Year 1 Flashcards
Describe the basics of tooth embryology
- Dentine is formed by cells called odontoblast
- Enamel is formed by cells called ameloblast
- Initially; (Ameloblast) | (Odontoblast)
- | = amelodentinal junction; the site of the future enamel-dentine junction (EDJ)
- Ameloblast is lost before the teeth erupts
- Odontoblast continue to produce dentine through out life
Describe the basic anatomy of tooth
Clinical crown; 1. Enamel 2. Contour lines 3. Dentin Anatomical crown; 1-3 4. Gingival crevice (sulcus) 5. Epithelium 6. Attachment epithelium Root; 7. Pulp 8. Odontoblast 9. Alveolar bone 10. Periodontal ligament 11. Noncellular and cellular cementum 12. Apical foramen
Describe properties of enamel
- Covers anatomical crown
- 96% hydroxyapatite crystals
- 4% proteins and water
- Hardest calcified matrix of the body (also very brittle)
- Incapable of renewing itself and repair (acellular)
- Insensitive
Describe the properties of dentine
- Hard tissue portion of pulp-dentine complex
- Forms bulk of tooth
- Characterised by multiple closely packed dentinal tubules that transverse it’s entire thickness
- Contains cytoplasmic extension of odontoblast
- 65-70% hydroxyapatite
- 20-25% organic material (collagen and glycoproteins)
- 10% water
- Capable of repair by odontoblast
- Sensitive
State the order of deciduous teeth eruption (including dates)
Man central incisor (6.5) > Man lateral incisor (7) > Max central incisor (7.5) > Max lateral incisor (8-9) > Second molars (10-12) > First molars (12-16) > Canines (16-20)
State the order of permanent teeth eruption (including dates)
First molars (6-7) > Man central incisor (6-7) > Max central incisor (7-8) > Man lateral incisor (7-8) > Max lateral incisor (8-9) > Man canine (9-10) > Max first premolar (10-11) > Man first premolar (10-12) > Max second premolar (10-12) > Man second premolar (11-12) > Max canine (11-12) > Man second molars (11-13) > Max second molars (12-13) > Third molars (17-21)
Compare deciduous and permanent teeth
Deciduous teeth:
- Are smaller (except E)
- Have a whiter and more opaque enamel
- Have crown that is lighter in colour
- Have anterior teeth that are more bulbous
- Have more pointy cusps
- Have shorter roots, less stronger and lighter in colour
- Have anterior teeth with roots that are longer than their crown
- Have posterior teeth with more divergent roots
- Have smaller pulp chambers
- Have enamel that bulges at cemento-enamel junction
- Fissures are shallower
- Do not have premolars
How many root(s) and root canal(s) does each tooth has?
- Max/Man central incisor; 1 : 1
- Max/man lateral incisor; 1 : 1
- Max/man canine; 1 : 1
- Max first premolar; 2 : 2
- Max second premolar; 2 : 1/2
- Man premolars; 1 : 1
- Max first molar; 3: 3
- Max second molar; 3 :3
- Man first molar; 2 : 2/3
- Man second molar; 2 : 2/3
What is the difference between x-ray and radiographs?
X-ray is the process in which radiographs are produce. Thus radiograph is the film we obtain from the process.
What do radiolucency and radiopacity indicate?
Radiolucency indicates that x-ray can pass through easily thus producing blackening.
Radiopacity indicates x-ray is absorbed producing no or little blackening.
What determines how many x-rays are absorbed by a material or tissue?
- Atomic number (the bigger the size of the atom the more x-ray they absorb)
- Density
- Thickness
How do tooth structures appear on a radiograph?
- Enamel is highly calcified: high radiopacity
- Dentine is less calcified: lower radiopacity than enamel
- Pulp not calcified: high radiolucency
- Periodontal ligament is made of tissues: high radiolucency
What is the purpose of bitewing radiograph?
- For caries diagnosis
2. For showing periodontal bones
What is the purpose of periapical radiograph?
For periapical diagnosis (around the root apex)
What are the types of extra oral imaging and their respective purposes?
- Panaromic radiograph: shows entire dentition. It’s main uses are;
a) to identify large or remote abnormalities that are not suitable for seeing on intraoral radiographs
b) to identify the presence and position of developing teeth for patients with need for orthodontics - Cephalometric radiograph: shows dentition and skull. For patients with both dental and skeletal problems
- Cone beam computed tomography (CBCT): shows 3D view of dentition
What are errors in development of teeth?
