Dental lab material selection
Hard vs Soft Splint Resin: A Dental Lab Selection Guide
Hard vs soft splint resin is a production decision only after the prescriber has defined the appliance. For the lab, the useful question is narrower: which material behavior fits the approved design, and can your printer, post-cure unit, finishing process, and quality checks reproduce it by batch?
This guide compares RayForm RF-HS-12 and RF-SS-13 from that laboratory perspective. It uses current TDS values, separates material screening from clinical judgment, and flags a documentation conflict that must be resolved before any clinical use.
Hard vs Soft Splint Resin: Which Should a Dental Lab Choose?
The table below compares typical values published in the current RayForm TDS summaries for RF-HS-12 Hard Splint Resin and RF-SS-13 Soft Splint Resin [1][2]. These are reference values, not guaranteed results for every printer or finished appliance.
| Selection factor | RF-HS-12 Hard Splint Resin | RF-SS-13 Soft Splint Resin | What the lab should infer |
|---|---|---|---|
| Hardness | 85–90 Shore D | 80–82 Shore D | HS-12 has the harder tested surface range. Hardness alone does not predict service life. |
| Tensile strength | 80–90 MPa | 30–35 MPa | HS-12 has the higher TDS tensile range under its stated ASTM D638 test. |
| Elongation at break | 8–10% | 75–85% | SS-13 permits much more deformation before break in the stated test. This is the clearest separation between the two materials. |
| Flexural strength | 85–95 MPa | 30–35 MPa | HS-12 withstands higher bending stress in the stated ASTM D790 test range. |
| Flexural modulus | 2200–2500 MPa | 1000–1200 MPa | HS-12 is the stiffer material; SS-13 is the more compliant one. |
| Viscosity | 600–700 mPa·s | 850–900 mPa·s | SS-13 is more viscous in the TDS. Qualify handling and exposure for each resin instead of copying one profile. |
| Published workflow context | TDS narrative: bite plates, occlusal splints, retainers; Applications row: “Retainer” | TDS narrative: occlusal pads and night-grinding pads; Applications row: “Bite pads, Night Guard” | Both entries conflict with the safety statement discussed below. Do not read the application wording as approval. |
Read the Numbers as a Material Map, Not a Clinical Verdict
Stiffness and elongation define the main split
The modulus and elongation ranges tell a cleaner story than the product names. HS-12 lists a flexural modulus of 2200–2500 MPa and 8–10% elongation at break; SS-13 lists 1000–1200 MPa and 75–85%. HS-12 sits on the rigid side of the decision, while SS-13 is more deformable [1][2]. A tensile bar is not a finished appliance, and comfort is a clinical outcome. The lab can report material behavior; the prescriber owns the indication and design.
Strength values do not equal wear life
HS-12 has higher published tensile and flexural strength ranges, and its TDS describes high wear resistance [1]. Those data do not provide a shared wear test, fracture-cycle result, or months-of-use claim against SS-13. When comparing suppliers, check the test method, specimen and post-cure conditions, and document revision.
Viscosity belongs in the process plan
The 600–700 mPa·s range for HS-12 and 850–900 mPa·s range for SS-13 matter to handling and process qualification, but do not prove that one prints faster [1][2]. RayForm lists representative settings for six LCD/DLP printers as starting points, not universal profiles. Check the RayForm printer parameter database, then qualify exposure, motion, orientation, supports, and cleaning on your machine.
Start With the Prescription, Then Translate It Into Lab Requirements
The U.S. National Institute of Dental and Craniofacial Research says mouth guards can separate the teeth, help prevent tooth damage, and may reduce muscle activity from grinding and clenching [3]. A 2021 systematic review found insufficient evidence to determine whether occlusal splints benefit bruxism compared with no treatment or several alternatives [4]. Do not turn a resin comparison into a treatment recommendation.
Before selecting hard or soft splint resin, obtain a case instruction that defines:
- appliance type and prescribed function;
- required rigidity or permitted flex;
- arch, coverage, insertion path, undercut plan, and prescribed thickness;
- contact, finishing, polishing, and labeling requirements;
- target market and required documentation.
If “night guard” is the only instruction, ask for the missing design requirements. Do not infer them from symptoms on an order form.
Qualify Hard and Soft Resin as Two Separate Workflows
Using the same printer does not make the two resins process-equivalent. The current TDS pages show different viscosity and very different mechanical ranges, even though both list LCD/DLP processing and the same six representative printer models [1][2]. Treat each material as its own controlled process.
Build a profile around a measurable acceptance part
Begin with a defined test part, not a production case. Inspect dimensions, seating, contacts, surface defects, support scars, and finishing damage. Record printer, build platform, resin lot, orientation, settings, wash and dry steps, cure unit and program, and operator. Repeat across platform positions; one good print proves little about repeatability.
Validate orientation instead of borrowing a generic angle
A 2026 laboratory study tested three non-RayForm occlusal-splint resins at 0°, 45°, and 90°, using 50 and 100 μm layer thicknesses. Resin type and orientation significantly influenced the tested surface and mechanical properties, while layer thickness had a more limited effect [6]. The exact results cannot be transferred to HS-12 or SS-13. The production lesson can: qualify orientation and layer strategy for the actual resin-printer-post-cure combination.
If a new orientation eases support removal but moves dimensions outside the acceptance window, the faster nesting strategy costs yield.
