Chapter 6: Genetics

Genetics

The inheritance and expression of inherited traits 

Syndrome

A distinctive association of signs and symptoms occurring together 

Phenotype

The physical, biochemical, and physiologic traits of an individual 

Genes

The hereditary units transmitted from one generation to another 

What is another name for Trisomy 21?

• Down Syndrome 

• Have an extra chromosome (47 instead of 46) 

What are the oral signs associated with Trisomy 21? 

• Fissured tongue

• Gingival and periodontal disease

• Hypodontia

• abnormally shaped teeth,

• Macroglossia (large tongue) 

Define Cyclic Neutropenia

a cyclic decrease in the number of circulating neutrophils

What are some oral signs of cyclic neutropenia ?

• Severe ulcerative gingivitis

• Gingivostomatitis

•  Ulcerations on tongue and oral mucosa

• Repeated episodes lead to sever periodontal disease

Define Papillon-Lefèvre Syndrome

• Peripheral blood neutrophils are depressed

• Hyperkeratosis of the palms of the hands and soles of the feet 

What can happen to primary and/or permanent teeth with Papillon-Lefèvre Syndrome?  

primary and permanent dentition are lost prematurely 

Gingival Hyperkeratosis

• hyperkeratinization of labial and lingual gingiva
• bandlike and a few millimeters wide

Gingival Fibromatosis

• results from the marked
  collagenization of the fibrous
  connective tissue

•  Composed of very firm tissue
  with a granular corrugated
  surface

Define Garline Syndrome

• Characterized by osteomas in various bones 

• Osteomas of the facial skeleton will obliterate the sinuses and cause 
  facial asymmetry 

•  Multiple odontomas can occur in jawbones 

Define Gorlin Syndrome

• Characterized by: Mild hypertelorism (increased distance between the eyes) 

• Multiple cyst of the jaw, Broad nasal root 

What is maxillary exostosis?

a benign bony growth that projects outward from the surface of a bone 

Where does maxillary exostosis occur?

on the buccal aspect of the maxilla 

How does a cleft palate occur?

when the palatal shelves fail to fuse with the primary palate 

How does a cleft lip occur? 

when the maxillary and medial nasal processes fail to fuse 

Osteogenesis Imperfecta 

• Mutations occur that affect collagen, resulting in abnormally formed bones that fracture easily 

• Teeth appear opalescent or translucent but darken with age 

•  Enamel is lost  

Amelogenesis Imperfecta

• inherited conditions characterized by defects in the formation of enamel 

• Multiple pits on the labial surface of the teeth 

Dentinogenesis Imperfecta

• affects the formation of dentin 

•  opalescent dentin 

•  No pulp chambers or root canals are seen 

Dentin Dysplasia Type I

Radicular

•  The teeth have normal crowns and
  abnormal roots

• blunted and short tooth roots

• pulp chambers have a half-moon appearance

•  The teeth are generally exfoliated prematurely

Dentin Dysplasia Type II

Coronal

•  Primary teeth are translucent with an amber color

•  Adult teeth appear normal

•  No coronal pulp chambers with small root canals