Techniques for anchorage control in lingual orthodontics

By – Dr. parag S. Deshmukh

Seminars in Orthodontics, Vol 12, No 3 (September), 2006: pp 167-177

Contents:

• Introduction to anchorage.

• Anchorage in labial orthodontics.

• Introduction to lingual anchorage technique.

• Various techniques for anchorage conservation in lingual orthodontics.

• Main article.

• Case report.

• Conclusion.

• Refrences.

Introduction:

ANCHORAGE

• Louis Ottofy(1923) – Base against which orthodontic force or reaction oforthodontic force is applied.

• According to White and Gardiner anchorage is the site of delivery fromwhich the force is exerted.

• Graber defined anchorage as the nature & degree of resistance todisplacement offered by an anatomic unit for the purpose of affecting toothmovement.

• According to Proffit it is resistance to unwanted tooth movement

• Nanda has define anchorage as – ‘The amount of movement of posterior teeth to close the extraction space in order to achieve selected treatment goals.’

All orthodontic applicants said to have 2 components namely the active component & the resistance component.

Active component is responsible for generating theforce.

Resistance component is responsible for providing the resistance to make this force effective.

There are anatomical units or regions which are

used for the purpose of providing the resistance to

movement i.e. anchorage.

• Further divided into 2 groups depending upon their

location.

1) Intraoral sources of anchorage. Anchorage units lie within oral cavity Alveolar Bone

Teeth

Basal Bone

Cortical Bone

Musculature

SOURCE OF ANCHORAGE

Extra oral sources –

• Can be utilized as sources of anchorage to bring about orthodontic or orthopaedic changes.

• Used when adequate resistance cannot be obtained from intra-oral sources for the purpose of anchorage.

• Include cranium, back of the neck & facial bones.

According to manner of force application :

a. Simple anchorage -

• Dental unit is utilized as anchor unit or

source of resistance without tipping

control.

• The resistance of anchorage unit to

tipping is needed to move another tooth

or teeth.

• Resistance offered by an anchorage unit

is greater than that offered by reactive

units that are being moved

b. Stationary anchorage -

• Dental anchorage in which anchor

units are not permitted to tip

• The displacement of the anchor

unit caused by the force if at all has

to occur, results in bodily

movement of anchor unit.

c. Reciprocal anchorage –

• Here two teeth or two groups of teeth of equal anchorage value are used against each other.

• Closure of midline diastema, use of crossbiteelastics

INTRAMAXILLARY ANCHORAGE

• All resistance unit are situated in the same jaw

• Teeth to be moved and anchorage are all situated either

entirely in the maxillary or mandibular arches.

INTER MAXILLARY ANCHORAGE

• Resistance unit are situated in one jaw and tooth/ teeth to be

moved are situated in the opposing jaw.

• Class II elastic traction applied between the lower molar and

upper anteriors

• Class III elastic traction applied between the upper molars and

the lower anteriors.

According to number of anchorage units:

a. Single or primary anchorage:

• Single tooth as a resistance unit.

b. Compound anchorage:

• Anchor unit is formed by more than one tooth.

c. Reinforced or multiple anchorage:

• More than one type of resistance unit is utilized.

According to Marcotte and Burstone: • Depending on how much of the anchorage unit contributes to

space closure.

13

•The anchorage value of the posterior teeth in the anterior-posterior and vertical directions appear to be higher in lingual orthodontics than in labial orthodontics (Takemoto, unpublished data, 1997).

• In a randomized study of 44 adult Class II, division 1 malocclusions or bimaxillary protrusion malocclusions, the anchorage value was significantly higher in lingually treated case than in those treated with labial techniques.

Differences in Anchorage Value: Lingual versus Labial Orthodontics -

Labial Orthodontics Lingual

Orthodontics24 cases: 20 cases:

2-extraction of teeth 14,24 (4–4) 3-extraction of teeth 14,24 (4–4)

15-extraction of teeth 14,24,34,44 10-extraction of teeth 14,24,34,44

7-extraction of teeth 14,24,35,45 7-extraction of teeth 14,24,35,45

Treated with straight wire appliance Treated by en masse retraction

Canine retraction with sliding mechanics Retraction with loop mechanics

Anterior segment retraction with loop

Mostly with T -loop mechanics

• Rickets cephalometric analysis was used to determine the amount of retraction of the

upper and lower incisors, the amount of intrusion, and the value of anchorage loss of

upper and lower first molars.

