Comparison of Patient-Reported Comfort Between Two Clear Aligner Trimming-Line Designs: A Split-Mouth Study

NCT07660809 | Recruiting

• 2 other identifiers: COMFORT-ALIGN-ORTHO3885/2025
• Study Type: observational
• Target: 70
• Locations: 1 country
• Sites: 1

Brief Summary

• The trimming-line design of clear aligners (supragingival versus juxtagingival) is a routine clinical decision whose influence on patient-reported comfort has not been established; available evidence on aligner comfort derives almost exclusively from comparisons with fixed appliances.
• This observational, cross-sectional study compares two clear aligner trimming-line designs with respect to patient-reported comfort: a supragingival design, whose edge rests on the marginal gingiva, and a juxtagingival design, whose edge follows the gingival contour without covering it. Because the two designs sit differently against the gingival soft tissue, they may be experienced differently during wear.
• Participants are patients already wearing one trimming-line design on one dental arch and the other on the contralateral arch; each participant thus serves as their own control. After a minimum of four weeks of wear, participants complete a 20-item questionnaire once, rating the frequency of defined oral experiences for the maxillary and mandibular arch separately on a three-point ordinal scale (0 = none, 1 = occasional, 2 = frequent).
• The questionnaire is anonymous; the design worn on each arch is identified from which of two identical forms a participant completes. Responses for the two designs are compared within each participant. The study evaluates whether trimming-line design is associated with differences in patient-reported comfort.

Conditions

Patient Comfort; Malocclusion; Oral Health

Keywords

clear aligners; trimming-line design; gingival margin; supragingival; juxtagingival; split-mouth design; patient-reported outcome; comfort; oral health-related quality of life; questionnaire; orthodontics; finishing orthodontic treatment

Outcome Measures

Primary Outcomes (1)

• Per-item patient-reported frequency (0-2) for the supragingival versus juxtagingival design

  For each of the 20 questionnaire items (each rated 0 = no, 1 = occasionally, 2 = frequently, recorded separately for the two dental arches), the response associated with the supragingival design is compared with the response associated with the juxtagingival design within each participant, using a paired non-parametric test (Wilcoxon signed-rank, two-sided, alpha 0.05). Responses are also summarized descriptively (frequencies, means, standard deviations).

  Day 28 (+/- 2 days) after the start of wear of the two designs

Secondary Outcomes (1)

• Total patient-reported discomfort score per design (0-40)

  Day 28 (+/- 2 days) after the start of wear of the two designs

Study Arms (1)

Group/Cohort (1): Split-mouth participants (both trimming-line designs)

Patients wearing the supragingival trimming-line design on one dental arch and the juxtagingival design on the contralateral arch, who completed the comfort questionnaire after at least four weeks of wear.

Device: Supragingival trimming-line design; Device: Juxtagingival festooned trimming-line design

Interventions

Supragingival trimming-line design DEVICE

Clear aligner edge covering approximately 2 mm of marginal gingiva (straight cut), worn on one dental arch.

Group/Cohort (1): Split-mouth participants (both trimming-line designs)

Juxtagingival festooned trimming-line design DEVICE

Clear aligner edge following the scalloped gingival contour, terminating at the free gingival margin without covering the gingiva, worn on the contralateral arch.

Group/Cohort (1): Split-mouth participants (both trimming-line designs)

Eligibility Criteria

• Age: 15 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adolescent and adult patients (aged 15 years or older) in active orthodontic treatment with clear aligners, including finishing (refinement) aligners, in whom a supragingival trimming-line design is worn on one dental arch and a juxtagingival design on the contralateral arch. Eligible participants have worn the two designs for at least four weeks at the time the questionnaire is completed. Recruitment is conducted at a single orthodontic practice.

