MBT

Presented by :Dr. Siddharth Konwar

CONTENTS :

• Introduction

• Review of literature

• MBT philospohy

• MBT treatment mechanics

• Conclusions

• References

MBT was developed by

• Richard P Mclaughlin

• John C Bennet

• Hugo J Trevisi

INTRODUCTION• Straight wire appliance(SWA) developed by

ANDREWS changed the concept of standard edgewise system.

• ROTH’S most important contribution to orthodontics was introduction of FUNCTIONAL OCCLUSION and spreading SWA as ROTH SETUP

FIRST GENERATION PEA

• Available from 1972

• It had Siamese edgewise brackets

Drawbacks:

• Traditional heavy edgewise forces continued to be used

• No specific measures were employed to control anchorage.

• In the early years of PEA, heavy forces were used and these were associated with deepening of the anterior bite and creation of lateral open bite –”ROLLER COASTER EFFECT”

SECOND GENERATION PEA

• After few years of clinical experience with SWA, Roth identified the short comings of SWA like multiple bracket system.

• Used a wider arch form than Andrews to avoid damage to canine tips during treatment

• He emphasized the use of articulators for

• Diagnostic setup• Early splint construction• Construction of gnathologic

positioners at the end of the treatment.

THIRD GENERATION PEA

• Work of Mc Laughlin and Bennett between 1975-1993

• The science and tradition which went to the original design are now balanced by wealth of clinical experience.

• Work of Mc Laughlin and Bennett and Trevisi between 1993-1997

• Work of Mc Laughlin and Bennett and Trevisi between 1997-2001

• MBT developed the treatment mechanics based on

• Sliding mechanics• Light continuous forces• Lace back and bend back• Designed to work ideally with sliding mechanics

McLaughlin, R.P., Bennett, J.C. The transition from standard edgewise to preadjusted appliance system. J Clin Orthod. 1989;23:142–153.

McLaughlin, R.P., Bennett, J.C.(1989).

The most significant changes in mechanics that occurred during the transition period from standard edgewise to preadjusted appliance systems.The changes are grouped under the six sequential but overlapping phases:

Anchorage : Need for early anchorage control was identified for which omega loops and molar tiebacks were used to control incisor and canine positions.

Leveling & aligning : 6-7mm of space opening in the anterior segments over six months, while leveling proceeds from light, multistranded wires into .020" round wires. If this space is more than desired the lacebacks are discontinued before leveling is completed.

Overjet & overbite : When the cuspids are upright or even more distally inclined, the effective way to manage this situation is to leave the incisors unbracketed, and place lacebacks to the cuspids, and wait for the cuspid roots to distalize and the cuspid slots to become more parallel to the occlusal plane.

Space closure : Single elastic modules to anterior archwire hooks with ligature wires extended forward from the molars and when activated 2-3mm, generate about 100-150g of force and delivers .5-1.5mm of space closure per month

Finishing : Source: The appliance prescriptions are based on averages, they cannot possibly account for all the variations of tooth size and shape. This means that detailing bends will be needed in the finishing wires of some patients.

Bennett, J.C., McLaughlin, R.P. (1990).

They have given the basic principles of space closure :

Mechanics of Space Closure : The force required for space closure is delivered by elastic "tiebacks" which is stretched by 2-3mm twice its normal length.

Inhibitors to Sliding Mechanics : Three primary sources of friction during space closure . First-order or rotational resistance at the mesiobuccal and distolingual aspects of the posterior bracket slots is produced by rotational forces on the buccal aspects of the posterior teeth.

Second-order or tipping resistance at the mesio-occlusal and distogingival aspects of the posterior bracket slots is caused by excessive and overactivated tieback forces, which lead to tipping of the posterior teeth.

Bennett, J.C., McLaughlin, R.P. Controlled space closure with a preadjusted appliance system. J Clin Orthod. 1990;24:251–260.

Third-order or torsional resistance occurs at any of the four areas of the bracket slot where the edges of the archwire make contact. Like tipping resistance, this is produced mainly by excessive and overactivated tieback forces,

Stephen Burke et al.(1998) applied 26 previous studies to assess the longitudinal stability of postretention mandibular intercanine width.

