Umar Mohamed

PART I

CONTENTS. Introduction Brief history An overview of treatment mechanics Appliance specification – Variations and Versatility Bracket positioning Arch form Anchorage control during levelling and aligning Arch wire sequence Over bite control Space closure by Sliding mechanics Finishing the case Appliance removal and retention protocol References

Introduction

FUNDAMENTALS OF TREATMENT

MECHANICS

The Work of ANDREWS

The work of Roth

The work of McLaughlin and Bennett between 1975 and

1993Worked with SWA brackets .Redefined treatment mechanics based on sliding mechanics continues light forces

The work of McLaughlin Bennett and Trevisi between

1993 and 1997• Redesigned entire bracket system

• MBTTM is a version of Preadjusted bracket system specifically for use with Light continuous forces ,Lacebacks ,bendbacks and designed to work with sliding mechanics

• Anterior tip specification for original SWA greater than research findings

The work of McLaughlin Bennett and Trevisi between

1997 and 2003

Overview of the MBT treatment philosophy

• Bracket selection• Versatility of the bracket system • Accuracy of bracket positioning • Light continues forces• The .022 vs the .018 slot• Anchorage control in early treatment • Group movement• The use of three arch forms • One size rectangular steel wires

• Arch wire hooks • Method of archwire ligation• Awareness of tooth size discrepancies • Persistence in finishing

Bracket selection

Accuracy of bracket positioning

Light continues forces

• Most effective way to move teeth is being comfortable to patient and minimizing the threat to anchorage

• Thin, flexible wires early on ,with minimal deflection and avoid too frequent arch wire changes.

• Clinician needs to recognize the signs of excess forces

• Later in sliding mechanics ,light continues forces are applied using active tie backs and rigid .019x.025 steel working wires

The .022 versus the .018 slot

Anchorage control in early treatment

Group movements

One size of rectangular steel

wire

Arch wire hooks

Appliance Specification -Variations and

Versatility

Design features of a modern bracket

system

• Range of Brackets

• i.d system and shape of the bracket

Torque in base –computer aided

design(CAD) factor

TIP SPECIFICATION

TORQUE SPECIFICATION

Recommended

torque

Incisor torque• It is helpful clinically have

torque control which moves upper incisor roots palatally and lower incisor roots labially.

• This treatment is necessary for many types of malocclusison

• Class II cases, Torque lose on the upper incisors and where lower incisors tends procline during levelling and in response to class ii elastics. Class I cases, correct torque help to achieve anterior tooth fit Class iii cases Correct torque can help to compensate for mild class iii dental bases

Canine torque

Upper premolar and molar toque

Lower Premolar and molar torque• Many orthodontic cases showed narrow maxillary

arch with lower arch showing compensating narrowing .

• They require buccal crown torque (uprighting )

• Rolling-in

The Versatility of the MBT Bracket

System

Versatility

1.Palatally Displaced Upper Lateral

Incisors

Three torque for upper canine (-70,00,+70) & lower canine (-60,00,+60)

• Effective torque control of the upper canines is necessary, because they are key elements in a mutually protected occlusion.

• The inefficiency of the PEA in delivering torque is evident when working with canines (longest roots in the human dentition).

• The MBT philosophy used two type of canine brackets (in each arch) to provide three possible torque options (in each arch).

1. Arch form• Well developed arches:

(not requiring substantial tooth movement)o -7° upper canineso -6° lower canines

• Ovoid or tapered arch form:o 0° for upper canineso 0° for lower canines

• Narrow tapered arch form:o +7° upper canineso +6° lower canines

2. Canine prominence• Prominent canines or • Gingival recession present:

o upper canines = 0° or +7° torqueo lower canines = +6° torque

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3. Extraction decision

• In premolar extraction cases or• In cases where there is considerable canine tip to

be corrected:o 0° torque As they tend to maintain the canine roots in

cancellous bone, thereby making tip control of the canine roots easier.

Canine bracket carries a hook

4. Overbite • In class II/2 cases and• Other deep bite situations

o Lower canine = 0° or +6° torqueThere is often a requirement to move the lower

canine crowns labially, but to maintain the roots centered in the bone.

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5. Rapid palatal expansion cases

• Widening of the upper arch creates a secondary widening in the lower arch = torque changes among lower teeth.o lower canine = 0° or +6° torqueRecommended to assist this favorable

change.

6. Agenesis of upper lateral incisor

• If to close the spaces of missing lateral incisors with canine mesialization:o Canine bracket = +7° torque

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Interchangeable lower incisor brackets

Interchangeable

Interchangeable upper premolar brackets

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Use of upper second molar tubes on

first molars in non HG- cases

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Finishing to a Class II molar relationship Use of

second molar tubes for the upper first and second molars

of the opposite side.

.

Bracket positioning and case setup

BRACKET POSITIONING

Direct visualization

HORIZONTAL POSITIONING

VERTICAL POSITIONING

AXIAL POSITIONING

Rotations

•On a rotated tooth the bracket bonded slightly more mesially or distally, with a very small amount of excess composite under the mesial or distal of the bracket base.

Clinical Use of gauges

Upper first molar band placement

When viewed from buccal side ,the tube and band should be parellel to buccal cusps

It is common error to allow the band to seat too gingivally at the distal,causing excessive crown tip.

Mesio-distally the bracket should straddle the buccal groove

Lower first molar band placement

Correct band positioning.

A common error is to allow the band to seat too gingivally at the mesial .

Horizontal bracket placement errors

• If brackets are placed to the mesial or distal of the vertical long axis of the clinical crown, improper tooth rotation can occur.

Axial or paralleling bracket placement errors

• These will occur if the bracket wings do not straddle the vertical long axis of the crown in a parallel manner.

• Such errors lead to improper crown tip.

Thickness errors.

• Excess bonding agent beneath the bracket base can cause thickness and rotational errors.

• Can be eliminated by pressing the bracket against the tooth.

Vertical errors

• Vertical errors in bracket placement are caused by placing brackets gingival or incisal\occlusal to the center of the clinical crown.

• May lead to extrusion or intrusion.

Gingival Concern.

• Partially erupted tooth.• It is difficult to visualize

the center of the clinical crown on partially erupted teeth, when treating young patients.

Gingival Inflammation

• Top:Healthy gingivae.• Bottom :The same

case with inflamed gingivae in the upper right quadrant.

Gingival inflammation causes foreshortening,effectively reducing the length of the clinical crowns.

Teeth with palatally or lingually displaced roots.

• Individual teeth with lingually displaced roots can produce short clinical crowns.

Incisal or Occlusal concerns.

• Incisal crown fractures or tooth wear make it difficult to visualize the center of the clinical crown.

• Restore crown

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Technique for Vertical Bracket Placement

• Measuring the clinical crown heights on as many fully erupted teeth as possible

The bracket placement guide is used to supplement the visual technique and is most helpful in those cases where the center of the clinical crown is difficult to locate due to partial eruption, gingival inflammation, or abnormal tooth size and shape.

Chart individualization in premolar extraction cases

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Chart individualization in deep bite and open bite cases

Deep-bite cases- the incisor and canine brackets 0.5 mm more occlusally. Open bite cases- 0.5 mm more gingival