MalocclusionSPECTRO-ALIGNNCT07628491

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

A study testing Tri-layer thermoplastic finishing clear aligner in people with Malocclusion and Esthetics, Dental, run by George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu Mures at 1 site in Romania.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial 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. Read more about this study

Who is it for?: Ages 15 years and older
Conditions the study is for: Malocclusion, Esthetics, Dental
What is being tested?: Tri-layer thermoplastic finishing clear aligner
Type of treatment: Medical device
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 50 participants
Where: 1 siteRomania
Study dates: 15 Jun 2026to 23 Jul 2026
Phase: Interventional
Are there results?: None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 15 years and older
All sexes
No healthy volunteers
Child, Adult, Older adult

Who may be able to join

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

Who cannot join

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

Trial locations and contacts

1 site in 1 country.

Romania1 site

Aorys Clinic
Sibiu, Sibiu County, 550118

Other trials in Romania

About this study

Official title: Colorimetric Stability of Finishing Clear Aligners According to Marginal Termination Design (Supragingival Versus Juxtagingival) After 14 Days of Intraoral Wear During Orthodontic Treatment: A Prospective Split-Mouth Study

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.

Read the detailed description

BACKGROUND AND RATIONALE
Two trimming-line (edge) designs are commonly used during the finishing (refinement) stage of clear aligner therapy. The supragingival design uses a straight edge positioned approximately 2 mm apical to the free gingival margin, covering approximately 2 mm of gingival tissue. The juxtagingival festooned design follows the natural scalloped contour of the free gingival margin, without covering gingival tissue. Color stability of the aligner during wear is relevant to esthetics and patient acceptance. Whether marginal termination design influences the colorimetric stability of the aligner during wear has not been investigated.
STUDY DESIGN
This is a prospective, within-person (split-mouth) interventional study. Each participant receives both designs simultaneously: the supragingival design on one dental arch and the juxtagingival festooned design on the contralateral arch. The split-mouth design controls for inter-individual variation in oral hygiene, diet, and salivary composition. The aligner material (CA Pro tri-layer, SCHEU-DENTAL GmbH, Iserlohn, Germany; CE-marked thermoplastic) is identical for both designs; only the marginal termination geometry differs.
ALLOCATION RULE (NON-RANDOMIZED)
Allocation follows a pre-specified hierarchical rule documented prior to enrollment. Primary criterion: the dental arch with the greater magnitude of planned dental intrusion (mm, from the digital treatment setup) receives the supragingival design. Tiebreaker (equal or zero planned intrusion on both arches): a pre-specified systematic alternating sequence in enrollment order. Planned intrusion magnitude per arch is recorded as a covariate.
TARGET TEETH AND MEASUREMENT
Colorimetric measurements of the aligner are performed extraorally at six target-tooth positions per participant: three maxillary (1.4, 1.1, 2.3) and three mandibular (4.3, 3.1, 3.4). Measurements are obtained with a dental spectrophotometer (VITA Easyshade V) operated in Custom Color mode, which simultaneously displays the CIE L, a, and b color coordinates. To ensure reproducibility, the aligner is measured under standardized optical conditions using a standardized optical substrate and a fixed positioning reference (methodological details reported separately). Each target position is measured in triplicate at each visit.
VISITS
Measurements are obtained at T0 (day 0, at placement of the finishing aligner) and T1 (day 14 ± 2 of wear), yielding 36 L, a, b measurements per participant (6 positions × 3 repetitions × 2 visits).
OUTCOME
The primary outcome is the colorimetric change (ΔE00, CIEDE2000) of the aligner between T0 and T1, computed per dental arch from the measured L, a, b coordinates, compared between the supragingival-design arch and the juxtagingival-design arch. The CIELAB ΔEab value is reported descriptively for comparability with prior literature.
STUDY CONTEXT
The study is conducted during the finishing (refinement) stage, when only small residual tooth movements remain, so that observed color changes can be attributed to wear and marginal termination design rather than to substantial tooth movement.
RELATIONSHIP TO COMPANION STUDY
A subset of participants may be concurrently enrolled in the companion study PATHO-ALIGN (ClinicalTrials.gov NCT07533058), a split-mouth study of finishing-aligner marginal termination design and subgingival periodontal microbiota conducted by the same investigator at the same sites. Co-enrolled participants wear the same finishing clear aligners with the same arch-level marginal-design allocation in both studies; the present study adds only a non-invasive, extraoral colorimetric assessment of the aligners and does not interfere with the companion study. The two studies have distinct outcomes.
STATISTICAL ANALYSIS
Primary confirmatory analysis: The confirmatory endpoint is the arch-level aligner color change (ΔE00) between T0 and T1. The supragingival-design arch and the juxtagingival-design arch are compared within participants using a paired test (two-sided, alpha = 0.05). Normality of the paired differences is assessed (Shapiro-Wilk); a paired t-test is used if the assumption holds, otherwise the Wilcoxon signed-rank test. A single confirmatory comparison is pre-specified, controlling the type I error rate without multiplicity correction.
Adjusted analysis: A linear mixed-effects model is fitted to arch-level ΔE00, with marginal termination design (supragingival vs juxtagingival), dental arch (maxillary vs mandibular), planned intrusion magnitude per arch, and self-reported daily wear time as fixed effects, and a participant-level random intercept to account for the paired (split-mouth) structure. Including dental arch as a covariate separates a potential arch-level effect from the design effect.
Secondary analyses (descriptive): Component color changes (ΔL, Δa, Δb) per arch between T0 and T1; overall aligner color change across all target positions (ΔE00 and ΔEab); and the proportion of arch-level changes exceeding the Paravina (2015) perceptibility (ΔE00 = 0.8) and acceptability (ΔE00 = 1.8) thresholds.
Measurement reliability: Intra-position reproducibility across the three repeated measurements is quantified using the intraclass correlation coefficient (ICC).
Missing data and quality control: Repeated measurements failing pre-specified inter-repetition agreement criteria are excluded, and the mean of the remaining repetitions is used; analyses use available per-protocol data.
SAMPLE SIZE JUSTIFICATION
Sample size was determined for a paired within-subject (split-mouth) comparison of arch-level aligner color change (ΔE00). In the absence of prior data specific to marginal termination design effects on aligner color, parameters were selected conservatively: a minimum meaningful between-arch difference of ΔE00 = 0.8 (50:50% perceptibility threshold; Paravina 2015), an assumed standard deviation of paired differences of approximately 0.9 (derived from an assumed arch-level standard deviation with an intra-subject correlation rho = 0.4), and a two-sided alpha = 0.05 (paired test). Under these assumptions, 50 participants provide power exceeding 90% to detect the specified difference and remain adequately powered (approximately 85%) for smaller between-arch differences (ΔE00 ≈ 0.4). The enrolled sample (50 participants; 100 aligners, two per participant) also serves to estimate within-subject colorimetric variability to refine power assumptions for subsequent confirmatory studies.

