For orthodontists and dental labs, the debonding appointment isn’t the end of treatment; it is the start of the most critical phase: retention.
For decades, the “Essix-style” clear retainer has been the gold standard. It is transparent, generally comfortable, and familiar. However, with the rapid advancement of dental materials, a formidable challenger has emerged: the 3d printed splint.
Labs and clinics are now asking: Is it time to move away from the vacuum former? Which method actually keeps teeth in place better? And which workflow makes more business sense?
This guide breaks down the technical showdown between traditional thermoformed aligners and modern splint 3d printing protocols.
The Contenders
1. The Traditional: Thermoformed Aligners
- The Process: Intraoral Scan → 3D Print Model (using Model Resin) → Heat Plastic Sheet → Vacuum Form → Manual Cut & Polish.
- The Material: Typically PETG or TPU plastic sheets (0.75mm – 1.0mm).
2. The Modern: Direct Printed Splints
- The Process: Intraoral Scan → CAD Design → Direct Splint 3d Printing (using Dental Splint Resin) → Wash & Cure.
- The Material: Biocompatible, high-impact photopolymer resins with shape memory properties.
Round 1: Accuracy and Retention (The “Stacking Tolerance” Issue)
When we discuss retention—the ability to hold teeth in their new positions—the 3d printed splint holds a distinct theoretical and practical advantage. This comes down to “cumulative tolerance.”
The Thermoforming Gap:
Manufacturing thermoformed aligners involves multiple steps where errors can creep in. First, you have the accuracy of the printed model. Second, you have the physical adaptation of the heated plastic. Research indicates that the gap between a thermoformed appliance and the teeth can range from 0.076mm to as high as 0.457mm. Furthermore, the thermoforming process itself can cause the plastic sheet to lose up to 35% of its original thickness due to stretching, leading to uneven retention forces.
The Direct Print Precision:
With a 3d print splint, you are manufacturing the final device directly from the digital scan data. You remove the “middleman” (the physical model). Clinical data suggests direct printing achieves a tighter fit with deviations often as low as 0.079mm. This 1:1 match with the patient’s anatomy ensures the appliance engages undercuts precisely, offering superior stability without the guesswork.
Round 2: Durability and Bruxism
Material science is where the gap between the two methods widens, particularly for patients who grind their teeth.
Material Fatigue in Thermoforming:
Standard clear retainers are susceptible to “creep”—the tendency of the material to permanently deform under stress. In the oral environment, factors like saliva enzymes and temperature fluctuations degrade thermoplastics like PETG. For patients with bruxism, a standard thermoformed retainer can wear down or crack rapidly, losing its retentive hold.
The Strength of the 3D Printed Splint:
Modern dental resins are engineered for longevity. A high-quality 3d printed splint can be designed with variable thickness—thicker on the occlusal surface to withstand grinding, and thinner on the facial aspect for comfort. In load testing, certain splint resins can withstand forces exceeding 500 Newtons without permanent deformation, compared to thermoformed materials which may deform at much lower loads (around 200N).
Round 3: Workflow and Labor Costs
For a dental lab business, time is currency. Thermoforming aligners is inherently labor-intensive.
The Manual Bottleneck:
To make a traditional retainer, a technician must print the model, wash/cure it, heat the plastic, vacuum form it, and then spend significant time cutting out the appliance and polishing sharp edges by hand.
The Digital Efficiency:
Splint 3d printing streamlines this significantly:
- Nest 10+ splints on a single build platform.
- Print.
- Wash and Cure in bulk.
- Minimal support removal and polishing.
By eliminating the manual cutting and polishing steps, labs can reduce hands-on labor time by up to 40%. Additionally, you save on material costs by not consuming resin for a physical model that will simply be discarded.
Round 4: Patient Compliance and Comfort
The best retainer is the one the patient actually wears. Retention fails if compliance drops.
Thermoformed aligners rely heavily on the technician’s skill to smooth the cut lines. Sharp edges near the gingiva are a common complaint, leading to patients taking the device out during sleep. Conversely, a 3d print splint features digitally smoothed edges and a uniform surface. Studies have reported patient comfort ratings exceeding 80% for printed appliances due to the lack of sharp physical cut lines and better adaptation to the gum line.
The Verdict: Which Should You Choose?
The answer depends on the specific clinical scenario and your business goals.
Choose Thermoformed Aligners If:
- Aesthetics are the #1 Priority: High-quality PETG sheets are often clearer and thinner, making them ideal for daytime wear where invisibility is key.
- Simple Retention: For patients without parafunctional habits (grinding), this remains a cost-effective standard.
- Pro Tip: To ensure the best fit, use a high-temp resistant Model Resin that won’t deform during the vacuum process.
Choose a Direct 3D Printed Splint If:
- The Patient is a Bruxer: You need the high impact resistance and 500N+ load capacity.
- High-Volume Production: You need to reduce labor costs per unit and speed up turnaround times.
- Retention is Critical: You need a precise, non-deformable fit that won’t stretch over time.
Ready to Upgrade Your Retention Workflow?
Whether you are printing precision models for thermoforming aligners or transitioning to direct production, having the right resin is the foundation of success.
For the Traditionalist: Explore our Dental Model Resin—fast printing, low shrinkage, and high heat resistance.Dental Model Resin 3160
For the Innovator: Try our Dental Splint Resin—crystal clear, fracture-resistant, and fully biocompatible for the ultimate 3d printed splint experience.Dental Occlusal Splint (#3162)