Control post-processing and finishing
Both current RayForm pages summarize the same TDS sequence: wash with IPA in an ultrasonic cleaner, avoid high-frequency shock or forceful brushing, dry thoroughly, remove supports before post-curing, and use the conditional five-minute UV cure only when the workflow calls for toughness [1][2]. Follow the current batch instructions. Record the material lot, wash-fluid status, cure-unit ID, cure cycle, and final inspection result.
What Does the Clinical Evidence Say About 3D-Printed Splints?
In a 2023 randomized pilot trial, 47 patients received either a thermo-flexible 3D-printed splint or a milled splint. At three months, the groups had similar patient satisfaction, complication rates, and wear behavior within the study’s limits [5]. The finding concerns the tested material, hardware, design, and follow-up period; it does not make printable splint resins interchangeable. “3D printed” is a manufacturing route, not a finished performance specification.
Regulatory Gate: Resolve the Current TDS Conflict Before Clinical Use
Do not solve that conflict with marketing copy or assume that “biocompatible” means cleared for a specific use. Before clinical production, request the current intended-use statement, market-specific regulatory status, labeling, instructions for use, SDS, TDS revision, and required declarations. Pause the case if the documents do not support the prescribed use.
This guide makes no claim that RF-HS-12 or RF-SS-13 is approved, cleared, or registered for an intraoral indication. It is a technical selection framework for laboratory due diligence.
Dental Lab Buying and Validation Checklist
Use this checklist before adding either material to routine production:
- Confirm that the prescriber has specified the appliance design and required material behavior.
- Compare the current TDS mechanical values and viscosity.
- Obtain and review intended-use, safety, regulatory, labeling, and traceability documents for the destination market.
- Qualify a separate printer profile, orientation, support plan, wash cycle, dry step, cure cycle, and finishing method for each resin.
- Define measurable acceptance limits for fit, dimensions, contacts, surface, support marks, and finishing damage.
- Repeat qualification across the builds, positions, operators, and lots required by your quality plan.
- Estimate cost from accepted parts, not bottle price: include failed builds, remake labor, solvent, cure time, finishing, and documentation work.
- Train operators on changeover and cleaning; review the process after material, hardware, firmware, or document changes.
You can compare related materials through the RayForm dental resin range and review process resources in the RayForm Support Center. Neither page replaces the case-specific document review above.
Frequently Asked Questions
Is hard splint resin always more durable than soft splint resin?
No. RF-HS-12 has higher TDS tensile and flexural values, but the reviewed documents provide no matched service-life test against RF-SS-13. Design, printing, post-cure, finishing, loading, and ageing can change durability.
Does higher elongation make soft splint resin more comfortable?
Higher elongation means the test specimen can deform further before break: 75–85% for RF-SS-13 versus 8–10% for RF-HS-12 [1][2]. It does not prove comfort, which is a clinical outcome.
Can hard and soft splint resin use the same printer profile?
Do not assume so. Despite sharing six representative LCD/DLP printer models, the resins have different viscosity and mechanical ranges. Validate their printing and post-processing separately.
Which resin should a lab choose for a night guard?
The prescriber must define the appliance behavior. The lab may then screen HS-12 for a rigid, low-elongation design or SS-13 for a more deformable, high-elongation design. This is not a treatment recommendation.
Can a lab combine hard and soft resin in one printed appliance?
This guide does not present a RayForm-validated multilayer or hybrid splint process. Do not market or produce one unless the complete material-and-process system is documented and qualified for the intended use.
What documents should a distributor or lab request before purchase?
Request the current TDS, SDS, instructions for use, intended-use statement, labeling, lot traceability, market-specific regulatory documents, processing instructions, and change-control contact. Resolve contradictions before clinical supply.
Next Step: Validate the Material as a Workflow
Hard versus soft is not a ranking. RF-HS-12 supplies the stiffer, stronger, low-elongation profile in the current TDS; RF-SS-13 supplies the more deformable, high-elongation profile. The right laboratory choice is the one that matches the prescribed design, passes your controlled production tests, and has a document package that supports the target use and market.
For current files, printer-profile discussion, and sample qualification, contact RayForm. Send your printer model, cure unit, target market, expected monthly volume, and required appliance behavior. Ask for the documentation conflict to be resolved before planning clinical production.
References
- RayForm — RF-HS-12 Hard Splint Resin: current product page, TDS values, workflow context, and safety limitation. View source
- RayForm — RF-SS-13 Soft Splint Resin: current product page, TDS values, workflow context, and safety limitation. View source
- National Institute of Dental and Craniofacial Research — Bruxism; mouth-guard function and treatment boundaries. Page last reviewed March 2025. View source
- Hardy RS, Bonsor SJ — The efficacy of occlusal splints in the treatment of bruxism: A systematic review. Journal of Dentistry. 2021;108:103621. View source
- Herpel C, Kykal J, Rues S, Schwindling FS, Rammelsberg P, Eberhard L — Thermo-flexible resin for the 3D printing of occlusal splints: A randomized pilot trial. Journal of Dentistry. 2023;133:104514. View source
- Tandogan B, Emir F, Ceylan G — Effect of Resin Type, Layer Thickness, and Printing Orientation on the Mechanical and Surface Properties of 3D-Printed Occlusal Splints. Polymers. 2026;18(2):290. View source