Conditions: Malocclusion, Esthetics, Dental
Being tested: Tri-layer thermoplastic finishing clear aligner
Keywords: clear aligners, color stability, spectrophotometry, CIELAB, CIEDE2000, trimming line, marginal termination design, split-mouth design, finishing orthodontic treatment
Medical subject headings: Malocclusion

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Tri-layer thermoplastic finishing clear alignerDevice
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.)

Study groups in NCT07628491
Study group	Role	What they receive
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. Receives: 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. Receives: Device: Tri-layer thermoplastic finishing clear aligner

What is being measured

The primary outcome is the main question the study is designed to answer.

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).
Measured: Day 0 and day 14

Secondary outcomes (2)

Component Color Changes (ΔL*, Δa*, Δb*)
Mean changes in the individual CIE coordinates per arch between day 0 and day 14, characterizing the direction of color change (lightness; red-green; yellow-blue axes).
Measured: Day 0 and day 14
Overall Aligner Color Change (ΔE00 and ΔE*ab, pooled)
Color change of the finishing aligner across all target positions regardless of marginal termination design, reported as ΔE00 (CIEDE2000) and, for comparability with prior literature, ΔE*ab (CIELAB), characterizing overall colorimetric stability during wear.
Measured: Day 0 and day 14

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

15 Jun 202623 Jul 2026

First posted5 Jun 2026
Study start15 Jun 2026
Primary completion23 Jul 2026
Study completion23 Jul 2026

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Publications (8)Papers the sponsor has linked to this study.
Other trials for MalocclusionStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase N/A
Primary purpose: Basic science
Allocation: Non-randomised
Intervention model: Crossover
Model description: 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.
Masking: Single blind
Who is masked: Outcomes assessor
Enrolment: 50 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT07628491
Sponsor's protocol ID: SPECTRO-ALIGN-ORTHO
Acronym: SPECTRO-ALIGN
Status last verified: Jul 2026
First submitted: 31 May 2026
Last updated: 24 Jul 2026
Results posted: No
Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: No
Individual data sharing: Yes: De-identified individual participant data (participant codes, arch-level color change values ΔE00 and ΔE\*ab, component changes ΔL\*/Δa\*/Δb\* and baseline covariates) will be made available as a CSV or Excel file upon reasonable request to the corresponding author following publication of study results.

