* 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.
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
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
Crossover
Tri-layer thermoplastic finishing clear aligner
DeviceFinishing 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.)
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).
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).
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.
Proportion of Measurements Exceeding Perceptibility / Acceptability Thresholds
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.
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George Emil Palade University of Medicine, Pharmacy, Sciences and Technology of Targu Mures
Lead sponsor
Aorys Clinic, Sibiu, Romania
Collaborator
SC APARAT DENTAR SRL, Sibiu, Romania
Collaborator
