anchorage final- lec

8/3/2019 Anchorage Final- Lec

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In simple terms anchorage in orthodonticsis defined as resistance to unwanted toothmovement.

Angle stated that there were many means forobtaining anchorage, including the tooth themselvesand sources external to the teeth. He classified

anchorage as simple , stationary, reciprocal, intermaxillary and occipital.


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Given Angles insistence on expansion of archesrather than extraction to deal with crowdingproblems, it is ironic that his edgewise appliancefinally provided the control for root positionnecessary for successful extraction treatment.

One of Angles last student, Charles Tweed,adapted the edgewise appliance for extractiontreatment. Tweed placed tip back bends in the

lower arch to vary the amount of distoaxialinclination of the lower posterior teeth. Theamount of distal tip varied depending on theseverity of malocclusion.


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When anchorage preparation as advocated byTweed was used with standard edgewise appliance thetip, torque and offset bends had to be placed in eachedgewise arch. The bends were then duplicated orincreased in the successive arches as the caseprogressed.

Reed Holdaway in 1952 described pre-angulation of the edgewise appliance in mandibularbuccal segments as a method of setting up posterior

anchorage units into tipped back or anchorageprepared positions.


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Graber: defines anchorage as the nature and degreeof resistance to displacement offered by an anatomicalunit when used for purpose of effecting tooth movement.

Bennett and McLaughlin: emphasized the need toconsider anchorage in all the three planes of space i.e.,horizontal, vertical and lateral (transverse).

White & Gardiner:it is the site of delivery fromwhich a force is exerted.


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Horizontally anchorage control means limitingthe mesial movement of the posterior segmentwhile encouraging the distal movement of anterior

segment.

Vertically, anchorage control involves thelimitation of vertical skeletal and dentaldevelopment in the posterior segment andlimitation or vertical eruption of, or even intrusionof anterior segments.

In transverse plane It comprises of themaintenance of expansion procedures, primarily inupper arch, and the avoidance of tipping or

extrusion of posterior teeth during expansion.


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Sources of Anchorage:(i)extra-oral(ii)intra-oral

Extra-oral anchorage is the anchorage in which oneof the anchorage unit is situated outside the oralcavity . Extra-oral anchorage can be furtherclassified as :

Cervical Cranial

o Occipitalo parietal

Facial eg. Delaire FacemaskIntra-oral anchorage : It is the anchorage in

which the resistance units are all situatedwithin the oral cavity e.g., teeth, palate,

muscular forces, inclined planes of teeth.


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Classification of anchorage: Acc to Moyers

(i)Dep. On manner of force application:

Simple

Stationary

Reciprocal

(ii)Dep. On jaws involved:

Intermaxillary

Intramaxillary


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(iii) Dep. on site of anchorage:

Intra oralExtra oralMuscular

(iv) Dep. on no. of anchor units:

Single / primaryCompoundMultiple/ reinforced


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1.Natural anchorageIt comes from any resistance afforded within the arch

according to the application of forces between any given teeth

or group of teeth.Simple Anchorage : Dental anchorage in which the manner and application of force

tends to displace or change axial inclination of the tooth or teeth

that form the anchorage unit in the plane of space in which theforce is being applied.

In other words resistance of anchorage unit to tipping is utilizedto move another tooth or teeth.

Compound Anchorage : Here anchorage is provided by more than one tooth with

greater support is used to move teeth with lesser support.


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Reciprocal / Multiple anchorage :It involves pitting of two teeth

or two groups of teeth of equal

anchorage value against each otherto produce reciprocal toothmovement. Eg: closing of diastemas: twocentral incisors are pitted against eachother.


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Stationary Anchorage :Dental anchorage in which the manner

and application of force tend to displace theanchorage unit bodily in the plane of space inwhich the force is being applied is termedstationary anchorage (Graber).


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2. Reinforced Anchorage :

It involves reinforcing theanchorage or resistance area

either by adding more resistanceunits or by the use of variousadjuncts.

