Influence of Finishing Clear Aligner Marginal Termination Design on Subgingival Periodontal Microbiota During Orthodontic Treatment: A Split-Mouth Study.

NCT07533058 | Recruiting

• 3 other identifiers: PATHO-ALIGN-ORTHO3597/20254045/2026
• Study Type: interventional
• Target: 39
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to learn whether the edge design of a finishing orthodontic clear aligner at the gumline affects the bacteria living in the groove between the tooth and the gum (the gingival sulcus) in patients undergoing the finishing phase of orthodontic treatment. The main question it aims to answer is: \- Does a supragingival aligner edge design - which covers approximately 2 mm of gum tissue - lead to higher levels of disease-associated bacteria in the gingival sulcus compared to a juxtagingival edge design that follows the gumline exactly, after 4 and 8 weeks of aligner wear? Researchers will compare the supragingival trimming-line design to the juxtagingival festooned design to see if covering gum tissue with the aligner edge creates conditions that favor the growth of anaerobic bacteria associated with gum disease. Participants will:

• Wear finishing clear aligners with both designs simultaneously - one design on the upper jaw and one on the lower jaw - for 8 weeks
• Provide fluid samples from the gum groove at 3 visits: at the start of treatment (baseline), at 4 weeks, and at 8 weeks. Two aligner edge designs are compared: a supragingival design, which has a straight horizontal edge positioned approximately 2 mm over the gumline, covering approximately 2 mm of gum tissue with direct contact but without entering the gum groove itself, and a juxtagingival design, which follows the natural scalloped shape of the gumline exactly, terminating at the free gingival margin without covering gum tissue and without entering the groove. The biological rationale for comparing these two designs is the following: the supragingival design, by covering 2 mm of gum tissue, creates a partially enclosed space at the entrance of the gum groove, potentially reducing the clearance of saliva and limiting oxygen access to that area. These conditions may favor the growth of anaerobic bacteria associated with gum disease. The juxtagingival design, by following the gum contour exactly at its edge, leaves the gum groove entrance more accessible to saliva and oxygen, potentially maintaining a less favorable environment for those bacteria. Each participant receives both designs at the same time - one on the upper jaw and one on the lower jaw - and serves as their own comparison group. This within-person (split-mouth) approach eliminates differences between individuals in general health, oral hygiene habits, and saliva composition, making the comparison between the two designs more precise. Samples are analyzed using the PeriodontScreen Real-TM real-time PCR kit (Sacace Biotechnologies Srl, Como, Italy; CE-marked in vitro diagnostic device), which detects and quantifies seven bacteria known to cause gum disease: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Porphyromonas endodontalis, Fusobacterium nucleatum, and Prevotella intermedia. The main measurement is the number of these seven bacteria that exceed the clinically significant concentration threshold defined by the kit at each jaw arch and time point. A score of 0 means none of the seven bacteria exceed the threshold; a score of 7 means all seven do. The study hypothesis is that the supragingival trimming-line design - by covering gingival tissue and partially enclosing the sulcus entrance - creates microenvironmental conditions that favor anaerobic periodontal pathogen colonization, resulting in higher pathogen burden scores compared to the juxtagingival design after 4 and 8 weeks of finishing aligner wear. The study is conducted during the finishing phase of orthodontic treatment, when planned tooth movements are minimal (no more than 0.5 mm per tooth), so that any differences in bacterial levels can be attributed to aligner edge design rather than to tooth movement forces.

Conditions

Periodontal Diseases; Malocclusion; Oral Health

Keywords

clear aligners; trimming line; periodontal pathogens; split-mouth design; finishing orthodontic treatment; subgingival microbiota; real-time PCR; gingival sulcus

Outcome Measures

Primary Outcomes (1)

• Periodontal Pathogen Burden Score per Dental Arch (0-7)

  Number of periodontal pathogen species with quantitative real-time PCR signal exceeding the kit-validated clinical significance threshold per dental arch. Seven species tested: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Porphyromonas endodontalis, Fusobacterium nucleatum, Prevotella intermedia. Detected by PeriodontScreen Real-TM assay (Sacace Biotechnologies Srl, Como, Italy; REF T01707-96-S; CE-marked IVD). Score range: 0 (no species above threshold) to 7 (all seven above threshold). Assessed per arch at T1 and T2.

