Periodontal disease Flashcards
What is the difference between gram positive and gram negative bacterium?
Gram negative - 2 cell membranes with thin cell wall between creating a space called the perioplasm - more transport proteins, outer capsule is LPS
-don’t retain stain so appear pink
Gram positive - thick cell wall (peptidoglycan) retains stain (purple) and one cell membrane
What are polymicrobial infecfions?
Interactions between two or more organisms leading to disease,
- sum of parts and their virulence factors cause disease and not one in isolation, -
- interaction with host defences are key
Describe the arrangement of subgingival plaque
Microorganisms firmly attached at the bottom of the JE, more loosely attached towards the top, lots of polymicrobial attachments in the gingival crevicular fluid
- Contains a predominantly Gram-positive layer attached to hard tissue
- Overlying layers contain Gram-negative anaerobes and motile bacteria
- All exist in close, mixed communities
Treatment for periodontal disease?
RSD, removing plaque, antimicrobial therapy
What changes a quiescent site into an active site?
Change in the host e.g. smoking, immune status, age, environmental factors
Change in microbial challenge - type, number, virulence factors
What bacteria dominates in ANUG?
Fuso-spirochaetal complex
What is amelogensisis imperfecta?
Enamel hasn’t formed properly - very sensitive teeth with rough enamel
Which teeth are probed in children?
6 teeth - UR6, UR1, UL6, LL6,LL1, LR1
Challenges to toothbrushing?
Retroclined teeth in cleft lip and palate, abnormalities of tooth, Orthodontic appliances, sensitive teeth, physical or learning disabilities
How do periodontal pockets develop?
When the junctional epithelium detaches from the enamel
Why is the JE thin?
This allows the transport of nutrients from the connective tissue to the tooth and outside of it as well (sulcus).
What is the depth of normal sulcus?
0.5-2.0mm
When do the inital changes of early gingivitis occur?
Occurs in the first week
When does the early lesion occur?
Occurs in second week
When does chronic marginal gingivitis occur: established lesion?
within 2-3 weeks
When does destructive periodontitis occur?
Timescale unknown
What is the initial response to plaque?
Increased blood flow (looks red)
oedema
development - plasma leaking out of blood, increased blood vessels
Migration of neutrophils
Loss of perivascular collagen of blood vessels - leaky
What changes occur in the early lesion?
Increase in neutrophils and crevicular fluid (macrophages and lyphocytes)
- junctional epithelium starts to proliferate (hyperplastic - rete pegs) but still attached to tooth and ends at the ACJ
fibroblasts show signs of damage and get collagen loss but fibres inserting into cementum still attached
What happens in chronic marginal gingivitis: the established lesion?
Increased in vascularity and formation of GCF
Increase in lymphocytes and plasma cells (chronic cells now not acute cells)
JE becomes detached from tooth but still attached at ACJ
JE may be ulcerated
Marked loss of collagen but fibres into cementum still intact
sulcus may appear deepened but no true pocket formation
What happens in destructive periodontitis?
Loss of the collagen fibres inserting into cementum
Junctional epithelium migrates downwards onto cementum
Destruction of alveolar bone (due to inflammation damaging the bone)
True pocket formation
Quite a lot of PDL fibres lost
destruction is not continuous but occurs in bursts?
How do we manage destructive periodontitis?
RSD
Removal of plaque, calculus, debris
Inflammation subsides
Junctional epithelium proliferates
Attaches to tooth- long epithelial attachment
Little or no regeneration of bone or
collagen fibres inserting into cementum (fibroblasts)
What type of studies are the Loe studies?
Longitudinal studies
What do germ free animals show?
No bacteria, no disease
germ free animals + bacteria = disease but not all animals equally
periodontitis causing bacteria is transmissable but not for all animals - disease may or may not arise
How would you sample subgingival plaque?
Curette/paper point - perio probe (difficult)
Why can 16s rRNA be sequenced easily?
16s rDNA gene is very well conserved due to essential function -acts as molecular clock and species signature as evolves slowly in time.
16s = bacteria 18s = human/animal
What type of bacteria are raised in perio disease?
Anaerobic gram negative bacteria
What evidence for specific microbial aetiology?
High numbers of certain bacteria cultured from diseased sites and sequences identified in molecular studies
Can cause disease in certain animal models
Have demonstrable virulence factors
What is the evidence against specific microbial aetiology?
Potential pathogens present in health and in non-diseased sites
Do these indicate a pathogenic environment or are we missing a key organism?
Which 3 bacteria are always associated with increased probing depth, BOP in high numbers?
P.gingivalis
Ta.forsythia
T.denticola
What is the key nutritional source for tannerella and how do they get this?
Sialic acid - acquisition of this requires cleavage from host proteins
Inhibition with Tamiflu STOPS growth
What shape is T.denticola?
Small, thin spiral shaped bacrerium
Why are groups of organisms more important than single pathogens?
Different bacteria have different virulence factors
A combination of these factors is more likely to cause disease
The qualitative mixture of pathogens determines disease progression
What has p.gingivalis shown in mouse models?
Has been shown to shift the whole population from non- pathogenic to pathogenic even though itself only being present in low numbers
New idea of one pathogen causing a dysbiosis of a community is new and important theory also being noticed in other conditions e.g. obesity
What are some mechanisms of tissue damage by bacterium?
- evasion of host defences
- infuction of inflammation
- soft tissue damage
- bone resoprtion
Why does ANUG differ clinically and in aetiology?
Tissue invasion
selection of specific bacteria by host-derived nutrients - fuso-spirochaetal complex (treponema vincentii, other treponemes, fusobacteria, p.intermedia
Why would visible plaque be present in more 8 year olds than 5 year olds?
Parents stop helping with brushing at 8 years old but still helping at 5 years old
What percentage of 15 year olds had bleeding on probing in 2013 survey of childrens’ dental health in the UK?
40%
Why is gingivitis less prevalent on the left hand side of the mouth than the right hand side?
More right handed people better at brushing left side of mouth than right side
Which gender has lower plaque and calculus scores?
Females
Which BPE codes are used for 7-11 year olds?
0-2
Which BPE codes are used for 12-17 year olds?
0-4
What are the common gingival disorders in children?
Chronic gingivitis (plaque-induced)
Gingival hyperplasia
Traumatic lesions
Acute gingivitis (infective)
What can chronic gingivitis be exacerbated by?
exfoliating teeth, malocclusion or presence of orthodontic appliances
What is localised gingival recession in children ususally associated with?
Malaligned teeth, self inflicted injury, toothbrushing habits