Oral Anatomy & Histology (Review: Outcome 14)

Question 1

Role of the DA - Tooth Anomalies

Answer 1

• Recognition of anomaly
• Patient education
• Treatment considerations

Question 2

Types of Developmental Disorders

Answer 2

i. Inherited disorders are different from developmental disorders because they are caused by an abnormal gene
- a congenital disorder is one that is present at birth
- either inherited or developmental; however, exact cause of most congenital abnormalities is unknown

ii. Genetic factors
- malformations that are often the result of genetic factors such as chromosomal abnormalities

iii. Environmental factors
- called teratogens; include infections, drugs, and exposure to radiation

Question 3

Disturbances in Jaw Development

Answer 3

• Macrognathia
• Micrognathia
• Exostoses: a benign bony growth projecting outward from the surface of a bone
• Torus palatinus: a bony overgrowth at the midline of the hard palate
• Torus mandibularis: a bony overgrowth on the lingual surface of the mandible

Question 4

Disturbances in lip, palate, and tongue development

Answer 4

• Cleft lip: results when maxillary and medial nasal processes fail to fuse
• Cleft palate: results when palatal shelves fail to fuse with primary palate
• Cleft uvula: mildest form of cleft palate
• Ankyloglossia: often called tongue-tie; results in a short lingual frenum that extends to the apex of the tongue

Question 5

Tooth Anomalies

Answer 5

• Stage of development
• Length of effect
• Hereditary or environmental cause
• More often in permanent dentition

Question 6

Etiology of Anomalies

Answer 6

Stages of development
1. Initiation
2. Proliferation
3. Histo-differentiation
4. Morpho-differentiation
5. Apposition
6. Maturation

Question 7

Abnormal number of teeth

Answer 7

i. Initiation stage
ii. Lack of initiation within the dental lamina
- absence of a single tooth or an entire dentition
iii. Associated with:
- ectodermal dysplasia
- endocrine dysfunction
- systemic disease
- radiation

Question 8

Anodontia (Hypodontia)

Answer 8

Partial or complete absence of teeth

Commonly include:
- permanent third molars
- maxillary lateral incisors
- mandibular second premolars

Question 9

Hyperdontia

Answer 9

Supernumerary tooth or teeth

Commonly found:
- between permanent maxillary incisors
- distal to third molars

Cause:
- Hereditary

• Mesiodens
• Small extra central incisor
• Erupts between two centrals

Question 10

Abnormal size

Answer 10

• Bud stage of the development (Proliferation)
• Abnormal proliferation of the tooth bud can cause a single tooth or multiple teeth or an entire dentition to be larger or smaller than usual
• Generally genetic with partial
• Endocrine dysfunction associated with complete

Question 11

Macrodontia

Answer 11

• Abnormal increase in tooth size
• Childhood hyperpituitarism (gigantism) can cause

Question 12

Microdontia

Answer 12

Complete Microdontia - Rare
- all teeth small
- associated with Hypopituitarism or Down’s Syndrome

True Partial Microdontia
- hereditary factors involved
- commonly affects the permanent maxillary lateral incisors and permanent third molars

Question 13

Abnormal Shape

Answer 13

• Later stages of tooth development
• Proliferation and morphodifferentiation processes
• Can present as abnormal crown or root shape

Question 14

Dens in Dente

Answer 14

• Cap Stage
• Enamel organ invaginates into the dental papillae
• Commonly affects permanent lateral incisor

Cause: Hereditary factors

Question 15

Gemination

Answer 15

• Cap stage
• Tooth germ tries to divide and develops a large single-rooted tooth with one pulp cavity and “twinning” in the crown of anterior teeth
• Correct number of teeth will be present
• Unsuccessful attempt is indicated by an incisal notch

Cause: Hereditary

Question 16

Fusion

Answer 16

• Cap Stage
• Union of 2 adjacent tooth germs
• Results in a large tooth with 2 pulp cavities
• One fewer tooth in the dentition
• Common on anteriors in primary dentition

Cause: pressure

Question 17

Tubercle

Answer 17

• Cap stage
• Small rounded enamel extension
• Commonly found on posterior occlusal surface or anterior lingual surfaces

Cause:
- trauma, pressure or metabolic disease affecting the enamel organ

Question 18

Enamel Pearl

Answer 18

• Apposition and Maturation Stage
• Sphere of enamel on root

Cause:
- displacement of ameloblasts to root surface

Question 19

Hypercementosis

Answer 19

• Refers to the excess deposition of cementum on root surfaces
• A variety of local and systemic factors have been associated: trauma, inflammation, supraeruption, pituitary gigantism, arthritis, calcinosis, Paget’s disease, rheumatic fever and goiter
• Occurs predominantly in adults and an increased frequency is seen with increasing age
• May cause concrescence

