bracket selection & placement / orthodontic courses by indian dental academy

The Implications of Bracket Selection & Bracket Placement

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

www.indiandentalacademy.com

Although many authors –written - finishing details in orthodontic treatment,

No adequate attention – impact of proper bracket selection and placement on finishing details.

www.indiandentalacademy.comwww.indiandentalacademy.com

Objective Versus Subjective Assessments

some of the finishing details - discuss involve variables that are quantifiable - measured objectively.

The presence or absence of spaces can be quantified.

Number of variables involve a high degree of subjectivity--preferences of patients and clinicians,

Partly due to the difficulty in quantifying them due to the difficulty in obtaining objective measurements.


Degree of mesio-distal tip U ant. teeth - to a certain degree, with a difference in the esthetic outcome of the treatment.

range of axial inclinations U ant. teeth -esthetic appearance – pleasing to the patient or the clinician, without having any significant impact on stability &result/pt.'s long-term dental health and function.

A Three-Dimensional Graphic Analysis There are many pre torqued and pre-angulated

appliance systems available to the orthodontic practitioner today, and these prescriptions are based on a foundation of clinical principles,


Selection of Brackets and Tubes Mandibular second molars ought to be

aligned properly within the dental arches at the completion of orthodontic treatment- long-term

periodontal and dental health

mandibular molar tube- distal offset - on the contact point b/w I,II molars- undesirable DL rotation of mandibular first molar

Requires compensation - offset in the AW


Arch wire adjustment - undo the movement expressed by the offset built into the tubes.

This would argue in favor of a molar tube that does not have a distal offset (Figs 5 and 6),

us to recognize that the morphology of the buccal surface of the mandibular first molar dictates

that the mesiodistal position of the tube / bracket will have an impact of the final position'

of the tube. However, our ability to affect the mesiodistal position of the tube is quite limited.

This limitation is obviously greater with bands, since the majority of practitioners today use preformed bands with prewelded brackets and tubes. Since the bands are preformed ,durability to change the mesiodistal position of the molar is greatly inhibited.

With direct bonding, one might have slightly greater flexibility, although the preformed shape of the bracket base generally limits the amount" of modification available to us (Fig 7). With indirect bonding, particularly if a custom resin base is created, there is a little more flexibility available to ,the clinician.www.indiandentalacademy.comwww.indiandentalacademy.com

Bracket Selection and Effect on ThirdOrder Movements

Since the advent of pre torqued and preangulated brackets, orthodontists have had a wide array of torques and angulations to select from.

Each prescription is based on a foundation of clinical principles, as well as the personal philosophical preferences of the individual clinician.

There is considerable variation in the prescribed torques and angulations between the Hilgers and the Alexander prescriptions (Ormco Orthodontics, Orange, CA), for example, not to mention added differences in mechanics introduced by using the 0.018 slot or the 0.022 slot.

It is interesting to contemplate that one practitioner treating a patient population in a given area may use an Alexander prescription, with on the U CI + 14° of torque ULI +7°of torque canines -3° of torque.

Practitioner treating a similar patient population may use the Hilgers prescription, with +22° of central incisor torque, + 14° of lateral

incisor torque, and+ 7° of canine torque. These differences are substantial,


Differences become applicable only when full-size arch wires are used-a relatively uncommon event. Further, the choice of prescriptions may be governed by the practitioner's philosophy on occlusal function and its potential impact on temporomandibular disorders.

seen in Figure 8, same degree of torque placement in the tube on the 17,27 as one has on the 16,26 --- lesser degree of torque expressed on 17,27.

relative low position lingual cusps, ---- balancing interferences, inadequate

settling of the posterior occlusion.

MBT 17,27 torque 4 degrees >16,26.

Torque should be increased to an even greater degree for the average second molar- Dr. Sondhi

27.17 erupt --- buccal crown inclination & lingual root torque.


