Developmental disorders

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Chapter 5

Inherited Disorders- caused by an abnormality in the genetic makeup of an individual and are transmitted from parent to offspring through the egg or sperm

Congenital Disorder - present at birth

Embryonic Development of the face oral cavity and teeth

Face*

3^rd week of embryonic life,  enfolding of the ectoderm forms the primitive oral cavity = stomodeum

just above that is the frontal process

just below it first brachial arch = maxillary and mandibular process

Maxillary gives rise to the upper part of the cheeks and lateral portions of the upper lip and part of the palate

Mandibular – forms lower part of the cheeks, the mandible and part of the tongue

Odontogenisis – tooth development, 5^th week, primary dental lamina, ectoderm is involved

Dentogenisis = dentin formation, first mineralized part of the tooth appears, later followed by pulp formation

Enamel organ is derived from the ameloblasts = Amelogenisis

Dental papilla gives rise to  odontoblasts

Dental follicle = cementum, perio ligament , hertwigs root sheath, pdl

Ankyloglossia

Frenum is attached to the floor of the mouth,

“tongue tied”

may have speech problems

Frenumectomy = most common treatment

Commissural Lip Pits corners of the mouth, epithelial lined blind tracts

Congenital lip pits - mid line of vermilion border and can be unilateral

Incomplete fusion during developmental process

Common

Lingual Thyroid

Occurs posterior base of the tongue region, away from the normal location

Can be the only functioning thyroid tissue in patient

If not it can be removed if needed

Failure of the tissue to migrate

Tooth Abnormalities

Hyperdontia – too many teeth

Hypodontia – to little teeth

Anodontia – no teeth, rare,

Hereditary ectodermal displasia -  inherited disease, deciduous or permanent may be affected

Most commonly missing – (permanent) third molars, lateral incisors, mandibular 2^nd premolar 

Causes – trauma, radiation,

Primary – maxillary laterals

Missing teeth require prosthetic replacement

Hypodontia –partial Anodontia

Always get a radiograph to make sure tooth is not impacted

Supernumerary teeth – extra teeth found in the dental arches

Either from formation of extra tooth buds in the dental lamina or from the cleavage of already existing tooth buds

Mesiodens – most common supernumerary

Rarely have odd shape, size, often impacted

2^nd most common- distomolar- distal to the third molar

treatment – extraction if necessary

Natal teeth –‘ prediciduous teeth” come in before deciduous dentition, born with them,  not common,

Abnormalities in the size of teeth

Microdontia – one or more teeth are smaller then the normal,  usually incisors, and third molar,

Peg Lateral – very common

True generalized Microdontia – teeth are really small, like in midgets, dwarf, extremely rare

Generalized relative microdontia- teeth are not really small but they are small compared to the jaw, 

Microdontia involving a single tooth – more common then the rest

Can be restored with bonding if necessary for cosmetic reasons

Macrodontia

Uncommon

One or more teeth are larger

True generalized Macrodontia – Puberty gigantism

Relative generalized macrodontia – small jaws

Macrodontia single tooth – uncommon

Facial hemihypertrophy – enlargement of half of the head with enlarging teeth involving one side

Abnormalities in the shape of the teeth

Gemination – geminate means paired or occurring

Not truly a macrodontia

Teeth under going an incomplete twin process

Something stimulated tooth bud to separate

Two crowns, one root

Mainly effects anterior teeth notched incisal area

Full complement of teeth

Poses an esthetic problem

Alteration of the tooth so it resembles a normal tooth

FUSION

***************************Exam ****question************

Different from gemination because it has 2 roots,

Union of two normally separated adjacent tooth germs

1 less tooth in dentition, ( merges together) *** count the teeth

fusion can be complete or incomplete

complete- confluence of dentin

not easy to differentiate between gemination**

History from patient, good chart keeping, Radiographs will help you decide

Keep eye on it

CONCRESCENCE

2 adjacent teeth are united by cementum only

takes place after tooth formation is complete

type of fusion

discovered on radiographs

cause: crowding or trauma, close approximation of adjacent teeth

looks like two roots stuck together, not real common

DILACERATION

Curvature

Angle in root

Due to trauma during development

Discovered by radiographs

May be difficult to extract if necessary

Enamel Pearl

Enameloma

Root surface******, usually at the bifurcation, usually max. molars, complicates periodontal treatment

