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Etiology of Malocclusion

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ETIO ETIO LOG LOG Y OF Y OF MAL MAL OCC OCC LUSI LUSI ON ON 2008 Jai pu r D en tal Co lle ge
Transcript
Page 1: Etiology of Malocclusion

ETIOETIOLOGLOGY OF Y OF MALMALOCCOCCLUSILUSI

ONON

2008Jaipu

r D

ental College

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A SEMINAR REPORT Submitted By- Arpita Pareek

Final Year B D S

Jaipur Dental College

Dhand, Tehsil -Amber, Jaipur-Delhi (N.H.-8), JAIPUR-303 101

CERTIFICATE

This is to Certify that Miss Arpita Pareek Of BDS Final Year has satisfactorily completed the Seminar on Eiology of Malocclusion & clinical and practical programmers ’ conducted by the Department of Orthodontics and Dentofacial Orthopeadics, during the academic Year 2007-08

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Prof. & Head

Dept. of Orthodontics

& Dentofacial Orthopeadics

JAIPUR 28-05-08

ETIOLOGY OFETIOLOGY OF MALOCCLUSIONMALOCCLUSION

INTRODUCTION

What cozes a Malocclusion?

This question has to be answered correctly before any decision can be taken regarding its prevention or correction; hence, several classifications have been

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put forward to help us understanding the etiology of malocclusion.

The various classifications proposed are-

1. White & Gardiner’s classification2. Salzmann’s classification3. Moyer’s classification4. Graber’s classification

WHITE & GARDINER’S CLASSIFICATION

It was the Ist attempt made to classify malocclusion & to distinguish between skeletal & dental etiological factors.

DENTURE BASE ABNORMALITIES

1. Anterio-posterior mal relationship2. Vertical mal relationship3. Lateral mal relationship

4. Disproportion of size between teeth and basal bone

5. Congenital abnormalities.

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PRE-ERUPT1ON ABNORMAL1TIES

I. Abnormalities in position of developing tooth germ

2. Missing teeth

3. Supernumerary teeth and teeth abnormal in form

4. Prolonged retention of deciduous teeth

5. Large labial frenum

6. Traumatic injury. -

POSTERUPTION ABNORMALITIES

1. Muscular

a. Active muscle force

b. Rest position of musculature

c. Sucking habits

d. Abnormalities in path of closure

2. Premature loss of deciduous teeth

3. Extraction of permanent teeth.

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GRABER’S CLASSIFICATION

GENERAL GENERAL FACTORSFACTORS

1. Heredity

2. Congenital

3. Environment

a. Prenatal (trauma, maternal diet, German measles, material maternal metabolism, etc).

b. Postnatal (birth injury, cerebral palsy, TMJ injury)

4. Predisposing metabolic climate and disease:

a. Endocrine imbalance

b. Metabolic disturbances

c. infectious diseases

5. Dietary problems (nutritional deficiency)

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6. Abnormal pressure habits and functional

Aberrations:

a. Abnormal sucking

b. Thumb and finger sucking

c. Tongue thrust and tongue sucking

d. Lip and nail biting

e. Abnormal swallowing habits (improper deglutition)

f. Speech defects

g. Respiratory abnormalities

h. Tonsils and adenoids

i. Psychogenetics and bruxism

7. Posture

8. Trauma and accidents.

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LOCAL FACTORSLOCAL FACTORS

1. Anomalies of number:

• Supernumerary teeth

• Missing teeth (congenital absence or loss due to

Accidents , caries, etc.)

2. Anomalies of tooth size

3. Anomalies of tooth shape

4. Abnormal labial frenum: mucosal barriers

5. Premature loss

6. Prolonged retention

7. Delayed eruption of permanent teeth

8. Abnormal eruptive path

9. Ankylosis

10. Dental caries

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11. Improper dental restorations

ETILOGY – GENERAL ETILOGY – GENERAL FACTORSFACTORS

HEREDITARY

Hereditary causes of malocclusion include al factors

that result in amaLocc1usion and are inherited from the parents by offspring’s. These may or may not he evident at birth, but are likely to express themse1ve as the child grows. These can be those influencing the-

Neuromuscular system

Dentition

Skeletal structures

Soft tissues (other than the Neuromusculature).

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NEUROMUSCULAR SYSTEM

The anomalies that have been found to possess some inherited component include deformities in size, position, tonicity, contractility, and in the neuromuscular coordination pattern of facial, oral, and tongue musculature.

DENTTION

Certain characteristics, especially related to the dentition are definitely inherited. These include:

Size and Shape of the Teeth

Studies on twins have proved that the size and relative shape of the teeth is inherited e.g. Peg shaped

Lateral are the most commonly seen and noticed abnormally shaped teeth encountered clinically. To produce a malocclusion the discrepancy should exist

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between the basal bone and the teeth size, or the associated skeletal structures.

Number of teeth

Presence of either more or less no. of teeth can also be inherited. This includes condition such as Anodontia, Oligodontia, and Hypodontia.