Pretreatment (green) and posttreatment (yellow)

superimposition of maxilla on palatal plane at point ANS

and of the mandible on the mandibular plane at point

menton:

Incisors and first molars horizontal changes measured at the

incisal edges and the distal end of first molars.

Pretreatment (green) and posttreatment (yellow)

superimposition of maxilla on palatal plane at point ANS

and of the mandible on the mandibular plane at point

menton:

Incisor vertical changes measured at the center of resistance.

Results - upper Results - lower

Statistical values shows that in upper arch the

anchorage value of the first molar, and the anterior

retraction and intrusion were significantly greater in the

lingual group as compared to the labial group. Headgear

and Class II elastics were used for shorter period of

time in the lingual group.

Statistical values shows that in lower arch the

anchorage value of the first molar, and the anterior

retraction and intrusion were significantly greater in

the lingual group as compared to the labial group.

Class II elastics were used for shorter period of time in

the lingual group (both in first and second premolar

extraction) than in the labial group.

17

ANCHORAGE

Anchorage

Anteroposterior Vertical

Horizontal anchorage:

• Vectors of orthodontic forces applied to

anterior teeth with a lingual appliance are

directed lingually to the center of rotation of

each tooth, providing anterior teeth with a

lingual crown torque. As a result, distally

uprighting forces are applied to posterior

teeth through the archwire, which makes

posterior teeth more resistant to anchorage

loss.

• Posterior anchorage is lost as posterior teeth rotate

mesially.

• Distally rotating forces are constantly applied to

molars during en masse retraction and through the

use of headgear, thus providing a greater amount

of molar anchorage than in labial orthodontics.

Vertical Anchorage:

• With brackets placed on lingual surfaces, it is easier to control lingual cusps

through the constant application of buccal root torque (vertical anchorage)

which tips molars lingually.

• In the upper arch, the vertical height of lingual cusps, which are functional

cusps, can be maintained without extrusion through the application of

intrusive forces.

• This is particularly helpful in controlling the lingual cusps of the upper second

molars, which are most likely to cause interference.

• Also an intrusive force is applied to the functional or lingual cusps of upper

molars because appliance is placed near these cusps.

• Therefore, the CO-CR discrepancy caused by the primarily initial contact and

the mandibular clockwise rotation caused by the elongation of molars are

reduced

Mechanics Used to Control Anchorage in the Upper Arch:

• Mechanical advantages gained from lingual treatment are buccal root torque and

distal rotation of the molars, especially due to the easily established cortical bone

anchorage.

Applied intrusion force to the upper

molars resulting in cortical bone

anchorage.

Distal rotation can be easily established with

the posterior teeth by retraction forces.

MAXIMUM ANCHORAGE (UPPER ARCH):

• Helical loop and T-Loop mechanics (.017 X .025 TMA) are combined with

a transpalatal arch and a buccal sectional arch from first to second upper

molars for stabilization. Also, high-pull headgear and Class II elastics are

used

Anchorage preparation for a maximum

anchorage case with helical loop

mechanics in the upper arch, using a .017

X .025 TMA with a transpalatal arch

are also used.

Anchorage preparation for a maximum

anchorage case with T-loop mechanics in

the upper arch.

MODERATE ANCHORAGE (UPPER ARCH)

• L-Loop mechanics are combined with a transpalatal arch to prevent a

transverse bowing effect. The anterior segment and the posterior segment

are "figure eighted“ with ligature wire.

• When a transpalatal arch is not used,

sliding mechanics are used by placing a

power chain from the lingual of the canine

to the lingual of the second premolar in

first premolar extraction cases.

• The sliding mechanics are used with a .016

X .022 stainless steel archwire. If the

transverse bowing occurs, a power chain

can be used from the lingual of the canine

to the buccal of the first molar to rotate the

first molars mesially.

MINIMUM ANCHORAGE (UPPER ARCH)

• Extraction spaces are closed by a

reciprocal elastic force, with a

power chain placed on both the

buccal and lingual of the canine

and first molar.

