Anchorage in orthodontics- Dr Lubna Abu Alrub

Anchorage in orthodontics

Anchorage in orthodonticsDr-Lubna Mohammad Abu Al-RubSupervised by :Dr-Ahmad Al-TarawnehDr-Raed Al-RbataDr-Nancy Al-sarairah

OutlineDefinition of anchorage.Optimal force in orthodontics assessment of anchorage demandsTypes of anchorageWays to reinforce anchorageOrthodontic perscriptions and anchorageMeasuring anchorageMonitering anchorageAnchorge in 3 planes of space/clinical scenarios


AnchorageWebsters international dictionary defines anchorage as a secure hold suffiecient to resisit a heavy pull

Anchoragethe resistance to unwanted tooth movement (proffit 2000)or those sites that provide resistance to the reactive forces generated on activation of any orthodontic appliance to control unwanted tooth movement(mitchell2001)

For example, if an upper canine is being retracted, the force applied to the tooth must be resisted by an equal and opposite force in the other direction. This equal and opposite force is known as anchorage.

If an upper canine is to be retracted, with bodily movement using a fixed appliance. the force applied to the tooth will be approximately 100 g.

Forces in the opposite direction varying from 67g on the first permanent molar to 33 g on the upper second premolar.

Resist this Low levels will produce negligible tooth movement and the effect of a light force of 100 g would be to retract the canine with minimal anterior unwanted movement of the anchored teeth.

However, if the force level is increased to say 300 g.

the force levels on the anchor teeth increase dramatically to the level where unwanted tooth movements will occur loss of anchorage.

Although the canine may move a little distally, the buccal teeth will also move mesially.

Space for the canine retraction may be eliminated with insufficient space left for alignment of the anterior teeth.


Optimal force level in orthodontics

Optimal force level in orthodontics defined as a mechanical input that leads to maximum rate of tooth movement with minimal irreversible damage to the root, periodontal ligament and alveolar bone. The theory of optimum forces was proposed by Storcy and Smith in 1952.

Force threshold is defined as the minimum force to produce movements. Classically, ideal forces in orthodontic tooth movement are those that just overcome capillary blood pressure 20-25gm/cm3 as per Schwartz (1932).


Assessment of the anchorage demand

1. General factorsAgeMedical conditionMedicationIndividual variationPatient compliances

Assessment of anchorage demands2.Treatment plan factors Treatment aims: correction of molar relationship after extraction require little anchorage than correction of sever OJ or crowdingType of movement required, bodily movement require higher anchorage demand than tipping movement.Extraction pattern, the more posterior teeth extracted the more anchorage demand will be.

Assessment of anchorage demands3.Treatment mechanics factors Appliance prescription: MBT less anchorage demand than Roth and Andrews prescriptionAppliance type, tip edge appliance required less anchorage demand than andrews straight wire appliance. URA is less anchorage demanding than FA.Mechanotherapy: heavy force need more anchorage.

Assessment of anchorage demands4. Intra-arch relationshipInvolved arch: The maxillary arch is particularly susceptible to anchorage loss. This is probably due to a combination of factors: Maxillary anterior teeth are bigger and wider.The upper anterior brackets have more tipping built into than the lower anterior brackets.The upper incisors require more torque control and bodily movement than the lower incisors, which only require distal tipping or uprighling.Mandibular bone is harder than cancelous maxillary bone. So that the upper molars move mesially more easily than the lower molars.