Primary Position of Tooth, Germ and the Path of Eruption

Considered to be inherited. eg., Crossbites, Ectopic tooth eruption.

Shedding of Deciduous Teeth & Sequence of Eruption

Mineralization of Teeth

Inherited defects of the tooth structure differ from defects in mineralization as they are present in both the deciduous dentition as well as permanent dentition and are localized in the enamel or the dentine.

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SKELETAL STRUCTURES

Skeletal structures r partially inherited

e.g, Class III skeletal pattern is associated with familial tendency

SOFT TISSUES (OTHER THAN THE NEUROMUSCULATU RE)

These generally includes the size & shape of the frenum especially the maxillary labial frenum.

CONGENITAL FACTORS

Congenital defects include those malformations that are seen at the time of birth. These are –

a. Micrognathismb. Oligodontia c. Anodontia , etc.

Endocrine imbalance

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Certain endocrinal disorders may result in mal occlusion. The following are some of the endocrinal disturbances that can cause malocclusion.

Hypothyroidism: Hypothyroidism is characterized by the presence of one or more of the following features:

a) Retardation in rate of calcium deposition in bones and teeth

b) Marked delay in tooth bud formation and eruption of teeth

c)Delayed carpel and epiphyseal calcification d) The deciduous teeth are often over-retained and

the permanent teeth are slow to erupt Abnormal root resorption

e)Irregularities in tooth arrangement and crowding of teeth can occur

Hyperthyroidism: This condition is characterized by increase in the rate of maturation, and an increase in

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metabolic rate. The patient exhibits premature eruption of deciduous teeth, disturbed root resorption of deciduous teeth and early eruption of permanent teeth. The patient may have osteoporosis which contra-indicates orthodontic treatment.

Hyperparathyroidism : This endocrinal disorder is associated with changes in calcium metabolism. It can cause delay in tooth eruption, altered tooth morphology, delayed eruption of deciduous and permanent teeth and hypo plastic teeth.

Hyperparathyroidism : Hyperparathyroidism produces increase in blood calcium. There is demineralization of bone and disruption of trabecular pattern. In growing children, interruption of tooth development occurs. The teeth may become mobile due to loss of cortical bone and resorption of the alveolar process.

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METABOLIC DISTURBANCES

Acute febrile diseases are believed to slow down +he pace of growth and development. These conditions may cause a disturbance in tooth eruption and shedding thereby increasing the risk of malocclusion.

DIETARY PROBLEMS (NUTRITIONAL DEFICIENCY)

Nutritional deficiencies during growth may result in abnormal development, causing malocclusion. Nutrition related disturbances such as rickets, scurvy and beriberi can produce severe malocclusion.

POSTURE

Poor postural habits are said to be a cause for malocclusion.

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Children who support their head by resting the chin on their hand and those who hang their head so that the chin rests against the chest ore observed to have Mandibular deficiency.

ACCIDEINTS AND TRAUMA

Children are highly prone to injuries of the dento-facial region during the early years of life when they learn to crawl, walk or during play. Most of These injuries go unnoticed and may be responsible for non-vital teeth that do not resorb and deflection of erupting permanent teeth into abnormal positions.

Etiology – LocalEtiology – Local FactorsFactorsANOMALIES OF NUMBER

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Each jaw is designed to hold only a specific number of teeth at a particular age. However, if the number of teeth present increases, or size of teeth is abnormally ige, it can cause crowding or hamper the eruption i succedaneous teeth in their ideal positions. Similarly, if the number of teeth present is less than normal then gaps will be seen in the dental arch. The anomalies in the number of teeth can be of two types (I) supernumerary teeth, (II) less number of teeth or missing teeth.

SUPERNUMERARY TEETH

Supernumerary teeth can vary remarkably size, shape and location. They may closely resemble a teeth of the group to which they belong, i.e. mimics, premolars or molars, etc

Supernumerary teeth, which bear a close resemblance to a particular group of teeth and erupt close to the original sight of these teeth, are called

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supplemental teeth. Commonly seen in the premolar region or the lateral incisor region

The most commonly seen supernumerary tooth is the “mesiodens”

Supernumerary teeth can cause

a. Non-eruption of adjacent teeth

b. Delay the eruption of adjacent teeth

c. Deflect the erupting adjacent teeth into abnormal locations

d. Increase the arch perimeter.

e. Crowding in the dental arch

MISSING TEETH

Congenitally missing teeth are far more commonly seen as compared to supernumerary teeth (true partial anodontia or hypodontia or Oligodontia)

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Certain teeth show a greater predilection to be congenita1ly missing .The most commonly

are the third molars, followed by the maxillary lateral incisors.

