early transvrse treatment

7/29/2019 Early Transvrse Treatment

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DR.MUHAMMAD ASIM

RII(ORTHODONTICS)

SBDC,PESHAWER


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Introduction Expansion of the maxillary arch to improve transverse inter-arch

relationship during primary & mixed dentition

Part of a two-phase treatment protocol


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Background Posterior crossbite

Nomenclature: based on the position of maxillary teeth

Posrterior lingual crossbite

Posterior buccal crossbite


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Incidence

Estimated range: 7-23% with greater prevalence of unilateral crossbitecoupled with a lateral shift of the mandible

Thilander & co-workers: 9.6% Helm: girls 14% , boys 9%

Hanson & co-workers: >23%


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Etiological factors

Transverse skeletal maxillary difficiency

Congenital,developmental,traumatic,iatrogenic

Asymmetric growth of amxilla or mandible

Discrepant widths of basilar maxilla or mandible Improper function of TMJ

Nasal breather

Oral digit habits

Premature loss or prolong retention of primary teeth Crowding

Abnormilities in eruption sequence

Aberrant tooth anatomy


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Can spontaneous correction of posterior crossbite occur?

Controlled studies have reported wide variation in rates of spontaneouscorrection in the primary & early mixed dentition, ranging from 8 to45%

Kutin & Hawes: 8% Kurol & Bergland: 45%

Thilander & co-workers: 21%


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Rationale for early correction of posterior crossbite with afunctional shift

Lateral shift of the mandible may promote adaptive remodling of TMJand asymmetric mandibular growth


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Diagnosis Systematic evaluation of face and dentition in

The Frontal view

The Sagittal jaw relationship

The Transverse dental relationships on study cast


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Frontal examination

Clinical examination + facial & intra-oral photography

If obvious facial asymmetry

Check for functional shift If any doubt,disarticulate teeth using a bite plate or fixed expander i.e

hyrax

If no functional shift. True Skeletal asymmetry

PA ,SMV view


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In the absence of chin or facial asymmetry

Analyze transverse tooth inclination & arch asymmetry on study casts


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Sagittal relationship

Transverse interarch relationship changes as the sagittal relationshipchanges

Relative transverse discrepency exists when the posterior teeth do notshow proper transverse cusp-fossa relationships in centric relation, butproperly occlude when the canines of the casts are placed in Class Iocclusion

if a crossbite still exists when the casts are articulated into a Class Icanine relationship, then the transverse discrepancy is absolute


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Transverse Dental Relationships

Study casts are used to determine whether the discrepancy is of dentalor skeletal origin and to determine the magnitude of the discrepancy

1st examine for posterior dental compensations

Estimated by viewing the casts from front can be measured using the American Board of Orthodontics (ABO)

measuring gauge

measuring width differences between the midline of the dental archand the right and left posterior teeth


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Counting the number of teeth in crossbite: that if two or moreposterior teeth are in crossbite, then the discrepancy is skeletal.

Comparing a patients maxillary and mandibular intermolar width topublished norms to determine the magnitude of a posteriortransverse discrepancy.


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Treatment


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When should early treatment for crossbite begin?

Other than attempting to correct functional shifts in the primarydentition by selective occlusal adjustment, it is recommended thattreatment be postponed until the early mixed dentition.

Treatment in primary dentition

high failure rates

Poor compliance

with the eruption of the first permanent molars, transverse

relationships can be assessed more thoroughly. There is still adequate time for growth modification in the mixed

dentition


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It is recommended to postpone crossbite correction until thepermanent first molars erupt

It is further recommended that fixed appliances are used to make thecorrection in the early mixed dentition to avoid problems of patientcooperation.


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How should crossbites be treated

There is no single treatment approach for every patient. A range oftreatment options exists, and the choice is based on the diagnostic

findings and other factors.

The treatment decision is based on following factors: the presence or absence of a lateral mandibular shift

the degree of skeletal discrepancy

the degree of posterior tooth compensations in each arch


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there are fundamentally two treatment options to correct posteriorcrossbites in the early mixed dentition

Increasing the basilar maxillary width by lateral expansion of the

midpalatal suture Medial or lateral dental tipping and/or translation


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Skeletal crossbites

Maxillary expansion with Hyrax jackscrew appliance or other fixedexpanders

Separation of the two hemimaxillae may be symmetric or asymmetric,

depending on rigidity of the bony architecture the maxillary first permanent molars or the maxillary primary second

molars provide adequate expansion anchorage


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Dental crossbites

In the maxilla

Removable expansion plate

Transpalatal arch

2x4 edgewise appliance using a round archwire expanded at the 1stmolars

In the mandible

Lower lingual holding arch

Lip bumper

2x4 edgewise appliance using a round archwire constricted at thefirst molars


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Crossbite elastics

tip opposing teeth in opposite directions

By incorporating a cross-arch stabilizing appliance tipping can be

restricted to one arch only.

For pure lateral dental translation

A removable 0.032x0.032-inch transpalatal or lingual arch fitted to0.032-inch edgewise lingual molar band attachments is very effective in

translating molar teeth laterally.


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How should true unilateral (maxillary lingual) crossbites

be treated in children?

A rapid maxillary expander (RME) with reverse crossbite elastics on thenoncrossbite side, in conjunction with a lower lingual holding arch, isrecommended.

A unilateral crossbite can sometimes be treated with uni-lateralcrossbite elastics alone.

If the crossbite involves permanent first molars and deciduous molars,then elastics should also include the deciduous teeth because failure to

correct the deciduous tooth crossbite will result in a high probability ofthe permanent premolars erupting into crossbite.


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In the absence of a posterior crossbite, should rapid

maxillary expansion be used to correct a Class II relationship?

it is doubtful that rapid maxillary expansion enhances mandibulargrowth. Any Class II improvement with RME in adolescence is probablydue to simple unlocking of the occlusion and the greater normal forward

growth of the mandible compared with the maxilla.

Lagerrecommended elimination of intercuspal locking in a growingClass II patient with a biteplate to allow forward movement of themandibular dentition


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You and coworkers compared mandibular growth in a sample ofuntreated Class II malocclusion children to a sample of norms.

Forward growth of the mandible during adolescence exceeded thatof the maxilla (by over 4mm)

In ClassII children,the effect of forward growth of the mandiblevanished because of intercuspal locking


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Guymon noted that when the inner bow of a facebow(cervical pull HG)was expanded, the mandible grew at a rate comparable to controlsduring the initial treatment period.

However, during the retention period, the mandible grew at asignificantly accelerated rate compared with controls.

The author concluded that, as the maxillary arch widened; themandibular arch was unconsciously postured forward to maintain the

occlusion


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Should dental arches be expanded in the absence of acrossbite to gain arch perimeter and avoid extractions?

Mandibular arch limits the amount of maxillary expansion that can be

achieved. Expansion of the arches beyond the point where themandibular molar crowns are upright is unstable and notrecommended.


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Gianelly noted that 68% of patients with crowding will have adequatespace for alignment if a lower lingual holding arch is used to preserveleeway space, another 19% will have adequate space with only marginalarch length increase (up to 1mm per side)

For mixed dentition cases with favorable leeway space, treatmentresults using a lower lingual holding arch appear stable.

Other than uprighting lingually inclined posterior teeth, transverseexpansion of the mandibular arch to increase arch perimeter is notrecommended.


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early transvrse treatment

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