Microbial aetiology of pulp and periapical disease Flashcards
Aetiology of pulpitis (Kakehashi et al 1965)
Maxillary molars of conventional and germ-free animals exposed
Left for 1-42 days
Conventional animals –> necrotic pulps
-periapical abscess and granulomas by 8 days
Germ-free animals –> no devitalised pulps
-evidence of healing by 14 days
Routes of entry to the pulp
Carious dentine (via dentinal tubules) Subgingival plaque bacteria present in deep periodontal pockets via lateral canals Gingiva Lateral root canal Anachoresis Abscess
What leads to bacteraemia?
Accute inflammation –> abscess –> bacteraemia
What leads to cyst?
Chronic inflammation –> granuloma –> cyst
Invasion of dentinal tubules
Bacteria invading from oral cavity into pulp space
Or invading radicular dentine from infected root canal
Dentinal tubules
Produced during dentin formation by odontoblast migration
Wider and contain more collagen at pulpal side
Dentinal fluid within tubules (albumin, trnasferrin, proteoglycans)
Bacterial infection - change in hydrostatic pressure within tubules increasing sensitivity
Bacteria within tubules are protected
Example mechanism of invasion
Streptococci bind to collagen type I in tubules
Adhesin in ‘antigen I/II’ family of proteins
Bacteria move along tubules by growth and fluid flow
Some streptococci can ‘carry’ other bacteria with them
-e.g. S.gordonii co-aggregates with P.gingivalis via protein I/II
Co-operative invasion
P.gingivalis needs to cooperatively invade with S.mutans
Pulp response to infection
Rapid acute inflammation involving whole pulp –> pulp necrosis
Development of chronic localised abscess (most pulp remains viable)
Micro-organisms in caries v. pulp infection
Enamel caries and dentine caries: Strep and Lactobacillus
Necrotic pulp: (anaerobic organisms) Peptostreptococcus, fusobacterium, black pigmented anaerobes
Specificity of oral disease-associated microbiota
Slight overlap between caries and endodontic infections, slight overlap with endodontic and periodontal infections, but overall all 3 have different species due to different environments
Bacteria recovered from infected pulps by culture
Anaerobes (57) -black-pigemented ** -eubacterium -peptostreptococcus Facultatives (43) -streptococcus** -actinoyces
Overview of bacteria in pulpal infection
Polymicrobial infections
Propertions of groups of bacteria in 7 pulp infection
-not all the same but trend
Treatment of pulpal infection
Endodontic treatment - pulp removed, cleaning, decontamination, pulp replaced by inert material, restoration
Extraction - esp. if there is insufficient coronal tissue remaining for restoration once root canal therapy is complete
Bacteria associated with endodontic treatment failure
Enterococcus faecalis S. anginosus* S. constellatus* S. intermedia* A. israeli B. gracilis *Milleri group
Dentoalveolar infections
Pus-producing infections associated with teeth and surrounding suppoerting structures
Periapical abscesses
Clinical presentation depends on
Locations of common dental abscesses
Palatal abscess
Periodontal abscess
Spread into fascial spaces
Follows path of least resistance
Dependent on anatomical location of original abscess to adjacent tissues
Infection via fascial planes often spreads rapidly and for some distance
May occasionally cause severe respiratory distress as result of airway occlusion by oedema
Where can abscesses spread to
Submandibular space
Micro-organisms in caries v. pulp and periapical infection
Streptococcus Peptostreptococcus Fusobacterium Black-pigmented anaerobes -succession of species -related to their ability to use local nutrients (e.g. by proteolytic activity and avoid host defences)
Bacteria genera in periapical abscesses
Anaerobes
- gram-: prevotella, porphyromonas, fusobacterium, campylobacter
- gram+: peptostreptococcus, eubacterium
Link between whether patients are symptomatic or not
With symptoms: P. gingivalis, Prev. intermedia
Without symptoms: Prev. denticola
Pathogenic factors
Enzymes -proteases (e.g. trypsin-like) -phospholipases Metabolic by-products -acids (e.g. butyric) -H2S -Amines (e.g. putrescine) Bacterial structures -capsules -peptidoglycan -endotoxin (LPS - gram-s)