• The anterior segment is "figure-

eighted" with ligature wire.

• Frequently, cases requiring

minimum anchorage control are

those in which second premolars

have been extracted and mesial

molar movement is encouraged.

• Sometimes Class III elastics are

used to enhance mesial

movement of the molars.

Mechanics Used to Control Anchorage in

the Lower Arch

• The anchorage value of the lower arch is higher than that of the

upper arch because the mandible has a thicker cortical layer and

thinner cancellous layer of bone.

• Because of this difference in anchorage value, a buccal sectional

arch is usually placed on the posterior teeth to control the

functional or buccal cusp.

• Sliding mechanics using a .016 X .022 stainless steel archwire are

used most frequently for space closure.

• Sliding mechanics minimize the bowing effect and avoid tongue

irritation from loops.

• When sliding mechanics are not the optimum choice for space

closure, loop mechanics may be used.

• This includes Class III malocclusions treated nonsurgically,

where dental compensations by tipping the anteriors lingually

may be needed, when the right and left extraction spaces are not

symmetric, or when the space closure cannot be accomplished

with sliding mechanics because of root contact with the cortical

bone.

• In these cases, the lower six anterior teeth are tipped lingually

with loop mechanics.

MAXIMUM ANCHORAGE (LOWER ARCH)

• An elastic power chain is used

on the lingual, with a buccal

sectional arch for stabilization

(.017 X .025 TMA or .016 X

.022 SS).

• The anterior segment and the

posterior segment is "figure-

eighted" with ligature wire.

• Class III elastics are used both

buccally and lingually for

reinforced anchorage.

MODERATE ANCHORAGE (LOWER ARCH)

• Sliding mechanics are used with

reciprocal elastic forces (power

chains from 3-5 on both sides).

• The anterior segment and the

posterior segment are "figure-

eighted" with ligature wire.

• Buccal segmental wires are not

needed.

MINIMUM ANCHORAGE (LOWER ARCH)

• An elastic power chain is placed

circularly from the lingual of the first

molar, encircling the canine, and

attaching to the buccal of the first

molar.

• Class II elastics are used to facilitate

mesial movement of the molars.

• The anterior segment is "figure-

eighted" with ligature wire.

• As the molars move mesially, gingival

recession over the mesial root of the

first molar should be prevented.

Anterior and Lateral Concerns

• Patients with severe anterior tongue thrust often present a

challenge when attempting to retract the anterior

dentition.

• The lingual appliance, due to the discomfort associated

with tongue contact, redirects the tongue tip to the palatal

vault in speech and swallowing.

• Therefore, the anterior thrust component is eliminated,

and normal muscle balance is restored.

• The excessive pressure from the tongue against the

anteriors is minimized while retraction is facilitated.

“FENCE EFFECT"

• The lingual appliance or the elastics create a

fencing of the tongue musculature from the

dentition.

• This contributes to the increase in anchorage

values seen with lingual appliances as opposed

to labial appliances.

Transverse Control

• With the use of lingual appliance most undesirable

expansion occurs in buccal segments.

• Lingual appliance has a tendency to cause

Mesiobuccal molar rotation during space closure

• Intermolar dimension becomes more. This effect is

also called – “TRANSVERSE BOWING EFFECT”

MEASURES TO MINIMISE TRANSVERSE

BOWING

Use of Transpalatal arches.

Use of Heavy vestibular arches through buccal headgear tubes

Crossover technique

Most effective method is a continuous archwire from second

molar to second molar.

Advantages; -

• Maintenance of proper arch from

• Reduction of post interferences from dental arch bowing.

Lateral occlusal function

• The lateral occlusion prevents the transverse bowing

effect and contributes to anchorage.

• Forces used for retraction should be light,

minimizing anchorage loss while maintaining lateral

occlusal function.

Anchorage Considerations in LingualOrthodonticsSilvia Geron

Seminars in Orthodontics, Vol 12, No 3 (September), 2006: pp 167-177

Introduction:

•Anchorage provision and control is a key requirement for the successful treatment of most malocclusions irrespective of the treatment technique.

