Effect of Finishing Clear Aligner Marginal Termination Design (Supragingival vs Juxtagingival) on Aligner Color Stability After 14 Days of Wear: A Split-Mouth Study

NCT07628491 | Not Yet Recruiting

• 1 other identifier: SPECTRO-ALIGN-ORTHO
• Study Type: interventional
• Target: 50
• Locations: 1 country
• Sites: 1

Brief Summary

• The goal of this clinical study is to learn whether the gumline edge design of a finishing orthodontic clear aligner affects how much the aligner's color changes after 14 days of wear.
• The main question is: does a supragingival edge design - a straight edge covering about 2 mm of gum tissue - lead to a different amount of color change in the aligner compared with a juxtagingival edge design that follows the gumline exactly, after 14 days of wear?
• Each participant wears finishing clear aligners with both edge designs at the same time - one design on the upper jaw and the other on the lower jaw - and serves as their own comparison (split-mouth). This within-person approach removes differences between individuals in oral hygiene, diet, and saliva.
• The aligner's color over six selected teeth (three upper, three lower) is measured with a dental spectrophotometer (VITA Easyshade V) at placement (day 0) and after 14 days. Each measurement is repeated three times under standardized optical conditions. The amount of color change is expressed as a color-difference value (ΔE).
• The study hypothesis is that marginal termination design (supragingival versus juxtagingival) is associated with a difference in the 14-day colorimetric change (ΔE00) of the finishing aligner.
• The study is carried out during the finishing (refinement) stage of orthodontic treatment, when only small residual tooth movements remain, so that color changes can be attributed to wear and edge design rather than to tooth movement.

Conditions

Esthetics, Dental; Malocclusion

Keywords

clear aligners; color stability; spectrophotometry; CIELAB; CIEDE2000; trimming line; marginal termination design; split-mouth design; finishing orthodontic treatment

Outcome Measures

Primary Outcomes (1)

• Aligner Color Change (ΔE00) After 14 Days of Wear

  Mean color change (ΔE00, CIEDE2000) of the finishing aligner between day 0 and day 14, per dental arch, computed from CIE L\*, a\*, b\* coordinates averaged over three target positions measured in triplicate. The supragingival-design arch and the juxtagingival-design arch are compared within each participant (paired split-mouth).

  Day 0 and day 14

Secondary Outcomes (2)

• Component Color Changes (ΔL*, Δa*, Δb*)

  Day 0 and day 14

• Overall Aligner Color Change (ΔE00 and ΔE*ab, pooled)

  Day 0 and day 14

Other Outcomes (1)

• Proportion of Measurements Exceeding Perceptibility / Acceptability Thresholds

  Day 0 and day 14

Study Arms (2)

Supragingival Trimming-Line Design

EXPERIMENTAL

Finishing clear aligner with a straight trimming-line positioned approximately 2 mm apical to the free gingival margin, covering approximately 2 mm of gingival tissue. 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: Tri-layer thermoplastic finishing clear aligner

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, terminating at the gingival margin without covering gingival tissue. Assigned to the contralateral arch.

Device: Tri-layer thermoplastic finishing clear aligner

Interventions

Tri-layer thermoplastic finishing clear aligner DEVICE

Finishing clear aligner fabricated from CA Pro tri-layer thermoplastic (SCHEU-DENTAL GmbH, Iserlohn, Germany; CE-marked), fabricated by SC APARAT DENTAR SRL, Sibiu, Romania. Each participant receives aligners with both trimming-line designs simultaneously - supragingival on one arch and juxtagingival festooned on the contralateral arch. Material and thickness are identical for both designs; only trimming-line geometry differs. (Cross-referenced to both arms.)

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:

• Adolescent and adult patients (age 15 years or older at enrollment)
• Undergoing a finishing (refinement) stage of clear aligner therapy, with only small residual tooth movements remaining, including both patients completing active orthodontic treatment and patients with prior orthodontic treatment who require additional refinement (e.g., minor relapse or loss of retention)
• Adherence to the prescribed oral hygiene instructions
• Written informed consent; for participants aged 15-17 years, written consent from a parent or legal guardian

You may not qualify if:

• Deficient oral hygiene
• Excessive consumption of intensely staining beverages (coffee, tea, red wine, colored carbonated drinks)
• Systemic conditions or medications that may affect salivary secretion or tooth color
• Non-compliance with the aligner / orthodontic appliance wear protocol

Sponsors & Collaborators

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

Study Sites (1)

Aorys Clinic

Sibiu, Sibiu County, 550118, Romania

Location

Related Publications (8)

• Kim-Pusateri S, Brewer JD, Davis EL, Wee AG. Reliability and accuracy of four dental shade-matching devices. J Prosthet Dent. 2009 Mar;101(3):193-9. doi: 10.1016/S0022-3913(09)60028-7.

