* 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.
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
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)
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.
Cohort
Cross-sectional
Supragingival trimming-line design
DeviceClear aligner edge covering approximately 2 mm of marginal gingiva (straight cut), worn on one dental arch.
Juxtagingival festooned trimming-line design
DeviceClear aligner edge following the scalloped gingival contour, terminating at the free gingival margin without covering the gingiva, worn on the contralateral arch.
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).
Total patient-reported discomfort score per design (0-40)
Pre-specified secondary analysis. For each participant, the 20 item scores associated with each design are summed to a total from 0 (no reported discomfort) to 40 (maximum reported frequency across all items); the supragingival and juxtagingival totals are compared within participants (Wilcoxon signed-rank, two-sided, alpha 0.05). Internal consistency of the total score is assessed (Cronbach's alpha).
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