•When using the lingual technique, specific problems relating to the provision of adequate anchorage may be attributed to a number of factors.

● The majority of patients seeking lingual orthodontics arenongrowing adults.

● Many have mutilated malocclusions with one or more missingteeth.

● Often there is a compromised periodontal condition withreduced alveolar bone levels reducing the anchorage value ofthe posterior dentition.

● These patients as a group have high esthetic demandsprecluding the use of many conventional orthodonticanchorage devices such as extraoral appliances, pendulum, lipbumper, or intermaxillary elastics.

• The placement of lingual brackets invariably causes anterior bite

opening and posterior disocclusion in cases with normal or deep

overbite. While the contribution of an intercuspated occlusion to the

provision of a degree of anchorage may be debatable and vary with

different malocclusions, the bite plane effect of the lingual

appliance with resulting loss of occlusion and intercuspation may in

certain cases reduce the anchorage achieved with the lingual

technique.

• It has been suggested that the lingual technique provides superior

anchorage control because of the smaller arch perimeter, which in

turn increases the rigidity of lingual archwires during retraction.

• Takemoto compared anchorage loss in labial versus lingual extraction cases

treated with loop mechanics and found higher anchorage value of the posterior

dentition in lingual cases.

Takemoto K: Anchorage control in lingual orthodontics, in Romano R (ed): Lingual Orthodontics. Hamilton,

Canada, BC Decker, 1998, pp 75-82

• He suggested that the anchorage value of posterior teeth in the lingual technique

is higher than that of the labial technique due to the proximity of the lingual

brackets to the center of resistance of the tooth.

• In addition, the direction of forces during space closure creates a degree of

buccal root torque and distopalatal rotation of the molar crown, which in turn

produces cortical bone anchorage.

• In certain cases where anchorage needs to be reinforced, a modified pendulum

appliance can be placed to reduce anchorage loss.

Echarri P, Scuzzo G, Cirulli N: A modified pendulum appliance for anterior anchorage control. J Clin Orthod

37:352-359, 2003.

6 Anchorage keys:

• Standard lingual bracket jig prescription for the anterior teeth, incorporating slight extra palatal root torque and no extra tip for extraction cases; molar tubes placed off-center in a more mesial position and incorporating a mesial tip to encourage molar tip back (uprighting)

• Reduced friction, using sliding mechanics together with bi dimensional archwires incorporating a rectangular anterior section and round posterior sections or using a standard archwire and placing brackets on the posterior teeth with larger slot sizes

• Posterior bite stops placed on the molar teeth to open

the bite

• Light Class I, II, or III forces for retraction or space

closure

• Incorporation of the second molars in the anchorage

unit

• Incorporation of an exaggerated curve of Spee in the

maxillary space-closing archwire

Case 1:

• A 25-year-old female patient presented with a chief complaint of dental protrusion and difficulty in closing her lips.

• Extraoral examination showed a long face with a convex

profile, retrognathic mandible, bimaxillary protrusion, and

incompetent lips with reduced tonicity

Intraoral views show half cusp Class II occlusion on the right and left sides,

anterior open bite, and proclination of upper and lower incisors

Cephalometric measurements confirm the clinical signs, mild skeletal Class II

with a high mandibular plane angle and upper and lower incisor proclination.

Treatment goal :

• To reduce incisor and lip protrusion.

Treatment plan:

• Extraction of four second premolars and incisor retraction using maximum

anchorage mechanics.

• On the premise that there is no difference in anchorage loss between first and

second premolar extractions, the second premolars were selected for

extraction as an esthetic consideration.

• First premolar extraction sites are more noticeable than second premolar

extraction sites

• The selection of the second premolars for extraction also simplifies the space

closure mechanics in lingual cases, because the premolar offset placed

between the canine and premolar may interfere with the final space closure in

first premolar extraction cases.

Anchorage Strategy:

• The second molars were included in the anchorage unit.

• A bi dimensional bracket system was used to reduce friction during space closure, 0.018 inch slot brackets for anterior teeth from canine to canine and 0.022 inch for all the posterior brackets.

• Bracket positioning was performed by using the lingual bracket jig (LBJ) in an indirect in-office procedure.

• Anterior brackets were positioned with slight extra torque prescription.

