developmental disturbances of the oral region 15

8/2/2019 Developmental Disturbances of the Oral Region 15

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Developmental disturbances of

the oral regionDevelopmental disturbances of the oral region arediscussed under three categories:

1- disturbances affecting teeth

2- disturbances limited to soft tissue

3- disturbances affecting bone.


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Disturbances affecting the teeth

A -Disturbances in the size: 1- Microdontia: Mean tooth or teeth smaller than the normal, either localized or

generalized.

In generalized its either true or relative:

True: small teeth with normal size jaw bone & this occur in dwarfism. Relative: the jaw bone is larger than normal which lead to spacing

between teeth giving picture of false microdontia.

*in localized microdontia, usually one tooth affected & mostly in lateralincisor (peg lateral) & max third molar.


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2- macrodontia:

Mean tooth or teeth larger than the normal, it may be generalized orlocalized

In generalized its either true or relative

True: large teeth in normal jaw bone size, occur in Giantism.

Relative: normal teeth in small size jaw, cause crowding of teeth &

give false picture of macrodontia.

*in localized macrodontia, usually affect one side of jaw such inhemifacial hypertrophy.


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B- Disturbances in number:

1- Anodontia: Complete absence of teeth (deciduous & permanent)

It usually occurs in association with a generalized disorder such ashereditary ectodermal dysplasia. Therefore, all tissues derived fromectoderm are absent such as teeth, hair follicle, sweat gland,

sebaceous gland. The patient suffer from smooth, thin & dry skin, cant tolerate heat due

to absence of sweat glands.

However, sometimes some teeth are present such as cuspids &molars


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2- Hypodontia: (partial anodontia)

Mean congenital absence of one or more teeth.

Although any tooth can be congenitally absent, but the most commonare the 3rd molars, followed by the max, lateral incisors & the 2ndpremolars

Familial tendency for congenitally absent teeth is recognized.

3- Supernumerary teeth:

Teeth in excess of the normal number They are more common in max, than in the mand

A supernumerary tooth located between max, central incisors referred toas a mesiodens. The 4th molar called paramolar.

A supernumerary tooth may resemble the corresponding normal tooth,

or it may be smaller or conically shaped, bearing little or no resemblanceto its normal counterpart.

Supernumerary teeth may be single or multiple & erupted or impacted

Multiple supernumerary teeth, which are generally impacted, arecharacteristically seen in Cleidocranial dysplasia.


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C- Disturbances in eruption:

1- Premature eruption:

Teeth erupt earlier than its normal eruption time

Usually involves only one or two teeth, most commonly the deciduousmand, central incisors, & usually are part of the normal complement ofdeciduous teeth, they are not supernumerary tooth & should therefore beretained if possible.

We have 2 types:

Natal teeth: deciduous teeth present at birth

Neonatal teeth: deciduous teeth that erupt during the 1st 30 days of life.


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2- Delayed eruption:

Teeth fail to erupt at its normal time & it may be associated with:

Systemic conditions like, Cleidocranial dysplasia, cretinism & rickets.

Local conditions like, gingival fibromatosis, insufficient space in the dentalarch, abnormal position of tooth germ, & supernumerary teeth whichprevent eruption of original one.

3- Impacted teeth:

Teeth that continue to form within bone but fail to erupt, the causes same

that of delayed eruption

We have 3 types:

*complete impaction: impacted tooth that is totally surrounded by bone

*partial impaction: the tooth partly in bone & partly in soft tissue

*retained (embedded) tooth: teeth that fail to erupt due to unknown reason 4- Eruption sequestrum:

This occurs as small spicule of bone that is extruded through the alveolarmucosa that overlies an erupting molar.


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D- Disturbance in shape

1- Dilaceration: A sharp bend or angulation of the rootportion of a tooth. Cause difficulty in extraction & rootcanal therapy.

2- Taurodontism: A molar with an elongated crown &apically placed furcation of the roots, resulting in anenlarged rectangular coronal pulpal chamber, (bull like)teeth.

There is no constriction at the area of crown & root

(cementoenamel junction).

3- Dens invaginatus: A focal area of the crown of amax, lateral incisor is folded inward (invagination) whichlead to small opening & accumulation of food debris,then caries. Sometimes this condition called dens in

dentin which mean tooth inside the tooth. 4- Dens evaginatus: Is a developmental abnormality

that primarily affects premolars. Its characterized by thedevelopment of an abnormal nodular or globe-shapedprojection appearing as an extra cusp centrally locatedon the occlusal surface between the buccal & lingual

cusps of premolars, although any tooth may be involved


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5- Talon cusp: A form of supernumerary cusp,typically seen on the lingual aspect of max, incisors, iscalled a talon because its resembles an eagles talon.

6- supernumerary roots: Additional roots, more thanthe expected number, are termed supernumeraryroots. This is common in mand, premolars & cuspids.

7- Gemination: Is a developmental anomaly thataffects anterior teeth, they result from partial divisiontwinning of a single tooth germ, resulting in a tooth

with two separated or partly separated crowns & asingle root & root canal.

8- Fusion: Result from the union of two normallyseparated tooth germs, it can be complete orincomplete.

* we can differentiate between gemination & fusionclinically by counting the teeth in each arch, if onetooth is missing mean fusion, but if with normalnumber mean gemination.


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9- Concrescence: Is a type of fusion of two teeththrough cementum. The condition is thought to occur asa result of traumatic injury to the area or crowdingwhere interseptal bone is lost, allowing close

proximation of the tooth roots. 10- Hypercementosis: Excess cementum at the root

area (usually at the apex) & known as bulbous root.

11- Cervical enamel projection: A focal apicalextensions of the coronal enamel beyond the cervical

margin (cementoenamel junction) & onto the root of thetooth.

Their clinical significant is that they could contribute toperiodontal pocket formation.

12- Enamel pearls: Globular droplets of enamel thatpresent usually at the bifurcation or trifurcation area ofthe molars; its also called Enameloma.

developmental disturbances of the oral region 15

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