Bacterial Diversity Study Using 16S rRNA Sequencing of Periodontal Samples From Patients With Orthodontic Retainers

NCT07718061 | Recruiting

• 1 other identifier: 725/2025
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

After completion of orthodontic treatment, a retention phase is required to prevent relapse of tooth malposition. Fixed retention in the mandibular anterior region is commonly used. This type of retainer is bonded to the lingual surfaces of the canines and incisors and may hinder oral hygiene, thereby promoting bacterial plaque accumulation and gingival inflammation. Currently, probably due to the increasing use of clear aligner therapy, clear removable Essix-type retainers are becoming more widely used. Since these retainers can be removed by the patient, they may facilitate oral hygiene. However, studies assessing gingival health and the composition of the subgingival microbiota in patients wearing orthodontic retainers remain scarce. Therefore, the aim of this study will be to assess the composition of the gingival sulcus microbiota and gingival health in patients wearing fixed or removable orthodontic retainers. Ten adult patients who have completed orthodontic treatment will be recruited and divided into two groups:

1. 1.Fixed retention group.
2. 2.Removable retention group.

Conditions

Fixed Orthodontic Retainer; Orthodontic Appliances, Removable; Orthodontic Appliance Complication; Gingivitis; Periodontal Diseases

Keywords

Orthodontic retainer; Periodontal health; Gingivitis; Microbiota

Outcome Measures

Primary Outcomes (2)

• Longitudinal change in subgingival microbial community composition assessed using Bray-Curtis dissimilarity

  Subgingival plaque samples collected from the mandibular anterior teeth will be analyzed using 16S rRNA gene sequencing. Overall microbial community composition will be assessed using the Bray-Curtis dissimilarity index. Longitudinal differences in microbial community composition will be evaluated between participants receiving fixed orthodontic retainers and those receiving removable Essix retainers, considering the effect of study group, assessment time point, and their interaction.

  T0: pre-debonding; T1: pre-retainer baseline, 3 days after T0; T2: 1 month post-retainer; T3: 3 months post-retainer; T4: 6 months post-retainer.

• Longitudinal change in bleeding on probing

  Bleeding on probing will be recorded as present or absent at six sites per tooth in the mandibular anterior region following gentle periodontal probing. The outcome will be calculated as the percentage of examined sites showing bleeding for each participant. Longitudinal changes in bleeding on probing will be compared between participants receiving fixed orthodontic retainers and those receiving removable Essix retainers, considering the effect of study group, assessment time point, and their interaction.

  T0: pre-debonding; T1: pre-retainer baseline, 3 days after T0; T2: 1 month post-retainer; T3: 3 months post-retainer; T4: 6 months post-retainer.

Secondary Outcomes (9)

• Longitudinal change in subgingival microbial alpha diversity assessed using the Shannon diversity index

  T0: pre-debonding; T1: pre-retainer baseline, 3 days after T0; T2: 1 month post-retainer; T3: 3 months post-retainer; T4: 6 months post-retainer.

• Longitudinal change in subgingival microbial evenness assessed using Pielou's evenness index

  T0: pre-debonding; T1: pre-retainer baseline, 3 days after T0; T2: 1 month post-retainer; T3: 3 months post-retainer; T4: 6 months post-retainer.

• Longitudinal change in subgingival microbial dominance assessed using the Simpson dominance index

  T0: pre-debonding; T1: pre-retainer baseline, 3 days after T0; T2: 1 month post-retainer; T3: 3 months post-retainer; T4: 6 months post-retainer.

• Longitudinal change in subgingival microbial taxonomic composition

  T0: pre-debonding; T1: pre-retainer baseline, 3 days after T0; T2: 1 month post-retainer; T3: 3 months post-retainer; T4: 6 months post-retainer.

• Differential abundance of subgingival bacterial taxa

  T0: pre-debonding; T1: pre-retainer baseline, 3 days after T0; T2: 1 month post-retainer; T3: 3 months post-retainer; T4: 6 months post-retainer.

Study Arms (2)

Fixed Orthodontic Retention

ACTIVE COMPARATOR

Participants assigned to this arm will receive a fixed lingual orthodontic retainer bonded to the mandibular anterior teeth, extending from tooth 33 to tooth 43. The same retainer wire and bonding materials will be used for all participants

Device: Fixed Orthodontic Retainer

Removable Essix-Type Orthodontic Retention

EXPERIMENTAL

Participants assigned to this arm will receive a clear removable Essix-type orthodontic retainer. Participants will be instructed to wear the retainer for 22 hours per day. All retainers will be manufactured using the same material and by the same dental technician.