Assessment of anchorage demandsAmount of crowding: sever crowding requires more anchorageLocation of crowding, the more distance between anchor unit from the irregular teeth to be align or retracted, the more anchorage demand.Angulation of the teeth, distally angulated canines required higher anchorage to align and retract them than upright or mesially inclined canines.Inclination of the teeth, palatally tipped upper incisor require more anchorage to retract them than proclined one

Assessment of anchorage demands5. Inter-arch relationshipAmount of OBAmount of OJAmount of centreline problemSkeletal relationship AP: camouflaging moderate to severe skeletal relationship is more anchorage demanding than mild casesSkeletal relationship vertically, high angle cases require higher anchorage demand because:

Assessment of anchorage needsinterarch relationshipBone is less dense than bone of low angle case which favour teeth movement and anchorage lossThe direction of the occlusal plane favour the mesial movement of the anchor teeth A weaker muscle fibres associated with high angle case produce less occlusal interlocking than normal.

Assessment of anchorage demands6.Occlusal interlock Some extraction patterns e.g. upper first and lower second premolars can create useful interlocking of the dentition and increase the root surface area resisting a loss of upper arch posterior anchorage.

Conversely upper canines stuck mesial to lower canines can lose upper arch anchorage as can attempted reduction of an overjet in the presence of a complete overbite


Types of anchorageIntraoralIntramaxillaryoriginating from the teeth : simple , compound , stationary , reciprocal .Originating from the soft tissuesOriginating from the boneintermaxillaryMyofunctional appliancesInetrmaxillary elastics Extraoral ; Headgear

Intraoral anchorage1.IntramaxillaryA.Originating from teeth Simple anchorage (one tooth providing anchorage to other tooth)

Compound anchorage (group of teeth providing anchorage to one tooth or smaller number of teeth.

Stationary anchorage (refers to the advantage that can be obtained by putting bodily movement of one group of teeth against tipping of another).

Intraoral anchorageDifferential anchorage: mean moving the teeth by tipping them first then upright them to reduce the stress on the anchor teeth

Differential force theoryDifferential force theory: is a combination of Stationary and Differential anchorage. The active units are allowed to tip by relying on the anchor units which are hold by the effect of their bodily reaction. Then the active units are uprighted.

Differential force theoryIt does however remain a theory which is far from fully proven, although there seems strong indirect evidence that the differential force theory has substance.This theory states that within limits, the rate of tooth movement is related to the applied force per unit root surface area. i.e. within a certain range of force, a given force will result in less tooth movement if spread over a larger number of teeth.

Reciprocal It may be that equal movement of both the active and reactive units is desirable, such as expansion or closing a midline diastema.

Types of anchorageExtraoral ; Headgear IntraoralIntramaxillaryoriginating from the teeth : simple , compound , stationary , reciprocal .Originating from the soft tissuesOriginating from the boneintermaxillaryMyofunctional appliancesInetrmaxillary elastics

Intraoral anchorageB.Originating from soft tissueLip bumperBone palatal vault like Nance and URA

Lip bumperMuscular forces lip bumper It mainly consists of a thick round stainless steel wire that fit in the headgear tube of the molar band and stays away from the labial surface of the incisor by the effect of the loop mesial to the entrance to the molar tube. The acrylic pad is embedded in the anterior part of the wire and act to actively displace the lip forward. The reciprocal force of the displaced lip will be transferred to the molars via the heavy wire and result in molar uprighting and distalisation


C. Originating from boneSkeletal or bone OA (implants/miniscrews/plates)Cortical Anchorage

Orthodontic bone anchorage devicesOrthodontic bone anchorage devise (BAD) can be defined as the use of implants, plates, screws or screw-retained devices inserted into bone to provide resistance to unwanted tooth movement (indirect anchorage) or a point from which traction can be applied (direct anchorage).Bone anchorage devices can broadly be divided into two categories:Conventional osseointegrated implants.Temporary bone anchorage devices (TADs).

Osteointegrated implantsConventional implants may provide a useful point of absolute anchorage in patients for whom an implant-born restoration is planned following pre-restorative orthodontics, or who already have an implant-born restoration in place

. Orthodontic attachments can be mounted on implants using temporary copings, to allow them to be incorporated into a fixed appliance (dman et al., 1994). Whilst it is useful to have conventional implants available for anchorage control during pre-restorative orthodontic treatment, it is important that they are in the correct position, since they cannot easily be re-sited later on. Where the implant(s) are already in situ, the teeth will have to be positioned around them, which may not always give the best result.

