After removal of the orthodontic appliance, your teeth have just been moved; they still “want” to return to their original position. Without a retention device, relapse can occur within a few months. The fixed retainer is the standard solution to lock in the new alignment. Let’s explore what it is, why it exists, and how it has evolved up to today’s PEEK retainer wire. This article reviews the very definition of a fixed retainer and its usefulness. For a more comprehensive overview, see our dedicated guide – the fixed retainer – complete guide.

What is a fixed retainer ?

A fixed retainer is an ultra-thin dental splint bonded to the lingual surface of the six anterior teeth. Completely invisible when smiling, it acts like a stabilizing bar that maintains the alignment achieved after orthodontic treatment. Worn day and night, it neutralizes the micro-forces exerted by the tongue, lips, and periodontal ligament. Follow-up studies show > 95% of teeth remain aligned ten years after placement, provided the retainer wire remains intact.

Why was the fixed retainer invented ?

Even after perfect treatment, teeth retain an “elastic memory” : the periodontal ligament and gingival fibers exert constant micro-movements capable of reopening a diastema or causing crowding to reappear. In the 1970s, the first fixed retainers were designed to continuously neutralize these forces and prevent orthodontic relapse.
Initially, it was thought that wearing a retainer for 3 to 5 years was sufficient; recent literature now recommends lifetime retention – any interruption exposing the patient to the risk of late tooth movement. This underlines the importance of choosing a comfortable and durable retainer wire to support the patient long term.
To learn more, check out our dedicated article – how long to keep a fixed retainer

Why use a fixed retainer ?

After orthodontic treatment, periodontal ligament fibers attempt to return teeth to their original position; a fixed retainer neutralizes these micro-forces 24/7. Without it, 60 to 70% of patients experience relapse in crowding or diastema within five years after appliance removal.

The history of the fixed retainer : from steel to PEEK retention

• 1919 – The Hawley plate

The very first retention solution was the Hawley plate, a removable resin appliance with a visible metal wire on the front of the teeth. Although effective at maintaining alignment after treatment, it lacked discretion and comfort. It was widely used for a long time before becoming marginal, reserved for specific cases.

• 1977 – The bonded multistrand steel wire

With the arrival of light-cured composite — a resin that hardens under a specific light — orthodontists were able for the first time to permanently bond a retainer wire directly on the inner surface of the teeth.

The twisted multistrand steel wire quickly became the standard. Low cost, relatively discreet, and flexible, it improved comfort and hygiene. It could be replaced in case of damage.
However, it has some limits: the steel can cause allergies, and repeated stress can lead to wire fracture and debonding.

• 1993 – Transparent Essix retainer

The introduction of clear plastic thermoformed retainers (Essix) brought an alternative solution. These removable retainers are invisible, easy to clean, but require patient compliance and can be lost or broken.

• 2015 – NiTi shape-memory retainer

Nickel-Titanium (NiTi) wires with shape memory were introduced to improve flexibility and reduce breakage risk. They adapt to slight tooth movements while maintaining stability.

• 2025 – Biocompatible PEEK wire by eZtain

Recently, PEEK (polyether ether ketone), a biocompatible, non-metallic polymer, has been developed as a new retainer wire. It offers high durability, excellent biocompatibility, and is allergy-free, representing the future of fixed retention.

What materials make up a fixed retainer today ?

Currently, fixed retainers are made from stainless steel wires (multistrand or single strand), nickel-titanium alloys, or innovative materials like PEEK. The choice depends on clinical requirements, patient allergies, and desired longevity.

Advantages and limitations of the fixed retainer

Bonded behind the incisors, the fixed retainer acts like an invisible lock : it blocks micro-movements of the periodontal ligament 24/7 and maintains alignment without ever pushing the teeth. Over time, however, two issues may occur : torsional fatigue which can crack a metal wire, and debonding after trauma or bruxism; there may also be possible reactions to nickel contained in steel or in the wire. 

An exception – retainer wire syndrome

In rare cases (< 2%), teeth can move despite a wire still being in place. This phenomenon, called retainer wire syndrome, happens when retention is no longer fully passive : residual tension or slight deformation is enough to exert an unwanted force. The result ? A rotation of an incisor or the reopening of a diastema — that is, a gap between two teeth, often visible between the incisors — sometimes within a few weeks.

The solution is to remove the wire, realign if necessary, then place a perfectly neutral fixed retainer.

The complete procedure to ensure perfect placement of your fixed retainer is available in our dedicated article – placement of a fixed retainer

With eZtain, this risk is almost zero : the PEEK wire, digitally milled to perfectly fit the patient’s oral environment and prevent any retainer wire syndrome. 

What are the drawbacks of the fixed retainer ?

The wire promotes plaque retention; careful brushing with interdental brushes is essential. Minor risks : occasional debonding, long-term metal fatigue, or nickel allergy for some alloys. Six-month check-ups limit these issues; a PEEK option eliminates allergy risk.

Is the fixed retainer effective ?

Yes : meta-analyses show more than 95% alignment retention ten years after placement if the wire is intact and well maintained. Effectiveness increases further when combined with nightly use of an Essix night guard.

Can a fixed retainer tighten teeth ?

No. A well-bonded wire is completely passive; it maintains without applying orthodontic force. If a tooth moves, it means the wire has deformed or was bonded under tension; consult quickly to replace it.

Maintenance & follow-up : keeping your retainer wire healthy 

After placement, little changes : the wire is designed to be discreet and minimally invasive. But some habits help ensure its longevity and the health of your teeth.

Daily use of an interdental brush under the wire is essential, as well as electric brushing twice a day with fluoride toothpaste. A weekly mouthwash completes the routine. In case of irritation, a short course of chlorhexidine can be prescribed.

A six-month check-up is recommended to verify bonding, perform targeted scaling, and monitor possible cavities under the adhesive with an annual X-ray.

With a PEEK retainer such as eZtain, maintenance becomes even simpler : no metal, less plaque, no allergy risk and increased durability. More peace of mind, for longer.

The new innovation in fixed retainers – PEEK retainers 

Latest advancement adopted by a growing number of practitioners in France and Europe : custom-made PEEK retainers by eZtain.
Digitally milled, they combine the continuous stability of fixed retainers with the benefits of a biocompatible material, without metal, allergy, or discoloration. Their smooth surface limits plaque formation, while their mechanical strength almost eliminates long-term fracture risks.

Already integrated into many orthodontic offices, they gradually replace traditional metal wires. To date, eZtain shows 0% breakage at 5 years.

Another advantage : completely invisible in MRI, they avoid removal before cranial scanning and eliminate metal artifacts in the oral cavity. In a word, it is the most reliable, comfortable, and modern solution for lasting smile stabilization.

FAQ 

10. conclusion & next steps

The fixed retainer is the discreet shield that protects your new smile : placed in minutes, invisible, it guarantees dental stability for decades. Its long evolution, from steel wire to PEEK technology, has made retention more comfortable, hygienic, and biocompatible than ever. 

By following simple maintenance (interdental brushes, six-month check-ups), you eliminate most risks and keep a lasting alignment. To explore in detail wear duration, cost, clinical studies, and all alternatives, dive into the fixed retainer – detailed guide.