In the name of GOD

Orthodontic indices and Epidemiology of

malocclusion

Presented by:

Dr Somayeh Heidari

Orthodontist

Reference:

*Contemporary Orthodontics

Chapter 1

William R. Proffit, Henry W. Fields, David M.Sarver. Fifth Edition 2013. MosbyWilliam R. Proffit, Henry W. Fields, David M.Sarver. Fifth Edition 2013. Mosby

How much deviation from the

ideal occlusion

should be accepted within the bounds of normal?

Prevalence of malocclusion in the USA (1930- 1965)

35% 95%

Advantages of Angle’s classification

• simple

• clear

• assessment of antero-posterior dental relationships

Limitations of Angle’s classification

Anteroposterior dental arches discrepancies

≠≠

Anteroposterior facial imbalances

Limitations of Angle’s classification

No assessment of vertical and horizontal inter-arches problems.

Antero-posterior or Sagittal plane

•molars relationship ( class I / II / III )

• canines relationship ( class I / II / III )

• incisors relationships ( overjet / anterior cross bite)

Horizontal plane

• upper to lower midlines

• posterior cross bite (buccal or lingual)• posterior cross bite (buccal or lingual)

Vertical plane

• overbite (deep bite or open bite)

Limitations of Angle’s classification

No assessment of intra- arch problems

•malalignment (crowding, rotation, spacing, …)

•missing

• impaction

• …

Dental Aesthetic Index (DAI)

crowding

spacing

overjet

overbite

molars relationship

Index of Orthodontic Treatment Need (IOTN)

1- dental health component

derived from occlusion and alignmentderived from occlusion and alignment

2- esthetic component

derived from comparison of the dental appearance to

standard photographs

IOTN : Dental health component

• overjet

• over bite

• cross bite• cross bite

• crowding

• impaction

•missing: hypodontia

• craniofacial anomalies: cleft lip and palate , ...

IOTN: Dental health component

IOTN : Dental health component

Grade 5: Extreme / need treatment

Grade 4: Sever / need treatment

Grade 3: Moderate / borderline need

Grade 2: Mild / little need

Grade 1: No need

IOTN: Esthetic component

IOTN : Esthetic component

1 – 4 : no/slight need

5 – 7 : moderate/borderline need

8 – 10 : definite need

• IOTN grades seem to reflect clinical judgments better than previous

methods

• There is a surprisingly good correlation between treatment need

assessed by dental health and esthetic components of IOTN

Epidemiology of the usual orthodontic problems

Incisors alignment

in the age 8-11 years old, just over half of US children have well aligned incisors.

the percent with excellent alignment decreases in the age 12- 17 years as the

remaining permanent teeth erupt.remaining permanent teeth erupt.

incisors alignment remains essentially stable in the upper arch but worsens in

the lower arch for adults.

only 34% of adults have well aligned lower incisors.

Nearly 15% of adolescents and adults have severely or extremely irregular

Incisors alignment

Nearly 15% of adolescents and adults have severely or extremely irregular

incisors.

Maxillary diastema

a wide space between the maxillary central incisors often is present in childhood:

26% have >2mm space

this space tends to close but over 6% of youths and adults still have a noticeable

diastema.

Maxillary diastema

blacks are more than twice as likely to have a midline

diastema than whites and Hispanics.diastema than whites and Hispanics.

Posterior cross bite

posterior cross bite is relatively rare at all ages.

overjet

overjet of 5mm or more, suggesting Angle’s class II malocclusion, occurs in

23% of children

15% of youths

13% of adults

overjet

reverse overjet, indicative of class III malocclusion, is much less frequent:

about 1% of American children and increases slightly in youths and adults.

overjet

sever class II and class III problems occur in about 4% of the population.

sever class II problems is much more prevalent. sever class II problems is much more prevalent.

sever class II problems are less prevalent, and sever class III problems are

more prevalent in the Hispanic than the white and black groups.

overbite

• vertical deviations from the ideal overbite of 1-2mm are less frequent in adults

than children but occur in half of adult population, the great majority of them

have deep bite.

• sever deep bite (overbite ≥ 5mm) is found in nearly 20% of children

13% of adults

while open bite (negative overbite > -2mm) occur in less than 1%

overbite

• there are striking differences between the racial / ethnic groups in vertical

dental relationships.

• sever deep bite is nearly twice as prevalent in whites as blacks or Hispanics.

• open bite > 2mm is five times more prevalent in blacks than the whites and• open bite > 2mm is five times more prevalent in blacks than the whites andHispanics.

• despite their higher prevalence of antero-posterior problems, vertical problems

are less prevalent in Hispanics than either blacks or whites.

normal occlusion

class I malocclusion

30%

15%

1%

class I malocclusion

class II malocclusion

class III malocclusion

50-55%

class II problems are most prevalent in whites of northern Europe

class III problems are most prevalent in Oriental population

class III and open bite are more frequent in African than European class III and open bite are more frequent in African than European

population deep bite less frequent

Why is malocclusion so prevalent?

present prevalence of malocclusion is several times greater than it was only

a few hundred years ago.

crowding and malalignment of the teeth were uncommon but the majority

of a group might tend toward a mild antero-posterior or transverse discrepancies

, such as a class III or less commonly a class II jaw relationships., such as a class III or less commonly a class II jaw relationships.

the fossil record documents a decrease in the size of teeth,

decrease in the number of teeth, and a decrease in the size

of jaws.

the third incisor and third premolar have disappeared, as has the fourth molar

at present, the human third molar, second premolar, and second incisor often fail to

develop, which indicates that these teeth may be on their way out

the progressive reduction in jaw size, if not well matched to a decrease

in tooth size and number, could lead to crowding and malalignment.

malocclusion may be on of the “diseases of civilization”

increasing malocclusions perhaps resulting in part from less use of the increasing malocclusions perhaps resulting in part from less use of the

masticatory apparatus with softer foods now.

Although it is difficult to know the precise cause of any specific malocclusion,

we do know in general what the etiologic possibilities are.

What difference does it make if you have a malocclusion??!! What difference does it make if you have a malocclusion??!!