Late Expression of Class III Malocclusion

8/3/2019 Late Expression of Class III Malocclusion

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Angle (1899) - classified the malocclusions based on occlusalrelationships, considering the first permanent molar as the "key"of occlusion

Class III malocclusion is defined in cases that mandibular first

molar is positioned mesially relative to the first molar of maxilla


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A complicating factor for diagnosis and treatment of Class IIImalocclusion is its Etiologic Diversity

ENVIRONMENTAL

CONGENITALHERIDITARY

Cleft lip and palate causing teratogens likeAspirinDilantin

Cigarette smoke6- mercaptopurine

ValiumVitamin D excess premature closure of

sutures leading to class iii malocclusion.

Best known examples of genetic

influences are the classic HAPSBURG

JAW ( Mc Guigan 1966)

1/3rd of a group of children who

presented with a severe class III

malocclusion had a parent with the

same problem and 1/6th had an affected

sibling.Litton et al (ajo 1970)


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Environmental

factors

Enlargedtonsils

Difficulty in

nasalbreathing

Disease ofthe pituitary

gland

Harmonaldisturbances

a habit ofprotrudingthe

mandible

prematureloss of thesixth-year

molar

Retaineddeciduousincisors

Excessive mandibular growth could arise as a result of abnormal mandibular posturebecause constant distraction of the mandibular condyle from the fossa may be a growthstimulus- Rakosi & Schilli 1981


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Pseudo Class III:

Class I

with mandibular

anterior shift due to

premature occlusalcontacts

TRUE CLASS III

-Mesiocclusion of molars

-Class III canine relationship

-Anterior crossbite

-Possible posterior crossbite

-Crowding and /or spacing-Overbite - normal

- deep

- open

ANB=< 0O

Habitual occlusion Centric relAtion

Kwong & Lin 1987 conducted a cephalometric study class I, pseudo class III and class IIImalocclusions. Most of the measurements suggest that pseudoclass III is an intermediateform between class I and skeletal class III malocclusions . Only exception was the gonial

angle. It was more obtuse in skeletal class III and more or less similar in pseudo class IIIand classs I malocclusions


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Dentoalveolar Skeletal

mandibular anterior

positioning

(PROGNATHISM)

or growth excess

(MACROGNATHIA)

maxillary

posterior positioning

(RETROGNATHISM)

or growth deficiency

(MICROGNATHIA),

combination of

mandibular and

maxillary

discrepancies.


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DENTAL ASSESSMENT(Molar relationship and overjet)

Class III molar relationshipNegative overjet

Class III molar relationshipPositive overjet or endend

incisal relationship

FUNCTIONAL

ASSESSMENT

True class IIImalocclusion

Pseudo class IIImalocclusion

Compensated class IIImalocclusion

No CR- CO shift CR- CO shift

Ngan Pediatr Dent 19; 386- 395, 1997


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PROFILE ASSESSMENT

Evaluate the chinposition

Evaluate midface

1. Patients with maxillary deficiency usually have a concave profile, evidenced by aflattening of the infraorbital rim and the area adjacent to the nose

2. By blocking the upper lip and lower lip the chin position is evaluated3. By blocking out the lower lip and chin , midface is evaluated. There should be a

convexity to an imaginary line extending from the inferior border of the orbit

through the alar base of the nose, and down to the corner of the mouth.-A straight or concave tissue contour indicates a midface deficiency.


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Vertical proportions should be assessed in CO and CR

The normal ratio of LFH to TFH is approx 0.55.

This ratio is decreased in patients with functional shift andoverclosure of the mandible

Cephalometric assessment:

To confirm the contributions of the

Maxilla

Mandible

Maxillary incisors &

Mandibular incisors to the class III skeletal and dentalrelationships


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Cranial base:

More anteriorly positioned articulare when compared to class I

Mid cranial fossaposterior and superior alignmentpositions

nasomaxillary complex more retrusive relationship

Maxilla :

Decreased horizontal maxillary growth when compared to

class I malocclusion patients Horizontal A point movement

0.4mm/yrin class III patients

1.0mm/yrin class I patients

Battagel EJO 1993


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Mandible:

Gonial angle more obtuse Short ascending ramus

Steeper mandibualr plane angle

Mandibular prominence along with decreased length of the maxillarycomplex accentuate the straight or concave profile

Duration of the Pubertal Peak in Skeletal Class I and Class III Subjects

The growth interval corresponding to the pubertal growth spurt waslonger in Class III subjects than in subjects with normal skeletalrelationships

The larger increases in mandibular length during the pubertal peakreported in the literature for Class III subjects may be related to thelonger duration of the pubertal peak. (Angle Orthod 2010;80:5457.)


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Early class III treatment

Good facial esthetics

Mild skeletal disharmony

No familial prognathism

Anteroposterior functionalshift

Symmetrical condylargrowth

Growing patients withgood co-operation

Poor facial esthetics

Severe skeletal disharmony

familial pattern established

No Anteroposteriorfunctional shift

assymmetrical condylargrowth

Poor co-operation

Indications Contraindications

Turpin 1981


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SKELETAL EARLY TREATMENT

Face mask

Chin cup

Frankel III appliance

Reverse twinblock

LATE TREATMENT- SURGICAL or CAMOUFLAGE

Mandibular prognathism- ramus osteotomy

Maxillary retrognathism- lefort I osteotomy with maxillary

advancement

Pseudo class III Correcting the path of closure


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Age : 13yrs 9 monthsC/O: Dental crowding


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Class I molar relation

NORMAL TRANSVERSEINTERARCH RELATIONSHIPMAXILLARY LATERALINCISOR IN CROSS BITE

4MM CROWDING IN THE

MAXILLARY AND THEMANDIBULAR ARCHES

HARMONIOUSPROFILE


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PANORAMIC RADIOGRAPH


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LATERAL CEPHALOGRAM

Class I skeletal relationship

proportional jaws

Craniofacial pattern in equilibrium

The lower anterior facial height wasshort

mandibular incisors were upright in thebasal bone.