  4 weeks and 8 weeks after finishing aligner placement

Other Outcomes (1)

• Number of Arches with Red Complex Periodontal Pathogen Positivity

  4 weeks and 8 weeks after finishing aligner placement

Study Arms (2)

Supragingival Trimming-Line Design

EXPERIMENTAL

Finishing clear aligner with a straight horizontal trimming-line positioned approximately 2 mm apical to the free gingival margin. The aligner edge covers approximately 2 mm of gingival tissue with direct contact, partially enclosing the gingival sulcus entrance, but does not penetrate the sulcus itself. Material: CA Pro tri-layer thermoplastic aligner (SCHEU-DENTAL GmbH, Iserlohn, Germany; CE-marked). Worn 22 hours/day or more during finishing orthodontic treatment. Assigned to the arch with greater planned intrusion; if equal or zero on both arches, assigned by pre-specified systematic alternation in enrollment order.

Device: CA Pro tri-layer finishing clear aligner (SCHEU-DENTAL GmbH)

Juxtagingival Festooned Trimming-Line Design

ACTIVE COMPARATOR

Finishing clear aligner with a festooned trimming-line following the natural scalloped contour of the free gingival margin. The aligner edge terminates exactly at the gingival margin without covering gingival tissue and without entering the gingival sulcus, leaving the sulcus entrance accessible to saliva and oxygen. Material: CA Pro tri-layer thermoplastic aligner (SCHEU-DENTAL GmbH, Iserlohn, Germany; CE-marked). Worn 22 hours/day or more during finishing orthodontic treatment. Assigned to the arch with lesser or no planned intrusion; if equal or zero on both arches, assigned by pre-specified systematic alternation.

Device: CA Pro tri-layer finishing clear aligner (SCHEU-DENTAL GmbH)

Interventions

CA Pro tri-layer finishing clear aligner (SCHEU-DENTAL GmbH) DEVICE

Finishing clear aligner fabricated from CA Pro tri-layer thermoplastic material (SCHEU-DENTAL GmbH, Iserlohn, Germany; CE-marked). Used during the finishing phase of orthodontic treatment with planned tooth movements 0.5 mm or less per tooth per aligner stage. Fabricated by SC APARAT DENTAR SRL, Sibiu, Romania. Each participant receives aligners with both trimming-line designs simultaneously: supragingival (straight, approximately 2 mm apical to free gingival margin, covering gingival tissue) on one arch and juxtagingival festooned (at free gingival margin, no gingival coverage) on the contralateral arch. Aligner material and thickness are identical for both designs; only trimming-line geometry differs.

Juxtagingival Festooned Trimming-Line Design; Supragingival Trimming-Line Design

Eligibility Criteria

• Age: 15 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• Permanent dentition (excluding third molars)
• Age 15 years or older at enrollment
• Currently undergoing the finishing phase of orthodontic treatment with clear aligners
• Residual planned tooth movements no greater than 0.5 mm per tooth per aligner stage
• Absence of active periodontal disease at baseline: probing depth 3 mm or less at all sites, and no bleeding on probing at index sampling sites
• Written informed consent; for participants aged 15-17 years, written consent from parent or legal guardian is also required

You may not qualify if:

• Systemic conditions known to affect periodontal tissues (e.g., uncontrolled diabetes mellitus, immunosuppressive therapy)
• Antibiotic therapy within the 3 months preceding enrollment
• Active gingivitis (modified gingival index 2 or greater) or periodontitis at baseline
• Habitual mouth breathing (self-reported or clinically assessed)
• Poorly adapted fixed prosthetic restorations adjacent to planned index sampling sites
• Visible plaque at more than 50% of tooth surfaces at baseline
• Self-reported aligner compliance below 22 hours per day during the study period
• Pregnancy or breastfeeding

Sponsors & Collaborators

• George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu Mures: lead
• SC APARAT DENTAR SRL, Sibiu, Romania: collaborator
• Aorys Clinic, Sibiu, Romania: collaborator
• Spitalul Clinic Judetean Mures, Targu Mures, Romania: collaborator

Study Sites (1)

Aorys Clinic

Sibiu, Sibiu County, 550027, Romania

RECRUITING

Related Publications (5)

• Socransky SS, Haffajee AD, Cugini MA, Smith C, Kent RL Jr. Microbial complexes in subgingival plaque. J Clin Periodontol. 1998 Feb;25(2):134-44. doi: 10.1111/j.1600-051x.1998.tb02419.x.