The Implications of Vertical Placementon Expressed Torque

impact of appliance choice -- expressed torque counts> torque in the bracket on the tooth.

with the new higher resiliency archwires, --- force diminution final activation -- diminution in force --- 17° torque in a bracket ---- fully expressed s.s. / HANT Niti

Important – to discern the differences --by vertical bracket position changes on torque expression on different teeth.

23,13 & 11,21-- degree of convexity of the labial surface has a profound impact on this variable.

11,21– labial surface--- mild degree of convexity when the bracket level is changed


change in-- vertical position relative to the archwire, -- slight change in the expressed torque.

vertical placement of the bracket --modified for deep overbites & open bites without introducing a significant compromise in the expressed torque.


similar changes - vertical position of the bracket -- does not merely change its vertical orientation to the arch wire.

A rather profound impact on the expressed torque is immediately apparent (Fig 12 B & C) effect of –labial convexity surface

Choice of torque in the

bracket –significant -specific vertical placement of the bracket


Figure 13 - Attention is drawn to the vertical position of the maxillary canine & root angulation in the labio-lingual plane


•In Figure 14, the vertical position of the canine bracket -1mm change, while maintaining every other variablein the dental arch, and the appliance configurationconstant. •Canine-- extruded, -- equally evident that thereis a noticeable change in the labio-lingual inclinationof that'. tooth.


In Figure 15—vertical position of the canine bracket-- 2 mm,

quickly apparent that the tooth

not only extrudes, but also shows--change in the labio-lingual inclination.


Figure 16 is an occlusal view with theoriginal bracket placement, Figure 17 isan occlusal view with the bracket having beenmoved gingivally by two millimeters.


Figure 18 clinicians - unable to understand -occlusion not settle

For example,if it is the clinician's intent to place a bracket at a height of 4.5 mm from the cusp tip, and the patient happens to have bruxed enough to flatten the cusp tip by 2 mm,


the habit of placing the bracket at 4.5 mm – create-interference of the canine in the occlusion.

2mm of-cusp tip wear on the canine- is hardly an unusual event - impact of this information - carefully evaluated -the finishing details during treatment.

An effort to overcome this by deliberate over torquing or stepping out of the tooth, is unlikely to create a favorable result.

Cases - appropriate - reshaping the lingual surface of the maxillary canine.


The Effect that the Starting Position ofthe Tooth Will Have on the Finished

Result .

Least understood aspects of treatment PEA assumption- fixed degree of second and third order adjustments built into the bracket – expressed in a uniform manner

Treatment - completed with a full sized archwire 0.022x 0.028 archwire in a 0.022 x 0.028 slot, or a 0.018 x 0.025 archwire in a 0.018 x 0.025 slot.

Clinicians - 0.018 x 0.025 slot -0.016 x 0.022 finishing archwire. Figure 19 A


incisor, such as that seen in a Class II Division 1 malocclusion.

Figure 22, finished position will be the same if a 0.018 x 0.025 archwire is used.

However, the finished position - different if a 0.016 x 0.022 archwire -archwire will not engage in the third order

until the tooth has been retracted to a certain degree.


Finishing With the Preadjusted Orthodontic Appliance Final stage of orthodontic treatment, treatment

goals. The generally accepted goals of treatment.

condyles in a seated position-in centric relation;1 relaxed healthy musculature;2 a "six keys"l,2 Class I occlusion with 3 mm of3 overjet and overbite;4 ideal functional movements-a "mutually protected" occlusion;5. periodontal health; and6. best possible esthetics. Goals viewed - from anterior to posterior. The incisors - set in the face to establish proper

harmony between the upper lip, the lower lip and the chin


In July of 2000, the American Board of Orthodontics~ Emphasis seven features of dental casts. These

features include:1. Tooth alignment: The incisal edges of the anterior

teeth - aligned, - mesio-buccal and disto-buccal cusps of the mandibular posterior teeth and the central fossae of the maxillary posterior teeth.

2. Marginal ridges: The marginal ridges of adjacent posterior teeth, in maxillary and mandibular arches should be at the same vertical level.

3. Buccolingual inclination: The torque features in the molar regions should be correct, as measured using a flat surface extending between the occlusal surfaces of the right and left posterior teeth.


