Digestive System - oral Flashcards
Layers of oral mucosa
Epithelium
Lamina Propria
Muscularis mucosae
Submucosa in oral region
—> in “soft” regions: cheeks, lips, soft palate, Floor of mouth
Loose CT with blood vessels, nerves, minor salivary Glands…
Submucosa is absent in hard palate, gums, tongue
Regions of lip
- External Surface: stratified squamous keratinized
- Transitional Zone: stratified squamous keratinized
- Inner Surface: stratifies squamous non-kratinized –> muco-cutaneous junction
Parts of tongue
Body: movable, from ectoderm
Root: has Lingual tonsils, from endoderm
Ventral Surface: no papillae, non-keratinized, lamina propria mucosae
Dorsal Surface: papillae
Types of papillae
Filiform
Foliate
Fungiform
Circumvallate
Filiform papillae
- conical
- stratified suqmaous keratinized
- no taste buds!!!
- lamina propria mucosae
Primary CT papillae: Broad penetrations of the CT in the epiheltium
Secondary CT papillae: small penetrations from Primary papillae
Foliate papillae
- ridges on lateral Surface
- stratified squamous non-keratinized
- lamina propria mucosae
- has taste buds
Fungiform papillae
- among filiform papillae
- stratified squamous non-keratinized
- has taste buds
- lamina propria mucosae
Circumvallate papillae
- at border between Body and root
- 7 to 14
- encircled by a Deep cleft
- minor salivary Glands open in cleft
- stratified suqamous non-keratinized
- lamina propria mucosae (loose CT)
Tooth parts
- Crown: Projects into oral cavity
- Root: embedded in jaw
- Neck: Junction of Crown and root
- Pulp cavity
Tissues of tooth
- dentine: mineralized tissue, surrounds entire Pulp, has tubules
- Enamel: highly mineralized, covers dentine of Crown
- Dental Pulp: CT inside Pulp cavity
- Periodontium: all tissue which surround and support the tooth: cementum, periodontal ligament, alveolar bone, gums
developmental Sources of tooth
Surface ectoderm –> enamel
Head Mesenchyme –> Dentin, dental Pulp, periodontium
Stages of tooth formation
- Bud (Formation of tooth germs)
- Cap (Differentiation of tooth germs)
- Bell (Formation of tooth tissue)
4th week: primitive mouth of Surface ectoderm
6-7th week: dental laminae form
In each dental lamina: 10 enamel Organs form
Bud stage
- Enamel Organs of 10 deciduous teeth: external side of dental lamina –> 6-8th week
- EO of 32 permanent teeth: internal side in 12th week
- head Mesenchyme around EO: DENTAL FOLLICLE
- Mesenchyme that proliferates and bends the bud: DENTAL PAPILLA
Cap stage
- outer Surface cells: squamous or cuboidal, outer enamel Epithelium
- inner Surface cells: inner enamel Epithelium
- central bulk: stellate reticulum
- below stellate reticulum: intermediate layer
- cervical loop
look at drawing
Bell stage
Alemogenesis until tooth erupts
Dentinogenesis and cementogenesis at all viable time of tooth
look at drawing!!!!!
Dentine
Mineralized Matrix with dentine tubules
- produced by odontoblasts
- odontoblast: columnar, apical processes
- as dentine thickens, odontoblast move centrally, leaving the tubules behind
Dentinogenesis
- Secretion
- Mineralization
unmineralized Matrix: predentin
Matrix consists of: Collagen fibers type I, Ground substance
Mineralization: hydroxyapatite Crystals develop, formdentine globules with interglobular spaces
Main types of dentine
- Primary: until Eruption of tooth
- Secondary: after Eruption, less mineralized
- Tertiary: as reaction to external insult
Amelogenesis
- Secretion
- Mineralization
- Primary: 40% is mineralized, crysals lie down
- secondary
- ameloblast produce Matrix
- NO FIBERS IN MATRIX!
- each ameloblast lays down a column –> prism (rod)
Prism (rod)
- 5-12 Million in one tooth
- perpendicular to tooth Surface
- core of Crystals and sheath of organic matrix
Formation of teeth roots
- form during teeth Eruption
- cervical loop forms HERTWIG’S ROOT SHEATH
- in dental follicle: cementoblast and fibroblasts (for periodontal ligament)
Cementum
- avascular and aneural
- cementocytes that occupy lacunae and processes
- Matrix: Collagen fibers and Ground substance
Cementogenesis
- Secretion
2. Mineralization
Types of Cementum
Primary (acellular): during Eruption, near Cervix
Secondary (cellular): as tooth is alive
Periodontal ligament
- in periodontal space
- dense CT: fibroblasts and ECM
- Collagen Fibers spead out (Sharpey’s fibers) from alveolar bone to cementum or dentine
Dental Pulp and its regions
- Coronal Pulp: in Pulp chamber of Crown
- Radicular Pulp: in root canals
Regions of Pulp:
- Peripheral odontogenic Region: bodies of odontoblasts
- Central Region: loose CT with blood vessels and nerves
Teeth replacement
Diphyodonty
Primary (deciduous) dentition
- 20 teeth
- from 6 to 30 months
Mixed dentition
- 6 to 13 years
- when permanent teeth continue their Formation –> push the toots of deciduous teeth
- Osteoclasts are significant here!!!
Secondary dentition
32 permanent teeth