They found that mandibular intercanine width tends to expand during treatment 0.8 to 2mm.

Mandibular intercanine width tends to constrict postretention by 1.2 to 1.9 mm.

Burke S P., SilveiraA M., Goldsmith, Yancey, Stewart,Scarfe. A meta-analysis of mandibular intercanine width in treatment and postretention.Angle orthod 68(1):53-60

Thomas ,Steve ,Nicole (2007) : They found that added force to overcome friction during canine retraction in sliding mechanics, the result of which can be increased anchorage loading and anchorage loss.

The frictional force that reduces the force of retraction on the canine must also reduce the protraction force on the molar.

Emphasis on using reduced-friction( selfligating) brackets during sliding mechanics to help preserve posterior anchorage.

Southard, T.E., Marshall, S.D., Grosland, N.M. Friction does not increase anchorage loading. Am J Orthod Dentofacial Orthop. 2007;131:412–414.

Xiaomo Liu;Peng Ding;Jiuxiang Lin.(2013): Explore how the position of the bracket slots relative to the archwire influences the friction between them, and how bracket design affects the critical contact angle (Ѳc).

In their study they used two kinds of stainless steel archwires (0.016 and 0.019 x0.025-inch)were tested against four kinds of brackets (Transmission Straight Archwire bracket, Domestic MBT bracket, Tip-Edge Plus bracket, and BioQuickself-ligation bracket) in the dry state.

They found that the relationship between the archwire and bracket slot significantly affects the resistance to sliding.

Liu,ding,lin. Effects of bracket design on critical contact angle. Angle Orthod. 2013;83:877–884.

Mohit Mittal; Badri Thiruvenkatachari; Paul Jonathan Sandler; Philip E. Benson(2015): Investigate if there are any significant differences in the final inclination of the upper and lower anterior teeth of patients treated with a Roth or an MBT bracket prescription.

Forty sets of posttreatment study models from patients treated using apreadjusted edgewise appliance (20 Roth and 20 MBT) were selected using predetermined inclusion and exclusion criteria.

They found thatthere were no statistically significant differences in terms of the final inclination of the anterior teeth between the two bracket prescriptions.

Mittal,Thiruvenkatachari,Jonathan,Benson. A three-dimensional comparison of torque achieved with a preadjusted edgewise appliance using a Roth or MBT prescription. Angle Orthod. 2015;85:292–297

MBT TREATMENT PHILOSOPHY1. Bracket selection2. Versatility of bracket system3. Accuracy of bracket position4. Light continuous force5. 0.022 versus 0.018 slot6. Anchorage control early in treatment7. Group movement8. Use of 3 arch forms9. One size of rectangular steel wire10.Arch wire hooks11.Methods of arch wire ligation12.Awareness of tooth size discrepancies13.Persistence in finishing

BRACKET SELECTION

• AVAILABLE IN 3

• STANDARD SIZE METAL BRACKETS

• MID SIZE METAL BRACKETS

• ESTHETIC BRACKETS

• Brackets are rhomboidal in shape and have reduced bulk so coordination is only in 2 planes which assists in accuracy of bracket placement.

TIP SPECIFICATION

MBT TIP

• The tip of pre adjusted brackets is fully expressed and there is 1 degree of slop when a .019/.025 rectangular wire is placed

• Upper and lower molar attachment have 0 degree tip when placed parallel to the buccal cusps of molars this delivers 5 degree tip in upper and 2 degree tip in lower.

TORQUE SPECIFICATION

Torque in the base• Important issues in 1st and 2nd generation PEA was

level slot line up was not possible with brackets with torque in the face

• In MBT versatile brackets are finished with all the torque in the base in

• Full size metal brackets and esthetic brackets

• Combination of torque in the base and face with absolutely no difference in slot position in mid size brackets

There is 10 degree of slop when a 0.019/0.025 wire is placed in a 0.22 slot

• TORQUE is not efficiently expressed in PEA due to 2 mechanical reasons

1. Area of torque application is small2. In order to slide the teeth it uses under sized arch wire so torque

would not be fully expressed.