4.Occlusal contacts: Good posterior occlusion should be achieved and evaluated based on the adequacy of occlusal contact of molars and premolars. A common problem area relative to occlusal contacts is seen in the upper and lower second molars.

5.Occlusal relationship: AlP relationship of molars, premolars and canines is assessed using Angle's classification.

6.Overjet: In the anterior region, the mandibular incisors and canines should contact the lingual surfaces of the maxillary incisors and canines. In the posterior region, the buccal cusps of the mandibular molars and premolars should contact in the center of the occlusal surfaces, buccolingually, of the maxillary molars and premolars


7.Interproximal contacts: All of the maxillary& mandibular teeth should be in contact with one another, as viewed from the occlusal surfaces.

Root -anglulation - the roots of the maxillary and mandibular teeth should be

parallel to one another and oriented perpendicular to the occlusal plane. The fewer the errors made as treatment

progresses the less work required during finishing. Horizontal Considerations Coordination of Tooth Fit


A major finishing consideration in the horizontal plane is the coordination of tooth fit between the anterior and posterior segments.

60% of cases,--finishing stage approaches, --crowns of the upper anterior teeth do not occupy enough space m-d - crowns of the lower anterior teeth.

Examples - posterior occlusion is correct-the overjet and

overbite are each 3 mm, but spaces remain in the upper arch, frequently in

the extraction site.

Overjet is correct, -buccal segments - slight to moderate Class II position

Posterior occlusion is correct-all spaces are closed, but there is inadequate overjet and overbite in the anterior area.www.indiandentalacademy.comwww.indiandentalacademy.com

20% of cases-> upper anterior tooth mass - lower anterior tooth mass.

upper anterior crowns > crowns lower anterior segment & patient shows some excessive overjet - posterior segments are in a Class I relationship.

Patients with large upper incisors some Class III cases where upper incisors are proclined forward and lower incisors retroclined

T/T- enamel reduction in upper anterior segment & residual space.

In the horizontal plane, this difficulty relates primarily to the factors of tip in the anterior teeth and bicuspids,incisor torque and tooth size (Fig 1).


Establishing Correct Tip of the Anterior and Posterior Teeth

Tip nearly full expression of the bracket tip - by the time rectangular steel wires

Standard edgewise appliance, tip (second order) bends were placed in the arch wires 2 reasons.

First, to properly position teeth relative to the 0° of tip in

the brackets.

Second, to compensate for the forces used to move teeth (second order compensation), particularly in

extraction cases.


The Andrews nonorthodontic normal model study -baseline reference for the tip figures in the human dentition

Fully programmed PEA- additional tip- added to the anterior segments (second order compensation)

Heavy edgewise forces-previously.

Additional amounts of tip- added to- needed second order compensation- counteract the force levels being used '(Fig 2)

True in the-canine region


Dependent - amount of force used during space closure in extraction cases

Heavier forces are used>2nd order compensation/ anti-tip required in the appliance.& vice versa.

Direction of contemporary orthodontics- lighter forces & minimal anti-tip-- less anchorage loss during tooth movement and better parallelism

of roots, especially in the canine region.

Providing Adequate Incisor Torque

Torque control -weakness PEA--- two factors:

1) Approximately a 1 mm segment of rectangular steel wire is placed in a bracket of about the same dimension.


Small contact area -required - difficult tooth movement, which involves moving an entire portion of the root through alveolar bone and

No use full size-- wires do not slide efficiently through the posterior bracket slots during space closure.

E.g. 0.018 x 0.025 or a 0.019 x 0.0250.022 slot,

0.016 x 0.022 or a 0.0175 x 0.025 0.018 slot.

< effectiveness rectangular wire, relative to torque control (Fig 3).


Clinicians-- added modified torque values- upper and lower incisor brackets.

With most Class I and Class II patients, there is a tendency for upper incisors to be retroclined and lower incisors to be proclined (Fig 4).


