Effect of Finishing Clear Aligner Marginal Termination Design (Supragingival vs Juxtagingival) on Aligner Color Stability After 14 Days of Wear: A Split-Mouth Study (SPECTRO-ALIGN)
maanantai 15. kesäkuuta 2026 päivittänyt: Emilia Rusu, George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu Mures
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.
Tutkimuksen yleiskatsaus
Tila
Rekrytointi
Interventio / Hoito
Yksityiskohtainen kuvaus
- 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.
Opintotyyppi
Interventio
Ilmoittautuminen (Arvioitu)
50
Vaihe
- Ei sovellettavissa
Yhteystiedot ja paikat
Tässä osiossa on tutkimuksen suorittajien yhteystiedot ja tiedot siitä, missä tämä tutkimus suoritetaan.
Opiskeluyhteys
- Nimi: EMILIA (PRODEA) RUSU, DDS, Specialist Orthodontist
- Puhelinnumero: +40756607316
- Sähköposti: rusu.emilia.24@stud.umfst.ro
Opiskelupaikat
-
-
Sibiu County
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Sibiu, Sibiu County, Romania, 550118
- Rekrytointi
- Aorys Clinic
-
Ottaa yhteyttä:
- EMILIA (PRODEA) RUSU, DDS, Specialist Orthodontist
- Puhelinnumero: +40756607316
- Sähköposti: rusu.emilia.24@stud.umfst.ro
-
Päätutkija:
- EMILIA (PRODEA) RUSU, DDS, Specialist Orthodontist
-
-
Osallistumiskriteerit
Tutkijat etsivät ihmisiä, jotka sopivat tiettyyn kuvaukseen, jota kutsutaan kelpoisuuskriteereiksi. Joitakin esimerkkejä näistä kriteereistä ovat henkilön yleinen terveydentila tai aiemmat hoidot.
Kelpoisuusvaatimukset
Opintokelpoiset iät
- Lapsi
- Aikuinen
- Vanhempi Aikuinen
Hyväksyy terveitä vapaaehtoisia
Ei
Kuvaus
Inclusion Criteria:
- 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
Exclusion Criteria:
- 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
Opintosuunnitelma
Tässä osiossa on tietoja tutkimussuunnitelmasta, mukaan lukien kuinka tutkimus on suunniteltu ja mitä tutkimuksella mitataan.
Miten tutkimus on suunniteltu?
Suunnittelun yksityiskohdat
- Ensisijainen käyttötarkoitus: Perustiede
- Jako: Ei satunnaistettu
- Inventiomalli: Crossover-tehtävä
- Naamiointi: Yksittäinen
Aseet ja interventiot
Osallistujaryhmä / Arm |
Interventio / Hoito |
|---|---|
|
Kokeellinen: Supragingival Trimming-Line Design
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.
|
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.)
|
|
Active Comparator: Juxtagingival Festooned Trimming-Line Design
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.
|
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.)
|
Mitä tutkimuksessa mitataan?
Ensisijaiset tulostoimenpiteet
Tulosmittaus |
Toimenpiteen kuvaus |
Aikaikkuna |
|---|---|---|
|
Aligner Color Change (ΔE00) After 14 Days of Wear
Aikaikkuna: 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).
|
Day 0 and day 14
|
Toissijaiset tulostoimenpiteet
Tulosmittaus |
Toimenpiteen kuvaus |
Aikaikkuna |
|---|---|---|
|
Component Color Changes (ΔL*, Δa*, Δb*)
Aikaikkuna: Day 0 and day 14
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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).
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Day 0 and day 14
|
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Overall Aligner Color Change (ΔE00 and ΔE*ab, pooled)
Aikaikkuna: Day 0 and day 14
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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.
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Day 0 and day 14
|
Muut tulostoimenpiteet
Tulosmittaus |
Toimenpiteen kuvaus |
Aikaikkuna |
|---|---|---|
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Proportion of Measurements Exceeding Perceptibility / Acceptability Thresholds
Aikaikkuna: Day 0 and day 14
|
Proportion of arch-level color changes exceeding the 50:50% perceptibility (ΔE00 = 0.8) and acceptability (ΔE00 = 1.8) thresholds (Paravina 2015).
Interpreted descriptively; these thresholds were established for permanent restorations compared with adjacent teeth and are used here only as a reference standard, not as a clinical failure criterion for a temporary 14-day aligner.
|
Day 0 and day 14
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Yhteistyökumppanit ja tutkijat
Täältä löydät tähän tutkimukseen osallistuvat ihmiset ja organisaatiot.
Sponsori
Tutkijat
- Opintojen puheenjohtaja: 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
- Päätutkija: 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
Julkaisuja ja hyödyllisiä linkkejä
Tutkimusta koskevien tietojen syöttämisestä vastaava henkilö toimittaa nämä julkaisut vapaaehtoisesti. Nämä voivat koskea mitä tahansa tutkimukseen liittyvää.
Yleiset julkaisut
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
Opintojen ennätyspäivät
Nämä päivämäärät seuraavat ClinicalTrials.gov-sivustolle lähetettyjen tutkimustietueiden ja yhteenvetojen edistymistä. National Library of Medicine (NLM) tarkistaa tutkimustiedot ja raportoidut tulokset varmistaakseen, että ne täyttävät tietyt laadunvalvontastandardit, ennen kuin ne julkaistaan julkisella verkkosivustolla.
Opi tärkeimmät päivämäärät
Opiskelun aloitus (Todellinen)
Maanantai 15. kesäkuuta 2026
Ensisijainen valmistuminen (Arvioitu)
Lauantai 15. elokuuta 2026
Opintojen valmistuminen (Arvioitu)
Lauantai 15. elokuuta 2026
Opintoihin ilmoittautumispäivät
Ensimmäinen lähetetty
Sunnuntai 31. toukokuuta 2026
Ensimmäinen toimitettu, joka täytti QC-kriteerit
Sunnuntai 31. toukokuuta 2026
Ensimmäinen Lähetetty (Todellinen)
Perjantai 5. kesäkuuta 2026
Tutkimustietojen päivitykset
Viimeisin päivitys julkaistu (Todellinen)
Keskiviikko 17. kesäkuuta 2026
Viimeisin lähetetty päivitys, joka täytti QC-kriteerit
Maanantai 15. kesäkuuta 2026
Viimeksi vahvistettu
Maanantai 1. kesäkuuta 2026
Lisää tietoa
Tähän tutkimukseen liittyvät termit
Avainsanat
Muita asiaankuuluvia MeSH-ehtoja
Muut tutkimustunnusnumerot
- SPECTRO-ALIGN-ORTHO
Yksittäisten osallistujien tietojen suunnitelma (IPD)
Aiotko jakaa yksittäisten osallistujien tietoja (IPD)?
JOO
IPD-suunnitelman kuvaus
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.
IPD-jaon aikakehys
Beginning 6 months after publication of primary study results.
IPD-jaon käyttöoikeuskriteerit
Upon reasonable request to the corresponding author (PI); requests reviewed within 30 days.
IPD-jakamista tukeva tietotyyppi
- STUDY_PROTOCOL
- MAHLA
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