  PMID: 19231572 BACKGROUND

• Elshazly TM, Bourauel C, Ismail A, Ghoraba O, Aldesoki M, Salvatori D, Elattar H, Alhotan A, Alkabani Y. Effect of material composition and thickness of orthodontic aligners on the transmission and distribution of forces: an in vitro study. Clin Oral Investig. 2024 Apr 19;28(5):258. doi: 10.1007/s00784-024-05662-x.

  PMID: 38637429 BACKGROUND

• Elshazly TM, Keilig L, Salvatori D, Chavanne P, Aldesoki M, Bourauel C. Effect of trimming line design and edge extension of orthodontic aligners on force transmission: An in vitro study. J Dent. 2022 Oct;125:104276. doi: 10.1016/j.jdent.2022.104276. Epub 2022 Aug 30.

  PMID: 36055460 BACKGROUND

• Gracco A, Mazzoli A, Favoni O, Conti C, Ferraris P, Tosi G, Guarneri MP. Short-term chemical and physical changes in invisalign appliances. Aust Orthod J. 2009 May;25(1):34-40.

  PMID: 19634462 BACKGROUND

• Lombardo L, Arreghini A, Maccarrone R, Bianchi A, Scalia S, Siciliani G. Optical properties of orthodontic aligners--spectrophotometry analysis of three types before and after aging. Prog Orthod. 2015;16:41. doi: 10.1186/s40510-015-0111-z. Epub 2015 Nov 18.

  PMID: 26582007 BACKGROUND

• Narkhede S, Rao P, Sawant V, Kambli S, Garg N, Shah SP, Sachdev SS. Comparative Assessment of Color Stability in Four Commercial Clear Aligner Materials Exposed to Common Beverages: An In Vitro Study. Cureus. 2025 Dec 4;17(12):e98482. doi: 10.7759/cureus.98482. eCollection 2025 Dec.

  PMID: 41492584 BACKGROUND

• G P V S, Shukla V, Ghosh M, Barde S, Mustafa M, Almokhatieb AA. Evaluation of the Root Canal Centering Ratio and Canal Transportation Associated With Three Rotary File Systems Using Cone Beam Computed Tomography (CBCT) Analysis. Cureus. 2024 Oct 8;16(10):e71117. doi: 10.7759/cureus.71117. eCollection 2024 Oct.

  PMID: 39525218 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

Related Links

• Companion study PATHO-ALIGN (same investigator; partially shared participants and aligner allocation)

MeSH Terms

Conditions

Malocclusion

Condition Hierarchy (Ancestors)

Tooth Diseases; Stomatognathic Diseases

Study Officials

• EMILIA (PRODEA) RUSU, 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 (PRODEA) RUSU, 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: The outcomes assessor is masked. (1) Treating clinician (orthodontist, PI): assigns the marginal termination designs to the arches at baseline, holds the participant code and allocation key, and performs the extraoral colorimetric measurements of the aligners under standardized optical conditions; not masked, as allocation is inherent to treatment planning. (2) Data manager / outcomes assessor: receives the recorded L\*, a\*, b\* values labeled only by participant code and arch (e.g., "SPC001 maxillary", "SPC001 mandibular"), with no reference to which design was assigned to which arch, and performs all data centralization and the between-arm comparison; completely blinded to allocation. The arch-to-design key is held by the treating clinician and released only after the colorimetric dataset is locked. Probe positioning is standardized by protocol (fixed measurement height and fixed positioning references) and each target position is measured in triplicate, limiting operator influence on
• 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: Within-person split-mouth design: each participant receives the supragingival design on one dental arch and the juxtagingival festooned design on the contralateral arch simultaneously, serving as their own control. Allocation is non-randomized and clinician-determined following a pre-specified hierarchical rule based on planned intrusion magnitude per arch.

Study Record Dates

• First Submitted: May 31, 2026
• First Posted: June 5, 2026
• Study Start: June 15, 2026
• Primary Completion (Estimated): August 15, 2026
• Study Completion (Estimated): August 15, 2026
• Last Updated: June 5, 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)