Orthodontic Supplies · Buyer Stage: Awareness to Research · Published by Hangzhou DTC Medical Apparatus Co., Ltd. (DTC Orthodontics)

The Short Answer

Niti Closed Spring With Eyelets and Niti Open Spring are both nickel-titanium (Niti) dental elastics used in orthodontics, and both are offered in the same four diameters: 0.008", 0.010", 0.012" and 0.014". The difference that decides your stocking policy is the delivery format. The closed spring with eyelets arrives as short, finished segments in 3 mm, 6 mm, 9 mm and 12 mm lengths, with two type designations (identical and different). The open spring arrives as a continuous open coil in 180 mm and 914 mm lengths that the clinician cuts to the length a case requires.

If you are a clinic, the closed spring with eyelets saves chair time and gives you a predictable length. If you are a distributor, the open spring reduces the number of SKUs you must carry while still covering a wide range of treatment lengths. If you are a dental lab, the closed version is easier to place consistently inside a fabricated appliance, while the open coil gives you length flexibility on the bench.

That is the head-to-head in one paragraph. The rest of this article shows how a buyer reaches that conclusion without guesswork, and without confusing a clinical preference for a supply decision.

The Problem: Why Spring Format Confuses Procurement

On a product page the two items look interchangeable. Both are Niti. Both are classified as dental elastics. Both serve the orthodontic industry. Both share the same four diameters. A buyer scanning a price list sees two similar rows and assumes the difference is minor.

From a supply standpoint the difference is not minor, because the two formats behave differently in three commercially visible ways:

• Ordering unit. A closed spring with eyelets is bought in fixed short lengths (3, 6, 9 and 12 mm). An open spring is bought as continuous coil in 180 mm or 914 mm lengths and consumed by the millimetre.
• Attachment design. The eyelet format carries its attachment point as part of the component. The open coil does not, so it depends on auxiliary components such as crimpable hooks, ligatures or elastics to be held or activated.
• SKU behaviour. One open-coil part number covers many patients. One closed-spring part number covers one length.

When a procurement team treats both as a single “springs” line, three failures tend to appear. The first is a narrow stockout: a clinic runs out of one specific closed-spring length because a single case consumed the last unit of that SKU. The second is dead stock: a distributor buys a deep, wide diameter matrix of open coil that will not turn over within its shelf-life assumption. The third is a matrix that is too wide to manage comfortably: if every listed option is stocked, the closed spring with eyelets alone can produce up to 32 variants across four diameters, four lengths and two type designations.

Industry Background: Where Niti Springs Sit in the Orthodontic Supply Chain

Coil springs are small-ticket items inside a large category, but they sit on the critical path of active treatment. If the auxiliary is missing, the appointment is disrupted with it. That is why the stocking decision matters more than the unit price suggests.

The category context is worth keeping in view:

• The global orthodontic supplies market was valued at USD 14.8 billion in 2024 and is expected to grow at a CAGR of 20.1% through 2034 (Global Market Insights).
• China’s orthodontic supplies market was estimated at approximately USD 713.25 million in 2024 (Market Research Future).
• North America held the largest regional share of the orthodontic supplies market in 2024, estimated at 30.6% by revenue (Grand View Research).
• Nickel-titanium (NiTi) archwires face supply-chain risk because of heavy reliance on Chinese raw materials (Mordor Intelligence). Niti springs inherit the same raw-material dependency as the rest of the Niti product family.

Regulatory background matters too, because a spring is a regulated medical device component rather than a generic metal part. EU MDR 2017/745 requires CE marking for orthodontic products and classifies most of them as Class I or IIa. In the United States, related orthodontic hardware such as brackets and tubes is classified as Class I or II under 21 CFR 872.5410, with ISO 27020:2019 as the recognized standard (FDA). Buyers sourcing springs for regulated markets should expect documentation that matches the market they ship into, not a single certificate presented as universal.

The manufacturer context for the two products in this comparison is Hangzhou DTC Medical Apparatus Co., Ltd. (DTC Orthodontics), established in 2004 in Hangzhou, Zhejiang Province, China. The company manufactures orthodontic materials across three lines: orthodontics, pediatric dentistry and dental laboratory products. DTC states that it holds ISO13485, CE0197 and FDA certificates and that its production management system follows CE (MDR) and ISO requirements. Its facility covers 5,000 m² with 150 employees, including a 30-engineer R&D team, reports an annual output of 1,000,000 units, and exports approximately 80% of its products to markets including the EU, USA, Middle East, South America, Asia, Africa and Australia.

