An interventional study of Smile Arc Protection (SAP) bracket positioning and Smile Arc and Marginal Ridge Approach (SAMRA) bracket positioning; Procedure in Malocclusion, Angle Class I and Dental Crowding, sponsored by Future University in Egypt. Completed at 1 site in Egypt. Open to participants aged 14 Years to 25 Years. Per ClinicalTrials.gov, last updated 2026-07-16.
Sponsored by Future University in Egypt · Not applicable, Interventional, and Treatment
This three-arm randomized clinical trial compares three orthodontic bracket positioning techniques - Smile Arc Protection (SAP), Smile Arc and Marginal Ridge Approach (SAMRA), and the McLaughlin-Bennett-Trevisi (MBT) bracket placement chart (control) - in young patients with Angle Class I malocclusion and mild-to-moderate crowding treated non-extraction. The primary aim is to determine which technique yields the highest quality of orthodontic finishing, measured with the American Board of Orthodontics Objective Grading System (ABO-OGS). Secondary aims compare anterior tooth tip and torque (assessed by CBCT) and mini-esthetic smile parameters (gingival display, incisal display, buccal corridor, and smile arc, assessed on standardized posed-smile photographs) among the three techniques.
Bracket positioning is one of the most influential operator-dependent factors affecting the quality of orthodontic finishing and the resulting smile esthetics. Three contemporary positioning philosophies are compared in this trial.
Design. Eligible participants are randomly allocated 1:1:1 to one of three parallel arms. Allocation is generated with an online randomizer, concealed in sequentially opaque sealed envelopes held by a co-supervisor, and revealed only on the day of intervention. Outcome assessors are blinded; operator blinding is not feasible.
Intervention. All arms receive a fully digital indirect-bonding workflow (intraoral scanning, virtual bracket placement in 3Shape Ortho-Analyzer, 3D-printed casts, vacuum-formed transfer trays) using a 0.018-inch MBT prescription, and an identical arch wire sequence ending in a 0.017 in × 0.025 in stainless steel wire maintained for three months. The arms differ only in the vertical/angular bracket-positioning rule applied (SAP, SAMRA, or MBT chart).
Assessment. Records are captured before bonding (T₀) and at the end of levelling and alignment (T₁). The ABO-OGS is scored on 3D-printed casts and the panoramic radiograph; tip and torque are measured on dentoalveolar CBCT; mini-esthetic parameters are measured on standardized frontal posed-smile photographs calibrated in Adobe Photoshop.
35 studies on the registry are indexed under Malocclusion, Angle Class I; 10 are open to participants now.
This study's enrollment of 39 is above the median of 32 across 31 interventional studies indexed under Malocclusion, Angle Class I.
Browse Malocclusion, Angle Class I studies →Future University in Egypt is the lead sponsor of 104 studies on the registry; 31 are open to participants now.
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Exclusion Criteria:
1. Medication that may cause gingival inflammation (e.g., cyclosporine, phenytoin).
2. Impacted, extracted, or missing permanent teeth (except third molars). 3. Periodontal disease or parafunctional habits (bruxism, tongue thrusting, mouth breathing).
4. History of previous orthodontic treatment. 5. Craniofacial anomalies, facial asymmetry, or skeletal discrepancy.
Bracket positioning by the Smile Arc Protection technique (anterior brackets placed relatively more gingival, referenced to canine crown height).
Procedure: Smile Arc Protection (SAP) bracket positioning
Bracket positioning by the Smile Arc and Marginal Ridge Approach (digital workflow referencing the marginal-ridge line and facial axis).
Procedure: Smile Arc and Marginal Ridge Approach (SAMRA) bracket positioning; Procedure
Bracket positioning by the McLaughlin-Bennett-Trevisi bracket placement chart (bracket-to-incisal-edge distances from the standardized chart).
Procedure: McLaughlin-Bennett-Trevisi (MBT) chart bracket positioning
Bracket positioning by the Smile Arc Protection technique (anterior brackets placed relatively more gingival, referenced to canine crown height).
Bracket positioning by the Smile Arc and Marginal Ridge Approach (digital workflow referencing the marginal-ridge line and facial axis).
Bracket positioning by the McLaughlin-Bennett-Trevisi bracket placement chart (bracket-to-incisal-edge distances from the standardized chart).
Quality of orthodontic finishing - ABO Objective Grading System (ABO-OGS) total score
Total ABO-OGS score obtained on the Cast-Radiographic Evaluation (CRE) form. Seven parameters - alignment/rotations, marginal ridges, buccolingual inclination, occlusal contacts, occlusal relationships, overjet, and interproximal contacts - are scored on 3D-printed casts with the ABO measuring gauge; root angulation is scored on the panoramic radiograph. Point deductions are summed to give the total score (a lower total indicates better finishing).
Time frame: At completion of the levelling and alignment phase (T₁), after the 0.017 in × 0.025 in stainless steel arch wire has been maintained for 3 months - approximately 7 months after bonding.
Anterior crown angulation (tip) - CBCT
Change in mesiodistal crown angulation (tip) of the anterior teeth, measured in degrees on dentoalveolar CBCT using defined landmarks and reference planes.
Time frame: Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding
Anterior crown inclination (torque) - CBCT
Change in labiolingual crown inclination (torque) of the anterior teeth, measured in degrees on dentoalveolar CBCT.
Time frame: Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding
Maxillary gingival display
Change in maxillary gingival display - the vertical distance (mm) between the inferior border of the upper lip and the gingival zenith of each maxillary anterior tooth (central incisor, lateral incisor, canine, both sides) on standardized posed-smile frontal photographs, measured in Adobe Photoshop after calibration against a metric ruler.
Time frame: Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding
Maxillary incisal display
Change in maxillary incisal display - the vertical amount (mm) of maxillary incisor crown visible relative to the upper lip during a posed smile, on standardized photographs.
Time frame: Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding
Buccal corridor width
Change in buccal corridor (lateral negative space) - the linear distance (mm) between the most posterior visible maxillary tooth and the corner of the mouth during posed smile, measured on each side and averaged.
Time frame: Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding
Smile arc category
Smile arc classified as consonant, flat, or reversed based on the relationship between the curvature of the maxillary incisal/canine/premolar edges and the curvature of the lower lip during posed smile.
Time frame: Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Undecided — Study data are stored confidentially within the Department of Orthodontics with access restricted to the investigator and supervisors; results will be disseminated through the institutional thesis repository and peer-reviewed publication.
Ran from Jul 2024 to primary completion in Jul 2026, 24 months.
Of 23 interventional studies with no phase under Malocclusion, Angle Class I, half reached primary completion within 21 months of starting (the median), counting those still running; a quarter within 15 and three quarters within 24. This study's 24 months is above that.
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This study is completed, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
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