Publications

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.
PubMed 19231572
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.
PubMed 38637429
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.
PubMed 36055460
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.
PubMed 19634462
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.
PubMed 26582007
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.
PubMed 41492584
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.
PubMed 39525218
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.
PubMed 41892738

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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Not yet recruiting
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All Malocclusion trials

Study at a glance

From the registry record, last updated by the sponsor on 24 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Colorimetric Stability of Finishing Clear Aligners According to Marginal Termination Design (Supragingival Versus Juxtagingival) After 14 Days of Intraoral Wear During Orthodontic Treatment: A Prospective Split-Mouth Study
ClinicalTrials.gov ID: NCT07628491
Acronym / sponsor ID: SPECTRO-ALIGN / SPECTRO-ALIGN-ORTHO
Conditions: Malocclusion, Esthetics, Dental
Keywords: clear aligners, color stability, spectrophotometry, CIELAB, CIEDE2000, trimming line, marginal termination design, split-mouth design
Study type: Interventional
Recruitment status: Completed
Enrolment: 50 participants (actual)
Lead sponsor: George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu MuresUniversity, hospital or other
Collaborators: Aorys Clinic, Sibiu, Romania, SC APARAT DENTAR SRL, Sibiu, Romania
Study start: 15 Jun 2026 (actual)
Primary completion: 23 Jul 2026 (actual)
Study completion: 23 Jul 2026 (actual)
First posted: 5 Jun 2026 (actual)
Results: Not posted in the source record

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

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.

Detailed description

BACKGROUND AND RATIONALE
Two trimming-line (edge) designs are commonly used during the finishing (refinement) stage of clear aligner therapy. The supragingival design uses a straight edge positioned approximately 2 mm apical to the free gingival margin, covering approximately 2 mm of gingival tissue. The juxtagingival festooned design follows the natural scalloped contour of the free gingival margin, without covering gingival tissue. Color stability of the aligner during wear is relevant to esthetics and patient acceptance. Whether marginal termination design influences the colorimetric stability of the aligner during wear has not been investigated.
STUDY DESIGN
This is a prospective, within-person (split-mouth) interventional study. Each participant receives both designs simultaneously: the supragingival design on one dental arch and the juxtagingival festooned design on the contralateral arch. The split-mouth design controls for inter-individual variation in oral hygiene, diet, and salivary composition. The aligner material (CA Pro tri-layer, SCHEU-DENTAL GmbH, Iserlohn, Germany; CE-marked thermoplastic) is identical for both designs; only the marginal termination geometry differs.
ALLOCATION RULE (NON-RANDOMIZED)
Allocation follows a pre-specified hierarchical rule documented prior to enrollment. Primary criterion: the dental arch with the greater magnitude of planned dental intrusion (mm, from the digital treatment setup) receives the supragingival design. Tiebreaker (equal or zero planned intrusion on both arches): a pre-specified systematic alternating sequence in enrollment order. Planned intrusion magnitude per arch is recorded as a covariate.
TARGET TEETH AND MEASUREMENT
Colorimetric measurements of the aligner are performed extraorally at six target-tooth positions per participant: three maxillary (1.4, 1.1, 2.3) and three mandibular (4.3, 3.1, 3.4). Measurements are obtained with a dental spectrophotometer (VITA Easyshade V) operated in Custom Color mode, which simultaneously displays the CIE L, a, and b color coordinates. To ensure reproducibility, the aligner is measured under standardized optical conditions using a standardized optical substrate and a fixed positioning reference (methodological details reported separately). Each target position is measured in triplicate at each visit.
VISITS
Measurements are obtained at T0 (day 0, at placement of the finishing aligner) and T1 (day 14 ± 2 of wear), yielding 36 L, a, b measurements per participant (6 positions × 3 repetitions × 2 visits).
OUTCOME
The primary outcome is the colorimetric change (ΔE00, CIEDE2000) of the aligner between T0 and T1, computed per dental arch from the measured L, a, b coordinates, compared between the supragingival-design arch and the juxtagingival-design arch. The CIELAB ΔEab value is reported descriptively for comparability with prior literature.
STUDY CONTEXT
The study is conducted during the finishing (refinement) stage, when only small residual tooth movements remain, so that observed color changes can be attributed to wear and marginal termination design rather than to substantial tooth movement.
RELATIONSHIP TO COMPANION STUDY
A subset of participants may be concurrently enrolled in the companion study PATHO-ALIGN (ClinicalTrials.gov NCT07533058), a split-mouth study of finishing-aligner marginal termination design and subgingival periodontal microbiota conducted by the same investigator at the same sites. Co-enrolled participants wear the same finishing clear aligners with the same arch-level marginal-design allocation in both studies; the present study adds only a non-invasive, extraoral colorimetric assessment of the aligners and does not interfere with the companion study. The two studies have distinct outcomes.
STATISTICAL ANALYSIS
Primary confirmatory analysis: The confirmatory endpoint is the arch-level aligner color change (ΔE00) between T0 and T1. The supragingival-design arch and the juxtagingival-design arch are compared within participants using a paired test (two-sided, alpha = 0.05). Normality of the paired differences is assessed (Shapiro-Wilk); a paired t-test is used if the assumption holds, otherwise the Wilcoxon signed-rank test. A single confirmatory comparison is pre-specified, controlling the type I error rate without multiplicity correction.
Adjusted analysis: A linear mixed-effects model is fitted to arch-level ΔE00, with marginal termination design (supragingival vs juxtagingival), dental arch (maxillary vs mandibular), planned intrusion magnitude per arch, and self-reported daily wear time as fixed effects, and a participant-level random intercept to account for the paired (split-mouth) structure. Including dental arch as a covariate separates a potential arch-level effect from the design effect.
Secondary analyses (descriptive): Component color changes (ΔL, Δa, Δb) per arch between T0 and T1; overall aligner color change across all target positions (ΔE00 and ΔEab); and the proportion of arch-level changes exceeding the Paravina (2015) perceptibility (ΔE00 = 0.8) and acceptability (ΔE00 = 1.8) thresholds.
Measurement reliability: Intra-position reproducibility across the three repeated measurements is quantified using the intraclass correlation coefficient (ICC).
Missing data and quality control: Repeated measurements failing pre-specified inter-repetition agreement criteria are excluded, and the mean of the remaining repetitions is used; analyses use available per-protocol data.
SAMPLE SIZE JUSTIFICATION
Sample size was determined for a paired within-subject (split-mouth) comparison of arch-level aligner color change (ΔE00). In the absence of prior data specific to marginal termination design effects on aligner color, parameters were selected conservatively: a minimum meaningful between-arch difference of ΔE00 = 0.8 (50:50% perceptibility threshold; Paravina 2015), an assumed standard deviation of paired differences of approximately 0.9 (derived from an assumed arch-level standard deviation with an intra-subject correlation rho = 0.4), and a two-sided alpha = 0.05 (paired test). Under these assumptions, 50 participants provide power exceeding 90% to detect the specified difference and remain adequately powered (approximately 85%) for smaller between-arch differences (ΔE00 ≈ 0.4). The enrolled sample (50 participants; 100 aligners, two per participant) also serves to estimate within-subject colorimetric variability to refine power assumptions for subsequent confirmatory studies.

