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NCT Number: NCT07730476

3D-Printed vs Conventional Fixed Retainers After Orthodontic Treatment

This randomized clinical trial aims to compare the clinical performance of two types of three-dimensionally printed fixed retainers (Cobalt-Chromium and Titanium Grade 5) with the conventional multistranded stainless steel fixed retainer following orthodontic treatment. Thirty-six participants will be randomly allocated into three parallel groups with a 1:1:1 allocation ratio. The primary outcome is post-treatment stability assessed by Little's Irregularity Index and lower arch dimensions. Secondary outcomes include bond failure rate and periodontal parameters over a 12-month follow-up period.

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Key information

Conditions

Orthodontic Relapse Malocclusion Stomatognathic Diseases Tooth Diseases

Age range

21 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

About this study

Orthodontic relapse remains one of the greatest challenges following the completion of orthodontic treatment. Conventional multistranded stainless steel fixed retainers are considered the gold standard for long-term retention; however, they have several limitations including operator-dependent adaptation, prolonged chairside time, structural instability, and possible unwanted tooth movement.

Advances in digital dentistry have introduced CAD/CAM technology and additive manufacturing (3D printing), allowing the fabrication of customized fixed retainers with improved adaptation and manufacturing accuracy. Three-dimensional printed retainers fabricated from Cobalt-Chromium (Co-Cr) and Titanium Grade 5 (Ti-6Al-4V) alloys may provide better mechanical properties, improved precision, and enhanced clinical performance.

This study is a three-arm, parallel-group randomized clinical trial including 36 participants who have completed orthodontic treatment. Participants will be randomly assigned in a 1:1:1 ratio to receive either a conventional multistranded stainless steel fixed retainer, a 3D-printed Cobalt-Chromium fixed retainer, or a 3D-printed Titanium Grade 5 fixed retainer.

The primary outcome is post-treatment stability assessed using Little's Irregularity Index and lower arch dimensions. Secondary outcomes include retainer bond failure and periodontal health, assessed by plaque index, gingival index, probing depth, and bleeding on probing. Participants will be followed for 12 months after retainer placement.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age range 21-35 years old after finishing orthodontic treatment.
  • Presence of all maxillary and mandibular anterior teeth with normal shape and size.
  • Completion of orthodontic treatment with full fixed appliances.

Exclusion criteria

  • Patients with cleft lip and/or palate or any other craniofacial syndrome
  • Patients with compromised oral hygiene or periodontal disease
  • Patients who had orthognathic surgery
  • Lingual appliance treatments
  • Enamel hypoplasia, fluorosis, active caries, restorations, or fractures in the anterior teeth
  • Patients who had separate arch debondings with a difference of more than 2 months in-between jaws

Treatment and study plan

Conventional Multistranded Stainless Steel Fixed Retainer

Device

Conventional 0.0215-inch six-stranded stainless steel bonded fixed retainer.

3D-Printed Cobalt-Chromium Fixed Retainer

Device

Customized 3D-printed cobalt-chromium bonded fixed retainer fabricated from intraoral scans.

3D-Printed Titanium Fixed Retainer

Device

Customized 3D-printed titanium (Ti-6Al-4V) bonded fixed retainer fabricated from intraoral scans.

Primary outcomes

  1. Orthodontic stability assessed using Little's Irregularity Index

    Time frame: 12 months

    Orthodontic stability will be assessed using Little's Irregularity Index on digital models. Lower scores indicate better stability.

Secondary outcomes

  1. Retainer failure rate

    Time frame: 12 months

    Assessment of the failure rate of conventional stainless steel, 3D-printed cobalt-chromium, and 3D-printed titanium fixed retainers.

  2. Plaque Index (Silness and Löe Plaque Index)

    Time frame: 12 months

    Assessment of dental plaque accumulation using the Silness and Löe Plaque Index. Lower scores indicate better oral hygiene.

  3. Gingival Index (Löe and Silness Gingival Index)

    Time frame: 12 months

    Assessment of gingival inflammation using the Löe and Silness Gingival Index. Lower scores indicate better gingival health.

  4. Bleeding on Probing (BOP)

    Time frame: 12 months

    Assessment of bleeding on probing as an indicator of gingival inflammation. The percentage of bleeding sites will be recorded. Lower values indicate better periodontal health.

  5. Probing Pocket Depth (PPD)

    Time frame: 12 months

    Assessment of periodontal pocket depth using a periodontal probe. Pocket depth will be recorded in millimeters (mm). Lower values indicate better periodontal health.

Study contacts

Contact information is provided by the study sponsor or research team.

Ahmed Sh Hashem, Professor

CONTACT

[email protected]

+201002024437

Salma A Daabis, BDS

CONTACT

[email protected]

+201066600270

Sponsors and collaborators

Lead sponsor

Minia University

Other

Registry information

Official study title

Comparison Between Three-Dimensionally Printed Fixed Retainers Versus Conventional Multistranded Stainless Steel Fixed Retainers: Randomized Clinical Trial

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Jul 28, 2026
Registry last updated
Jul 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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