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NCT Number: NCT07669129

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

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.

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Key information

Conditions

Orthodontic Retention

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Faculty of Dentistry, Universiti Malaya

Kuala Lumpur, 50603, Malaysia

About this study

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

Who can participate

Healthy volunteers accepted: Yes

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

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

Treatment and study plan

Partial coverage vivera retainer

Device

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

Full coverage Vivera retainer

Device

A removable lower retainer (Vivera retainer) with full coverage design which covers the entire inside surface of lower teeth including the fixed bonded retainer

Primary outcomes

  1. Full mouth plaque score

    Time frame: baseline, 1 month, 3 months and 6 months

    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)

  2. Full mouth bleeding on probing score

    Time frame: Baseline, 1 month, 3 months and 6 months

    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)

  3. Periodontal probing depth of lower anterior teeth

    Time frame: baseline, 1 month, 3 months and 6 months

    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)

  4. Gingival recession on lower anterior teeth

    Time frame: Baseline, 1 month, 3 months and 6 months

    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)

  5. Integrity of clear retainer

    Time frame: 3 months and 6 months

    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

  6. Breakages of fixed bonded retainers

    Time frame: 1 month, 3 months, 6 months

    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.

Secondary outcomes

  1. Stability of lower anterior teeth

    Time frame: Baseline, 3 months, 6 months

    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)

  2. Quality of Life in Patients Wearing Orthodontic Retainers

    Time frame: 3 months and 6 months

    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. Patient's compliance

    Time frame: 3 months and 6 months

    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.

Study contacts

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

ZHI MEI CHIA

CONTACT

[email protected]

+60143438922

Sponsors and collaborators

Lead sponsor

University of Malaya

Other

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Jun 25, 2026
Registry last updated
Jul 23, 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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