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treatment plan - to eliminate the dental crowding and establish a goodocclusion

TREATMENT OPTIONS:

1. EXTRACTION OF FOUR PREMOLARS2. NON EXTRACTION (expansion of the maxillary arch and buccal tipping of the mandibular

posterior teeth to gain space in both arches)

SECOND OPTION WAS CHOSEN ..

REASON:

CROWDING WAS MODERATE

extractions could make the profile too retrusive


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TREATMENT PROGRESS:UPPER ARCH- QUAD HELIX

FOR EXPANSION

LOWER ARCH- LARGER SIZE WIRES WERE USED

After seven months of leveling and alignment

a developing Class III relationship was noted on the right side

the right central and lateral incisors in crossbite and

slight deviations of the mandibular dental midline and chin to the left.

To correct this Class III canine relationship, the anterior crossbite, and the midline deviation,

mandibular right first premolar WAS EXTRACTED

The patient and his parents were not concerned about themild chin deviation, since it did not compromise his facialappearance.


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After 25 months of treatment final occlusion showed

Class III molarrelation

CLASS I MOLARRELATION

CLASS I CANINERELATION


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maxillary incisors were tipped labially andthe mandibular incisors slightly uprighted andretrudedANB HAS DECREASED FROM 3 TO -0.5INCREASED MAXILLOMANDIBULAR DIFFERENTIALTOWARDS CLASS III


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Unilateral Class III caninerelationship on the left side

witha negative overjet of 2mm

CLINICAL EXAMINATION SHOWEDCEPHALOMETRIC ANALYSIS SHOW

ANB had decreased to 4.2MAXILLOMANDIBULAR differential iNCREASED

TO ANOTHER 5.3 mm


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Due to the severity of the malocclusion, the patient agreed toretreatment

Retreatment Options:1. surgical-orthodontic correction with maxillary advancement, or

2. orthodontic treatment involving extraction of the mandibular left first premolar.

Patient opted for the second option

Retreatment progress:

Bilateral Class III elastics in place, along with anterior intermaxillary elastic from palatalbuttons on maxillary incisors to labial hooks on mandibular incisors.

Retention :

Maxillary-Hawley plate and

Bonded mandibular 4-to-4 retainer

TOTAL TREATMENT TIME WAS 27 MONTHS

RETREATMENT RESULTS


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RETREATMENT RESULTS

Bilateral Class IIIMolar and

Class I caninerelationshipSlight maxillaryprotrusion andmandibularretrusion

improving the lippositionThe occlusalplane wasrotated slightlycounterclockwise


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This patients initial records did not predict this

subsequent dental abnormality.

He exhibited a Class I dental relationship, with

no cephalometric indication of a developing ClassIIImalocclusion.

The mandibular incisors showed a slight Class III tendencydue to their subtle lingual inclination, but such inclinationscan also be found in Class II cases.

There was no family history of Class III malocclusion.


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7 months into treatment the patient developed a Class III relationshipon the right side

In an average male patient of this age, the effective mandibular length(Co-Gn) would be expected to increase twice as much as the effectivemaxillary length (Co-A)

In this patient, the effective maxillary length increased by 3.9mmduring the treatment period, while the effective mandibular lengthincreased by 9.6mm1.8mm more than expected.

The Class III relationship on the right side probably appeared as a

consequence of this unusual mandibular overgrowth.

Still, there were no clinically evident skeletal discrepancies, andtreatment was resumed after extraction of the mandibular right firstpremolar.


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A more accentuated mandibular growth tendency continued in

the post-treatment years, resulting in a complete Class IIImalocclusion on the left side.

Maxillary protrusion (SNA) decreased by 2.5 and the effectivemaxillary length remained unchanged, while the effective

mandibular length increased by 5.3mm . This pattern produced a reduction in ANB and more of an

increase in the maxillomandibular differential than would beexpected in the patients age group.

Therefore, it seems likely that the late Class III malocclusionwas caused by an absence of maxillary growth in combinationwith an overgrowth of the mandible.


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A more unusual aspect of this case is the asymmetrical

manifestation of the Class III malocclusion, with an interval ofseveral years between the right and left sides.

Unusual mandibular growth could be precipitated by condylarhyperplasia during or after orthodontic treatment

However in this patient no common indications of hyperplasia,including

severe facial asymmetry,

excessive condylar neck length and/or head width,

TMJ complaints, open bite on the affected side,

a history of facial or mandibular trauma or injury, and

hereditary or hormonal disturbances such as acromegaly

were found


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After the unilateral Class III relationship developed on the rightside,

the case should have been handled as a Class III malocclusion,

with follow-up visits scheduled every three months to monitormandibular growth

A chin cup or a functional appliance could have been prescribeduntil the end of the growth period.


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Although relapse of Class II or Class III malocclusion is notuncommon, more active retention in this case might have

reduced the Class III tendencyor at least prompted earlyretreatment, when the discrepancy would have been moreamenable to conservative orthodontics.


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Careful observance of occlusal features suggesting a latent ClassIII tendency may help the clinician anticipate a delayedmanifestation, either during or after treatment.

Special attention should be given to patients exhibiting signs ofsuch late growth, with active retention used to prevent relapseand follow-up visits scheduled every three months to monitor

the patients growth and occlusal relationship.

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Late Expression of Class III Malocclusion

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