Temporary bone anchorage devices (TADs)

Osstiointegrated retained devises1-midpalate implants Mid-palatal implants are designed to osseointegrate, but are surgically removed following use.2- onplantsa subperiosteal titanium alloy disk, 2 mm thick and 10 mm wide, coated with hydroxyapatite.

Mechanically retained devises1-Mini-plates (Maxillofacial bone plating kits) of maxillofacial bone plates. In particular, the orthodontic versions have transmucosal necks and customised heads to facilitate their connection to fixed appliances

2-Mini-implants or mini-screw

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Cortical anchorage: Rickets technique by intentionally bringing the buccal roots of the anchor teeth into contact with the cortical plates of bone thus increasing the anchorage value of such teeth. It should be appreciated that this process should be carried out with great care and precision since overzealous torque can produce root resorption or in extreme cases cortical perforation. (Brezniak & Wasserstein, 2008)The transpalatal arch, qaudrihleix & the lingual arch. It also depends on the idea of compound-cortical anchorage by increasing the number of teeth in the anchorage system as well as cortical bone anchorage theory. However there is a risk of root resorption


Intermaxillary (from the opposing arch) likeMyofunctional applianceIntermaxillary elastic.

Functional appliancesRely on Musculature forces, It must be remembered that a reactionary mesially directed force occurs in the mandible and the reactionary distally directed force occurs in the maxilla during the use of the functional appliance. This could lead to upper teeth distalization and lower teeth mesialization

Fixed functional appliancesFixed functional appliancesThese differ from fixed forms of class 2 traction only in that the force is stored in the muscles and ligaments rather than in the elasticity of a metal spring.Types of fixed functional appliance:Herbst applianceMARA applianceSabbagh appliance with spring element locked(Fixedtwin-block)AdvanSync 2molar-to-molarappliance

Herbst appliance

MARA appliance

Fixed twin block

Fixed Functional appliancesFunctional appliances are another source of intermaxillary anchorage. Herbst ( force derived in muscles / ligaments)

Whilst some clinicians may believe these devices simply make the mandible grow, this is not the case and whatever mandibular growth does take place, is accompanied by quite substantial movement of the dentition over the apical base.

This means that mesial tipping of the lower and distal tipping of the upper teeth occurs.

Intermaxillary elastics

This relies on using the opposing arch to provide anchorage to the other arch. Care must be taken to realise that intermaxillary traction is an inefficient method of space closure and if prolonged can lead to excessive extrusion and tipping of the anchor teeth.

Intermaxillary elastics One popular example of utilizing intermaxillary elastics is closing a mandibular premolar extraction site , it would be possible to stabilize all the teeth in the maxillary arch as one group so that they could only move bodily and then run an elastic from the upper posterior to the lower anterior thus pitting forward movement of the entire upper arch against distal movement of the lower anterior segment .This can be described as stationary as well

Bear in mind that elastic force from one arch to the other tend to be intermittent whileother sources such as HG can be described as more constant.

Types of anchorageIntraoralIntramaxillaryoriginating from the teeth : simple , compound , stationary , reciprocal .Originating from the soft tissuesOriginating from the boneintermaxillaryMyofunctional appliancesInetrmaxillary elastics Extraoral ; Headgear

Methods to reinforce anchorage4. Extraoral orthodontic anchorage support : Example HG or PHG which get its support from a very stable skeletal structure outside the mouth like cranium, occipital area and the chin.

Extraoral anchorageHeadgearThe force from the headgear is usually applied to the teeth via a face-bow (Klen bow)

This is fitted either to tubes attached to the appliance or integral with it as in the en masse appliance. The direction by which the force is applied can be varied depending on the type of headgear that is fitted.