Device: Removable Essix-Type Orthodontic Retainer

Interventions

Fixed Orthodontic Retainer DEVICE

A fixed lingual orthodontic retainer bonded to the mandibular anterior teeth, extending from tooth 33 to tooth 43

Fixed Orthodontic Retention

Removable Essix-Type Orthodontic Retainer DEVICE

A clear removable Essix-type orthodontic retainer prescribed for 22 hours of daily wear

Removable Essix-Type Orthodontic Retention

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Treatment involving both dental arches
• Permanent dentition with at least 24 teeth
• Treatment duration longer than 12 months
• Treatment using the Versatile MBT system with a 0.022-inch slot

You may not qualify if:

• Patients with systemic disease or taking medications that may affect periodontal health
• Inadequate restorations or active carious lesions
• iodontal disease
• Plaque index greater than 20% before placement of the retainer or during the study
• Use of oral antiseptics within the previous 6 months or during the study period
• Use of antibiotics within the previous 14 days or during the study period
• Smokers
• Pregnant or breastfeeding women
• Presence of open gingival embrasures, crowding, or dental malposition in the mandibular anterior region after orthodontic treatment

Sponsors & Collaborators

• Universidad de Murcia: lead

Study Sites (1)

University Dental Clinic

Murcia, 30008, Spain

RECRUITING

Related Publications (9)

• Yanez-Vico RM, Iglesias-Linares A, Ballesta-Mudarra S, Ortiz-Ariza E, Solano-Reina E, Perea EJ. Short-term effect of removal of fixed orthodontic appliances on gingival health and subgingival microbiota: a prospective cohort study. Acta Odontol Scand. 2015;73(7):496-502. doi: 10.3109/00016357.2014.993701. Epub 2015 Jan 29.

  PMID: 25631494 BACKGROUND

• Choi DS, Cha BK, Jost-Brinkmann PG, Lee SY, Chang BS, Jang I, Song JS. Microbiologic changes in subgingival plaque after removal of fixed orthodontic appliances. Angle Orthod. 2009 Nov;79(6):1149-55. doi: 10.2319/111808-593R.1.

  PMID: 19852608 BACKGROUND

• Pan S, Liu Y, Zhang L, Li S, Zhang Y, Liu J, Wang C, Xiao S. Profiling of subgingival plaque biofilm microbiota in adolescents after completion of orthodontic therapy. PLoS One. 2017 Feb 3;12(2):e0171550. doi: 10.1371/journal.pone.0171550. eCollection 2017.

  PMID: 28158292 BACKGROUND

• Levin L, Samorodnitzky-Naveh GR, Machtei EE. The association of orthodontic treatment and fixed retainers with gingival health. J Periodontol. 2008 Nov;79(11):2087-92. doi: 10.1902/jop.2008.080128.

  PMID: 18980517 BACKGROUND

• Manzon L, Fratto G, Rossi E, Buccheri A. Periodontal health and compliance: A comparison between Essix and Hawley retainers. Am J Orthod Dentofacial Orthop. 2018 Jun;153(6):852-860. doi: 10.1016/j.ajodo.2017.10.025.

  PMID: 29853243 BACKGROUND

• Al-Moghrabi D, Johal A, O'Rourke N, Donos N, Pandis N, Gonzales-Marin C, Fleming PS. Effects of fixed vs removable orthodontic retainers on stability and periodontal health: 4-year follow-up of a randomized controlled trial. Am J Orthod Dentofacial Orthop. 2018 Aug;154(2):167-174.e1. doi: 10.1016/j.ajodo.2018.01.007.

  PMID: 30075919 BACKGROUND

• Rody WJ Jr, Elmaraghy S, McNeight AM, Chamberlain CA, Antal D, Dolce C, Wheeler TT, McGorray SP, Shaddox LM. Effects of different orthodontic retention protocols on the periodontal health of mandibular incisors. Orthod Craniofac Res. 2016 Nov;19(4):198-208. doi: 10.1111/ocr.12129. Epub 2016 Sep 20.

  PMID: 27647720 BACKGROUND

• Eroglu AK, Baka ZM, Arslan U. Comparative evaluation of salivary microbial levels and periodontal status of patients wearing fixed and removable orthodontic retainers. Am J Orthod Dentofacial Orthop. 2019 Aug;156(2):186-192. doi: 10.1016/j.ajodo.2018.08.022.

  PMID: 31375228 BACKGROUND

• Li B, Lu C, Yao X, Wu X, Wu G, Zeng X. Effects of three orthodontic retainers on periodontal pathogens and periodontal parameters. Sci Rep. 2023 Nov 24;13(1):20709. doi: 10.1038/s41598-023-46922-2.

  PMID: 38001102 BACKGROUND

MeSH Terms

Conditions

Gingivitis; Periodontal Diseases

Condition Hierarchy (Ancestors)

Infections; Gingival Diseases; Mouth Diseases; Stomatognathic Diseases

Study Officials

• Antonio J Ortiz Ruiz, MD PhD

  Universidad de Murcia

  STUDY CHAIR

Central Study Contacts

Ascensión Vicente, DDS PhD

CONTACT

+3486888664; ascenvi@um.es

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: The study will be open-label because fixed and removable orthodontic retainers are readily distinguishable. Participants, care providers and investigators will be aware of the assigned retention method. Microbiological samples will be coded, and laboratory personnel performing 16S rRNA sequencing and bioinformatic analysis will be unaware of group allocation.
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: This is a prospective, two-arm, parallel-group interventional study. Ten adult participants completing orthodontic treatment with fixed multibracket appliances will be allocated to receive either a fixed mandibular lingual retainer or a removable Essix-type retainer. Periodontal parameters and subgingival plaque samples will be assessed before retainer placement and at 1, 3, and 6 months after retainer placement.

Study Record Dates

• First Submitted: July 16, 2026
• First Posted: July 21, 2026
• Study Start: January 12, 2026
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): July 1, 2027
• Last Updated: July 28, 2026

Record last verified: 2026-07

Locations

ES (1)