The Effect of Full Versus Partial Coverage Thermoformed Retainers in Dual Retention With a Lower Bonded Retainer, on Periodontal, Orthodontic, and Patient-Reported Outcomes

The Effect of Full Versus Partial Coverage Thermoformed Retainers in Dual Retention With a Lower Bonded Retainer, on Periodontal, Orthodontic, and Patient-Reported Outcomes: A Randomised Controlled Trial

After braces are removed, teeth may move back toward their original positions. Retainers are used to help keep teeth straight after orthodontic treatment. This study compares two types of clear removable retainers used together with a fixed wire retainer behind the lower front teeth. One retainer covers the entire inner surface of the teeth (full coverage), while the other covers only part of the inner surface (partial coverage).

The purpose of this study is to find out whether the two retainer designs differ in their effects on gum health, comfort, retainer breakages, stability of the orthodontic correction, comfort, and compliance. The findings from this study may help orthodontists choose the most suitable retainer design for future patients.

Participants in this study will receive a fixed wire retainer on the lower front teeth and upper and lower clear removable retainers. They will be randomly assigned to receive either the full coverage or partial coverage lower retainer. Participants will attend follow-up visits at 1 month, 3 months, and 6 months after starting retainer wear. At these visits, the orthodontist will examine the teeth, gums, and retainers, and participants will complete a short questionnaire about their experience wearing the retainer.

This study excluded participants who are pregnant or breastfeeding within the first 6 months, have uncontrolled medical conditions or gum disease, smoke or vape, require a Hawley retainer instead of a clear retainer, or have missing front teeth or certain jaw conditions.

Participants may benefit from receiving retainers, oral hygiene care, and regular monitoring of their teeth and gum health at no additional cost. Participants will also receive an oral care kit during the debond appointment and at the 3-month and 6-month review visits.

Possible risks include breakage of the retainers, which may require repair or replacement, gum problems if oral hygiene is not maintained, and slight tooth movement despite retainer use. If gum problems develop, appropriate cleaning and referral for further treatment may be provided. Replacement retainers required during the study period will be provided free of charge.

Study Overview

• Status: Not yet recruiting
• Conditions: Orthodontic Retention
• Intervention / Treatment: Device: Full coverage Vivera retainer; Device: Partial coverage vivera retainer

Detailed Description

Vivera retainers will be the only thermoformed retainers used throughout this study.

• Study Type: Interventional
• Enrollment (Estimated): 42
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: ZHI MEI CHIA; Phone Number: +60143438922; Email: s2102418@siswa.um.edu.my

Study Locations

• Malaysia
  • Kuala Lumpur
    • Kuala Lumpur, Kuala Lumpur, Malaysia, 50603
      • Faculty of Dentistry, Universiti Malaya

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Aged over 18 years.
• Controlled systemic diseases and conditions.
• Probing pocket depth ≤ 3 mm
• Bleeding on probing < 10 per cent
• Full mouth plaque scores of less than 20 per cent
• Just completed active orthodontic treatment involving lower arch
• Patient consent to dual retention in the lower arch

Exclusion Criteria:

• Require a Hawley retainer in the lower arch.
• Patients in retention phase requiring replacement of retainers
• Uncontrolled systemic disease, including chronic or metabolic diseases.
• Pregnant or lactating mothers within six months postpartum.
• Taking medications that affect gingival health and architecture.
• Have one or more missing anterior teeth.
• Have congenital craniofacial deformities and syndromes, including cleft lip and/ or palate
• Cigarette or vape smokers

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Full coverage clear retainer; A removable lower retainer covers the entire inside surface of lower teeth including the fixed bonded retainer	Device: Full coverage Vivera retainer; A removable lower retainer (Vivera retainer) with full coverage design which covers the entire inside surface of lower teeth including the fixed bonded retainer
Active Comparator: Partial coverage clear retainer; A removable lower retainer covers part of inside surface of lower teeth excluding the fixed bonded retainer	Device: Partial coverage vivera retainer; A removable lower retainer (Vivera retainer) with partial coverage design which covers part of the inside surface of lower teeth excluding the fixed bonded retainer