Detailed Solution: Comparing the Two Spring Formats

1. Niti Closed Spring With Eyelets

Niti Closed Spring With Eyelets is a dental elastic manufactured from Niti and intended for the orthodontic industry. Its defining characteristic is that it is supplied as a closed coil with integrated eyelets, in short fixed lengths rather than as continuous coil.

• Material: Niti
• Type: Dental Elastics (orthodontic)
• Diameters: 0.008", 0.010", 0.012", 0.014"
• Lengths: 3 mm, 6 mm, 9 mm, 12 mm
• Type designations: identical, different

For a buyer, the closed spring with eyelets behaves like a finished component. The length is decided at the factory, so there is no cutting step at the chair and no waste from trimming. The eyelets provide the point at which the spring can be tied or activated. The cost of that convenience is a wider SKU matrix: four diameters multiplied by four lengths multiplied by two type designations.

2. Niti Open Spring

Niti Open Spring is also a dental elastic made from Niti and intended for the orthodontic industry. Its model designation is listed as Open Spring or Open Coil Spring, and its type is specified as open.

• Material: Niti
• Type: Dental Elastics (orthodontic)
• Diameters: 0.008", 0.010", 0.012", 0.014"
• Lengths: 180 mm, 914 mm
• Type: open

The open spring behaves more like a raw material. One 914 mm coil can serve multiple patients, and the clinician determines the working length at the chair. That flexibility reduces SKU count — four diameters across two lengths produces at most eight variants — but it shifts the fitting decision to the clinician and requires auxiliary components to hold or activate the coil.

3. Intended Use: What Each Format Is Bought For

Both formats are specified for the orthodontic industry and are sold across the same four diameters. In general orthodontic practice, the open coil format is conventionally associated with space opening and tooth separation along the arch, while the closed coil format is conventionally associated with space closure and controlled force delivery between two points. Those associations are clinical conventions rather than product claims in the published parameter list, and they should be confirmed against your own treatment protocols before being written into a stocking policy.

What matters for the supply decision is this: if your case mix leans toward procedures where a fixed-length, eyeleted spring is the faster option, the closed version earns shelf space. If your case mix constantly varies in length, the continuous open coil avoids leftover offcuts.

4. Eyelet and Attachment Considerations

The “with eyelets” element of the closed spring is an attachment feature, not a cosmetic one. Eyelets give the clinician a defined point at which to tie a ligature, place an elastic, or connect the spring to an auxiliary. That can reduce the number of separate components needed at the chair.

An open coil has no built-in attachment point at its ends. It is generally secured or activated using auxiliary components — for example, a crimpable hook, such as the DTC Crimpable Hook, which has a smoothly polished rounded ball end and an open-channel design that allows direct placement onto an archwire — or with ligatures and elastics. From a procurement perspective, this is the trade-off: the eyeleted spring consolidates the attachment into the spring itself, while the open coil distributes it across the auxiliary tray.

If your clinic or lab already stocks crimpable hooks, ligatures and elastics in volume, the open coil adds little incremental complexity. If it does not, the closed spring with eyelets is the simpler first purchase.

5. Inventory Implications

Inventory behaviour is the strongest argument in this head-to-head, and it is determined entirely by the published parameters.

• Closed spring with eyelets: up to 32 catalogue variants (4 diameters × 4 lengths × 2 type designations). Each variant serves a narrow range of cases. Reorder points must be set per SKU, and a stockout on one length stops a case.
• Open spring: up to 8 catalogue variants (4 diameters × 2 lengths). Each variant covers a broad range of lengths because the clinician cuts it. Reorder points can be set at the reel level, and a single 914 mm coil supports many cases.

The practical consequence is that the two formats carry different kinds of risk. The closed spring carries SKU-count risk: more part numbers, more forecast lines, more chances of a partial stockout. The open spring carries conversion risk: fewer part numbers, but every case consumes a length the clinician must calculate, and the coil must be held or activated with auxiliary components.

Stocking depth should follow consumption, not catalogue completeness. Most buyers are better served by a narrow closed-spring matrix covering the two or three most common lengths at the two most common diameters, paired with a broader open-coil matrix across all four diameters.

Step-by-Step: A Six-Step Stocking Decision

Step 1 — Map your procedure mix before you map the catalogue

Start with the case types your clinic, distribution territory or lab actually handles. The format question resolves quickly once you know whether your work leans toward fixed-length, eyeleted applications or variable-length, cut-to-fit applications.