Need of extra torque in incisors

• When class II elastics are used ( in class II cases) there is a tendency for the torque to be lost on the upper incisors and lower incisors tend to procline during leveling in response to class II cases.

• In class I cases, where correct incisor torque helps for better anterior tooth fit.

• Class III cases where correct torque can compensate for mild class III dental bases.

• Due to this frequent clinical requirements there is a need for greater palatal root torque in upper incisors and labial root torque in lower incisors

• +17 and +10 for upper central and lateral and -6 for lower incisors are recommended by MBT

Canine torque• Original SWA -11 torque

for lower canine was not satisfactory because it tends to leave canine in a prominent position

• +7,0,-7 - upper canines• +6,0,-6 - lower canines

• -7/-6 -square or ovoid arch form

• 0/0 -ovoid or tapered arch form

• +7/+6- tapered arch form

6 factors which determine selection of canine brackets

• Arch form• Canine prominence• Extraction decision • Over bite• Rapid palatal expansion• Agenesis of upper lateral incisor

Upper premolar and molar torque

• Upper premolar torque of -7 is considered adequate.

• In molars MBT has found -9 torque in SWA is inadequate so they prefer -14 so as it gives better control over the palatal cusps from hanging down.

Lower premolar and molar torque

• Original SWA molar torque(-30)• 2nd molar torque(-35) causes “rolling in” of

lower molars.

• So MBT brackets they changed lower premolar brackets by 5 ,1st molar by 10, and 2nd molar by 25 degrees.

• -17 2nd premolar• -20 1st molar• -10 2nd molar

VERSATILITY OF BRACKET SYSTEM Seven main versatility features :

•Options for Palatally displaced lateral incisor• Three torque options for upper canine • Three torque options for lower canine • Interchangeable lower incisor brackets• Interchangeable upper premolar bracket • Use of upper second molar tubes on first molar in non HG cases • Use of lower second molar tubes for upper first and second molars of opposite side

36

PALATALLY DISPLACED LATERAL INCISOR:

37

TORQUE OPTIONS FOR UPPER CANINE LOWER CANINE

38

Interchangeable lower incisor brackets

39

Interchangeable

Interchangeable upper premolar brackets

40

In non-HG cases Use of

upper second molar tubes on first molars

41

Finishing to a Class II molar relationship

Use of second molar tubes for the upper first and second molars of

the opposite side.

42

0.022 v/s 0.018 inch slot

• PEA system works well in 0.022 slot More freedom of wire in a larger slot in initial

phase of treatment – lighter force Later in the treatment full slot engagement gives

control for retraction Rigidity for surgical / fixed functional treatment

43

BRACKET POSITIONING

• “In the past best results were achieved by orthodontist who were the best wire benders ,in the future best results come from those orthodontist who are best bracket positioners”-MBT”

Accuracy of bracket positioning is essential, so that the built-in features of the bracket system can be fully and efficiently expressed. This helps treatment mechanics and improves the consistency of the results.

• In 1990 because of continuing difficulty with vertical bracket positioning, McLaughlin and Bennett investigated the location of the centre of clinical crowns.

• MBT recommends vertical positioning of brackets with gauges and charts.

In the incisor region, the gauge is placed at 90° to the labial surface

In the canine and premolar regions the gauge is placed parallel with the occlusal plane.

In the molar region the gauge is placed parallel with the occlusal surface of each individual molar.

Technique for choosing rows

• Step 1-dividers and millimeter rulers are used to measure the clinical crown height on as many fully erupted teeth as possible on patients study model.

• Step 2-these figures are recorded and is divided into half rounded to nearest 0.5mm to obtain distance from occlusal surface to the centre of clinical crown.

• Step 3-the row on the bracket placement chart that contains the greatest number of recorded figure is selected for bracket placement.

Chart individualized in deep bite and open bite cases.

• It is helpful to place the incisor and canine bracket 0.5 mm more

• Incisally in deep bite cases.• Gingival in open bite cases.

Chart individualization in premolar

extraction cases

ARCH FORM SELECTION

• Recent classification according to MBT system is

• Tapered arch form• Square arch form• Ovoid arch from

• Tapered arch form

o Has the narrowest inter canine width useful in patients with narrow tapered arch forms

o Arch is useful in patients with gingival recession in canine and premolar

o This arch form is used in combination with inverted canine bracket.