Not just enamel, can be enamel and dentin or pulp

Can not scrap it off*******

TALON CUSP

Accessory cusp located in the area of the cingulum of a maxillary or mandibular permanent incisor

CLAW***

Has its own pulp horn,

Like extra tooth that grows

Problems with occlusion

Pushed facially or buccally( tooth it affects)

Treatment for occlusial reasons: root canals and major work

TAURODONTISM

Elongated, enlarged pulp cavities with short roots

“ bull like teeth”

apically displaced furcation

\uncommon

cause may be implicated to heredity, emelogenisis imperfection

deciduous or permanent dentition,

teeth can have a pyramidal shape

GIVE AWAY:** Furcation is near the apices of the molar

No treatment need

DENS IN DENTE

DENS INVAGINATUS

A tooth in a tooth

Seen radiographically

Tooth may look like it has a deep pit in the cigulum

Max. Lateral( most common)**

Problem for endo

These teeth turn out to be non vital

No treatment needed

Enamel organ invaginates into the crown prior to crown formation

Sealants may help

DENS EVANGINATUS

Accessory cusp on occlusal surface

Tuberculated premolar, mand. Premolar

Out pouching with its own pulp horn

TREATMENT:  endodontic if necessary

Sealants******

SUPERNUMERARY ROOTS

Extra roots

External pressure, trauma, metabolic dysfunction during root development

Root formation after birth

Maxillary and mand third molars

No treatment necessary

Enamel Hypoplasia

Incomplete formation of enamel

Alteration of tooth form or color

Disturbance to the ameloblast

Numerous factors:

Amelogenisis Imperfecta – inherited enamel hypoplasia

Febril illness fever 102degrees – ( chicken Pox, scarlet, measles) ( 1^st year of life)  usually

Vitamin Deficiency A<C<D

Local Infection -

Ingestion of fluoride

Congentital syphilis

Birth injury, premature birth

Idiopathic factors

Enamel Hypoplasia caused by Febril Illmess or Vitamin Deficiency

Pitting of the Enamel

Only crowns that are developing at the time of the febril illness are effected

Usually involves : Perm. Central Incisors, laterals cuspids, and first molars

These pits tend to be stained

They may be restored with composites or veneers

Local Illness or Trauma

Turners tooth – result of a deciduous tooth infection with periapical pathology,

Whenever you see periapical pathology on deciduous teeth it is grounds for EXTRACTION

Turners tooth erupts that way, yellow brown in color,pitting

From the inflammatory process destroying the tooth

Fluoride Ingestion

Permanent teeth will be decay resistant, but they will not all look nice and white

Irregular areas of discoloration, and mottling

Increase concentrations of fluoride

Ideal .2-1.2 parts

2-3 times that  mild Fluorosis

whiter areas on teeth,

4 times that number  brown  black stain and pitting( decay resistant but ugly)

Congenital Syphilis – mulberry molars or Hutchinson incisors, screw driver like incisors ( permanent Incisors and First Molars)

Esthtics< depending on how bad the notching is

Molars sealants***

BIRTH INJURIES

Anything that can happen in development can hurt your teeth

Premature*,

Regional Odonodysplasia

Look like GHOSTS,

Very thin enamel, and dentin, huge pulp chamber

Teeth may not develop

It can erupt, usually not fuction

Enamel Hypocalcification

Disturbance of the enamel matrix

Chalky white appearance middle third of smooth crowns

ESTHETICS

Impacted – CAN NOT erupt b/c of PHYSICAL OBSTRUCTION

EMBEDDED – DO NOT ERUPT lack of eruptive force

ANKYLOSED TEETH

Or submerged teeth deciduous teeth in which bone has fused to cementumand dentin

Deciduous molars mostly effected

Trauma and infection of PDL have been suggested

Extraction usually necessary to prevent maolocclusion of permanent teeth