Cervical headgearThis is applied via an elastic strap or spring, which runs around the neck .

It has the advantage of being relatively unobtrusive and easy to fit. However, it does tend to extrude the upper molars and tip them distally because of the downward and backward direction of force.

This later effect can be counteracted to some degree by adjusting the height and length of the outer bow. Cervical headgear should not be attached to removable appliances because it is prone to dislodge the appliance and propel it to the back of the mouth.

Cervical headgear

Occipital headgearThis is also known as high pull headgear and is applied via an occipitally placed head-cap. It is easy to fit but is more obvious than the neck strap and tends to roll off the head unless carefully adjusted. Because the force is in a more upward direction, there is generally less distal tipping of the upper molar and less extrusion, but also less distal movement than with cervical headgear. The tipping and extrusion effect again depend on the length and height of the outer bow.

Occipital headgear

Combination (variable) pull headgearThis applies a force part way between cervical and occipital.

It takes slightly longer to fit than either cervical or occipital and is more obtrusive.

However it is secure and comfortable and the vector of the force can be varied to produce relatively less tipping and/or extrusion.

Combination pull headgear

Reverse pull headgearReverse or protraction headgear is useful for mesial movement of the teeth. either to close spaces or help to correct a reverse overjet. It does not employ a face-bow, which is an advantagebut instead employs intra-oral hooks to which elastics are applied.

Reverse pull headgear

Force level

No well designed studies investigating the effects of differing force levels.Force is inherently intermittent, so level probably less important than direction.Anchorage : 200-250 gm /side for 10-12 hourDental : 400-500 gm/side for 16 hours + assisting device.Orthopedic : 500-900 gm/side for 12-14 hours

Hours of wearIf headgear is prescribed, we would favour using it only in bed at nights and this has shown to increase the patients cooperation with wearing headgear.

Molars distalisation /assissting headgearMagnets (Gianelly 1989)Coilspring distalisers eg Gianelly 1998Pendulum appliance (Hilgers 1992)Nudger (Cetlin & Ten Hoeve 1983)

These devices incur a high level of anchorage loss (OJ)

Must be supported with HG or class II

Some (eg Nudger) may cause excessive molar tippingNudger very useful in selected cases

TADs or HG. Junqing in 2008 showed again a better result by TADs in comparison with HG.


Methods to reinforce anchorageThe extent to which anchorage should be reinforced by adding teeth to the anchor unit depends on the tooth movement to be achieved For significant differential tooth movement , the ratio of the PDL area of the anchor unit to the PDL area in the tooth movement unit should be at least 2 to 1 without sliding and 4 to 1 with sliding , anything less produce something close to reciprocal movement especially if force level is not well controlled.

Methods to reinforce anchorageCompound anchorage: Include more teeth in the anchor unit. In other words , subdivision of the desired movement rather than dividing the arch into more or less equal segments

Methods to reinforce anchorageTipping and uprighting (Differential force theory): In the TipEdge or Begg principle the upper anterior teeth are allowed to tip distally using the force of the intermaxillary class II elastic, but the molar is prevented from moving forward by a tipback bend. Additionally, the tipback bend helps to overcome the vertical extrusive effect of the elastic on the anterior teeth. However, it is not clear whether tipping and subsequently uprighting a tooth consumes less anchorage than achieving the same result with bodily movement. More recently, a good study by Shpack , found that bodily retraction of a canine consumes the same anchorage as tipping followed by uprighting and incidentally, bodily retraction was more rapid by an average of 38 days.

Methods to reinforce anchorageTipping and uprightening (diffrential force theory)In our familiar extraction site example this would again require two steps in treatment , first the anterior teeth would be tipped distally bybeing pitted against mesial bodily movement of posterior segments .Allowing the teeth to tip as they slide along the arch wire keeps the cntact angle between the wire and the brackets small , this reduces binding and and keeps resistance t sliding small.