• Molar brackets were positioned with 5° mesial inclination (to encourage molar tip back).

• Space closure was performed by en mass retraction of the eight anterior teeth

by using sliding mechanics with light intra arch elastics.

• En masse retraction is the routine space closure mechanics used in lingual

orthodontics because the esthetic requirement of the patient does not permit

retracting the canines and premolars separately with resulting opening of

unsightly spaces in the anterior region.

Treatment Progress

• Upper and lower lingual brackets were bonded indirectly at the same

appointment.

• The initial archwires were Copper Niti 0.017 inch followed by steel 0.016 X

0.022 inch archwires (Ormco Corp, Orange, CA).

• The anterior teeth and the posterior group of teeth were laced with steel

ligature wire and space closure was performed by using elastic chains tied

between the first premolars and the first molars with an initial force level of

150 gm of force.

• The elastic chains were replaced every 6 weeks.

• Nine months after bonding, the spaces were almost closed and the overjet and overbite were corrected.

Treatment Results

• A functional occlusion was achieved with overjet and overbite within normal limits. Final radiographs showed correct root positions. Superimposition of the pre- and post-treatment cephalometric tracings indicated significant retraction of the upper incisors and slight lingual tipping of lower incisors due to the tip back position of the molar brackets. Upper molars were found to have moved mesially about 1/3 of the extraction space, which is compatible with the anchorage requirements of the case. Incisor and lip protrusion were significantly improved and lip competence was achieved with concomitant reduction in lip strain.

• The main treatment goals were achieved with an esthetic, simple lingual orthodontic appliance in a comparatively short treatment time of 14 months.

Case 2:

• A 27-year-old male patient presented with a chief complaint of an unesthetic smile.

• Extraoral examination showed an increased lower facial height with straight to mildly retrusive lips and an obtuse nasolabial angle.

• Analysis of the smile revealed insufficient exposure of the incisors and a reversed smile line

• Intraoral examination showed a full Class II occlusion with an overjet of 10 mm and an

anterior open bite of –4 mm.

• The patient also presented with extensive restorations in both arches and a periapical

lesion on the roots of the upper left first molar necessitating the extraction of this tooth.

• The cephalometric analysis indicated a skeletal Class II jaw

relationship with a high mandibular plane angle and proclination

of the upper incisors.

• The main treatment goals were retraction and extrusion of the

upper incisors for overjet and overbite correction.

• The treatment plan included extraction of the upper right second

premolar and the upper left first molar and the retraction of the

incisors with maximum anchorage mechanics.

Anchorage Strategy

• This case required maximum anchorage due to the large overjet and anterior open bite.

• The anterior open bite with the tongue interposition is a complicating factor that may contribute to anchorage loss during treatment.

• The anchorage problem was further complicated by the extraction of the upper left first molar.

• The second molar on the right side and the third molar on the left side were included in the anchor unit.

• Spaces were closed by enmass retraction of the nine anterior teeth, including the first right premolar, first and second left premolars, canines, and incisors as one unit.

• Sliding mechanics was used with a light intra arch elastic chain. Class II elastics were also used at night.

• The Class II elastics were attached to the lingual hook of lateral incisor brackets and to a lower clear vacuum formed plate, since there were no brackets on the lower arch, as brackets were placed in the maxillary arch only

Treatment Progress:

• Immediately after brackets were bonded the patient was instructed to position his tongue behind the brackets, on the palate, and to practice tongue positioning during swallowing.

• Lingual brackets can help in correcting anterior open bite because of the tongue crib effect.

• The first arch wire was 0.017 inch Copper Niti, followed by a steel 0.016 X 0.022 inch archwire for space closure.

• The finishing wire was 0.016 TMA lingual arch wire (Ormco Corp, Orange CA).

Treatment Results:

• Treatment time was 20 months.

• Despite the severity of the malocclusion and the anchorage difficulties, it was possible to achieve most of the treatment goals, that is, ideal overjet and overbite, Class I canine and Class II molar relationships, although a slight maxillary midline deviation to the left side is evident.

• Cephalometric analysis and superimpositions revealed retraction of the maxillary incisors with only slight mesial movement of the molars. Posttreatment facial pictures show significant esthetic improvement of the smile, full face, and profile. The incisor retraction inevitably affected the nasolabial angle; however, the straight profile still appears harmonious and acceptable.

