Oral Anatomy & Histology (Review: Outcome 14) Flashcards
Role of the DA - Tooth Anomalies
- Recognition of anomaly
- Patient education
- Treatment considerations
Types of Developmental Disorders
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
Disturbances in Jaw Development
- 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
Disturbances in lip, palate, and tongue development
- 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
Tooth Anomalies
- Stage of development
- Length of effect
- Hereditary or environmental cause
- More often in permanent dentition
Etiology of Anomalies
Stages of development
1. Initiation
2. Proliferation
3. Histo-differentiation
4. Morpho-differentiation
5. Apposition
6. Maturation
Abnormal number of teeth
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
Anodontia (Hypodontia)
Partial or complete absence of teeth
Commonly include:
- permanent third molars
- maxillary lateral incisors
- mandibular second premolars
Hyperdontia
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
Abnormal size
- 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
Macrodontia
- Abnormal increase in tooth size
- Childhood hyperpituitarism (gigantism) can cause
Microdontia
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
Abnormal Shape
- Later stages of tooth development
- Proliferation and morphodifferentiation processes
- Can present as abnormal crown or root shape
Dens in Dente
- Cap Stage
- Enamel organ invaginates into the dental papillae
- Commonly affects permanent lateral incisor
Cause: Hereditary factors
Gemination
- 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
Fusion
- 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
Tubercle
- 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
Enamel Pearl
- Apposition and Maturation Stage
- Sphere of enamel on root
Cause:
- displacement of ameloblasts to root surface
Hypercementosis
- 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
Concrescence
- 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
Root Formation
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
Structural Anomalies
- Resulting from disturbances in enamel and dentin formation
- Apposition and Maturation Stages
- Enamel or dentin dysplasia
Enamel Dysplasia
- Results from a reduction in the quantity of enamel matrix
- Teeth appear with pitting and intrinsic colour changes in enamel
Amelogenesis Imperfecta
- 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
Dental Fluorosis
- 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
Turner’s Teeth
- 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
Hutchinson’s Incisors
- Abnormally shaped permanent front teeth (incisors)
- Usually associated with congenital syphilis (treponema palladium)
Mulberry Molars
First molar tooth whose occlusal surface is pitted due to congenital syphilis with nodules replacing the cusps
Dentin Dysplasia
Faulty development of dentin
Dentinogenesis Imperfecta
- 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
Tetracycline Staining
- 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
Odontoma
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
Complex odontomas
When the calcified dental tissues are simply arranged in an irregular mass bearing no morphologic similarity to rudimentary teeth
Compound odontomas
Composed of all odontogenic tissues in an orderly pattern that results in many teeth-like structures but without morphologic resemblance to normal teeth
Ameloblastoma
A tumor composed of remnants of dental lamina
Degeneration Changes
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
Bruxism
- 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
Orofacial piercings
- 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
Abnormal eruption of teeth
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