Methods to reinforce anchorage4.Palatal vault: Example URA & Nance appliance which relies on the bone and soft tissue anchorageContact between the appliance and the labial or lingual mucosa can increase anchorage considerably for either fixed or removable appliances.

Contact between an orthodontic appliance and the vault of the palate provides resistance to mesial movement of the posterior teeth

Methods to reinforce anchorageThe anchorage provided by this means is considerably greater if there is a high vaulted palate, which will produce a greater buttressing effect.

Methods to reinforce anchorageA shallow vaulted palate will provide much less anchorage control because the appliance will simply tend to slide down the inclined plane of the palate

Methods to reinforce anchorageThe mucosa and underlying bone can also be used when fixed appliances are used.

For example a Nance palatal arch. This is an acrylic button that lies on the most vertical part of the palate behind the upper incisors and is added to a trans-palatal arch.

Methods to reinforce anchorageThese buttons are again of more limited use if the palatal vault is shallow.

Use of TPA as an achorage aid Transverse anchorageAnterior posterior anchorageVertical anchorage

Transverse anchorageTPAs can be used to improve arch width stability when aligning palatally impacted maxillary canine (Fleming, Sharma et al. 2010)

Transverse anchorage

In cleft palate, TPA has its application to maintain the form of the expanded arch just before alveolar bone grafting. (Harris and Reynolds 1991) TPAs have been claimed to provide horiantal anchorage of 1 mm per yeer ( rot 1986 ) however there have been doubts in this context and they are no longer used for this purposes.


For almost the same application, TPAs act as a retainer after RME after surgical expansion of the palate in order to hold the osteotomies part together during healing period. (Harris and Reynolds 1991).

TPA -Transverse anchorage

As an adjunct to headgear (HG), TPAs are used to reduce buccal tipping of the molar and palatal cusp hanging the molar distalization. (Baldini and Luder 1982) However, a study by Wise et al. showed no difference between the use of HG with or without a TPA during molar distalization


TPAs are used to counteract the buccal tipping of the crown of the molars during intrusion of the anterior teeth using Segmented Burstone Arch Wires mechanics. (Burstone 1966

TPA Transverse anchorage

Lastly, TPAs were used with palatally or buccally placed TAD to control molar tipping when posterior teeth are intruded to treat anterior open bites. (Cousley 2010)

TPA use an anchorage aidVertical anchorage It had been showed that placing the TPA 4mm away from the palate might introduce some intrusive effect by the tongue on the molars which can help in correcting or controlling the over eruption of maxillary molars

Vertical anchorage of upper molars by placing the bar 5-6 mm away from palatal mucosa with a large and mesially facing loop is said by cetline to prevent molars extrusion and probably cause intrusion .

TPA use as an anchorage aidAnterior posterior anchorageNance appliance can be used to provide anchorage to distalize the molars such as the Pendulum Appliance, rapid molar distalization (REF); the distal jet, Jones Jig and the Lokar Distalising Appliance .In the same field, TPA can be used to maintain molar position after distalization.(Prakash, Tandur et al. 2011) again TPA can be used to provide anchorage during fixed appliance treatment through bringing the roots of the upper molars in contact with cortical bone (Cortical anchorage).However, there are many studies that compare the effectiveness of the TPA with other methods., McNamara concluded that the mean anchor loss of 4.1 mm was seen in association with the TPA and 4.5 mm in control group.

Ways to reinforce anchorage5. Natural anchorage. Ankylosed teeth possess no periodontal membrane and as such are not subject to the normal physiologic response to forces placed on the tooth and movement will be absolutely resisted.


Perscriptions and anchorageStandard edgewise less anchorage demanding.Andres straight wire appliance comparing to standard edgewise. Johnston et al (1988) reported that the use of the SWA cost 0.8mm more anchorage (measured by the Pitchfork method) in the maxilla when compared with Standard Edgewise treatment. However, this may be explained by the fact that a preadjusted appliance makes it less likely that a clinician will finish a case with inadequately torqued upper incisors, and the slightly higher anchorage requirement with the SWA therefore reflects the achievement of more anchorage demanding occlusal goals.