  PMID: 9495612 BACKGROUND

• Martha K, Kis EE, Muresan IE, Ioanovici AC. The Impact of Orthodontic Adhesives on the Subgingival Microbiota During Early Fixed Appliance Therapy: A Pilot Study. Medicina (Kaunas). 2025 May 7;61(5):858. doi: 10.3390/medicina61050858.

  PMID: 40428817 BACKGROUND

• Kredig C, Peuckert E, Schmidtmann I, Drechsler T, Erbe C. Oral health in adolescents: periodontal inflammatory biomarkers during orthodontic clear aligner therapy. Clin Oral Investig. 2025 Mar 5;29(3):168. doi: 10.1007/s00784-025-06212-9.

  PMID: 40042542 BACKGROUND

• Shokeen B, Viloria E, Duong E, Rizvi M, Murillo G, Mullen J, Shi B, Dinis M, Li H, Tran NC, Lux R, Wu T. The impact of fixed orthodontic appliances and clear aligners on the oral microbiome and the association with clinical parameters: A longitudinal comparative study. Am J Orthod Dentofacial Orthop. 2022 May;161(5):e475-e485. doi: 10.1016/j.ajodo.2021.10.015. Epub 2022 Mar 2.

  PMID: 35248417 BACKGROUND

• Lombardo L, Palone M, Scapoli L, Siciliani G, Carinci F. Short-term variation in the subgingival microbiota in two groups of patients treated with clear aligners and vestibular fixed appliances: A longitudinal study. Orthod Craniofac Res. 2021 May;24(2):251-260. doi: 10.1111/ocr.12427. Epub 2020 Oct 15.

  PMID: 32965768 BACKGROUND

MeSH Terms

Conditions

Periodontal Diseases; Malocclusion

Condition Hierarchy (Ancestors)

Mouth Diseases; Stomatognathic Diseases; Tooth Diseases

Study Officials

• EMILIA RUSU (PRODEA), DDS, Specialist Orthodontist

  George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gheorghe Marinescu Street, 540139 Targu Mures, Romania

  PRINCIPAL INVESTIGATOR

• LUMINITA LAZAR, PhD, Professor

  George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gheorghe Marinescu Street, 540139 Targu Mures, Romania

  STUDY CHAIR

Central Study Contacts

EMILIA RUSU (PRODEA), DDS, Specialist Orthodontist

CONTACT

+40756607316; rusu.emilia.24@stud.umfst.ro

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Three roles are distinguished. 1. Treating clinician (orthodontist, PI): assigns trimming-line designs to arches and fabricates treatment plan; not masked (allocation is inherent to treatment planning). 2. Sample collector (general dentistry specialist and orthodontic resident, separate from the treating clinician): performs all subgingival sampling at T0, T1, and T2 and is completely blinded to arch allocation --- the collector does not know which trimming-line design is assigned to which arch at any time point. 3. Laboratory personnel (UMFST Microbiology and Mures County Clinical Hospital): receive coded tubes labeled with participant code, arch, and time point only, without reference to trimming-line design assignment; fully blinded to allocation. Participant awareness of their aligner design does not influence the microbiological outcome and is not considered a source of bias for this study.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Doctoral Researcher in Dental Medicine; Senior Specialist in Orthodontics

Model Details: This is a within-person split-mouth design in which each participant receives both trimming-line interventions simultaneously: supragingival design on one dental arch and juxtagingival festooned design on the contralateral arch. Classified as Crossover Assignment because each participant is exposed to both interventions and serves as their own control. Allocation is non-randomized and clinician-determined following a pre-specified hierarchical rule based on planned intrusion magnitude per arch (see Detailed Description).

Study Record Dates

• First Submitted: April 9, 2026
• First Posted: April 16, 2026
• Study Start: May 6, 2026
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): August 1, 2026
• Last Updated: May 12, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: Beginning 6 months after publication of primary study results.
• Access Criteria: Upon reasonable request to the corresponding author (PI); requests reviewed within 30 days.

Locations

RO (1)