Case 3:

• A 28-year-old female presented with a chief complaint of severe upper incisor protrusion.

• The patient had orthodontic treatment as a child.

• Extraoral examination shows a straight profile acute nasolabial angle,

and the lower lip trapped behind the maxillary incisors

• Intraoral examination shows severe proclination of the upper incisors with a large

overjet of 12 mm, a deep overbite, asymmetric arches, and some spacing in the upper

and lower arches.

• Cephalometric analysis indicated a Class II skeletal relationship,

with severe proclination of maxillary and mandibular incisors.

• The main treatment goal was to reduce the overjet and correct the

incisor inclination.

• The treatment plan included extraction of the upper second

premolars and interproximal reduction in the lower arch

Anchorage Strategy:

• This was a maximum anchorage case complicated by a large overjetand the lower incisors occluding distal to the maxillary incisor brackets.

• If the lower incisors occlude directly on the bite planes of the maxillary brackets, the occlusal forces may aggravate the proclination of the incisors since the intrusive forces applied by the lower incisors are directed anterior to the center of resistance of the maxillary incisors.

• To avoid these potential complications, posterior bite blocks were bonded to the molars at the bonding appointment.

• Space closure was achieved by en masse retraction of the eight anterior teeth.

• Sliding mechanics was used with light intramaxillary forces and Class II elastics were used at night.

Treatment Progress:

• After achieving normal inclination of the incisors, the posterior bite blocks

were progressively reduced.

Treatment Results:

• The overjet and incisor proclination was fully corrected and good posterior

occlusion was achieved.

• Superimposition of pre- and post-treatment cephalometric tracings showed

tipping and retraction of the maxillary incisors with only slight forward

movement of the molars.

• Facial photos show a significant improvement in the incisal exposure at rest,

profile, smile, and facial appearance of the patient.

• Treatment objectives were fully achieved in a comparatively short treatment

time (21months).

CASE REPORT :

Micro-Implant Anchorage for Lingual Treatment of a Skeletal Class II Malocclusion JANG SEOP LEE, DDS, MSD HYO-SANG PARK, DDS, MSD, PHD HEE-MOON KYUNG, DDS, MSD, PHD

JCO/OCTOBER 2001

• A 19-year-old female presented with the chief complaint of lip protrusion.

• She displayed a severe overjet (10mm) and anterior open bite (–2mm), and was diagnosed as a skeletal Class II malocclusion with open bite and bialveolar protrusion.

• The dental relationships were Class II in the canine region and a mild Class III in the molar region, due to linguoversion of the mandibular second premolars.

• The dental midline was deviated to the right because of rotation of the right maxillary first premolar.

CEPHALOMETRIC ANALYSIS:

Treatment plan:

• The treatment plan involved maxillary first and mandibular second premolar extractions, followed by Class II mechanics with a high-pull J hook headgear.

• The patient preferred to be treated with lingual appliances.

Treatment Progress:

• The Class II canine relationship and overjet proved difficult to correct due

to poor cooperation with the headgear.

• They therefore decided to implant microscrews (1.2mm in diameter,

10mm in length) in the palatal alveolar bone between the maxillary first

and second molars.

• Because of the thick palatal mucosa, a palatal microimplant must be

longer than a buccal micro-implant.

• Two weeks after implantation, nickel titanium coil springs were attached

between the microscrews and hooks on the anterior part of the archwire

• Seven months after microscrew implantation, a Class I canine relationship

had been achieved.

• Total active treatment time was 16 months.

• Superimpositions of cephalometric tracings.

A. Before and after treatment.

B. After microscrew implantation and after treatment.

Results :

•Normal overjet and overbite were achieved.

•The profile was helped by the retraction of the maxillary anterior teeth, although further improvement was required.

• If mandibular micro-implants had been used, a more pronounced profile change might have been expected because of better vertical control of the mandibular posterior teeth.

Discussion :

• Although a transpalatal arch was used during the initial stages of treatment, the patient felt more comfortable with the micro-implants than with the transpalatal arch.

