges, where standard trays can cause tissue distortion and compromise your impression accuracy (Dentistry 3000, 2022).
Step-by-Step: Constructing a Light-Cure Special Tray
1. Apply a wax spacer on your model, leaving room around the sulcus.
2. Wrap foil over the wax. This prevents the light-cure material from sticking and helps maintain even spacing.
3. Roll out the light-cure material and apply it over the model in a horseshoe shape.
4. Use a chopping action with your instrument to keep the thickness consistent.
5. Add a handle—either a traditional one or opt for thumb pads (explained below) depending on the case.
6. Cure under light for around 30 seconds per section.
If using a plastic device (like the one shown in our demo), be cautious: the curing process can heat up the wax spacer, causing it to melt and stick to the tray. This melted wax will prevent your silicone from bonding properly, risking distortion. After curing, remove any wax residue and trim off flash or sharp edges using a burr.
Handling Flabby Ridges? Try Thumb Pads
For patients with mobile or flabby anterior ridges, using thumb pads in place of a central handle can improve stability during impression-taking. Simply roll a small amount of material, form it into two cubes, and attach one to either side of the tray.
When inserting the tray into the patient’s mouth, place your thumbs on the pads to keep it steady while the material sets. This avoids pressing on delicate tissue and helps prevent displacement or distortion. Traditional handles often tempt clinicians to hold the tray by the handle, which can shift the position during setting—leading to inaccurate results. (PubMed, 2023)
Watch the Heat: Curing Tips
When curing the tray with light, the generated heat can melt the wax underneath. Even with a short 30-second cure, parts of the tray—especially thinner, built-up areas—can stick. If the tray is left longer (say, a full minute), the wax melting will be even more significant, compromising your silicone bond.
To mitigate this, cure in short bursts and check for melting early. Clean thoroughly and re-surface the tray if needed before proceeding with the impression.
Using Light-Cure Material for Bite Blocks
You can also use light-cure material to make baseplates for bite blocks—particularly in full upper cases. This technique allows for more stable bite registrations than wax-only methods.
Key steps include:
1. Do not use a wax spacer.
2. Apply the material directly, but trim it shorter than a tray.
3. Avoid deep undercuts—this will make the block difficult to remove.
4. Keep edges thick and smooth for easier trimming and stability.
5. Cure for about 10 seconds, then clean and refine edges.
Next, add your wax blocks. For narrow arches or smaller mouths, you can adapt Manchester Towers, two cube-shaped blocks set laterally on either side rather than a continuous wax strip across the front. This creates balance during the bite, preventing tipping and offering a more reliable occlusal registration.
Sealing & Finishing the Bite Block
Use an induction heater and wax knife to seal the wax to the cured base. Always melt the wax away from your body and wear gloves to avoid injury. Melt and bond the wax to the base evenly, then check the blocks are roughly level.
For general bite blocks, you can use a continuous wax ring around the tray. However, Manchester Towers are often better for stability, especially when no anterior pressure is desired.
Marking Key Clinical Reference Lines
Once the bite block is fitted, mark the following reference lines:
- Centre line – Use a LaCron tool for accuracy.
- Length of teeth – This should sit where the relaxed lip meets the wax.
- Smile line – Ask the patient for a full smile and mark where the top of the teeth should appear, typically just below the gum line.
These marks help guide your technician in placing the teeth in the correct position. While some clinicians also mark canine positions, this can sometimes complicate things. If you’ve selected the correct tooth size and shape, the canines typically fall into place naturally without needing predefined markings.
Empowering Dental Nurses & Team Training
Dental nurses often show genuine curiosity about lab work, and fabricating special trays is an excellent starting point for hands-on learning. They’re simple to make and hard to get wrong with basic instruction. Creating a designated corner in the clinic where nurses can sit down and practice these skills helps build confidence and adds variety to their role. It can also save labs time and improve turnaround.
For those interested in more formal learning, we’re exploring the possibility of hosting short training courses—covering everything from special tray and bite block fabrication to taking alginate impressions. These are all within a nurse’s scope of practice and can greatly benefit the wider team.
💬 Interested in Training or Want to Learn More?
If you’re a CDT, dentist, or dental nurse and want to explore training, hands-on workshops, or just brush up your techniques, we’d love to hear from you. Reach out via the Modern Dentures website or drop a comment below to express your interest.
Let’s keep raising the standard of patient care, one tray at a time.
📺 Watch the full video: https://youtu.be/i7-mYcuMVU0?si=wGv101pcSMkWL4D8