• Square arch form.

o Used with broad arch from

o Example class II div-2

o Maintain the expansion of upper arch after RME.

• Ovoid arch form

• This arch form has been used as the standard arch form

• This arch form has shown good stability

• Minimal amount of relapse

Customization of arch form

MBT RECOMMENDS USE OF CLEAR TEMPLATES AT THE START OF THE TREATMENT.

LOWER MODELS.

Arch form control in early stages of treatment.

• Multi strand 0.0175” or 0.016” round HANT are used in treatment.

• MBT recommends to use ovoid arch form during initial stage without any customization due to 2 reasons :

• Low dimension wires do not exert heavy force on teeth so as to change the arch form drastically.

• Have little effect on the arch form for the short period of time it is used.

Arch form control during treatment

• Rectangular HANT cannot be customized • So stocked in tapered, ovoid and square.

• 0.019/0.025 S.S when placed should be customized for individual arch form.

A wax template is mounted over the lower arch to record the indentation of the bracket.

0.019/0.025 S.S is bent to the indentation of the wax biteIt is called as IAF-INDIVIDUALIZED ARCH FORM.

COORDINATION:-Upper arch form should be approximately 3 mm wider than the lower arch form in all areas.

63

• Modification after maxillary expansionModifications to Arch Form

64

• Upper arch expansions with archwires

Anchorage control in MBT

• Tooth leveling and aligning is first orthodontic objective during initial stage of treatment.

• Maximum anchorage is needed during leveling and aligning procedures.

Reducing anchorage needs during leveling

and aligning.• Bracket design in MBT:-

o Bracket tip is major factor in anchorage demands early in treatment

o Reduction in tip reduces the anchorage potential in the case

o MBT bracket system has • 10 degree less distal tip in

upper anterior segment.

• 12 degree less distal tip in lower anterior segment when compared with SWA.

• Arch wire forces:-• Use of very light arch wire forces early in treatment will

put less demand on anchorage.

Avoidance of elastic chain

Anchorage control in MBT.• Horizontal plane.

o Control of anterior segments

• Lace backs :-lace backs are 0.010’’ or 0.009’’ ligature wire which extends from the most distally banded molar to canine bracket.

•Lace back are used to prevent the canine crowns from moving forward during leveling and aligning.•Mainly used in premolar extraction cases and also in non extraction cases where the canine root is mesially tipped•Lace backs are passive devices and should not be over tightened•It is shown that lace back can be a effective method of distalizing canine without unwanted tipping.

• Bend backs for anterior-posterior incisor control.

• The arch wire is bent back immediately behind the tube on most distally banded molar

• This serves to minimize the forward tipping on incisors

•Control of posterior segments.

• Upper archo Head gearso TPAo Nance holding arch

• Lower arch• Lingual arch• Lip bumper• Class III elastic and head gear

Lateral or transverse plane• Maintenance of upper and lower inter canine

width

• Correction of molar cross bite if present• RME• QUAD HELIX• TPA.

73

Vertical Anchorage Control During Leveling & Aligning

• Vertical control of incisors

74

• Vertical control of canines

75

• Vertical control of molars in high angle caseso Palatal baro Upp 2nd molars not initially bandedo Headgear – high pull

76

Overbite Control• Development of Deep Overbite

• Anterior teeth continue to erupt until contact is made with opposing ant teeth

77

• Development of Deep Overbite• Unrestricted eruption of low 2nd molars in cl II

78

• The tooth movements of bite opening -

o Eruption/extrusion of post teetho Distal tipping of post teetho Proclination of incisorso Intrusion of incisorso A combination of two or more of the above

79

• Eruption/extrusion of post teetho Growing pts Adults – low angle Adults – high angle

80

• Distal tipping of post teeth

81

• Proclination of incisorso Deep bite with retroclined incisors

82

• Intrusion of anterior teetho Growing pts – preventing normal eruptiono Adults – intrusion arches

83

• Non-Extraction treatmento Generally favors bite opening

• Mechanical factors contributing to bite opening o Initial archwire placemento The bite-plate effect