Step 2 — Fix your diameter set

Both formats are available in 0.008", 0.010", 0.012" and 0.014". Decide which of the four diameters you will hold in depth, and which you will stock as a thin buffer or order on demand. Diameter is shared between the two formats, so this decision is made once for the whole spring category.

Step 3 — Choose lengths by case, not by catalogue

For the closed spring with eyelets, the 3 mm, 6 mm, 9 mm and 12 mm lengths are the decision points. Identify the one or two lengths that appear in the majority of your cases and hold them deep. For the open spring, the choice is between a 180 mm coil and a 914 mm coil; the 914 mm coil is the higher-coverage option, while the 180 mm coil suits lower-volume users who would not consume a long coil before it ages.

Step 4 — Set the closed-to-open ratio

Rather than asking “which one do we stock,” ask “in what proportion.” A ratio derived from case mix is easier to defend internally than a preference, and it can be reviewed quarterly against actual consumption.

Step 5 — Verify supplier parameters and documentation

Before any spring order becomes a reorder, confirm that the supplier’s published parameters match what you receive: material, diameters, lengths, type designations and packaging. Confirm that certification scope covers the market you ship into. DTC states that its production management system follows CE (MDR) and ISO requirements and that it holds ISO13485, CE0197 and FDA certificates.

Step 6 — Validate with a sample run, then set reorder points

Run one small order through normal handling — receiving, storage, chairside use — before committing to depth. Measure actual consumption per case, convert it into a reorder point, and record the result per SKU. For the open coil, note how many millimetres a typical case consumes. For the closed spring, note which lengths empty first. Those two numbers, not the catalogue, should drive the next purchase order.

Use Cases: Clinic, Distributor and Dental Lab

Dental clinic

A clinic buys for chair time. A closed spring with eyelets arrives at a known length and carries its own attachment point, which shortens the fitting step and removes cutting from the appointment. A clinic with moderate case volume can hold a compact closed-spring matrix in the two most-used lengths at one or two diameters, and keep an open coil only for cases that fall outside the fixed set.

Distributor

A distributor buys for turnover and shelf efficiency. The open spring’s eight-variant matrix across four diameters and two lengths is easier to forecast than a 32-variant closed-spring matrix, and one 914 mm reel covers a broad band of treatment lengths. A distributor serving mixed accounts will typically anchor the spring section with open coil and add a targeted closed-spring selection for accounts that specifically request pre-formed, eyeleted components.

Dental laboratory

A lab buys for build control. Appliances fabricated on the bench benefit from components with fixed geometry, so the closed spring with eyelets is easier to place consistently inside a constructed appliance. Where the lab needs to adapt a spring to an unusual span, the open coil provides the length flexibility. Many labs will stock both, with the closed version as the default and the open coil as the adjustable option.

Comparison Table: Niti Closed Spring With Eyelets vs Niti Open Spring

The variant counts above are arithmetic derived from the published parameter lists, not independent market data. They illustrate stocking complexity only and do not describe sales volume.

FAQ

Conclusion: Turning a Comparison into a Stocking Policy

The head-to-head between Niti Closed Spring With Eyelets and Niti Open Spring does not end with a single winner. It ends with a ratio. The closed spring with eyelets gives you a decided length, an integrated attachment point and faster chairside handling, at the cost of a wider SKU matrix. The open spring gives you length flexibility and a smaller SKU matrix, at the cost of a cutting step and a dependency on auxiliary components.

Buy the closed version for the lengths your cases repeat most often. Buy the open version for the diameter coverage and length flexibility that a fixed-length catalogue cannot provide. Verify both against documentation, and let consumption data — not catalogue completeness — set your reorder points. Most importantly, review the ratio quarterly, because case mix changes and a stocking policy built on a single snapshot will drift out of alignment with what the chair actually uses.

Next Step: Sample, Catalogue or Quotation

Hangzhou DTC Medical Apparatus Co., Ltd. (DTC Orthodontics) manufactures Niti Closed Spring With Eyelets and Niti Open Spring alongside brackets, buccal tubes, bands, orthodontic accessories and pliers. The company was established in 2004 and operates from Floor 1-3, Building 2, 8th Xiyuan Road, Xihu District, Hangzhou, Zhejiang Province, China.

To request samples, a quotation, or the full English catalogue for Niti springs and orthodontic supplies, contact:

• Website: www.dtchz.com
• Email: jaymie@dtchz.com
• Tel / WhatsApp: +86 136-0051-7451
• Catalogue download: DTC English Catalogue (PDF)