Aetiology of Plaque associated Diseases - risk factors

• What are the primary aetiological agents in periodontitis

  bacteria
• Bacteria is found in plaque but the amount of plaque doesnt fully explain the level of disease why?

  a susceptible host is a prerequisite
• in health pattern what occurs?

  host defence and microbial challenge is equal

  There is perio resistance aka no host susceptibility component
• In perio molar incisor pattern what occurs

  microbial challenge is greater than host defence

  Periodontal disease susceptibility in the ABSENCE of local risk factors
• Risk factors for perio?

  • genetics
  • age
  • smoking
  • Haematological
  • Hormonal
  • Nutritional
  • Stress
  • medications
  • Diabetes
• Genetics as a RF?

  3 subgroups:

  • no perio
  • moderate progression of perio
  • rapid progression of perio

  Loe et al 1986
• What do twin studies about genetics suggests

  50% susceptibility is due to genetically determined host factors
• Examples of conditions assoc. with severe periodontitis?

  Papillon - lefevre syndrom = affects neutrophil adhesion

  Downs syndrome = less leukocyte chemotaxis and phagocytosis

  Ehlers danlos = collagen defect

  Lazy leukocyte syndrome = less leukocyte chemotaxis
• Alleles 


  a slight difference in the DNA sequence of the same gene

  Can be of no consequence or may programme characteristic changes resulting in disease
• Gene mutation


  if gene is present in less than 1% of population

  rare and abnormal
• Gene polymorphism


  if gene exists within more than 1% of population

  Common with 2 or more variants
• IL1 gene cluster ?


  • increased production of IL1 which is pro inflammatory cytokine that regulates perio inflammation and bone resorption
  • Linked to increased severity of perio but not always
  • a non essential RF
  • IL-1b genotype linked to increased perio
  • IL-1b associated with presence of pathogenic mos - red and orange complex
• Hereditary Gingival Fibromatosis 


  Familial:

  • autosomal dominant
  • son of sevenless gene
  • affects max tuberosity and mandibular retromolar regions

  
  

  Sporadic:

  • spontaneous mutation of 2p21
• Smoking?


  • major independent RF
  • 2.6 - 6 x more likely to have perio
  • 50% of perio cases attributed to smoking (current or former)
  • modifiable
• E cigs?


  • Nicotine
  • Solvents (can transform into formaldehyde and acetaldehyde)
  • Flavourings
  • Vegetable glycerin (vapour production)
  • Propylene glycol (E1520) – humectant and solvent
• Smoking and perio link is

  dose dependent - severity directly related to the number smoked and number of years pt smoked for
• Light smoker 


  less than 10 cigarettes per day
• Heavy smoker 


  more than 1 pack per day
• Smoking affects on perio ?

  • higher PPD
  • More sites with deep pockets
  • More tooth loss post Tx
  • Greater gingival recession
  • Greater calculus formation
  • 2-4x more furcation involvement
  • great loss of alveolar bone
  • poor Tx response
  • Inc risk OC
  • more disease recurrence in maintenance phase
• Why else is smoking harmful?

  reduced clinical signs = non awareness of problem and diagnosis delay
• Impaired Immune Response of smokers?


  impaired PMN function: ↓chemotaxis, ↓vascular transmigration, ↓ phagocytosis

  
  

  Decreased IG production: salivary IgA, B cell function, Helper T cells, serum IgG

  
  

  Increased production of inflammatory mediators: IL1, IL6 TNFA, PG E2
• Why do smokers have impaired healing

  • nicotine inhibits fibroblast growth, attachment and function
  • Continine and nicotine found in GCF and on root surface they: promotes platelet clotting and blocks perfusing blood vessels/reduces blood flow
  • Heat and products of combustions = irritants
• Smokings affect on microbiollogy

  more anaerobic pathogen due to ↓  local oxygen tensions
• Smoking affect on GCF?

  reduces gcf = host susceptible to bacterial growth
• smoking affect on plaque?

  calcium concentration is higher = +++ calculus formation
• Effects of smoking. on response to Tx?

  • poorer response
  • Surgical more likely to fail in smokers
  • Maintenance smokers patients 2x likely to lose teeth
• smoking cessation on Tx outcome?

  • cant reverse past effects on the periodontium
  • Slow the rat of perio destruction
  • 13 years for risk profile to return to a non smoker
  • Blood flow does increase 3 days after quitting and will eventually respond the same as non smokers
• Nutrition and micronutrients RF?

  Counteract oxidative stress

  body cellular reactions involve oxidation and production of reactive species aka. " free radicals"
• What is oxidative stress?


  an imbalance between free radicals and antioxidants
• ROS - Reactive oxygen species 


  free radicals that contain oxygen molecules

  needed for:

  • hormone production
  • generated by host to kill some bacteria and engulf pathogens
  • needed for normal cell functions and cell signalling

  Example: ozone, superoxide anion hydroxyl radical
• Free Radical production?


  free radicals have an unbalanced electron

  
• How can free radicals be introduced or produced into the body?

  • smoking
  • Increased glucose and lipid intake = oxidative stress via krebs cycle
  • frying food
  • alcohol
  • sunlight
  • exercise
• Antioxidants?


  • can donate an electron as stable in either form = stabilises free radicals
  • act as scavengers to mop up free radicals
  • Inhibit ROS
• Examples of antioxidants?


  vitamin C = collagen synth

  Vitamin E = stabilises membrane structures
• What does a vitamin C deficiency lead to

  abnormal collagen turnover = inc. risk of perio attachment loss

  severe = scurvy
• Obesity


  positive assoc between obesity and perio in animal and human studies

  
  

  ? underlying mechanisms:

  
  

  • increased ROS production
  • Chronic subclinical inflammation
  • Adipose cell derived pro-inflammatory cytokines (adipocytokines) and hormones may play a key role
• Obesity relative risk 


  3.4x for 25 - 29.9

  8.6 for over 30
• Haematological disorders?


  Focuses on leukocyte disorders which can either be:

  quantitive - number

  qualitative - functional
• Quantitative disorder?


  caused by:

  • leukemia
  • cyclic neutropenia
  • agranulocytosis
  • aplastic anemia - a bone marrow disorder

  Results in: ↓ no. of functioning neutrophils = inc perio risk
• Acute leukemia?


  an increase number of leukocytes which are immature and non functional

  presents:

  
  

  • commonly in young
  • bruising
  • lethargy
  • oral ulceration
  • gingival bleeding