Bracketless Orthodontic Treatment (3D-BOT) Versus Conventional Fixed Braces for Mild-to-Moderate Lower Front Tooth Crowding in Adults

Mandibular anterior alignment is assessed on digital models using Little's Irregularity Index (LII). Measures include interval LII reduction (mm), improvement rate (mm per four weeks, using scheduled interval durations), cumulative percentage improvement from baseline, proportion achieving LII ≤1 mm, and time (days) from initial appliance placement to the first scan documenting LII ≤1 mm.

Digital-model changes from baseline (mm) in intercanine cusp-tip width, first-premolar Pont width, first-molar middle-buccal-cusp width and anterior arch depth. Pont points lie at the distal marginal ridge/distal buccal-cusp-slope junctions. Depth is the greatest perpendicular distance from either lower central incisor's most labial incisal-edge point to the first-premolar Pont line.

Changes from baseline on lateral cephalograms in the angles between the lower incisor's long axis and the mandibular plane (Go-Me) and nasion-point B line (NB), measured in degrees, and the perpendicular distance from its most labial crown point to NB, measured in millimeters.

Crown-axis angular deviations of the six lower anterior teeth from the digital target setup approved before randomization, measured in the reference occlusal plane. The main indicator is mean absolute error (MAE; degrees); root mean square error (RMSE; degrees) and percentage reduction from baseline MAE are supportive indicators. Lower angular errors indicate closer agreement with the target.

Mean Plaque Index score (0-3) across up to 48 sites on mandibular teeth 46-36. The mean is calculated from the sites actually assessed, with the number of assessed sites recorded. Higher scores indicate greater plaque accumulation.

Mean Gingival Index score (0-3) across up to 48 sites on mandibular teeth 46-36. The mean is calculated from the sites actually assessed, with the number of assessed sites recorded. Higher scores indicate greater gingival inflammation.

Mean Mühlemann Papillary Bleeding Index score (0-4) across up to 22 buccal and lingual papillary sides in the mandibular region 46-36. The mean is calculated from the papillary sides actually assessed, with the number assessed recorded. Higher scores indicate greater papillary bleeding.

Number and percentage of calculus-positive surfaces on the four mandibular incisors (42, 41, 31 and 32), assessed on four surfaces per tooth (labial, lingual, mesial and distal). The count ranges from 0 to 16 when all surfaces are assessed; the percentage uses the number of surfaces actually assessed as its denominator. Higher values indicate more calculus.

Arabic-language Oral Health Impact Profile-14 (OHIP-14), with a total score of 0-56 and a preceding-month recall period; higher scores indicate worse impact. Four separate descriptive indicators-oral function, orofacial pain, orofacial appearance and psychosocial impact-each range from 0-8.

Arabic Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ-Ar): 23 items, with six dental self-confidence items reverse-scored, yielding a total of 0-92. Higher scores indicate worse psychosocial impact. Assessments characterize changes during treatment, with the appliance present at the final assessment.

Study-specific 0-100 mm visual analogue scales assess appliance-related symptoms and functional and social impacts over the preceding 24 hours. Appliance-related satisfaction and willingness to choose the same appliance again or recommend it are assessed at Week 24 based on the participant's experience to date. Each item is analyzed separately; no overall score is calculated. Higher symptom and impact scores indicate worse experience, whereas higher satisfaction and willingness scores indicate more favorable responses.

Pain intensity is assessed using a 0-10 Numerical Rating Scale (0=no pain; 10=worst imaginable pain). Initial-placement pain burden is the trapezoidal area under the scheduled pain scores from 4 to 168 hours (score × hours), excluding the pre-procedure reading. Separate 0-10 ratings assess pain interference with sleep, mood, work/study and social life over the preceding seven days. Higher scores indicate greater pain or interference.

Measures include any analgesic use, number of days of use, number of doses, cumulative dose (mg) for each drug, and time to the first dose after the procedure. Different drugs are recorded and summarized separately. Analgesic use during the preceding 24 hours is recorded separately.

The main comparison is cumulative net clinical procedure time (minutes), including initial application, planned procedures and repairs/unplanned interventions, but excluding isolation, interproximal reduction and non-procedural pauses. Initial application, planned-procedure and repair times are also reported separately. Additional 3D-BOT digital setup and wire-planning time is described separately and added to clinical time for a supplementary total; control-group research-only setup is excluded. Cumulative clinical time, unplanned visits, repair counts and repair time are additionally summarized up to the first scan documenting Little's Irregularity Index ≤1 mm, excluding subsequent procedures at that visit. Non-achievement by Week 24 is recorded.

Clinically confirmed unplanned loss of appliance stability or mechanical integrity requiring intervention. Outcomes include the proportion with failure, event counts and days to first failure. Events are classified by type, site, suspected cause, wire stage and same-site recurrence. A fixation unit is a bonded bracket/tube in conventional treatment or a composite fixation point in 3D-BOT. Each failed unit and recurrence after repair counts separately. Unit-related failure rates are expressed as events per fixation-unit-week of exposure. Failure timing is classified relative to the most recent placement or rebonding of the affected unit: immediate (0-24 hours), early (>24 hours to four weeks), or late (>four weeks). Time to the participant's first failure is measured from initial appliance placement and does not reset after repair or wire replacement.

Proportion developing new lesions, new-lesion count, maximum clinically assessed severity on a study-specific 0-4 scale (0=no lesion; 4=severe/multiple ulceration, marked speech/chewing difficulty or medication requirement), maximum diameter (mm), speech/chewing effects, medication need and percentage of scheduled assessments with lesions. Pre-existing lesions are recorded separately; persistent lesions count once and recurrence after resolution counts as new.

Root shortening of the six mandibular anterior teeth, calculated as baseline root length minus Week 24 root length (mm) on paired cone-beam computed tomography images. Results are summarized per tooth and as the participant-level mean across evaluable teeth; the number of teeth assessed is recorded.

Changes from baseline in buccal, lingual and interradicular bone thickness and alveolar crest level (mm) around the six mandibular anterior teeth, assessed using cone-beam computed tomography, together with the number and proportion of assessable sites showing radiographic dehiscence or fenestration. Non-assessable sites are documented.