Teeth Development

Question 1

Disturbances in size

• Microdontia
• Macrodontia

Answer 1

Microdontia - Small

Macrodontia - Large (Don’t confuse with fusion)

Question 2

Gemination

Answer 2

Attempted division of tooth germ with incomplete formation of 2 teeth, usually single root.

Question 3

Fusion

Answer 3

Union of two tooth germs by dentin. Often with individual roots.

Question 4

Concrescence

Answer 4

Form of fusion where teeth joined by cementum, ↑↑ MxMs

Question 5

Dilaceration

Answer 5

Bend or curve in tooth or root

Possibly due to trauma

Problems with RCT or extraction

Question 6

Dens‑in‑dente

(Dens invaginatus)

Answer 6

“tooth within a tooth”

invagination in enamel organ before calcification

↑↑ MxLa I, can be bilateral

sequela of periapical infection

prophylactic restoration of pit

Question 7

Dens evaginatus

Answer 7

tooth-like structure in central fossa. ↑↑ MdBis, may contain pulp tissue

• interferes with occlusion and there is often a pulp horn inside the projection

Question 8

Taurodontism

Answer 8

block-shaped teeth with large pulps (“bull-like teeth”)

Elogated pulp chambers

one or multiple teeth

isolated (phenotypic expression of gene pool) or with syndromes,

esp. Klinefelter’s Syndrome (polyploidy of X chromosome, eg XXXY)

Question 9

Enamel Pearl

Answer 9

Excess of enamel at bi or trifurcation of molars at CEJ

Question 10

Oligodontia / Anodontia

Answer 10

A few or no tooth development

Anodontia invariably associated with systemic problem, most common, hereditary ectodermal dysplasia - if missing most teeth

evolutionary trend toward fewer teeth

Oligodontia - a few teeth

Anodontia - no teeth

Question 11

Supernumerary teeth

Answer 11

extra teeth

90% in Mx

_**Mesiodens_, between MxCeIs, most common

1. Gardner’s Syndrome (see also Bone, Neoplasms)

Often die of colon cancer

2. Cleidocranial Dysplasia

Question 12

Disturbances in structure

Enamel - Amelogenesis imperfecta

Answer 12

Hereditary

Amelogenesis imperfecta (Hereditary) (inherited defect of ameloblast)

autosomal dominant, recessive, sex-linked

12 - 15 types

clinically produces hypoplasia (quantitative defects)

hypocalcification

hypomaturation

Hereditary Environmental

All teeth Some teeth

Both dentitions One dentition

Family history No family history

Question 13

Disturbances in structure

Enamel -

Environmental enamel defects

Hypoplasia / Hypocalcification

Answer 13

(1) Rickets
(2) Exanthematous diseases - often viral diseases affecting epithelium
(3) Congential Syphilis
a. Hutchinson’s incisors
b. Mulberry molars
(4) Turner’s tooth - Local infection or trauma
(5) Fluorosis - Mottled enamel, generalized, > 1ppm discoloration due to other elements, ie Fe
(6) Tetracycline
(7) Idiopathic

Question 14

Disturbances in structure

Dentinogenesis Imperfecta

Answer 14

Dominantly inherited genetic defect of dentin independent or with osteogenesis imperfecta (due to mutation of dentin sialophosphoprotein DSPP) both dentitions, all teeth affected, mom or dad should have this. Autosomal dominant.

osteogenesis imperfecta - brittle bones ± blue sclerae ± DI (not mediated through DSPP)

Teeth - grayish to yellowish-brown, translucent, enamel fractures from dentin (lacks scalloping), exposed dentin prone to attrition

Radiographic findings: Obliteration of pulp chambers and canals ± attrition, ± root fractures

Treatment: Crowns to prevent attrition

Question 15

Disturbances in structure

Dentinal dysplasia

Answer 15

Autosomal dominant condition characterized by pulpal obliteration with abnormal dentin, defective root formation and tendency for periapical pathology.

Clinically affects all teeth and both dentitions but teeth clinically appear normal

Radiographic findings: Obliteration of pulp, short underdeveloped roots, periapical radiolucencies

Question 16

Disturbances in structure

Enamel and Dentin

Regional Odontodysplasia

Answer 16

(Ghost teeth) - Anomaly of unknown etiology, affecting several teeth in one region of jaws.

Mostly affects permanent teeth, ↑↑ Mx, unerupted

Radiographic findings: Anomalous teeth often with very thin shell of enamel and dentin

Question 17

Disturbances in structure

Disturbances in Eruption

Embedded teeth

Impacted teeth

Ankylosed teeth

Answer 17

Embedded teeth (pseudoanodontia) - Teeth lack eruptive force

• If generalized, suspect systemic cause, ie hypothyroidism

Impacted teeth - Teeth unerupted because of mechanical (tooth) obstruction

• ↑Md3M, MxCa

Ankylosed teeth - Tooth roots fused to bone, often in primary teeth with underlying succedaneous permanent tooth missing

• Distinctive percussion