84

• The bite-plate effecto Allows for early placement of low

incisor bracketso Intrusive force on low incisorso Allow for extrusion/uprighting of post

teeth

85

• Creating the bite-plate effecto Acrylic ant bite plates

• Low angle deep bite cases

86

• Creating the bite-plate effecto Direct bonding material on palatal surface of upp incisorso High angle – occlusal surfaces of molars

87

• The importance of second molarso Low-angle deep bite cases – earliest banding of 2nd molars

Importance of friction in orthodontics

• Applying the proper magnitude of force during orthodontic treatment will result in optimal tissue response and rapid tooth movement.

• With orthodontic mechanotherapy, a biologic tissue response with resultant tooth movement will occur only when the applied forces adequately overcome the friction at the bracket wire interface

Initial leveling in MBT.• Initial arch wire for alignment should provide

light continuous force to provide most efficient tipping movement.

• Arch wire should move freely inside the slot with minimal binding

MBT advocates• Use the lightest possible force to produce tooth

movement

• Do allow sufficient time for up righting of teeth especially canines

• Do not move up to next arch wire unless full bracket engagement has been achieved with present arch wire

• Do not leave initial arch wire unless rotational control has achieved.

• Do not attempt to align a tooth unless there is adequate space available.

Space closure and sliding mechanics.

• 2 schools of thought for retraction

o First is canines and incisors are retracted separately to conserve anchorage

o Second is enmasse retraction where all 6 anterior teeth are retracted at the same time.

o MBT advocates enmasse retraction in their cases

WIRE SELECTION IN SLIDING MECHANICS.

• Space closure in sliding mechanics require a wire which produces less friction between brackets.

• Rectangular wire produce more friction the round wires and larger wires produce more than smaller wires

• Cobalt chromium, beta titanium and Ni Ti produce more friction than stainless steel due to the surface topography of the wire.

• 0.016 stain less steel round wire has lowest friction but it is not good for sliding because wire does not offer control in all 3 planes of space and gets distorted easily and causes excessive tipping and more friction.

• So 0.016x 0.022 S.S in 0.018 slot and 0.019 x 0.025 S.S in 0.22 slot for ideal sliding mechanics.

• Composition of brackets will also affects sliding mechanics. Ceramic brackets create more friction than stainless steel.

Methods of space closures

• Closing loop arch wires

• Sliding mechanics with heavy forces (edge wise mechanics)

• Elastic chain

• Sliding mechanics with light continuous forces. (MBT)

Space closure in MBT.• ARCH WIRES.

o Rectangular 0.019 x 0.025 stainless steel wires in 0.022 slot.

o This is working wire in MBT.

o This wire gives good over bite control while allowing free sliding through the buccal segments.

• Soldered hooks

o 0.7 mm soldered brass hooks are preferred.

o Most common hook position are 36 mm or 38 mm in upper and 26 mm (lower).

• Passive tie backs

o Before starting space closure it is recommended that rectangular 0.019 x 0.025 wire left in place for at least 1 month with passive tie back

o It allows time for torque changes to occur individual tooth for final leveling of arches so sliding mechanics can proceed smoothly

• Active tie back using electrometric modules.

o Active tie back using electrometric modules are preferred for space closure in most case.

o There are 2 types of active tie back

o Type one active tie back ( distal module)

o Type two active tie back (mesial module)

Type one active tie backs (distal module)

One arm of ligature wire is carried under the arch wire. The electrometric module is stretched twice to unstretched size.

Type two active tie backs (mesial module)

• Here the electrometric module is placed on the soldered hook of the arch wire.

Force levels• It was found when modules were stretched twice it was

found to give 50 -100 gms after pre stretching

• Without pre stretching it is 200-300 gm .

• Natrass et al has confirmed that force decay of elastomeric chains is rapid in the first 24 hrs and is affected by oral environment and temperature.

Nattrass C, Ireland A J, Sheriff M: An investigation into the placement of force

delivery systems and the initial forces applied by clinicians during space

closure. BJO 1997:24:127-131

Other methods• Using nickel

titanium springs.

o It can be used when large spaces has to be closed

o If there is infrequent adjustment opportunities

• Samuels et al have found that optimal force while using Ni-Ti coil spring is 150 gms.

