Prion Diseases-

Implications In Dentistry

PRION DISEASES

•Group of fatal neurodegenerative disorders affecting humans and animals

•No host response •Long incubation periods

TSE in Brain

Prions??? Stanley Prusiner-Nobel Prize in Medicine 1997

Normal proteins in all mammalian tissues

α helical structure- Located on short arm of chromosome 20

No nucleic acid

Help in copper metabolism, signal transduction and cell adhesion

Active role in regulation and distribution of acetyl choline

Pathogenesis

So what?? Mutation of PrPC PrPSc

Very resistent to sterilization procedures

Insoluble, proteinase resistant, highly infectious molecule

Gives rise to TSE( transmissible spongiform encephalopathies) in humans and BSE, scrapie in animals.

How it effects humans??

• Sporadic• Inherited• Transmissible: Foodstuffs

Direct contact

Perinatal Iatrogenic

Beef, Milk, Animal protein, Yogurt

Handling of meat, infected animal products

Hormones, bone grafts, vaccines,Corneal transplant, cross contamination

Not only is this protein used in the food, it is in the products we use everyday

such as cereal bars, lipstick and hand lotion and garden fertilizers, yogurt and breath mints”

Any relation with Dentist ???

Causative!!!? or Risk?? / Both?

Potential area of crosscontamination

Resistant to sterilization

Bone grafts Surgical

handling of risk group

Oral infectivity Saliva is a risk factor?? Tonsils, posterior border

of tongue, trigeminal ganglion are potential sources

Gingiva has its highest presence

Diseases caused:

Animals

HumansCongenital Acquired

SporadicFamilial

GSS

Kuru

vCJD

Iatrogenic

BSE Scrapie

EPIDEMIOLOGY

First described in United States Has spread to UK, Asia and Europe. World wide: 400 cases

UK : 114 cases France : 23 cases India : 30 cases Reports of exports of infected products from India Emerged as major concern and challenge to health care professionals

Sporadic/ Classical CJD: Congenital, 85% of cases Effects middle aged or elderly Characterized by

- Rapidly progressive

multifocal dementia- Ataxia, myoclonus- Evident EEG changes

- Speech loss and finally death

Transmissible Spongiform Encephalopathies

Kuru Acquired Cannibalistic activity Women and young adults are effected Long incubation period

VCJD Effects adolescents and young adults Associated with intake of infected animal products Long course of illness Hallucinations, dysphagia, dysarthria, paraesthesia, Delirium, dementia and akinesia Ameloid deposition in lymphatic tissue Absence of EEG changes

Transmissible Spongiform Encephalopathies

Transmissible Spongiform Encephalopathies

Iatrogenic TSESpecial interest to Dentist.Risk of cross infection from instrumentsMost of infections occurred after- Neurosurgery- Duramater transplant- Corneal grafting, growth hormone,

xenogenic grafts, tonsillar surgery- Manipulation of post 1/3 of tongue

Oral manifestations of prion diseases

Most common manifestations:

- Dysphagia (may be initial symptom)

- Oro-facial Paraesthesia/ dysesthesia

- Dysarthria

- Motor incoordinations

- Involvement of trigeminal ganglion

Diagnosis & Treatment

Investigative procedures: - EEG, MRI, CSF analysis - Autopsy is definitive

Treatment: - No proper treatment is available

- Invariably fatal90% of deaths usually occur within one year of diagnosis, difficult to confirm diagnosis until post mortem.

Prevention & Infection control

Best method- avoidance of contactA complete medical, family and travel

historyInfectivity of the tissue:Brain, Spinal chord, Eye Liver, Lungs,

Spleen, Lymphnodes,

Placenta, Gingiva, Tonsils

Prevention & Infection controlAdvisory committee on Dangerous

pathogens:

General infection control practices are sufficient if the work does not involve neurovascular tissue

Proper infection control measures in high risk pts involving invasive procedures

Single use items-disposable needles, gloves –safest

Quarantining the instruments, linen, gowns, gloves and masks in rigid leak proof combustible waste container-incinerate

Prevention & Infection control

No use of animal derived graft procedures unless certified

Autoclaving the instruments at 134oc for 18 min

Schedule the risk pt appointment at the end of the day

Avoid activating water lines

Disposable bowl instead of spittoon

Study by Sogal et al assessed the

possibility of transmission of TSE from xenogenic bone substitute in periodontal and oral surgical procedures. The risk was found to be insignificant if strict sterilization protocols were followed.

A study by Blanquet-grossard showed the risk of iatrogenic contamination by endodontic surgery could not be rejected.

However several case control studies found no relation between tooth extraction, dental surgery and other dental procedures with human TSE.

Supporting evidences

Conclusion

References1. Stephen RP. Prion disease and possible

implications for oral care. JADA 2003;134:1486-91.

2. Begena PS, Esparza, Julian CT. Implications of prion diseases for dentistry-an update. OOOE 2008;105:316-20.

3. Stephan RP. Prions and Dentistry. J R Soc Med 2002;95:178-181.

4. Amir A .Prions in dentistry-what are they? Should we be concerned? What can we do? JCDA 2006;72(1):53-60.

5. Christine LW. Variant CreutzFeldt Jacob disease-a problem for general practitioner? Prim Dental Care 2002; 9(3):95-9.

6. Smith AJ, Bagg J. Prions and oral cavity. J Dent Res 2003;82(10):769-75.

Thank you