Question 20

Concrescence

Answer 20

• Apposition and Maturation Stage
• Union of the root structure of two or more teeth by cementum
• Commonly affects the permanent maxillary molars

Cause:
- traumatic injury or crowing of the teeth

Question 21

Root Formation

Answer 21

i. Dilaceration - results in a distorted root of severe crown angulation (caused by injury or pressure during tooth development)

ii. Flexion - a deviation or bend restricted to just the root

iii. Accessory roots - due to trauma, pressure or metabolic disease that effects HERS (Hertwig’s epithelial root sheath) during root development

Question 22

Structural Anomalies

Answer 22

• Resulting from disturbances in enamel and dentin formation
• Apposition and Maturation Stages
• Enamel or dentin dysplasia

Question 23

Enamel Dysplasia

Answer 23

• Results from a reduction in the quantity of enamel matrix
• Teeth appear with pitting and intrinsic colour changes in enamel

Question 24

Amelogenesis Imperfecta

Answer 24

• Type of enamel hypoplasia/dysplasia
• Hereditary etiology
• Can affect all teeth of both the primary and permanent dentitions
• Teeth have very thin enamel that chips off or have no enamel at all (crowns are yellow)
• Varies in severity
• Hereditary enamel hypoplasia is a type of amelogenesis imperfecta that is characterized by teeth with crowns that are hard and glossy, yellow, and cone-shaped or cylindrical

Question 25

Dental Fluorosis

Answer 25

- A change in the appearance of the tooth's enamel - Can vary from barely noticeable white spots in mild forms to staining and pitting in the more severe forms - Only occurs when younger children consume too much fluoride from any source over long periods when teeth are developing under gums

Question 26

Turner's Teeth

Answer 26

- Hypoplasia of the enamel involving a single permanent tooth - If found on a canine or a premolar, the most likely cause is an infection that was present when the primary tooth was still in the mouth - If found in the anterior area of the mouth, the most likely cause is a traumatic injury to a primary tooth

Question 27

Hutchinson's Incisors

Answer 27

- Abnormally shaped permanent front teeth (incisors) - Usually associated with congenital syphilis (treponema palladium)

Question 28

Mulberry Molars

Answer 28

First molar tooth whose occlusal surface is pitted due to congenital syphilis with nodules replacing the cusps

Question 29

Dentin Dysplasia

Answer 29

Faulty development of dentin

Question 30

Dentinogenesis Imperfecta

Answer 30

- Hereditary basis - Results in blue-gray or brown teeth with an opalescent sheen - Enamel appears as usual but chips off due to lack of support from the abnormal underlying dentin - Results in severe attrition - Teeth that have dentiogenesis imperfecta are opalescent and have an almost amber color

Question 31

Tetracycline Staining

Answer 31

- Incorporation into dentinal tissue that is calcifying at the time of administration - Antibiotic becomes chemically bound to the dentin for the life of the tooth and because of the transparency of enamel, it is visible - Permanent discoloration varies from yellow or gray to brown depending on the dose or the type of drug received in relation to body weight

Question 32

Odontoma

Answer 32

Etiology is unknown - local trauma - inflammatory and/or infectious processes - dental lamina remnants - hereditary anomalies - odontoblastic hyperactivity - alterations of the genetic component responsible for controlling dental development

Question 33

Complex odontomas

Answer 33

When the calcified dental tissues are simply arranged in an irregular mass bearing no morphologic similarity to rudimentary teeth

Question 34

Compound odontomas

Answer 34

Composed of all odontogenic tissues in an orderly pattern that results in many teeth-like structures but without morphologic resemblance to normal teeth

Question 35

Ameloblastoma

Answer 35

A tumor composed of remnants of dental lamina

Question 36

Degeneration Changes

Answer 36

i. Attrition - wearing down of incisal/occlusal - frictional contact - grinding/occlusion ii. Abrasion - mechanical wearing away of tooth - buccal/lingual surface - recession - toothbrush abrasion iii. Abfraction - V-shaped notches in dentin - confused with abrasion - shear and tensile stresses - CEJ - slight flexion iv. Erosion - chemical wearing away - dissolving enamel

Question 37

Bruxism

Answer 37

- Oral habit consisting of involuntary gnashing, grinding, and clenching of the teeth in movements other than chewing - usually occurs during sleep and is commonly associated with stress or tension

Question 38

Orofacial piercings

Answer 38

- Have become popular among some segments of the population - Dental complications include: chipped and broken teeth, serious infections at the sites of piercings - Infection can spread throughout the head and neck area, with serious results

Question 39

Abnormal eruption of teeth

Answer 39

i. Premature eruption - teeth are present at birth - neonatal teeth are those that erupt within the first 30 days of life ii. Ankylosis - in deciduous teeth affected by ankylosis, bone has fused to cementum and dentin, preventing exfoliation iii. Impaction - occurs when any tooth remains unerupted in the jaw beyond the time at which it should normally erupt