Study design

Primary purpose: Basic science
Allocation: Non-randomised
Intervention model: Crossover
Masking: Single blind (outcomes assessor)
Number of arms: 2
Model description: 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.

Arm	Type	Receives
Supragingival Trimming-Line Design	Experimental	Device: Tri-layer thermoplastic finishing clear alignerFinishing 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.
Juxtagingival Festooned Trimming-Line Design	Active comparator	Device: Tri-layer thermoplastic finishing clear alignerFinishing 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.

Who may qualify

Ages: 15 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Child, Adult, Older adult

Key inclusion criteria (4 listed)

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

Key exclusion criteria (4 listed)

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

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
Tri-layer thermoplastic finishing clear alignerFinishing 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.)	Device	Juxtagingival Festooned Trimming-Line Design, Supragingival Trimming-Line Design

Primary outcome

Aligner Color Change (ΔE00) After 14 Days of Wear
Time frame: Day 0 and day 14
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).

2 secondary outcomes

Component Color Changes (ΔL*, Δa*, Δb*)
Time frame: Day 0 and day 14
Overall Aligner Color Change (ΔE00 and ΔE*ab, pooled)
Time frame: Day 0 and day 14

Results and safety

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 24 Jul 2026.
Background: PubMed 19231572Kim-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.
Background: PubMed 38637429Elshazly 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.
Background: PubMed 36055460Elshazly 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.
Background: PubMed 19634462Gracco 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.
Background: PubMed 26582007Lombardo 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.
Background: PubMed 41492584Narkhede 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.
Background: PubMed 39525218G 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.
Background: PubMed 41892738Rusu 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.
Companion study PATHO-ALIGN (same investigator; partially shared participants and aligner allocation)Link provided by the sponsor.
Individual participant dataSharing planned: Yes. De-identified individual participant data (participant codes, arch-level color change values ΔE00 and ΔE*ab, component changes ΔL*/Δa*/Δb* and baseline covariates) will be made available as a CSV or Excel file upon reasonable request to the corresponding author following publication of study results.

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

EMILIA (PRODEA) RUSU, DDS, Specialist Orthodontist principal investigator

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

LUMINITA LAZAR, PhD, Professor study chair

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

1 site in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 24 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Romania. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Aligner Color Change (ΔE00) After 14 Days of Wear (time frame: Day 0 and day 14). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07628491, which also lists 8 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Jul 2026.