• Anchorage requirements are even more critical in lingual orthodontics than in labial treatment because of the anatomical relationship between the tongue and cortical bone.

• The maxillary posterior teeth, which are used for anchorage in conventional mechanics, were actually moved distally in this patient, while the anterior teeth were retracted simultaneously.

• This case demonstrates that micro-implants can provide reliable, absolute anchorage for lingual orthodontic treatment as well as labial treatment.

A Miniscrew-Assisted Transpalatal Arch for Use

in Lingual Orthodontics:

HYUN SANG PARK, DDS, MSD (JCO/JANUARY 2006)

Appliance Design:

• On the working cast, solder an .036" round stainless steel wire to the first molar bands and to an .028" round stainless steel connecting wire.

• Solder brass hooks to the TPA for application of the anterior retraction force.

• This is supplied by closed-coil springs or elastic chain attached to anterior lever arms, which are connected to the lingual archwire.

• After inserting a palatal miniscrew, sandblast the screw head for better mechanical retention.

• Bond the connecting wire directly to the screw head with composite resin.

• The appliance should be checked in the mouth to ensure that it does not cause discomfort or gingival irritation and that it will not compmise oral hygiene.

• Even if the point of retraction

force application and the line of

action of the force are

asymmetrical, most of the reactive

force will be transmitted to the

miniscrew rather than to the first

molars.

• If the bond fails during treatment,

a ligature wire can be added

between the miniscrew and

connecting wire before rebonding.

Case Report

• A 23-year-old female presented with the chief complaint of lip protrusion. She displayed 2mm of maxillary crowding; the lower dental midline was deviated 4mm to the right.

• The lower left second deciduous molar was retained, and 1mm of space remained between the lower right canine and second premolar due to a congenitally missing first premolar.

• Extraction of both upper first premolars and the lower left second primary

molar was planned, followed by maximum retraction of the upper anterior

teeth.

• After initial dental alignment, a miniscrew-assisted TPA was placed as

described above.

• The lever arms were connected to an .018” X.025" stainless steel lingual

archwire for sliding mechanics.

Patient after eight months of anterior retraction.

• Treatment was interrupted twice because of the patient’s personal problems, but anterior

retraction took a total of about eight months.

• After about 23 months of treatment, the patient showed Class I canine and molar relationships, 2mm of overbite, and 3mm of overjet .

• The dental midlines were coincident with the facial midline; the upper lip was retracted 4.5mm and the lower lip 6.8mm, so that the patient’s appearance improved dramatically.

• A lower lingual fixed retainer and an upper wraparound retainer were delivered.

Discussion:

• In this patient, the single miniscrew provided effective anchorage during anterior retraction with lingual orthodontics.

• The connecting wire remained attached to the miniscrew throughout treatment.

• Since the patient presented with minor mesial tipping of both first

molars, the reactive force was used for tipback movement.

• In Author experience, locating the miniscrew behind the TPA provides a better biomechanical point of retraction force application than when anchorage is supported extraorally.

Conclusions:

• Good anchorage control can be achieved with lingual orthodontic sliding mechanics when following simple anchorage principles. Cases presenting with difficult anchorage situations and with unusual extraction sites can be treated successfully with this technique. The cases presented demonstrate that lingual orthodontics is an efficient tool for the treatment of adult cases with severe malocclusions, difficult anchorage problems, and high esthetic requirements.

References

• Lingual orthodontics by Romano.

• Lingual orthodontics by Takimoto.

• Anchorage Considerations in Lingual Orthodontics - Silvia Geron Seminars

in Orthodontics, Vol 12, No 3 (September), 2006.

• Micro-Implant Anchorage for Lingual Treatment of a Skeletal Class II Malocclusion - JANG SEOP LEE, DDS, MSD HYO-SANG PARK, DDS, MSD, PHD HEE-MOON KYUNG, DDS, MSD, PHD; JCO/OCTOBER 2001

• Concepts on Control of the Anterior Teeth Using the Lingual Appliance- Rafi Romano Semin Orthod 2006;12:178-185

• A Miniscrew-Assisted Transpalatal Arch for Use in Lingual Orthodontics - HYUN SANG PARK, DDS, MSD. JCO/JANUARY 2006

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