Chapter 9 B: Dental Pathophysiology Flashcards
The tooth suffers some modifications in its structure throughout life, they can be?
- physiological
- response to multiple attacks
Physiological processes that the tooth undergoes by aging?
- aging changes in the enamel
- aging changes in the pulp dentin complex
- aging changes in the cement
- post eruptive tooth movements
Aging changes in the enamel include?
Attrition, abrasion, and changes in the composition of enamel
Attrition:
- TSL caused by masticatory activity
- teeth wear can be pathological if it’s excessive, developing a loss of vertical dimension
- it affects enamel first
- can be physiological or pathological due to malpositions, malformations, or dysfunctions
- concave shape
The first teeth that suffer attrition are?
Incisors
The first molar that wears is
The 1st lower molar, MB cusp
The greatest wear is on the
Lingual cusps in upper molars
The most wear in the lower molars is in the
Buccal cusps, active cusps
The degree of attrition depends on?
- type of enamel
- occlusion
- habits
- muscle power
- type of food ingested
- tooth loss
- presence and materials of the prosthesis
Abrasion is:
Wearing of the tooth substance that results from the friction of exogenous material forced over the surface by incisive, masticatory, and grasping forces
Changes in the composition of enamel:
- the composition and permeability vary with age due to an outer layer 0.1mm thick surrounding the enamel that is harder than the rest of the enamel
- the thickness increases with age, so enamel permeability decreases with aging of the tooth
- darkening of the tooth also occurs , the enamel becomes less white and less susceptible to tooth decay with age
The changes in the structure and composition of dentin and pulp throughout life of the tooth:
(8): STOP ADVS
- formation of secondary dentin and decrease of pulp chamber
- translucent apex dentin
- changes in odontoblasts
- progressive fibrosis of the pulp
- ability to pulp response in elderly teeth
- degeneration by calcification of the pulp
- decreased vascularity of the pulp
Dentin continues to form in a physiological way throughout life:
Secondary or physiological dentin
Is secondary dentin a defensive reaction or a protective mechanism?
Protective mechanism, protection of the pulp tissue, and the dentin tubules are still permeable allowing the pulp alert reactions
What happens the volume of the pulp chamber with age?
Decreases by continuous formation of dentin
Pulp canal narrows over time
This reduction in size engages the hydrodynamic balance of the pulp that has increasingly limited the possibility of expansion of the tissue volume
Translucent apex dentin:
The apical portion of the teeth in elderly is transparent , they’re fragile and susceptible to fracture during extractions
Changes in the odontoblasts?
- by decreasing the volume of the pulp chamber by secondary dentin formation
- the external surface where odontoblasts are housed is reduced
- the odontoblasts agglomerate to form a layer of 2-4 cells thick
Decreasing vascularity of the pulp?
- with degenerative changes that reduce the size of the vessels that leads to a pulp less reactive to the attacks and less able to produce reparative dentin
- size, vascularity, and innervation are reduced
Progressive fibrosis of the pulp?
May happen due to the narrowing of the apical canal with decreased blood supply and lymphatic drainage
Degeneration by the calcification of the pulp may be?
Diffuse or local
Diffuse degeneration of the calcification of the pulp?
- in old pulps, begins in the root canal calcifying the collagen fibrils, the great vessels and the pods of the nerves
Local degeneration of the calcification of the pulp:
- nodules
- At any age but more common in old age
- more often in chamber than in root which is easier to remove
- rounded
Changes in the sensitivity of the pulp?
Sensitivity decreases in elderly teeth
But doesnt vary responsivness to electrical stimuli
Reduction of pulp innervation by aging
Ability to pulp response in elderly teeth
Reduced by decreasing the number of cells and vessels
Apical foramen is reduced, hinders the vascular supply and lymphatic drainage
Aging changes in cement:
- cement is deposited intermittently throughout the life of the tooth
- its thickness corresponds to the age of the tooth, it increases with age
- generally exposed in advanced age in cervical area
External aggressions promotes the cement appositions:
- periodontal disease
- pulpal infection
- necrosis
Post eruptive tooth movements:
• Pre eruptive dental movements: performed by temporary and permanent germs within the
jaws.
• Eruptive dental movements: when the germs move from the jaws to their occlusal position.
• Post eruptive dental movements: these are the movements necessary to keep the erupted
tooth in its functional position.
- Purpose of these movements:
- Accommodate the occlusion to the growth of the jaws.
- Compensate for continuous occlusal wear.
- Accommodate to the inter-proximal wear of the teeth.
The only cell capable of producing enamel is
Ameloblasts
What happens to ameloblasts after tooth formation
It loses its Amelogenin capacity and can not be repaired or replaced
Mild aggressions cause:
Sensitivity, sclerotic and reparative dentin formation
Intensive aggressions cause:
Progressive inflammation
Dentin sensitivity:
Defence mechanism; warning of the presence of a defect of enamel or cement leaving exposed
dentin.
- It is a waning sign. Which can be masked by reparative dentin formation that blocks the dentin
tubules - protection mechanism more than defense
- when preparing a cavity, a smear layer is formed
-it seals the exposed tubules, forms layer of several microns thick and it reduces permeability
Mineralisation of the exposed dentin surface and dentinal tubules is a mechanism that protects the tooth from stimuli produced by
Abrasion
Attrition
Cervical scrapes
Caries
Cavities preparation
The smear layer is
Microcrystalline residues that cover the dentin surface , covers the tubules reducing their permeability
Microcrystalline structure is mixed with
Saliva
Water
Dentinal fluid
Organic material
Microorganisms in the oral cavity
What happens to this mineralised layer
Because of acids and brushing and saliva, they prevent it from forming
Sclerotic dentin formation occurs due to?
aging or chronic and mild irritation (such as slowly advancing caries) which causes a change in the composition of the primary dentin.
In the elderly it occurs physiologically
Sclerotic dentin is a hypo/hypermineralised dentin ?
Hyper
Change of structure of dentin
Purpose of sclerotic dentin formation:
- Establish a defensive barrier that prevents caries from spreading into the pulp chamber.
• Total occlusion of the dentinal tubule by peritubular dentin.
• Close the dentinal tubules, prevent caries from spreading into the pulp chamber.
Characteristics of sclerotic dentin:
• Translucent.
• Waterproof to dyes. (Because dentinal tubules are basically closed). • Radio-opaque.
• Harder than primary dentin.
Which tubules are closed first
The smallest and closest to the amelodentin and cementodentinal junction
Tertiary or reparative dentin:
formed as a response to external stimuli such as dental caries, attrition, and trauma.
If the injury is severe and causes odontoblast cell death, odontoblasts like cells synthesise
specific reparative dentin just beneath the site of injury to protect pulp tissue.
- Reparative dentin matrix has decreased permeability, therefore helping in prevention of
diffusion of noxious agents from the tubules.
Differences between sclerotic and reparative dentin ?
- Unlike physiological dentin, reparative dentin is irregular, with cellular inclusions.
- Also the tubular patten of the reparative dentin ranges from a irregular to an atubular nature.
- Extra dentin.
- Sclerotic is a change of structure, but this is extra dentin
Pulpar inflammation:
When the aggression to the tooth is important and acts for a long time, the pulp tissue begins to become inflamed.
The inflammatory response is a defensive mechanism as it attempts to destroy the irritant by preparing tissue for tissue repair.
- Without this inflammatory reaction and its immune response, the invasion of the pulp by the
bacteria would be much faster
