Dentine Caries Flashcards
Describe the structure and hardness of dentine
- 70% inorganic
- 20% organic
- 10% water
- Harder than bone
- Multiple close packed tubules
- Incremental growth
Describe the formation of mantle dentin
- Odontoblasts differentiate from cells of dental papilla
- Signal molecules from the IEE
- Collagen matrix secreted adjacent to IEE
- Odontoblasts move centrally and form a process
- Odontoblast process secretes HAP crystals that mineralise collagen matrix
- Mantle dentine
Describe the formation of Primary dentine
- Odontoblasts increase in size eliminating extracellular resources for matrix
- Less collagen secreted and more organised and tightly arranged
- Mineralised in and ordered fashion
- Primary mineralisation - expansion and fusion of calcospherules
- Secondary mineralisation - further expansion of globules into areas of complete fusion
- Primary dentin
Describe the shape and components of dentine tubules
- Minute wavy tubules within dentine
- Contain cytoplasmic processes of odontoblasts
- Extend from odontoblast layer at pulp to enamel dentine or cement dentin junctions
- S shaped pattern
Where are the dentine tubules widest and narrowest
- Widest near pulp
- Narrowest EDJ
Describe the features of primary dentine
- Laid down in dentinogenesis
- Normal dentine-pulp complex response
Describe the features of secondary dentine
- Laid down throughout life
- Normal dentine-pulp complex response
Describe the features of tertiary dentine
- Laid down in response to noxious stimuli
- ‘Altered’ dentine-pulp complex response
Describe all the morphologic features and characteristics of early enamel caries
- Plaque-acid demineralisation causes porosities within prism structure
- Subsurface demineralisation
- Surface zone intact
- Inverted cone shape
- Lesion sterile - no microbes
- No dentine-pulp response
- Reversible white spot lesion
- Zones
What are the features of late enamel caries
- Progressing lesions approach the EDJ
- May still not have cavitated
- Defensive dentine-pulp reactions initiated
- May still not be symptoms
What characterises dentinal caries
- Lesions cross the EDJ and spread into the dentine
- Lateral spread across the hypomineralised mantle dentine
- Increased side branching of tubules
- Defects within tissues of EDJ
- Penetration along dentine tubules towards pulp
What can occur if the dentinal caries lesion cavities
- Allows micro-organisms to directly penetrate lesion
- Acute pulpitis may develop
- Degenerative and reparative processes occur simultaneously in different parts of the lesion
Describe the type of dentinal caries that require the tooth to be removed
- Dark, brown, soft, wet, mushy
- Mineral component dissolution
- Collagen matrix denatured
- High bacterial load
- Dentine tubules destroyed
- Irreversible
Describe the type of dentinal caries that don’t require the tooth to be removed
- Sticky, scratchy, leathery
- Mineral component dissolution (lesser degree)
- Collagen matrix damaged by proteolysis but not denatured
- Lower bacterial load
- Dentine tubules remain intact
- Reversible
What ways can the dentine-pulp complex respond to injury
- Tubular sclerosis (tertiary dentine)
- Reactionary dentine
- Reparative dentine
- Pulpal inflammation
Describe the dentine-pulp complex tubular sclerosis mechanism to injury
- Noxious stimuli to odontoblasts
- Peritubular dentin laid down
- Occludes tubule
- Protects the dentine-pulp complex from further injury
- Dead tracts formed distal to occlusion
- Tubular sclerosis translucent on ground section as hypermineralised
Describe the dentine-pulp complex reactionary dentine mechanism to injury
- Tertiary dentine laid down at dentine-pulp interface
- Increases distance between dentine-pulp and stimulus
- Low grade stimulus = slower deposition and irregular tubules formed
- Odontoblasts survive
- Metabolically unregulated
Describe the dentine-pulp complex reparative dentine mechanism to injury
- Tertiary dentine laid down at dentine-pulp interface
- Increases distance between dentine-pulp and stimulus
- Higher grade stimulus - faster deposition, atubular dentine, disorganised
- Odontoblasts vitality compromised
- Progenitor cells in sub-odontoblastic layer differentiate and unregulate
Describe the dentine-pulp complex pulpal inflammation mechanism to injury
- Noxious stimuli leads to inflammation of pulp - pulpitis
- Acute or chronic
- Toxins released from progressing carious lesions
- If slow progressing - chronic pulpitis, cellular changes - fibrosis, vascular changes - plasma cells and lymphocytes
- If faster progressing - acute pulpitis, vascular changes - PMNs and MO/
Describe the features and treatment required for advanced lesions
- Dentine architecture destroyed
- Micro-organisms close to pulp
- Sterile zone demineralisation
- Irreversible pulpitis/pulpal necrosis
- Endodontics required
AY BAWS CAN I HABE DE NOTE PLZ
Patients may have an overlapping continuum where there are simultaneous areas of sclerotic, reactionary and reparative dentine
Describe the carious process by bacteria
- Acidogenic and proteolytic bacteria
- Acidogenic bacteria dissolve inorganic matrix (collagen)
- Proteolytic bacteria destroy organic matrix (collagen)
- Streptococcus mutans and lactobacillus sp.
- From liquefaction foci that coalesce to form transverse clefts at right angles to tubules