Class I / Class II m.o. -additional palatal root torque UI& labial root torque LI (Fig 5).

upper and lower

anterior torque -varies greatly,3rd order incisor archwire bends -- needed.


Management of Tooth Size Discrepancies

Tooth size is -7th key to normal occlusion - the Andrews‘ nonorthodontic normal models had balanced tooth size.

Spacing in one arch / crowding in the opposing arch.

Tooth size discrepancy – small (U)LI /large(L) LI


In the buccal segments– small15,25- tooth size discrepancy

Evaluation of tooth size discrepancy – Bolton’s analysis. Tooth size discrepancy- reducing tooth mass in one arch with

interproximal enamel reduction (usually the lower incisors)

Addition of tooth mass- restorative material (usually the upper lateral incisors).

Minimal crowding -- anterior segments- Bolton analysis confirms > tooth size LI - interproximal enamel reduction procedures lower anterior segment.

Early reduction – spacing in U arch- Restoration

Finishing stage- U ant. Segment > tooth mass -- interproximal enamel reduction the upper anterior segment


Controlling rotations in-out compensation-built + with

correct bracket positioning – rotation control.

10° of rotation - upper molars, 0° - lower molarsClass I Mo Relationship


Anterior teeth -rotations – bracket slightly-in the-direction rotation to-- correction.

33,43 brackets -- to the mesial - rotates the mesial aspect labially & provides better contact with the distal aspect 32,42

It is beneficial in Class I and Class II cases 14,24 brackets -1/2 mm to the mesial – buccal cusps of the upper premolars to rotate distally toward a Class I position, and the palatal cusps of these teeth to rotate mesially – occlude more accurately into the fossae of the lower arch (Fig 7).


Maintaining the Closure of All Spaces

important -spaces closed -finishing stage -figure-8 ligature wires from molars to cuspidswhen light wires - extraction

cases, during the settling stage, figure-8 ligaturewires -across

the extraction site to keep them closed (Fig 8).

areas - space closure - difficult, figure-8 ligature wires /light elastic thread -maintain space closure during settling.

Carrying out these simple procedures eliminates the troublesome problem of spaces opening in the finishing stages of treatment.


Horizontal Overcorrection Horizontal overcorrection- Class II and Class III cases. Finishing stages – important- correct the AlP position of the

dentition - Class II or Class III elastics, headgear, After correction completion, - methods of tooth-movement

can be discontinued /worn on a part-time basis. The patient - observed 6-8 weeks. Case – stable-appliances -removed. If not - cases – horizontally over-corrected. In Class II cases - anterior teeth edge to edge & held 6-8

weeks with nighttime elastics- settling can be observed (Fig 9).


Class III cases - horizontally over-corrected -producing 3 to 4 mm of additional overjet- observed - similar manner to Class II cases (Fig 10).

Over-correction techniques -carefully followed, problems – during retention.

These can be due to late aberrant growth /reestablished tongue or finger habits


Vertical Considerations Establishing Correct Crown Lengths, Marginal ridge

relationship & Contact Points Correct bracket positioning -' single most important mechanical step – orthodontist- lead to saving significant time during treatment.

Important - bracket placement- vertical bracket height- errors are 3-D (effect the torque, in-out and height of the

tooth). Mesio-distal, axial & thickness errors- one-dimensional. vertical bracket height - key to correction -vertical crown

positioning, marginal ridge relationships,and contact points. In initial leveling bracket repositioning corrected - before

placement of rectangular S.S.wires.

If - not done, -corrections -during the finishing stage - bracket repositioning or wire bending (Fig 11).


Late corrections - do not ensure stability of vertical tooth position.

It is - better for stability - relationships to be correct for one to two years before bracket removal.

Thus, correct bracket placement at an early stage is critical for stability.


Final Management of the Curve of Spee

Low angle cases. In most average to low angle -to level the entire curve of Spee. - include placement of bracketsor bands II molars to

complete theprocess (Fig 12). If curve of Spee - not fully corrected in these cases -- LI --

be positioned >gingivally on the palatal surfaceUI. Make it difficult or impossible to complete final space-closure in the upper arch & to keep spaces closed.

