Cario L2 - Etiology, Clinical Significance and Histopathology Flashcards
(19 cards)
dental caries definition
‘a bacterial disease of the calcified tissue of the teeth characterised by demineralisation of the inorganic and destruction of the organic substance of the tooth’
how do dental caries occur?
because of demineralisation of enamel and dentine by organic acids formed by bacteria in dental plaque though the anaerobic metabolism of sugars derived from the diet
- demineralisation: loss of calcified material from the structure of the tooth
- remineralisation: regain of calcified materials within the tooth structure
What do normal teeth look like clinically?
- yellow, white colour
- smooth, glossy, shiny
- teeth look very intact
- tactile: hard when probed
- very healthy enamel is translucent so the colour of the dentine shows through (slightly yellow)
- looks more yellow closer to the gingiva - enamel thinner here
- transparent area on incised edge means very healthy mineral
what are the four factors in the aetiology four factors theory?
- diet: external modifying risk factors. intake of fermentable carbohydrates especially sucrose (amount, composition, frequency)
- bacteria plaque: etiologic risk factors: bacteria colonise the tooth surface
- time: only true unit of measure, gives proof to the existence of matter
- tooth: general site of inspection for plaque stagnation
these circles represent the parameter invoiced in the caries process
all four factors must be acting concurrently (overlapping of the circles) for caries to occur
What is plaque?
- the soft tenacious minerals found on tooth surfaces which is not readily removed by rinsing with water
- biofilm or mass of bacteria that grows on surfaces within the mouth
what are the three dental plaque in cardiology aetiology
non-specific plaque hypothesis:
- thick plaque on tooth if left there allows acid to be produced in it and cause caries.
- carious lesions tend to develop on surfaces which plaque reoccurs often
specific plaque hypothesis:
- mutans streptococci - caries initiation
- lactobacilli - caries progression
- actinomyces - early colonisation and root caries
ecological plaque hypothesis:
- the oral microbiome is natural a dynamic balance is reach between the host, the environment, and the microbiome
- disruption of balance results in higher risk of caries basically
what are the virulence factors of carcinogenic bacteria?
- acid production (acidogenicity)
- acid tolerance (aciduricity)
- gluten formation (allows carcinogenic bacteria to stick onto teeth)
describe the role of dietary factors in aetiology, and the role it has in caries risk assessment
- frequent intake of free sugars results in increased caries
- flouride exposure results in decreased risk of caries
- WHO reccomends deceased free sugar intake
- ‘risk of dental cares and high exposure to sugared beverages and snacks. therefore, consumption of sugared beverages and snacks needs to be included as part of a pts caries risk assessment’
list the carries susceptibility permanent dentition rank
- fissure of the molars (occlusal surf.)
- medial and distal surfaces of the first molars
- medial surfaces of the second molars and distal surface of the second premolars
- distal and medial surfaces of the maxillary first premolars
- distal surfaces of canines and medial surfaces of the mandibular first premolars
- approximate surfaces of the maxillary incisors
describe the key points of the Stephan curve/critical pH
- critical pH of enamel is 5.5 (this is when the enamel starts to break down and becomes soft)
- critical pH of dentine is 6.2
- when you eat a meal the pH goes down (more acidic) until about 30 mins when saliva comes into play as buffer
4 ways to decrease caries
- plaque control
- reduction of risk levels
- long-term follow up
- preservation of dental tissues
describe how true ethology may be a complex combination
involves personal, oral environment and direct contributing factors. many of these and diff for each person
what are some high risk factors?
- xerostomia (dry mouth): due to auto-immune disease or some medications
- cancer therapy (radiation treatment): affects salivary glands - so again dry mouth
describe smooth surface enamel caries
- caries lesion starts from proximal surface appears triangular in sections cut through. carious dissolution follows the direction of the rods
- happens from the very outer layer of the surface. very first layer is high content of minerals so at the start it is non-cavitating
- early stages is white chalky bits but not present in every case
describe fissure enamel caries
- carious lesion stats at both sides of fissure rather than at the base. penetrating nearly perpendicular to the DEJ
- this produces a cone-shaped lesion, base towards the dentine (wider) and apex towards enamel surface (smaller). looks deceiving can be small looking at the fissure but x-rays show the depth and how bad it actually is.
describe the enamel pyramids and how that works for caries
- fissures pyramids have small apex and are wider at the base so could look like a small caries from the top but as you get x-ray can see it goes way deeper and widespread in the tooth
- smooth surface eg. buccal or lingual surfaces have wider apex and thinner base so looking at caries from outside is more truthful (but still be wary)
describe dentine caries
- dentine differs from enamel in that it is a living tissue and as such can respond to caries attack
- defense reactions of pulpodentinal complex include: sclerosis, reactionary dentine formation, sealing of dead tracts
Have five zones:
- zone of destruction (liquefaction eco containing bacteria enlarge and increase in number. bacteria no longer confined to tubules. little of normal dentin remains)
- zone of bacterial invasion
- zone of demineralisation (it is affected by a wave of bacterial acid. is this softened dentine is therefore sterile, cannot be clinically distinguished reliably from softened infected dentine)
- sclerotic reaction/translucent zone (has higher mineral content)
- reactive dentine
describe the reactive or tertiary dentine
- its formation effectively increases the depth of tissue between the carious dentine and the pulp
- varies in structure but the tubules are generally irregular, tortuous and sewing in number than in primary dentine
- reactive dentine is non-specific response to odontoblast irrigation, ie also to tooth wear and tooth preparations
describe the zone of bacterial invasion
- the bacteria extend down and multiple within the dentinal tubules
- the first wave consisting of acidogenic organisms, mainly lactobacilli, produce acid which diffuses ahead into the demineralised zone
- a second wave of mixed acidogenis and proteolytic organisms then attack demineralised matrix
- the walls of the tubules are softened by the proteolytic activity and some may then by distended by increasing mass of multiplying bacteria
- resulting in elliptical areas of proteolysis-liquefaction foci