A simple way of reinforcinganchorage is to band the secondmolars. Various other ways

include, the use of T.P.A., Nanceholding arch, lower lingual arch. Tissue anchorage such asobtained by lip bumper can be

efficiently used to distalize molars.


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This is obtained byvarious meansnamely:

1.Extra oral force toaugment anchorage

2.Upper anteriorinclined plane &SVED APPLIANCE

3.Trans palatal arch


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3. Prepared AnchoragePrepared anchorage pre sets the teeth into

disto-axial inclination, greatly increasing theirresistance to displacement. This method is veryeffective for controlling anchorage, especiallywhen anchorage is critical.

4. Active root thrust :This concept was put forward by Dr. Calvin

Case in 1908. It involves building bodilyresistance into the anchor area through the use ofextensions fixed to the bands of the molar teeth.


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Cortical anchorage : The cortical bone is more resistant to resorption

than the medullary bone. The cortical anchorageconcept makes use of this. Ricketts advocated torquing the rootsof buccalteeth outwards against the cortical plate as a way toinhibit their mesial movement. Torquing movements are limited by facial andlingual cortical plates. If a root is persistently forced

against the cortical plate, tooth movement is greatlyslowed, root resorption is likely and eventual penetrationof cortical bone may sometimes occur.


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Graberhas classified anchorage as intramaxillaryanchorageandintermaxillary anchorage.

1. Intramaxillary anchorage is the anchorage iswhich the resistance units are all situated with in thesame jaw. If appliances are placed only in maxillaryor mandibular arch they are considered, intra maxillary

resistance units.

2. Intermaxillary anchorage is anchorage in whichthe units situated in one jaw are used to effect toothmovement in the other jaw. Also called BAKERS

anchorage.


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SELECTION OF ANCHORAGE:

Since anchorage must be selected to make

proper use of the space created by extraction, amore rational approach of classifying anchoragewould be the one which guides the operator tomake use of the available space.

Accordingly anchorage in mandibular archcan be put into three classes:DEPENDING ON ANCHOR LOSS EXPECTED:

minimum,moderate andmaximum anchorage.


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Minimum anchorage mechanics involvedreciprocal forces between posterior teeth and anteriorteeth with no effort to maintain a moment on theanchor area.

Minimum anchorage mechanics are selectedwhen the mandibular posterior teeth may be permitted

to migrate mesially into half or more of the extractionsite.


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Moderate anchorage mechanics involve placingan active root thrust or movement on the anchor teeth,causing bodily resistance in this area.

Moderate anchorage mechanics are selectedwhen the mandibular posterior teeth may be permittedto move forward into one fourth to one half of theextraction site.


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Maximum anchorage mechanics involvereinforcing the anchor teeth with all means availableand reducing the workload required of the anchor areaby developing forces outside the mandibular arch foras much of the desired tooth movement possible.

Maxillary anchorage mechanics are selected

when the mandibular posterior teeth may be permittedto move forward into no more than one fourth of theextraction site.


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We have a wide array of appliances

available to gain and preserve anchorage in allthe three dimensions of space. These adjunctsavailable are broadly classified into:

extraoral and

intra-oral appliances


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The extra oral appliances: Various Headgearassemblies,or retractors as some author prefers to callthem, essentially constitute this group. Moyers adds

the face mask to this group.

The intra oral adjuncts can be grouped according tothe plane of space in which they act. The transpalatalarch acts in all the three dimensions. Whereas lacebacks, Nance/lingual holding arches, lip bumper act inanteroposterior direction.

Head gear and face mask give adequate control invertical plane. Where as T.P.A. and quad helix help topreserve the expansion in transverse plane.

HEAD GEAR


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HEAD GEARHead gears are classified according to the point of origin of force:

Cervical Anchorage obtained from nape of the neckOccipital /Straight pull anchorage obtained from back of

the head. The line of traction is parallel to occlusal plane.Parietal /High pull Anchorage obtained from upper part ofthe head and always above the center of resistance of tooth.Combi pull The line of traction is between high pull and

straight pull.Another variable in the headgear is the outer bow

of the facebow:

The outer bow can belong, medium or short.