If the bite -opened properly &the curve of Spee – level--possible to complete space closure in the upper arch with stability.

Upper bite plate retainers - show a tendency for bite deepening during retention.

This type of relapse-- spacing in the upper arch and/or crowding in the lower arch


High angle cases -- high angle+open bite tendencies-leavesome curve of Spee in the back of the arch- particularly in the second molar area.

This allows the bite to remain closed anteriorly. If the back of the curve of Spee is leveled - > risk of opening the

bite. For patients near the end of the growth period- difficult or

impossible to close this anterior open bite. To prevent bite opening - curve of Spee - placed in the lower

archwire, and a step-up bend can be placed distal to the first molar in the upper archwire.


Vertical Over-Correction-Deep Bite and open Bite Cases

Beneficial - over-correction in deep bite and open bite cases. This process begins with initial bracket placement. Brackets - anterior teeth - 1/2 mm> gingival in open bite cases

&1/2 mm more incisal in deep bite cases.

Assists - over-correction process.

In deep bite cases- leveling of the curve of Spee - flat steel rectangular archwire – effective bite opening – II mo. included.

If bite opening-not achieved using flat rectangular steel wires,-bite opening curves can be placed (Fig 13).

Done as late as -finishing stage - normally completed earlier.


At end of treatment - deep bite cases - 1 to 2 mm of overbite.

Generally settle -3 to 4 mm of overbite.

Bite plate retainers - to prevent relapse

Adequate upper incisor torque - maintaining bite opening.

Open bite cases - to evaluate tongue position and tongue habits before -fillishing stages

Problem - observed before- finishing stage, & Myofunctional therapy initiated.

These cases will often benefit from the use of positioners -- help bite closure.

Conventional upper retainer - a small hole- the palatal surface of the acrylic for tongue positioning - to modify their tongue position or activity,by holding the tip of the tongue in the roof of palate during swallowing and other activities.

Tongue - re-assert itself, despite the best-efforts of the patient and the orthodontist - patient informed of this possibility before treatment.


Transverse Considerations

Archform and Archwire Coordination

Expansion - lower arch- canine region-instable

Lower arch -rolled in lingualy-- occurs in most palatal expansion cases & many deep bite cases ---buccal up righting in the lower arch is indicated for stability (Fig 14).

Evaluating- original cuspid position & the curve of Wilson in the lower arch is important in determining the correct lower archform.

By the finishing stage of treatment, the lower archform - accurately established in the rectangular arch form.


(Fig 14). 178178


The upper archform coordinated with the lower (Fig 15).

Minor widening of the upper wire posteriorly is

recommended for cases with a relatively narrow maxilla.

After the rectangular wire stage, settling of the case with light archwire allows for further archform adjustment and stability.


Establishing Posterior torque:-

To provide adequate buccal root torque in the upper arch, it is most important to have a wide enough maxilla.

maxilla - not wide enough- buccal cortical plate will not allow for the incorporation of the appropriate amount of buccal root torque at the completion of treatment.

Leads to palatal cusps - create interferences during lateral excursions and compromises to proper functional occlusion.

Needs - evaluated carefully the beginning of treatment. PEA- additional buccal root torque built into the upper molars-

additional upper archwire bending – needed in this area Many PEA- added additional buccal crown torque in the lower

posterior segments relative to Andrews' norms. This has minimized tendency -- lower posterior teeth to roll in

lingually.


Transverse Over-Correction

Cases that show narrowing - maxilla - adequately over-expanded and held in the expanded position for an extended period of time.

Maxilla expanded until palatal cusps of the upper arch are in contact with the buccal cusps of the lower arch in the

posterior segments.

It is helpful to expand cases 1/2 years before full orthodontic treatment & to maintain this expansion with a palatal bar.

Then stability is normally assured. If expansion is performed at the beginning of orthodontic

treatment, a palatal bar -placed after the expansion procedures.


This palatal bar can remain in position until the rectangular stainless steel wire has been placed.