Perscriptions and anchorageRoth incisors are more OA demandingAndrews canines are less OA demanding

Perscriptions and anchorageMBT less OA demand than Roth and Andrews system because:The wagon wheel effect: because increasing the incisor torque will cause the mesial tip of ULS to reduce and this will reduce the anchorage demandsReduced canine, premolar and molar tip compared to RothIncreased molar root torque buccally, increase anchorage by cortical bone theoryReduce upper molar mesial tip reduced the OA demandUpper molar 10 degree offset, counteract the unwanted rotational movement during space closure in the upper arch and this might strengthen the anchorage

Perscriptions and anchorageTip-Edge is less anchorage demanding than SW because of the relying on the tip-uprighting principle.


Measuring anchorage1.Cephalometric using LLS position in relation to N-Pog or NB or MP This is probably the most common method in clinical practice. A more labial position of the lower incisors at the end of tooth movement is conventionally considered to represent an overall loss of posterior anchorage, although of course such a change can be an entirely deliberate treatment aim. Similarly, except in the treatment of bimaxillary proclination or in some class 3 cases, a more posterior position of lower incisors following treatment is considered to be unused intraoral posterior anchorage.

Measuring anchorage LLS positionCephalometric measures such as Lower incisor toNasion-Pogonion,or Lower incisor inclination to mandibular plane are used to assess this aspect of anchorage consumption/loss. The reference structures being used are theNasion-Pogonionplane or the mandibular plane or - in the Steiner analysis - the lineNasion-Bpoint. This is a simple and very useful tool, but does have its limitations. In particular, it gives no information about the quantity and sources of anchorage provided to move teeth distally, only about the anchorage consumed.

Measuring anchorage

2. pitchfork analysisThis is a very well known form of superimposition on bony structures, described and popularised byLysle Johnston (1985,1996).This reference structure is essentially the maxilla and zygoma. Johnston developed a comprehensive set of measures relative to a mean functional occlusal plane, which provide a measure of anteroposterior movement of upper and lower incisors and molars and the contributions of mandibular and maxillary growth. Whilst still not providing full quantification of the anchorage work done (no measurement of changes in incisor inclination or canine

Superimposition technique of stable cranial structures

Measuring anchorage3.Intraoral photograph 4.Study models by superimposing on the rugae area (Sandler 2014)Over many years, there have been investigations of the suitability of the palatal rugae for superimposition of changes in maxillary teeth. There has been a recent resurgence of interest in this method, prompted by the developments in digital imaging which assist the recording, enhancing and measuring of the upper study models.Hoggan and Sadowsky (2001)reviewed some of the previous papers and carried out a study which concluded that palatal rugae landmarks are as reliable as cephalometric structures for superimposition. However, it should be noted that the standard deviation of repeated measurements was 0.8 mm or more for several of the measures. This would mean that a real difference of 1.6 mm is unlikely to be shown to be statistically significant. Indeed in the study, a difference of 1 mm between the cephalometric and study model measurements of the same parameter was not statistically significant. Of course, this also reflects on the relative unreliability of cephalometric measures of molar position.Ashmore et al (2002)have utilised different digitising techniques to measure molar movement in the vertical and anteroposterior directions and concluded that superimposition on the palatal rugae was sufficiently reliable to pursue as a method.

There is no ideal method of measuring anchorage loss and anchorage achieved, but cephalometrics provides information of great value for both scientific and clinical purposes. The use of palatal rugae needs further investigation, but with newer digital techniques and the advantage of good identification of tooth landmarks, it may prove to have a useful place.

