1
Q
What reactions can occur when material is placed in the mouth?
A
- allergic reaction to materials
- material degradation
- material interaction with tissues
- and with bacteria
2
Q
Why can allergic reactions occur to material?
A
- the body’s way of responding to an ‘invader’
- immune system triggered when antigen sensed
- begins immediately after exposure usually
- anaphylaxis - most severe hypersensitivity reaction
3
Q
Clincial appearance of allergic reactions
A
- redness/whiteness of mucosa
- swelling of lips, tongue, cheek
- ulcers/blisters
4
Q
Frequency of allergic reactions
A
- 1:000 to 1:10000
- rare
- more common when using deoderants or antiperspirants
5
Q
How are allergies recorded?
A
- often not noticed by patients
- recorded in routine dental exams
- questioned about existing allergiesn at first exam and updated with new ones every time
6
Q
Who has increased potential for reaction?
A
- children have increased sensitivity to food additives
- dental practitioners more at risk repeated handling of unset products
7
Q
3 groups that can cause reactions
A
- metals
- polymers
- cements
8
Q
Types of metal we can have a reaction to
A
- metal and/or ionic metal hydroxides/oxides
- corrosion products
- wear products
9
Q
Kinds of polymers that cause reactions
A
- residual monomers
- leachable compounds
10
Q
Cements that cause reactions
A
- eugenol
- acids
- leachable compounds
- residual monomers
11
Q
Common problems in patients with material caused hypersensitivity
A
- stomatitis (chromium, cobalt, mercury, monomers, formaldehyde, eugenol)
- lichenoid reactions (amalgam, composite resins)
- plasma cell gingivitis
- angioedema
- erythema multiforme
12
Q
Issues for the dentist with material caused hypersensitivity
A
- contact dermititis
- when surface contacts allergen like nickel or monomers
- like monomers of bonding agent
- mainly distal parts of fingers and palmer aspects of fingertips
13
Q
List reasons why materials degrade
A
- oral environment
- corrosion
- wear
14
Q
How does the oral env degrade material?
A
- chemical degradation in aqueous env, hydrolysis and saliva esterases breaking down resins
- pH range
- temp
- solvents
- bacteria
15
Q
How does corrosion degrade material?
A
- metals and alloys
- dietary acids increase it
16
Q
How does wear degrade materials?
A
- contact and relative motion
- roughness effect
- loss of material
- wear debris - increase wear, biological response of inflammation and osteolysis/bone resorption)
17
Q
Consequences of degradation
A
- loss of materials (less mechanical proporties and reduction in mass)
- degradation products increase wear and cause immunological response locally and systemically
18
Q
Bulk properties of material
A
- chemical composition
- structure
- purity
- presence of leachables
19
Q
Bulk properties cause …
A
irritation
20
Q
Surface proporties of material
A
- roughness
- geometry
- hydrophilicity
- surface change
21
Q
Surface properties cause what?
A
adhesion (protein and cellular)
22
Q
Mechanical properties of material
A
- loading
- wear
- creep
- deformation
- stress corrosion cracking
23
Q
Mechanical properties cause what?
A
particulate release
24
Q
Interaction of material depends on …
A
application
25
Materials of dental implants
- titanium and its alloys
- coatings with ceramics
- all-ceramic implants available (zirconia)
26
Osseointegration
Biointegration
of dental implants
- direct bone contact with implant surface. Gap less than 10nm
- no gap
27
Materials in fracture fixation plates
- titanium and its alloys commonly
- resorbable polymers (polylactic acid, polyglycolic acid, copolymers)
28
Negatives to titanium as a fracture plate
- post-op complications
- stress shielding
- screw fixation
29
Features of resorbable polymers
- lower stiffness than titanium
- resorb over time
- acidic byproducts
30
Immediate biological reactions that happen within seconds and minutes
- water and ion interaction
- protein adsorption
- cellular deposition and spreading
- activation of body's cellular and immune response
31
Biological interactions that happen intermediately (hours/days)
- inflammation
- infection
32
Biological interactions that occur long term (months/years)
- remodelling of surrounding tissues
- calcification
- tumour or cancer formation
33
Local response to implanted material
- infection
- toxicity
- modification of normal healing
- tumorigenesis
34
Systemic effects to implanted material
- embolization
- hypersensitivity
- elevation of implant elements in blood
35
Patient characteristics can influence how tissues react. Which ones?
- age and health (immunology and metabolism)
- tissue damage - the procedure
- contamination (exposure to operating env, patient's response to infection)
36
Bacteria adhere to ... and form ...
- surfaces and form nucleated colonies
- form biofilms and all surfaces
- inflammation forms at interface of bacteria and tissues e.g gingivitis
37
Material dependent factors that help attachment ofbacteria
- chemical composition of material
- hydrophobic or philic
- material surface - morphology e.g roughness
38
Which is more resistant to bacterial adhesion? Hydrophobic or philic materials
hydrophobic
39
Bacteria dependent factors favouring attachment of bacteria
- hydrophobicity of bacteria
- surface charge of bacteria
40
Excluding material dependent and bacteria dependent factors, what other factors can affect bacterial adhesion?
fluid dynamics
41
Are there any links between oral and systemic health?
- yes between the oral biofilm and periodontal disease and systemic
- systemic dissemination of oral bacteria and their metabolites is linked to pathophysiology of atherosclerosis
Dental Materials
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