Three-Dimensional Bracketless Orthodontic Treatment (3D-BOT) Using E-WIRE Versus Conventional Fixed Braces for Mild-to-Moderate Lower Front Tooth Crowding in Adults (3D-BOT-RCT)

Participants will receive conventional labial fixed orthodontic treatment using metal brackets and a planned archwire sequence to align the mandibular anterior teeth.

Mini Master Series metal brackets (American Orthodontics), McLaughlin-Bennett-Trevisi (MBT) prescription with 0.022-inch slots, will be bonded to teeth 45-35, with buccal tubes on 46 and 36. Nickel-titanium (NiTi) archwires will follow the planned sequence (inches): 0.012 at initial appliance placement (APP0); 0.014 at Week 4; 0.016 at Week 8; 0.016×0.022 at Week 12; 0.017×0.025 at Week 16; and 0.019×0.025 at Week 20. Progression requires clinically appropriate engagement without excessive force; otherwise, the current wire will be retained and reassessed. A 0.019×0.025-inch stainless steel wire will be placed after all Week 24 research assessments. IPR will follow the plan locked before randomization. No chains, springs or other auxiliaries directly affecting lower anterior alignment will be used during evaluation. Actual wire changes, delays, repairs and clinically necessary deviations will be documented.

Participants will receive bracketless fixed orthodontic treatment using coated E-WIRE archwires secured with composite along a digitally planned path to align the mandibular anterior teeth.

At initial appliance placement (APP0), a round coated E-WIRE (E-Wireligner; nominal size 0.014 inch) will be secured with GC Ortho Connect Flow (GC Orthodontics) from teeth 46 to 36 along a digitally planned posterior occlusal/anterior lingual path. After light curing, the water-soluble coating will be removed with a 60-second water wash. After the Week 8 digital scan, the initial wire and its composite will be removed, and a coated Velodrome E-WIRE (E-Wireligner; nominal size 0.016 × 0.022 inch) will be bonded to the lingual surfaces of teeth 43-33 only, using the same bonding and coating-removal procedures. IPR will follow the plan locked before randomization. No auxiliaries directly affecting lower anterior alignment will be used. Clinically necessary delays, repairs and deviations will be documented.

LII is the sum of five horizontal displacements between corresponding anatomical contact points of adjacent mandibular anterior teeth (43-33), measured in millimeters on digital models. Decreases from baseline indicate improved alignment.

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 actual elapsed intervals), cumulative percentage improvement from baseline, proportion achieving LII ≤1 mm, time (days) from initial appliance placement to the first scan documenting LII ≤1 mm, and area under the LII curve (mm × weeks; trapezoidal rule using scheduled weeks; lower values indicate faster or more complete alignment).

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 (gonion-menton, 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). Pain burden is the trapezoidal area under the scheduled pain scores from 4 to 168 hours (score × hours), excluding the pre-procedure reading, calculated for initial placement and for each subsequent session with actual activation. Cumulative pain burden is the sum of these areas for all activation sessions from initial placement through the Week 24 session, including its full 168-hour follow-up; sessions without activation contribute zero. 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, burden 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 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.

Arabic five-item Oral Health Impact Profile (OHIP5-Ar), with seven-day recall and a total score of 0-20. Higher scores indicate worse oral health-related quality of life. Total scores and changes from baseline are assessed regardless of whether the preceding visit included activation.

Arabic Orthodontic Treatment Impact Questionnaire (OTIQ-Ar): 21 scored items, with two positively worded items reverse-scored, yielding a total of 0-42. Higher scores indicate greater impact. The global question is analyzed separately on a 0-2 scale. Recall starts at initial placement for the Week 4 assessment, the Week 8 visit for the Week 12 assessment, and the Week 20 visit for the Week 24 assessment.

Exploratory correlation coefficients describing associations between the baseline-to-Week-24 reduction in Little's Irregularity Index and actual interproximal enamel reduction, changes in mandibular arch widths and anterior arch depth, and changes in lower incisor inclination and protrusion. Correlations are calculated using participant-level data.

Changes from baseline in crown and root-apex positions (mm), mesiodistal angulation and buccolingual inclination (degrees), and buccal/lingual root-to-cortical distances (mm), measured on cone-beam computed tomography (CBCT) images after regional registration on stable mandibular body bone. Digital intraoral scans may additionally be fused with the corresponding CBCT data to refine crown surface representation. Components are reported separately; non-assessable measurements are documented.

An adapted Arabic questionnaire assesses appliance acceptance using symptom and functional-impact severity ratings (1-5), nominal and duration categories, and comfort and aesthetics ratings (0-10). Higher severity scores indicate worse symptoms or impacts; higher comfort and aesthetics scores indicate more favorable responses. Items are analyzed separately; no overall score is calculated.