5.Direct Clinical assessment especially if one arch is left as a base line


Monitering anchorageDuring treatment, the occlusion in centric relation should be monitored:OverjetMolar relationshipCanine relationshipResidual space

These measurements are used to assess how treatment is progressing, and what anchorage control measures are required

Can be divided into anchorage control methods during the first and second phases of treatment.

First phase: aligning and levelling Second phase: OB, OJ, space closure

Further subdivided into intra-oral and extra-oral sources of anchorage

First phase intra-oralTube / bracket selection:

MBT has less canine tip (8) than Roth (13) so is less anchorage demandingMBT and Roth molars provide more anchorage than Andrews

Lacebacks prevent mesial movement of canine crowns as tip corrects (note RCTs Usmani et al 2002, Irvine et al 2004)

Choice of extractions

First phase intra-oral (reinforcement)Palatal / lingual arches. TPA good at maintaining arch width . Nance better for anchorage support (shape of palatal vault is relevant). LLA, if used for anchorage support, risks proclination of the LLS

Band 2nd molars if possible

Anterior bite planes in deep bite cases good overbite reduction at virtually no cost to anchorage CIII elastics at night, supported by headgear to upper 6s, can be used in non-extraction cases, or maximum lower arch anchorage cases.

Second phase intra-oralBand selection: Roth and MBT provide more posterior anchorage for OJ reduction. However, high torque in Roth & MBT incisors are more demandingConstancy of archform.

Selective application of torque (eg lingual crown torque in LLS reduces anchorage demand

Choice of extractions (anchorage balance; occlusal lock)

Second phase intra-oral (reinforcement)Band maxillary second molars.

Intermaxillary elastics class II or III

Combination of class II elastics during the day, and EOT at night can be used to allow a 24-hour effect on the upper arch while limiting the demand on lower arch anchorage.

Nance and lingual arches need to be removed at this stage (standard TPAs may be left in place for part of this phase)

Second phase extra-oralHeadgear (Kloehn bow or J-hooks)

J-hook headgear to lower arch for retraction of lower canines and incisors in Class III cases. NB Light forces to avoid TMJ problems

Facemask (DeLaire) for molar protraction


Clinical scenariosanchorage in 3 planes of space Vertical anchorageLateral anchorageAnteriorposterior anchorage

Vertical anchorageLevel the curve of speeBoth posteior extrusion and anterior intrusion occure when levelling the curve of spee , to increase anterior intrusion for exmaple , banding of second molars is advised to increase the anchorage vlue of posterior segment

Vertical anchorageTreatment of anterior open bite The best example is utulized in the kim mechanics , which relies on anterior box elastics to counteract the effect of reverse curve of spee wire to intrude the molars Can be considered a kind of intermaxillary compound anchorage .

Lateral anchorageHorizantal anchorage in expansion cases Usually there is equivilant group of teeth on both sides to expand , occasionally both sides of the arch are assymetric in number of teeth in crossbite , one solution to this is to include a greater number of teeth on the anchore unit than in the unit in which maximum tooth movement is needed.

Lateral anchorageTraction of palatally ectopic canineThis is highly anchorage demanding , usually traction is applied once the arch form is stabilised by a heavy stanless steel wire or two molars are stabilizd by a transplatal arch

However, in some situations loss of anchorage can be used to advantage. for example, in a Class Ill malocclusion an increase in overjet can be advantageous. Therefore anchorage requirements need to be assessed at the time of treatment planning.

ReferencesContemporary orthodontics , william R.Proffit , 5th edition.Bristol notesExcellence in orthodontics, David Birnie , 2012.Fundementals of orthodontic treatment mechanics , Bennet and maclaughlin 2014 .British dental journal , Part 9: Anchorage control and distal movement ,D. Roberts-Harry1 and J. Sandy2

Thank you !

Anchorage in orthodontics- Dr Lubna Abu Alrub

Health & Medicine

Transcript of Anchorage in orthodontics- Dr Lubna Abu Alrub