- Hyperdontia: extra teeth
2. Hypodontia: missing teeth
What is the oral mucosa?
Oral mucosa is the moist mucous membrane lining the mouth. It consists of;
- Epithelium containing glands secreting mucous
- Underlying connective tissues (lamina propria)
- Muscularis mucosa
What are the roles of the oral mucosa?
- Mechanical protection from compression and shearing forces
- Barrier to microorganism, toxins and antigen
- Immunological defence
- Glands for lubrication, buffering and antibody secretion
- Rich innervation for touch, proprioception, pain and taste
- Entry of food
- Mastication
- Deglutition (swallowing)
- Speech (modification of sound)
What are the 3 types of oral mucosa?
- Masticatory mucosa
- Lining mucosa
- Specialised mucosa
What is masticatory mucosa and where would you find it?
Keratinised stratified squamous epithelium with a thick lamina propria usually bound to an underlying bone. It covers structures like;
- Hard palate
- Gingival mucosa
- Dorsum of tongue (not sure)
What is lining mucosa and where can you find it?
Non keratinised stratified squamous epithelium with a loose lamina propria and often a sub mucosa. The sub mucosa is made up of dense irregular connective tissue which contains blood vessels, nerves, minor salivary gland and fat. It covers structures like;
- Cheeks
- Lips
- Alveolar mucosa
- Floor of mouth
- Ventral surface of tongue
- Soft palate
What is specialised mucosa and where is it found?
Non keratinised thin epithelium (shows short papilla). It covers specialised gustatory mucosa on the dorsum surface of tongue.
State the boundaries of the oral cavity?
It extends from oral fissure to pharynx.
a) Roof: hard and soft palate
b) Wall: alveolar arches and their teeth
c) Floor: tongue
Define the following;
- Free gingiva
- Attached gingiva
- Interdental papilla
- Mucogingival junction
- Labial frenulum
- Lies unattached around cervical region of teeth
- Tightly adheres to the bone around roots of teeth
- Extension of the attached gingiva that fills the space between adjacent teeth
- Demarcation between firm, pink attached gingiva and moveable, red alveolar mucosa
- Fold of tissue on the midline that links labial mucosa and alveolar mucosa
What are the four basic types of tissues?
- Epithelium
- Connective
- Muscle
- Nervous
Where is epithelium found, what role does it play and what does it consists of?
- Covers body surfaces, lines cavities and tubes, forms glands
- Plays a role in protection and mediates selective diffusion, absorption and secretion
- Consists of closely bound cells supported by a basement membrane
State the 6 types of epithelium with their major function and where they are found?
- Simple squamous epithelium
a) Exchange of nutrients and gases
b) Alveoli, blood vessels (endothelium) - Non keratinised stratified squamous epithelium
a) Protection and barrier
b) Oral cavity, oesophagus - Keratinised stratified squamous epithelium
a) Protection and barrier (waterproof)
b) Skin - Simple cuboidal epithelium
a) Secretion and absorption
b) Glands,kidney tubules - Simple columnar epithelium
a) Secretion and absorption
b) Gastrointestinal tract
c) May have modification like micro villi - Pseudostatrified ciliated columnar epithelium with goblet cells
a) Mucocilliary escalator
b) Trachea, large respiratory airways
What are specialised connective tissues?
- Bone
- Blood
- Cartillage
What are types of connective tissue proper, state their properties and where they are found?
- Loose (areolar) connective tissue
a) Ground substance is predominant
b) Few collagen and elastic fibres
c) Cells: fibroblast, adipocytes, macrophages
d) Found under epithelium and lines body surfaces - Dense irregular connective tissue
a) Little ground substance
b) Collagen fibres predominate (ARRANGED HAPHAZARDLY)
c) Resists excessive stretching and distension
d) Found in dermis - Dense regular connective tissue
a) Little ground substance
b) Densely packed collagen fibres (ARRANGED IN PARALLEL ROWS)
c) Found in tendons and ligaments
What is the histological arrangement of oral mucosa?
Oral mucosa = Epithelium + lamina propria (fibroblast + macrophages + capillaries + ECM)