FORCE AND DURATION OF WEAR


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FORCE AND DURATION OF WEAR :Most of the authors agree that the amount of forceapplied to maxilla by the headgear should be between

400 800 gm(Graber, King, Blucher, Moore, Rickets,Wieslander, Sodensky, Ringberg, Borton, Pfieffer andGroberty ).Light continuous forces seem to produce more dental

changes than skeletal . Whereas heavy force andintermittent wear is found to produce more skeletalchange.According to Marcotte force values of 200 gms per side

in mixed dentition and 500 gms per side in permanentdentition for 18-20 hrs / day suggested.Graber advocates force application of more than 400gms for 10-12 hrs / day.


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FACE MASK: It is an extra oral

anchorage source. It derives anchorage from

facial bones. Sites of anchorage:

1.From skull2.From chin3.From skull & chin

Force applied: approx. 1pound (450 gms) per side.


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TRANSPALATAL ARCHTranspalatal arch is a secondary

method of anchorage support inupper posterior segment.It is made by 0.045 or 0.051 stainless steel round wirewhen it is soldered to the molar bands with loop placed

in the middle of palate so that wire is placed 2 mm fromthe roof of palate.If the TPA is placed 6-8 mm down from palate it caninduce molar intrusion due to tongue pressure. It can be

used to expand maxillary molar width as well as stabilizeagainst occipital pull head gear. After crossbitecorrection, it will maintain molar position againstundesirable side effects of utility arches used in the

maxillary arch.

NANCE AND LINGUAL HOLDING ARCHES


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NANCE AND LINGUAL HOLDING ARCHESThe nance holding arch extends from maxillary molarsto anterior portions of the palatal vault. It is a fixed

appliance. An acrylic button, but half inch or less indiameter, is attached to the palate. This button mustcreate light seal with the palate to prevent the creation offood trap.

It is important to position the acrylic button against the

vertical component of the palatal vault.The stabilizing lingual arch for the lower lie behind andbelow the lower incisors, so that it doesnot interfere withtheir retraction. The lower lingual arch is conveniently

inserted from distal than from the mesial of molar tube.

LIP BUMPER


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LIP BUMPER

Lip bumper has been used for molaranchorage, prevention of poor lip habits

and creation of increased space formandibular arch.The appliance hasstainless steel wire of 0.045 that spansthe facial surface of mandibular arch

without contacting teeth and is insertedinto tubes attached to the mandibularmolars. Anteriorly the wire is coveredwith plastic tubing or a shield made of

acrylic that holds the lower lip away fromthe mandibular incisors. Forces frommentalis muscle are transmitted tomandibular molars, enabling them tomove to an u ri ht and distal osition.


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BAKERS ANCHORAGE:

It is a type of intermaxillary anchorage.Class II traction applied between the lowermolars and upper anteriors as well as Class III

traction applied between upper molars and loweranteriors are referred to as BAKERS

ANCHORAGE.


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ANCHORAGE PLANNING:

It is of utmost importance in the success of

orthodontic treatment. Therefore it is very muchessential to carefully assess the anchoragedemands of the individual case and select the mostappropriate treatment plan.

It depends on the following factors:

1.NUMBER OF TEETH TO BE MOVED:

2.TYPE OF TEETH BEING MOVED

3.TYPE OF TOOTH MOVEMENT

4.DURATION OF THE TREATMENT


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CONCLUSIONAs orthodontic treatment continues to change and

improve, innovative techniques may find acceptance in

certain types of cases. Magnetic forces or electricstimulation may possibly show the path to an improvedmechanotherapy. But by and large, the basic concept ofarchwires placed in brackets to move teeth will remain

the most efficient method.Fundamental principles of anchorage laid down by

Tweed have remained unchanged and will continue to

remain so. The list of adjuncts available may increase.The objective in selection of treatment mechanics is tohave a bag a tricks that is large enough to treat most of

the conditions, but not so large as to be unmanagable to

incorporate into ones practice routine.


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anchorage final- lec

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