Flashcards in Oral Cavity Deck (310)
What is the importance of rectangular collimation?
Changes tube head from circular to rectangular
Red. dose by 50%
Describe the 2 mechanisms by which radiation can cause damage
Direct: more catastrophic
DNA/RNA; disturbs nucleic acid bonds, causes mutations
Indirect: more likely
Water molecules; radiolysis of water creates free radicals H2, H2O2 cause cellular damage
What are the 3 types of harmful radiation effects?
1. Somatic deterministic: threshold (only caused if above)
cataract formation: lens becomes opaque
obliterative endarteritis: radiolysis of small vessels
2. Somatic non-deterministic: no threshold (potential every time)
3. Genetic non-deterministic
Describe dental pulp
Unmineralised tissue composed of soft CT, vasculature, lymphatics and nerve endings
Mostly water: 75-80%
Developmentally, structurally and functionally closely related to dentine: both from neural crest-derived CT that forms dental papilla
Occupied pulp chamber and root canals
Pulp chamber molars ~4x larger than incisors
No inorganic components in normal pulp: pulp stones found pathologically in ageing pulp
What is the primary function of pulp?
Provide vitality to tooth: loss of pulp (RCT) doesn't mean lose tooth; tooth functions w/o pain but loses protective mechanisms
Maintains health of dentine through odontoblast layer
What are the inductive, formative and protective functions of pulp?
Inductive: early development; future pulp interacts w/ surrounding tissues initiating tooth development
Formative: odontoblasts of outer layer pulp organ form dentine that surrounds and protects
Protective: pulp reacts to stimuli; cold, hot, pressure, operative cutting, caries,
What are the 2 types of pulp?
Compare the 2 types of pulp
Coronal: occupies crown, 6 surfaces; mesial, distal, occlusal, floor, buccal, lingual
Radicular: extends down from cervix to apex, pre/molars have multiple radicular pulps, tapered and conical
Describe the fibrous matrix of pulp
Composed of T1 and 2 collagen
Unbundled and randomly dispersed, greater dentistry around blood and nerve vessels
T1: thought to be formed by odontoblasts
T2: probably produced by pulp fibroblasts
Older pulp contains more collagen
What is present in the GS of pulp?
Where are odontoblasts found in pulp?
Outermost region, immediately adjacent to dentine
Responsible for secretion of dentine, formation of dentinal tubules
What is special about pulp fibroblasts?
Shown ability to degrade and form collagen
Describe perivascular cells
Undifferentiated mesenchymal cells present in pulp
Give rise to odontoblasts, fibroblasts, macrophages
What other cells are common in the pulp?
Lymphocytes, plasma cells, eosinophils
What are the 4 zones of pulp from outer to inner?
Describe the odontoblastic layer of pulp
Lines outer pulpal wall, consists of odontoblast cell bodies
2ndary dentine may form here from apposition of odontoblasts
Describe the cell-free zone of pulp
Fewer cells than odontoblastic
Capillary and nerve plexus
Describe the cell rich zone of pulp
Inc. density cells, more extensive vasculature
@ base; nerve plexus of Raschow
Describe the pulpal-core of pulp
Located in centre of pulp chamber
Many cells, extensive vasculature
Similar to cell-rich
Polarised columnar cells w/ single process extending into dentinal tubules
Form continuous lining @ junction between pulp and dentine
Contribute to protection of pulp
What inflammatory cells are present in the pulp?
1. T lymphocytes
3. Dendritic antigen presenting cells
Describe the distribution of inflammatory cells found in the pulp
T lymphocytes: usually low no. inc. w/ inflammation
Macrophages: predominately around central blood vessels, adjacent to odontoblast layer
Dendritic presenting cells: similar to macrophages; may be found between odontoblasts and dentine
Describe the vascular supply to the pulp
1. Small arterioles enter pulp via apical foramen
2. Ascend through radicular pulp of root canal
3. Branch peripherally to form dense capillary network immediately under and extending into odontoblast layer
4. Small venules drain capillary bed, eventually leave as vein through apical foramen
Describe the structure of vascular supply in pulp
Pulpal vessel walls v thin as pulp protected by unyielding sheath of dentine
Capillary walls have many pores reflecting metabolic activity of odontoblast layer
Blood flow more rapid and BP quite high
Arterio-venous anastomoses freq.
Describe the innervation of the pulp
Pre/molars: several large nerve fibres enter apical foramen of each
Ant.: one fibre enters
Describe the autonomic innervation of the pulp
Sympathetic fibres, unmyelinated
From neurons whose cell bodies lie in sup. cervical ganglion at base of skull
Travel w/ blood vessels
Innervate arteriole SM, function in regulation of blood flow
Describe the path of afferent nerves in the pulp
Maxillary and mandibular branch of CN5
Terminate in central pulp
Send out small individual fibres that form subodontoblastic plexus under odontoblast layer
Terminate as free nerve endings: extend up between odontoblasts or further up into dentinal tubules
Describe the afferent fibres of the pulp
Transmit pain sensation from heat, cold, pressure
Subodontoblastic plexus: found in lat. walls and root of coronal pulp, less developed in root canals
Few nerve endings found among odontoblasts of root
What is the clinical importance of pulp?
1. Living pulp required to maintain dentine integrity and sensitivity
Inflammation causes high fluid conc. and swelling; nerve fibres compressed causing pain
Mechanical injury to dentine may induce pain and tertiary dentine formation
Severe damage/infection result in removal, filling of pulp chamber and root canal
2. Age related: cell death results in dec. no. cells, fibroblasts respond by producing more fibrous matrix but less GS w/ less water
Pulp becomes: less cellular, more fibrous, red. vol. due to continued dentine deposition