You may qualify if:

• Adolescent or adult patient (aged 15 years or older)
• Active orthodontic treatment with clear aligners, including finishing (refinement) aligners
• Wearing two clear aligners with different trimming-line designs, one per dental arch: a supragingival design on one arch and a juxtagingival design on the contralateral arch
• At least 4 weeks of wear of the two designs at the time of questionnaire completion
• Good treatment compliance
• Willing and able to complete the online questionnaire and provide the required consent

You may not qualify if:

• Mixed orthodontic treatment (aligners combined with fixed appliances)
• Pre-existing neurological, cognitive, or speech disorders
• Systemic conditions affecting the oral cavity (e.g., xerostomia, mucosal disorders)

Sponsors & Collaborators

• George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu Mures: lead

Study Sites (1)

Aorys Clinic

Sibiu, Sibiu County, 550027, Romania

RECRUITING

Related Publications (8)

• Tunca Y, Kaya Y, Tunca M, Keskin S. Comparison of anxiety, pain, and quality of life in individuals with mild or moderate malocclusion between conventional fixed orthodontic treatment versus Invisalign: a randomised clinical trial. BMC Oral Health. 2024 May 17;24(1):576. doi: 10.1186/s12903-024-04335-1.

  PMID: 38760747 BACKGROUND

• Jaber ST, Hajeer MY, Burhan AS, Latifeh Y. The Effect of Treatment With Clear Aligners Versus Fixed Appliances on Oral Health-Related Quality of Life in Patients With Severe Crowding: A One-Year Follow-Up Randomized Controlled Clinical Trial. Cureus. 2022 May 30;14(5):e25472. doi: 10.7759/cureus.25472. eCollection 2022 May.

  PMID: 35663697 BACKGROUND

• Zhang B, Huang X, Huo S, Zhang C, Zhao S, Cen X, Zhao Z. Effect of clear aligners on oral health-related quality of life: A systematic review. Orthod Craniofac Res. 2020 Nov;23(4):363-370. doi: 10.1111/ocr.12382. Epub 2020 May 13.

  PMID: 32340082 BACKGROUND

• Alajmi S, Shaban A, Al-Azemi R. Comparison of Short-Term Oral Impacts Experienced by Patients Treated with Invisalign or Conventional Fixed Orthodontic Appliances. Med Princ Pract. 2020;29(4):382-388. doi: 10.1159/000505459. Epub 2019 Dec 17.

  PMID: 31842018 BACKGROUND

• Di Spirito F, D'Ambrosio F, Cannata D, D'Anto V, Giordano F, Martina S. Impact of Clear Aligners versus Fixed Appliances on Periodontal Status of Patients Undergoing Orthodontic Treatment: A Systematic Review of Systematic Reviews. Healthcare (Basel). 2023 May 6;11(9):1340. doi: 10.3390/healthcare11091340.

  PMID: 37174882 BACKGROUND

• Crego-Ruiz M, Jorba-Garcia A. Assessment of the periodontal health status and gingival recession during orthodontic treatment with clear aligners and fixed appliances: A systematic review and meta-analysis. Med Oral Patol Oral Cir Bucal. 2023 Jul 1;28(4):e330-e340. doi: 10.4317/medoral.25760.

  PMID: 36641738 BACKGROUND

• Nakornnoi T, Srirodjanakul W, Chintavalakorn R, Santiwong P, Sipiyaruk K. The biomechanical effects of clear aligner trimline designs and extensions on orthodontic tooth movement: a systematic review. BMC Oral Health. 2024 Dec 20;24(1):1523. doi: 10.1186/s12903-024-05274-7.

  PMID: 39707339 BACKGROUND

• Rusu EP, Lazar AP, Erhan BL, Bud E, Pacurar M, Lazar L. Clear Aligner Therapy and Marginal Edge Design: Clinical and Laboratory Evidence on Periodontal and Biological Outcomes-A Scoping Review. Dent J (Basel). 2026 Feb 24;14(3):130. doi: 10.3390/dj14030130.

  PMID: 41892738 BACKGROUND

MeSH Terms

Conditions

Malocclusion

Condition Hierarchy (Ancestors)

Tooth Diseases; Stomatognathic Diseases

Study Officials

• EMILIA (PRODEA) RUSU

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

  PRINCIPAL INVESTIGATOR

• LUMINITA LAZAR, DDS, PhD

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

  STUDY CHAIR

Central Study Contacts

EMILIA (PRODEA) RUSU, DDS, Specialist Orthodontist

CONTACT

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

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: CROSS SECTIONAL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Doctoral Researcher in Dental Medicine; Senior Specialist in Orthodontics

Study Record Dates

• First Submitted: June 16, 2026
• First Posted: June 22, 2026
• Study Start: July 1, 2026
• Primary Completion: August 1, 2026
• Study Completion: August 1, 2026
• Last Updated: July 6, 2026

Record last verified: 2026-07

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)