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Bonding for an exquisite Finish/ Part I: Concepts of Bracket Bonding Dalia El-Bokle. Episode 124. August 25th 2021

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Farooq Ahmed

Join me for a summary of Dalia El Bokle’s lecture exploring finishing in orthodontics. Part 1 focuses on bracket positioning concepts and Dalia’s own take to achieve more predictable ideal outcomes

 

 

Current bracket positioning technique

1.     Middle middle – middle vertically and horizontally (FA point)

o   Challenges

§  Accuracy = measure each tooth

§  If gingival swelling / not fully erupted = inaccuracy

2.     Bracket charts – use of bracket gauges

o   Accurate and reproducible, introduced in 1994

§  Typical chart

·      Upper incisor 4-4.5mm from invasive edge

·      Lateral 0.5mm incisal than lateral

·      Canine 1mm more gingival than central

o   Challenges

§  Appropriate for ideal tooth sizes only, can result in uneven marginal ridge heights if tooth size discrepancy present = bone loss, food impaction, premature contact and relapse

§  Can flatten smiles

 

3.     Smile arch protection (SAC) Tom Pitts

o   Bonding for consonant arch

o   Method

§  Canine gingival to the contact point

§  Lateral 0.75-1mm cervical to the canine

§  Central 1.5mm more cervical to the canine

·      Side effects – oral hygiene and deep bite

 

Solution by Dalia

Customised approach

·      Factors

§  Marginal ridge heights, Upper incisor show, tooth size and shape, Incisor inclination, Overbite

·      Method of positioning

1.     Mesiodistal

§  All teeth bond in centre of the teeth

§  Molars – if extra cusp = tube design = mesial position and distal in rotation

·      Solution = bond centre of the tooth, even if not in Mesiobuccal grove = extra composite used or modify bracket

§  Canine = EXCEPTIONS

·      Place bracket mesial to long axis

·      Mesial in rotation if placed in the centre

o   Requires mesial out rotation to align with the lateral incisor

o   Solution

§  Place upper and lower canines mesially

2.     Axial (tip)

§  Draw long axis on the model

§  Use of OPG / CBCT to draw long axis

§  Modifications

·      Overcorrect 5 degrees adjacent to extractions = prevent dumping in

·      Overcorrect severely tipped teeth (usually in case of early loss of 1st molar)

 

3.     Vertical

§  Posterior bond first 7-3

·      Bond relative to marginal ridges – not incisal edges Kelange technique 2007

·      Draw marginal ridge height line, then slot line

·      Canine same level as premolars for marginal height

§  Anterior positioning

·       Lateral = bracket gauge of the canine to tooth tip, add 0.25mm (more cervical)

·      Central – add 0.25-0.5mm than canine

o   = subtle smile arc protection

o   Subtle smile arc – less steep difference in connectors when compared to SAP by Tom Pitts

§  Modifications

·      3-3 bonded 1mm more gingival = AOB / reduced incisal show, or 1mm more incisal for deepbite / gummy smile

§  Lower arch

·      Canines are bonded 0.5mm more cervical for canine guidance

·      Deep bite = 1mm more incisal

 

Incisal recontouring

·      At the beginning of treatment = visually aid final position and improve aesthetics for patient

 

Bracket positioning for torque positioning

 

Anterior brackets more cervical

·      Vertical Bracket position can change up to 94%, bracket prescription effect 42% Papageorgiou 2017

o   Rectangular wire

§  Incisal position = greater labial crown torque

§  Gingival position = less labial crown torque and more extrusion

 

Molar teeth

o   Morphology effect torque, mandibular molars greatest change in torque , 0.5mm change in lower molar position = 4.2 degrees difference in torque Mardarian 1997

§  Lower molar bracket more gingival = greater lingual crown torque and increased buccal overjet

 

·      Round wire

o   No torque, rotation effect

§  Gingival position  = wire is engaged by moving gingival = retrocline and extrude moment 

§  Ideal for AOB cases with proclined incisors, non-ext with class 3 elastics

 

 

Summary

Torque effected by bracket positioning height more so than prescription, tooth curvature

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