• Springs should not be expanded beyond 22 mm for 9 mm springs and 36 mm for 12 mm springs.

Samuels R H, Rudge S J, Mair L H: A comparison of the rate of space closure using a nickel-titanium spring and an elastic module: a clinical study, Am J Orthod 1993:103:464-467Samuels R H, Rudge S J, Mair L H: A clinical study of space closure with nickel-titanium closed coil springs and an elastic module: Am J Orthod 1998:114:73-79

TRAMPOLINE EEFECT.• Clinical experience have showed space closure can

continue for several months who have failed to present for normal adjustments and elastomeric module is poor condition with little force.

• This is explained by “trampoline effect” which occurs during the mastication which result in pumping activation.

Check list after space closure

• Anchorage maintenance should be evaluated.• Occlusal plane of anterior and posterior teeth

must be evaluated.• Axial inclination of the teeth (ex-root parallelism)• Rotation of teeth

THE FINISHING TOUCH.• “Finishing greatly affects stability" Hickman 1992

• Accurate arch form and accurate coordination, less work is required for finishing

Finishing the case:-• Condyles seated in centric relation position.

• Relaxed healthy musculature

• A six keys Class I occlusion

• Ideal functional movements- a mutually protected occlusion

• Periodontal health

• Best possible esthetics.

Final stage of finishing

• Lighter wires are used for settling because heavy wire inhibit the settling of the teeth.

• 0.014/0.016 braided s.s or HANT wire are used.

• It is accompanied by vertical triangular elastics

110

• Lower - .014” or .016” NiTi or .014” steel• Upper - .014” SS sectional• 4-6 weeks

111

Settling The Case

• Variations o Cuspids o Diastema o Extraction – fig 8 ligatureso Palatal expansiono Mod to severe Class II/1

Management of tooth size discrepancy.

• Tooth size is considered the 7th key of normal occlusion.

• Tooth size discrepancy may be corrected by reducing tooth mass in one arch with inter proximal enamel reduction.

• By adding restorative materials in the opposing arch.

Wire Selection in the MBT Versatile+ Appliance System

• It is the wire that drives or guides the teeth, no matter how advanced the brackets may be, or whether they are self-ligating or not.

Archwire role

• It has 2 modes of action1. In this, the wire is in its active state. Activation

of the wire is carried out by ligating the archwire to the irregularly positioned teeth. Energy is stored by pushing the elastic wires into the bracket slots. After this activation, the archwire uses this energy to move the teeth. Such an operating mode is typical for the aligning and leveling stages.

2. In this, the archwire is used as a guiding track for the mesial or distal movement of teeth along the arch. Here the archwire is initially passive and its stiffness and elasticity only comes into play when the teeth start to show side effects such as tipping or rotations.

Then the wire creates corrective forces and moments and assures that the teeth do not deviate from the intended track and angulations.

CONCLUSIONS

There is no such thing as an isolated orthodontic act. More effort and knowledge is required to prevent or control unwanted tooth movements than to apply the primary

forces

References• Mclaughlin RP, Bennett JC, Trevisi HJ: Systemized orthodontic

treatment mechanics: published by Mosby• Samuels R H, Rudge S J, Mair L H: A comparison of the rate of

space closure using a nickel-titanium spring and an elastic module: a clinical study, Am J Orthod 1993:103:464-467

• Nattrass C, Ireland A J, Sheriff M: An investigation into the placement of force delivery systems and the initial forces applied by clinicians during space closure. BJO 1997:24:127-131

• Samuels R H, Rudge S J, Mair L H: A clinical study of space closure with nickel-titanium closed coil springs and an elastic module: Am J Orthod 1998:114:73-79

• McLaughlin, R.P., Bennett, J.C. The transition from standard edgewise to preadjusted appliance system. J Clin Orthod. 1989;23:142–153.

• Bennett J C, McLaughlin R P 1990 Controlled space closure with a preadjusted appliance system. Journal of Clinical Orthodontics 24:251-260

THANK YOU