Comparison of 3D Printed Metal Fixed Retainer Versus Conventional Fixed Bonded Retainer

Despite the growing diversity of materials used for mandibular fixed retainers, the evidence base remains inconclusive. In particular, conflicting findings have been reported regarding the bond failure of titanium retainers across different evaluation periods, including immediate and 12-month outcomes. Additionally, the emergence of 3D metal-printed retainers has not yet been matched by sufficient clinical evidence, with current data being limited and lacking long-term validation.

Study Overview

• Status: Completed
• Conditions: Bond, Pair
• Intervention / Treatment: Device: conventional fixed retainer; Device: bar 3d printed metal fixed retainer

Detailed Description

In recent years, CAD/CAM technology and 3D printing have introduced new possibilities in orthodontic practice, with expanding applications across various treatment modalities. Additive manufacturing, commonly known as 3D printing, enables the fabrication of objects through the sequential layering of material to produce precise three-dimensional structures. While orthodontists are already familiar with 3D-printed appliances such as clear aligners, the application of these technologies in fixed retention is still evolving. Recent studies have reported the fabrication of customized lingual retainers using CAD/CAM techniques, including nickel-titanium-milled retainers and zirconia bars designed for use as bonded mandibular fixed retainers.

• Study Type: Interventional
• Enrollment (Actual): 64
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Egypt
  • Cairo University
    • Giza, Cairo University, Egypt
      • Amany Eltantawy

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age ≥ 13 years
• Complete permanent dentition up to second molars
• Completed Class I orthodontic treatment and requiring a mandibular fixed -bonded retainer
• No sex predilection.

Exclusion Criteria:

• Enamel defects that may compromise bonding (e.g., hypoplasia, fluorosis)
• Poor oral hygiene
• Active dental or periodontal pathology at the site of intervention
• Lingual restorations on mandibular anterior teeth
• Poor compliance or inability to attend follow-up visits
• Psychological or medical conditions that may interfere with study participation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Conventional fixed bonded retainer	Device: conventional fixed retainer; Participants will receive a conventional fixed bonded lingual retainer (canine-to-canine) fabricated using multistranded stainless steel wire and bonded using standard clinical procedures.
Experimental: Bar 3d printed metal fixed retainer	Device: bar 3d printed metal fixed retainer; Participants will receive a custom-designed 3D-printed metal fixed retainer. The retainer is digitally designed using intraoral scans and fabricated using metal 3D printing technology to achieve a precise fit tailored to each patient.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
bond failure	Bond failure will be assessed clinically by detecting any detachment of the retainer from the tooth surface (number of debonded teeth).	immediate (within 24 hours after bonding) and at 3, 6, 9, and 12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
chairside time	Time measurement will start from the beginning of acid etching of the teeth and end after completion of composite curing for all bonded teeth. The duration will be recorded in minutes using a digital stopwatch by an independent assessor using a digital stopwatch (minutes)	Periprocedural (during retainer bonding procedure on Day 1)
wire breakage		Every 3months for 12 months
plaque accumulation	Plaque accumulation will be assessed using the Silness-Löe Plaque Index, which scores plaque presence on the tooth surface adjacent to the fixed retainer. Each tooth will be scored on a scale from 0 to 3: 0: No plaque; Thin film of plaque detectable by probe; Moderate accumulation visible to the naked eye; Abundant plaque accumulation Assessment will be performed by direct intraoral clinical examination using a dental mirror and probe by a calibrated examiner. The outcome will be reported as the mean plaque index score per patient at each time point.	Baseline (before retainer bonding) and at 3, 6, 9, and 12 months
posttreatment relapse	Post-treatment relapse will be assessed using Little's Irregularity Index, which measures the linear displacement of the anatomic contact points of the mandibular anterior teeth. Relapse will be calculated as the difference in Little's Irregularity Index between baseline (pre-retention) and 12 months follow-up.	Baseline (before retainer bonding) and at 12 months

Collaborators and Investigators

• Sponsor: Amany Ibrahim

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2025
• Primary Completion (Actual): October 1, 2025
• Study Completion (Actual): October 1, 2025

Study Registration Dates

• First Submitted: April 8, 2026
• First Submitted That Met QC Criteria: April 13, 2026
• First Posted (Actual): April 20, 2026

Study Record Updates

• Last Update Posted (Actual): April 20, 2026
• Last Update Submitted That Met QC Criteria: April 13, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Behavior; Behavior, Animal; Consummatory Behavior; Sexual Behavior, Animal; Pair Bond
• Other Study ID Numbers: Ortho332; Cairo University (Other Identifier: Cairo University)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No