Midterm # 1 - GENERAL Flashcards
What are the 6 stages of tooth development?
1) Initiation stage
2) Bud stage
3) Cap stage
4) Bell stage
5) Stage of apposition
6) Stage of maturation
What happens during the ‘Initiation stage’ of tooth development? And when does it occur?
- The oral epithelium gives rise to the dental lamina (adjacent to the ectomesenchyme)
- 6 - 7 weeks in utero
What happens during the ‘Bud stage’ of tooth development? And when does it occur?
- The dental lamina grows into a bud shape, penetrating the ectomesenchyme.
- 8th week in utero
What happens during the ‘Cap stage’ of tooth development? And when does it occur?
- The dental lamina continues to grow into a cap-like structure called “the enamel organ”, which surrounds the ectomesenchyme and turns into the ‘dental papilla’ and the ‘dental sac/follicle’.
- 9 - 10 weeks in uterio
What happens during the ‘Bell stage’ of tooth development? And when does it occur?
- The enamel organ turns into a bell shape with 4 cell types within it. The cells in the dental papilla turn into 2 cell types.
- 11 - 13 weeks in utero
What happens during the ‘stage of Apposition’ of tooth development? And when does it occur?
- Dental tissue types (enamel, dentin and cementum) are secreted in layers.
- Varies according to the tooth, but usually 4 - 5 months in utero
What happens during the ‘stage of Maturation’ of tooth development? And when does it occur?
- Dental tissue types fully mineralize to mature form
- Varies according to tooth, but usually 4 - 5 months in utero
What is a ‘tooth germ’?
Buds within the alveolar process (crown and dentin form first, root later)
What are the 2 divisions of the oral cavity and what do they compose of?
1) Vestibular area - outer part of the mouth (inner part of lips and cheeks, facial surface of teeth)
2) Oral cavity proper - inside the mouth (backs of the front teeth to the faucial pillars)
What are the 3 components of the Gingiva?
1) Marginal/free gingiva
2) Attached gingiva
3) Interdental papilla
Describe ‘Enamel’
- Covers anatomical crown
- Avascular (without vessels = strong)
- Translucent (white, yellow or grey)
- Produced by ‘ameloblast cells’
Describe ‘Dentin’
- Covers pulp and forms bulk of tooth
- Avascular
- Yellow
- Produced by ‘odontoblast cells’
What are the 4 types of Dentin? Describe.
Mantel: outermost layer
Circumpupal: layer around outer pupal wall
Peritubular: within walls of dentinal tubules
Intertubular: between dentinal tubules
What are the 3 classifications of Dentin? Describe.
Primary: forms the body of the tooth
Secondary: forms AFTER tooth eruption (teeth grinders)
Tertiary: forms in response to trauma to the pulp (caries)
Describe ‘Cementum’
- Covers dentin along the root surface
- Attachment site for PDL
- Laid down by ‘cementoblasts’
What are the 2 types of Cementum? Describe.
1) Acellular: cervical 1/2 (middle/neck) of root
2) Cellular: apical 1/2 of root
Describe ‘Pulp’
- Innermost tissue of the tooth
- Compose of: intercellular substance, tissue fluid, lymphatics, vascular system, nerves and fibers
What are the 2 divisions in the pulp chamber?
1) Coronal pulp (pulp horns): in the crown
2) Radicular pulp (pulp canal): in the root
What are the 3 functions of pulp?
1) Nutrition
2) Sensory
3) Protective (secondary/tertiary)
What is the make up (%) of Enamel?
96% inorganic (hydroxapatite crystals)
1% organic
3% water
What is the make up (%) of Dentin?
70% inorganic (hydroxapatite crystals)
20% organic
10 % water
What is the make up (%) of Cementum?
65% inorganic
23 % organic
12% water
What are the 3 types of Dentition?
1) Primary/Deciduous Dentition (baby teeth)
2) Mixed Dentition (transitional)
3) Secondary Dentition (adult teeth)
What are ‘succedaneous’ teeth?
Permanent teeth that replace primary teeth (all teeth EXCEPT molars)
What are the functions of the 4 types of teeth?
1) Incisors: cut and bite
2) Canines: cute, tear and grasp
3) Premolars: tear and grasp
4) Molars: grind and pulverize
What are the components of the Periodontium?
- Gingiva
- Cementum
- Periodontal ligament (PDL)
- Alveolar process (bone)
Describe the types of furcations and which teeth have them.
Bifurcation: 2 roots (M and D) - Maxillary 1st premolar - Mandibular molars Trifurcation: 3 roots (2B and 1L) - Maxillary molars
What is an embrasure and what does it allow for?
- A spillway/ V-shaped space created between 2 teeth meeting in the same arch
- Allows for natural food flow and mechanical cleansing.
- Allows enough gingival stimulation for health (protects gingiva from trauma)
What is the difference between the embrasures in the anterior vs. the posterior?
- Anterior: facial and lingual are equal
- Posterior: lingual are wider than buccal (because teeth are narrower on the lingual)
What are the horizontal divisions of crowns and roots (anterior and posterior)?
- Anterior crown: incisal, middle, cervical
- Posterior crown: occlusal, middle, cervical
- Root: cervical, middle, apical
What are the vertical divisions of a tooth? (facial and proximal)
- Facial: mesial, middle, distal
- Proximal: facial, middle, lingual
What are the eruption ages of primary teeth?
- Central incisors: 6 - 12 months
- Lateral incisors: 9 - 16 months
- Canines: 16 - 23 months
- 1st molars: 13 - 19 months
- 2nd molars: 22 - 33 months
What are the 3 number systems?
1) Universal Numbering System (used in USA)
2) International Numbering System (what we use)
3) Palmer Notation Method (used in ortho)
Describe the Universal Numbering System.
- Permanent: 1 - 32 (quads 1 - 4)
- Primary: A - K
Describe the International Numbering System.
- Permanent: 1st number = quadrant, 2nd number = tooth (quads 1 - 4)
- Primary: (same except quads 5 - 8)
Describe the Palmer Notation Method.
Symbol/bracket on each number
- Permanent: 1 - 8 (in each quad)
- Primary: A - E (in each quad)