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Full mouth plaque score	To evaluate full mouth plaque score associated with clear retainers with partial or full coverage designs when used in conjunction with fixed bonded retainers in the lower arch. Scale title: Full mouth plaque score Minimum value: 0% Maximum value: 100% Higher score means indicate worse plaque accumulation and poorer oral hygiene. (worse outcome)	baseline, 1 month, 3 months and 6 months
Full mouth bleeding on probing score	To evaluate full mouth bleeding on probing score associated with clear retainers with partial or full coverage designs when used in conjunction with fixed bonded retainers in the lower arch. Scale title: Full mouth bleeding on probing score Minimum value: 0% Maximum value: 100% Higher score means indicate worse periodontal health (worse outcome)	Baseline, 1 month, 3 months and 6 months
Periodontal probing depth of lower anterior teeth	To evaluate periodontal probing depth of lower anterior teeth associated with clear retainers with partial or full coverage designs when used in conjunction with fixed bonded retainers in the lower arch Scale title: Periodontal probing depth Minimum value: 0mm Maximum value: No fixed upper limit Higher score means indicate worse periodontal health (worse outcome)	baseline, 1 month, 3 months and 6 months
Gingival recession on lower anterior teeth	To evaluate gingival recession on lower anterior teeth associated with clear retainers with partial or full coverage designs when used in conjunction with fixed bonded retainers in the lower arch Scale title: Gingival recession Minimum value: 0mm Maximum value: No fixed upper limit Higher score means indicate worse periodontal health (worse outcome)	Baseline, 1 month, 3 months and 6 months
Integrity of clear retainer	To evaluate the incidence of clear retainer breakages associated with partial or full coverage designs when used in combination with fixed bonded retainers in the lower arch	3 months and 6 months
Breakages of fixed bonded retainers	To evaluate the incidence of breakages involving bonded wire or adhesive resin of fixed bonded retainers when used in combination with clear retainers in either partial or full coverage designs in the lower arch.	1 month, 3 months, 6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stability of lower anterior teeth	To evaluate the stability of lower anterior teeth (using Little's Irregularity Index) associated with partial and full coverage designs of clear retainers when used in conjunction with fixed bonded retainers. Scale title: Little's Irregularity Index Minimum value: 0mm Maximum value: No fixed upper limit Higher scores indicate greater relapse and worse alignment. (worse outcome)	Baseline, 3 months, 6 months
Quality of Life in Patients Wearing Orthodontic Retainers	To evaluate the patient's quality of life associated with partial or full coverage designs of clear retainers when used in conjunction with fixed bonded retainers. Quality of life assessed using the Quality of Life in Patients Wearing Orthodontic Retainers questionnaire. Total scores range from 0 score to 56 score, with higher scores indicating poorer quality of life related to retainer wear.	3 months and 6 months
Patient's compliance	Patient compliance associated with partial or full coverage clear retainers used in conjunction with fixed bonded retainers will be evaluated using Part B, Questions 1 and 2 of the Quality of Life in Patients Wearing Orthodontic Retainers questionnaire. Compliance will be reported as "yes" or "no." For non-compliance responses, reasons for non-compliance will also be recorded, with multiple responses permitted.	3 months and 6 months

Collaborators and Investigators

• Sponsor: University of Malaya

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): June 30, 2027
• Study Completion (Estimated): September 30, 2027

Study Registration Dates

• First Submitted: May 12, 2026
• First Submitted That Met QC Criteria: June 21, 2026
• First Posted (Actual): June 25, 2026

Study Record Updates

• Last Update Posted (Actual): June 25, 2026
• Last Update Submitted That Met QC Criteria: June 21, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Orthodontic retention; periodontal health; breakage; clear retainer; fixed bonded retainer
• Other Study ID Numbers: DF CD2609/0046 (P)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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