This wire provides adequate stiffness to maintain the expansion that has been achieved.

Torque in the posterior brackets of the upper arch, as well as some additional buccal root torque in the archwire -- beneficial at this time, to allow the posterior segments to settle properly.


Dynamic Considerations--Establishing Centric Relation, Checking--Functional Movements and Reviewing TMJ Needs

Evaluate orthodontic cases CR at the beginning of treatment, monitor this position throughout treatment – finishing stage

Class I occlusion condyles in centric relation – checked-- interference during protrusive and lateral excursions.

If the patient has a history of clenching,TMJ sounds

or muscle dysfunction-Beneficial to provide them with a night guard type of retainer after treatment.


COrrection of Habits 70% to 80% of tongue thrusting & tongue posturing habits

will be corrected before the finishing stages of treatment. For two main reasons: 1) As the patient grows, the airway size increases and the tongue assumes a more posterior position; 2) As the dental environment is improved orthodontically, the tongue and lip musculature have the opportunity to

adapt to this improved environment & normal function can begin to occur.

Severe problems - referred to Myofunctional therapist on pt’s first examined.

Minimal to moderate problems - the habit is not under control by the time rectangular stainless steel wires are placed -referral for Myofunctional therapy is appropriate.


use of tongue spurs (Fig 16)- the patient adjusts to

them within 24 to 48 hours with little difficulty,

serve - reminder for correct tongue position.

Used in conjunction with basic Myofunctional therapy instructionswhich include:

1) Placement of the tongue in the "neutral position" on the palate, away from the incisors;

.2)Lips together& Muscle strengthening exercises, including bilateral chewing with lips together.


Cephalometric and Esthetic Considerations

Helpful - progress head films halfway through orthodontic treatment to determine how the skeletal, dental& soft tissue components are being managed.

Progress head films – reassessment

Final cephalogram 3 to 4 months before debanding, rather than after treatment.

It is better to take the head film before debonding- tooth positions - corrected if necessary.


Progress and final cephalogram –

1) soft tissue profile,

2) the antero-posterior position of the incisors torque of the incisors,

3)the changes in the mandibular plane of the patient,

4) the degree to which vertical development of the patient has occurred/ restricted, and

5) the success in correcting the horizontal, skeletal and dental components of the problem.

6)Evaluation involves superimposition of progress and final radiographs with the initial cephalometric radiograph, to accurately determine the changes that occurred.


The difficulty - significant variability in the position of cranial base structures, and this variability usually increases as the degree of facial deformityincreases.

> difficult - more unreliable these relationships become,

leaving the clinician in the position of making primarily subjective clinical judgments.

Secondly, traditional cephalometrics evaluate

-primarily dento-skeletal relationships-<emphasis on the soft tissues of the face.

Both the hard and soft tissues should be adequately evaluated cephalometrically.

In 1999, Arnett – soft tissue cephalometric analysis,"Ideal M& F norms - investigated in the study.

These norms can be used in their entirety as a supplement“ or a replacement for current cephalomeric methods.


The Final Phase of Finishing-Settling of the Case Rectangular stainless steel wires – 1)overbite control, 2)AlP correction, 3)and space closure,

- restrictive for settling of the teeth in the closing stages -treatment.

Lighter wires-- 0.014 or 0.016 round heat activated nickel titanium (RANT) wire is used in the lower arch, coordinated to the individual arch form for the patient.

Upper arch an0.014 round sectional wire can be placed from lateral incisor to lateral incisor.

These wires can be accompanied by the use of vertical triangular elastics where settling needs to occur .

The better the bracket placement, the less elastics need to be used in this way.

It is beneficial to keep all bands and brackets on the teeth during settling, so that if unwanted changes occur ,these can be corrected.

Managing the case in this manner allows teeth to individually settle into their final positionsbefore appliance removal.

Patients can be seen at approximately one to two week intervals



For more details please visit For more details please visit www.indiandentalacademy.comwww.indiandentalacademy.com

bracket selection & placement / orthodontic courses by indian dental academy

Documents