Congenitally missing teeth can lead to:

a. Gaps between teeth

b. Aberrant swallowing patterns

c. Abnormal tilting

d. Multiple missing teeth can cause a multitude of problems

ANOMALIES OF TOOTH SIZE

Only two anomalies of tooth size are of interest to an orthodontist-microdontia and macrodontia. The true generalized form of microdontia is rarely seen. It is usually associated with cases of pituitary dwarfism and, true generalized macrodontia, is seen

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in cases of pituitary gigantism .Most common localized microdontia involves maxillary lateral incisors. The tooth is called a ‘peg lateral”

ANOMALIES OF TOOTH SHAPE

Anomalies of tooth shape include true fusion, gemination, concrescence, talon cusp, and ‘dens in dente’. Dilaceration is also an anomaly of the tooth

a) True fusion is seen when the tooth arises through the union of two normally separated tooth germs - It might lead to spacing

b) Geminated teeth are anomalies, which arise from division of a single germ by an invagination, leading to the formation of two incomplete teeth

c)The term ‘twinning’ has been used to designate the production of equivalent structures

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d)The term concrescence refers to fusion of teeth which occurs after root formation has been completed

LABIAL FRENUM

At the birth the Labia1 frenum is attached to the alveolar same fibers crossing over and attaching with the dental papilla. As the teeth erupt, bone is deposited and the frenal attachment migrates

Superiorly with respect to the alveolar ridge. Some may persist between the maxillary central incisor

These fibers which persist between these teeth of preventing the two contra-lateral central incisor from coming into close approximation. It. Midline diastema may persist even after the “ugly duckling stage” or close simultaneously upon the amount of fibers crossing over interdentally. A midline

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diastema can exist due to various cozes and the ‘blanch test’ is used to determine the role of frenum as a causative factor.

PREMATURE LOSS OF DECIDUOUS TEETH

The permanent successor does not erupt for sometime following the loss of the deciduous tooth, during which the adjacent teeth get time to migrate in its space. This can lead to a decrease in the over all arch length as the posterior teeth have a tendency to migrate mesially. This might cause the permanent successor to erupt malpositioned or get impacted or cause a shift in the midline (in case of anterior teeth).

In case an anterior deciduous is lost prematurely, there is a tendency for spacing to occur between the erupted anterior teeth. It might also lead to a shift in the midline, towards the side where the deciduous

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Compensatory extraction for anterior deciduous tooth loss and space maintainer or the use of space regainers is highly recommended in case of the early loss of deciduous tooth

Which ever deciduous tooth may be retained beyond the usual eruption age of their permanent successor, is capable of causing:

i. Buccal/labial or palatal/lingual

deflection in its path of eruption; or

ii. Impaction of the permanent tooth

DELAYED ERUPTION OF PERMANENT TEETH

Nature has provided for a particular sequence for the eruption of individual teeth in each arch, but if one of the teeth does not occupy its designated place in this sequence there is a likelihood of migration of other teeth into the available space.

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Whatever the reasons for the delay in eruption ,it is important from a clinicians point of view to maintain and if required to create space for its eruption.

ABNORMAL ERUPTIVE PATH

Generally each tooth travels on a distinct path since its inception to the location at which it erupts. It can deviate from this eruption path because of many reasons . The tooth that most frequently erupts in an abnormal location is the maximally canine

Various reasons have been attributed for this behavior. These include:

1. Early loss adjacent primary teeth with a consequential flaring or spacing between erupted permanent teeth.

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2. Early loss of primary tooth leading to mucosal thickening over the succedaneous tooth

3. Early loss of the primary tooth might cause excessive bone deposition over the succedaneous tooth

4. Hereditary, in certain children teeth erupt much later than established norms

5. Presence of supernumerary tooth can block the erupting permanent tooth

6. Presence of odontomas or other cysts and tumors in the path of eruption

7. Presence of deciduous root fragment

8. Presence of ankylosed deciduous teeth

9. The succedaneous tooth might be congenitally missing, delaying the loss of the primary tooth

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10. In certain endocrine disorders the eruption of permanent teeth might be delayed, e.g. hypothyroidism

ANKYLOSIS

Ankylosis is a condition which involves the union of the root or part of a root directly to the bone, without the intervening periodontal membrane ,its encountered relatively frequently during the mixed dentition stage. Its seen more commonly associated with certain infections ,endocrine disorders and congenital disorders, e.g. Cleidocranial dysostosis, but these are rare occurrences.

Ankylosis should generally be suspected ,

where there is a past history of trauma, or a

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tooth has regained stability or apicoectomy

has been performed.

DENTAL CARIES

Caries can lead to premature loss of deciduous or permanent teeth thereby causing migration of contiguous teeth, abnormal axial inclination and supra-eruption of opposing teeth.

Proximal caries that has not been restored can cause migration of the adjacent teeth into the space leading to a reduction in arch length.

A substantial reduction in arch length can be expected if several adjacent teeth involved by proximal caries are left unrestored.

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IMPROPER DENTAL RESTORATIONS

a. Under contoured proximal restoration lead to a significant decrease in the arch length. Over contoured proximal restorations might bulge into the space to be occupied by a succedaneous tooth and result in a reduction of this space.

b. Overhang or poor proximal contacts may predispose to periodontal breakdown.

c. Premature contacts on over contoured occlusal restoration can cause a functional shift of the mandible during jaw closure,

d. Under-contoured occlusal restorations can lead to the supra-eruption of the opposing dentition.


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