Ultrasonographic Evaluation of Periodontal Effects of Fixed Retainers

Ultrasonographic Analysis of the Effects of Fixed Lingual Retainer Placed After Orthodontic Treatment on Periodontal Parameters

This prospective clinical study aims to evaluate the effects of fixed lingual retainers placed after orthodontic treatment on periodontal soft and hard tissue parameters using ultrasonographic imaging. A total of 53 participants (636 anterior teeth) who had completed fixed orthodontic therapy were examined at baseline, 3 months, and 6 months after retainer placement. Ultrasonographic assessments were performed to measure gingival thickness, marginal bone level, and gingival level. Periodontal clinical parameters, including plaque index, gingival index, probing depth, bleeding on probing, and clinical attachment loss, were also recorded. The study seeks to determine whether fixed retainers induce measurable alterations in periodontal structures and to explore potential correlations between gingival phenotype and ultrasonographic findings.

Study Overview

• Status: Completed
• Conditions: Fixed Orthodontic Retainer

Detailed Description

Orthodontic retention is a critical phase following active treatment, aiming to maintain the corrected tooth positions and ensure long-term stability. Fixed lingual retainers are widely used due to their minimal patient compliance requirements and aesthetic advantages. However, the long-term presence of fixed retainers may influence periodontal health by altering plaque accumulation patterns and modifying soft and hard tissue dynamics. The literature remains inconclusive regarding whether these appliances cause clinically significant periodontal changes.

This prospective observational clinical study was conducted to evaluate the ultrasonographic and clinical periodontal changes that occur following the placement of fixed lingual retainers in orthodontically treated individuals. Fifty-three participants (aged 16-24 years) who had completed fixed orthodontic treatment were enrolled. All participants received fixed stainless-steel lingual retainers bonded to the anterior teeth (canine-to-canine) in both maxillary and mandibular arches. Participants were divided into four subgroups according to post-treatment incisor inclination changes determined by cephalometric analysis: Maxillary Retroclination, Maxillary Proclination, Mandibular Retroclination, and Mandibular Proclination groups.

Ultrasonographic imaging was performed using a high-frequency intraoral probe with a custom-designed silicone stabilizing cap to ensure consistent contact with the gingival tissue. Measurements were taken perpendicular to the tooth surface at three time points: immediately after retainer placement (T0), three months (T1), and six months (T2). The following ultrasonographic parameters were recorded:

Gingival thickness (GT)

Marginal bone level (MBL)

Gingival level (GL)

Conventional periodontal indices were also assessed at each visit, including the Plaque Index (PI), Gingival Index (GI), Probing Depth (PD), Bleeding on Probing (BOP), and Clinical Attachment Loss (CAL). Gingival phenotype classification was determined based on gingival thickness and keratinized tissue width.

The main objective of this study is to determine whether fixed lingual retainers induce measurable changes in gingival or bone morphology as assessed by ultrasonography and to evaluate the relationship between periodontal phenotypes and ultrasonographic findings. The study also aims to contribute to the validation of ultrasonography as a noninvasive, radiation-free diagnostic method for longitudinal monitoring of periodontal tissue dynamics following orthodontic retention.

• Study Type: Observational
• Enrollment (Actual): 53

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Selçuklu
    • Konya, Selçuklu, Turkey (Türkiye), 42060
      • Selcuk University Faculty of Dentistry

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population consisted of individuals who had completed fixed orthodontic treatment at the Department of Orthodontics, Selçuk University Faculty of Dentistry. All participants were systemically healthy, non-smoking young adults aged between 16 and 24 years, with good oral hygiene and no active periodontal disease. Each subject had maxillary and/or mandibular anterior teeth bonded with fixed retainers in passive condition. A total of 53 individuals (636 anterior teeth) were evaluated and categorized into four subgroups according to the inclination of anterior teeth: maxillary retroclination, maxillary proclination, mandibular retroclination, and mandibular proclination.

Description

Inclusion Criteria:

• Inclusion Criteria:
• Patients who have completed comprehensive orthodontic treatment with fixed appliances.
• Patients with a fixed mandibular or maxillary lingual retainer in place for at least 6 months.
• Age between 18 and 40 years.
• Good general health with no systemic conditions affecting periodontal tissues.
• Non-smokers or light smokers (<5 cigarettes/day).
• Presence of all anterior teeth without significant restorations or prosthetic crowns.

Exclusion Criteria:

• History of periodontal surgery or advanced periodontitis prior to orthodontic treatment.
• Systemic diseases or medications affecting periodontal health (e.g., diabetes, immunosuppressive therapy).
• Pregnancy or lactation.
• Poor oral hygiene or non-compliance with oral hygiene instructions.
• Teeth with caries, large restorations, or endodontic treatment in the area of interest.
• Patients with removable retainers or interrupted use of fixed retainers.

Study Plan

How is the study designed?

Number of groups / cohorts

4

Cohorts and Interventions

Group / Cohort
1. Maxillary Retroclination Group; Participants with completed fixed orthodontic treatment presenting retroclined maxillary anterior teeth. This group represents patients whose upper incisors show a lingual inclination relative to the Sella-Nasion (SN) plane. Periodontal and ultrasound (USG) parameters are evaluated at baseline, 3 months, and 6 months following retention.
2. Maxillary Proclination Group; Participants with completed fixed orthodontic treatment showing proclined maxillary anterior teeth. The upper incisors present a labial inclination relative to the SN plane. Periodontal and ultrasound (USG) parameters are compared across time intervals during retention.
3. Mandibular Retroclination Group; Participants with completed fixed orthodontic treatment and retroclined mandibular anterior teeth. The lower incisors exhibit lingual inclination relative to the mandibular plane. Periodontal and ultrasound (USG) parameters are longitudinally monitored during retention.
Mandibular Proclination Group; Participants with completed fixed orthodontic treatment presenting proclined mandibular anterior teeth. The lower incisors display labial inclination relative to the mandibular plane. Periodontal and ultrasound (USG) measurements are performed at baseline, 3-month, and 6-month follow-ups.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Gingival Thickness Measured by Ultrasonography	Gingival thickness will be measured at baseline (T0), 3 months (T1), and 6 months (T2) after placement of fixed lingual retainers using high-frequency intraoral ultrasonography. Measurements will be performed at the mid-facial aspect of anterior teeth, perpendicular to the long axis of the tooth, through a customized silicone probe cap to ensure consistent contact and accuracy. The primary outcome is the mean change in gingival thickness (in millimeters) between baseline and 6-month evaluations, reflecting potential soft tissue alterations associated with fixed lingual retainers.	6 months

Collaborators and Investigators

• Sponsor: Selcuk University

Study record dates

Study Major Dates

• Study Start (Actual): October 24, 2024
• Primary Completion (Actual): August 4, 2025
• Study Completion (Actual): October 9, 2025

Study Registration Dates

• First Submitted: February 9, 2026
• First Submitted That Met QC Criteria: February 14, 2026
• First Posted (Actual): February 17, 2026

Study Record Updates

• Last Update Posted (Actual): February 17, 2026
• Last Update Submitted That Met QC Criteria: February 14, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Ultrasonography; Gingival Thickness; Orthodontic Retention; Fixed Lingual Retainer
• Other Study ID Numbers: SelcukU-DHF-MO-01

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