Dental Crowding, Malocclusion, Angle Class I
Conditions
Keywords
Bracket positioning, Smile arc, Indirect bonding, ABO Objective Grading System, Mini-esthetics, Tip and torque, Orthodontic finishing
Brief summary
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.
Detailed description
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.
Interventions
PROCEDURESmile Arc Protection (SAP) bracket positioning
Bracket positioning by the Smile Arc Protection technique (anterior brackets placed relatively more gingival, referenced to canine crown height).
PROCEDURESmile Arc and Marginal Ridge Approach (SAMRA) bracket positioning; Procedure
Bracket positioning by the Smile Arc and Marginal Ridge Approach (digital workflow referencing the marginal-ridge line and facial axis).
PROCEDUREMcLaughlin-Bennett-Trevisi (MBT) chart bracket positioning
Bracket positioning by the McLaughlin-Bennett-Trevisi bracket placement chart (bracket-to-incisal-edge distances from the standardized chart).
Sponsors
Future University in Egypt
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
14 Years to 25 Years
Healthy volunteers
No
Inclusion criteria
1. Males and females aged 14-25 years with a full permanent dentition. 2. Mild to moderate crowding requiring non-extraction orthodontic treatment (2-6 mm per Graber's classification). 3. Angle Class I malocclusion. 4. Normal skeletal vertical dimension (SN-MP angle 32° ± 5°).
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Quality of orthodontic finishing - ABO Objective Grading System (ABO-OGS) total score | 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. | 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). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Anterior crown angulation (tip) - CBCT | Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding | Change in mesiodistal crown angulation (tip) of the anterior teeth, measured in degrees on dentoalveolar CBCT using defined landmarks and reference planes. |
| Anterior crown inclination (torque) - CBCT | Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding | Change in labiolingual crown inclination (torque) of the anterior teeth, measured in degrees on dentoalveolar CBCT. |
| Maxillary gingival display | Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding | 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. |
| Maxillary incisal display | Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding | 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. |
| Buccal corridor width | Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding | 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. |
| Smile arc category | Change from before bonding (T₀) to end of levelling and alignment (T₁), approximately 7 months after bonding | 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. |
Countries
Egypt
Outcome results
None listed