SRI GANESH
INDIAN DENTAL ACADEMY
Leader in continuing dental
education
www.indiandentalacademy.com
www.indiandentalacademy...
www.indiandentalacademy.com
Biological properties
of Dental materials.
www.indiandentalacademy.com
Contents
 Introduction
 Biocompatibility v/s Biological properties
 Components of biocompatibility
 Adverse effects of...
 Advantages & disadvantages of biocompatibility tests
 Correlation among the tests
 How tests are used together ?
 Reg...
Introduction
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Biological properties of Dental
materials
 Biocompatibility = Lack of interaction
 Biocompatible material = list of nega...
Components
 Initial Physiochemical interaction
 Effect of the tissue environment
 Local host response
 Transport of pr...
Adverse effects from Dental
materials
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Toxicity
 Placement of a foreign material in the body carries the possibility
of toxicity
 Toxicity can be of 2 types
 ...
Inflammation
 May result from toxicity or allergy and often it
precedes toxicity.
 Oedema, inflammatory cell infiltrate
...
Allergy
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Allergy
 Body specifically recognizes material as foreign &
reacts disproportional to the amount of material
 Gell & Coo...
 Type 1, 2, 3 – quickly. Eosinophils, Mast cells & B
lymphocytes
 Type 4 – delayed. Monocytes & T cells
 Allergic respo...
Mutagenic reactions
 Alteration in base pair sequence (mutation)
 2 types
 Alteration in cellular process that maintain...
Carcinogenic response
 Currently no dental material has been shown to be
carcinogenic for dental applications in patients...
Local & Systemic effects of
materials
 Local effects
 Pulp
 Periodontium
 Root apex
 Oral tissues – buccal mucosa, to...
Key principles that determine
adverse effects from materials
 A) various types of metal corrosion & other types of
materi...
 B) Surface characteristics :
 Surface is quite different from interior
 Examples
 Dental casting alloy containing 70%...
Concept of
Immunotoxicity
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Concept of Immunotoxicity
“ Based on the principle that small alteration in
the cells of immune systems by materials can
h...
Oral anatomy that influences
the Biological response
 Enamel : “seals” the
tooth
 Peroxides permeate
intact enamel
 Den...
 Bone : Osseointegration & Biointegration
 Osseointegration
 Implant & bone closely approximate to each other
 Approxi...
Measuring the
Biocompatibility
 Is not simple and methods of measurement are
evolving rapidly as more is know about the
i...
In Vitro test
 Placement of a material
or component of it in
contact with
cell, enzyme or some
other isolated biological
...
Types of cells used in In-vitro
assays
 Primary cells :
 Directly from an animal into culture
 Grows for only a limited...
Testing procedures & extent of
testing
 Manufacturer‟s responsibility to test new material
 A) Initial tests :deals with...
Cytotoxicity tests
 Measures cell count or growth after exposure to a
material
 Method 1 :
 Place the cells in the well...
Tests
 Sensitization test
 Oral mucous membrane irritation test
 Subcutaneous implant test
 Bone implant test
www.indi...
Usage tests
 Pulp &Dentine test
 Response of dentine & pulp
 Minimum experimental variables
 Pulp capping & Pulpotomy ...
Correlation among the tests
 Lack of correlation
 Less prominent biological response
 Barriers may exist
 Measure diff...
Advantages & disadvantages
of Biocompatibility tests
 In-Vitro test
 Advantages
 Quick to perform
 Least expensive
 S...
 In- Vivo test
 Advantages
 Allows complex systemic interactions
 More comprehensive
 More relevant
 Disadvantages
...
 Usage test
 Advantages
 Relevance to use of material is assured
 Disadvantages
 Very expensive
 Time consuming
 Ma...
usage progression
secondary of
primary testing
 Linear paradigm, relies on the accuracy of the primary tests (challenged ...
 Non linear thinking
U Progression
S of
P Testing
 All the 3 tests are done
 As test progresses Usage test predominates...
 Most common progression
Usage
„Recognizes
Primary Secondary complexity‟
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Standards that regulate the
measurement of Biocompatibility
 ANSI / ADA : earliest attempt in 1933
 1972 – The Council o...
 ISO Standard 10993 :
 Not restricted to dental materials only
 First published in 1992
 In 2002 ISO 10993 consisted o...
Current Biocompatibility
issues in dentistry
www.indiandentalacademy.com
 Reactions of pulp to
different materials
 Micro leakage :
 If a material does not
bond or debonds at
enamel or dentine...
 Dentine bonding :
 Bonding to dentine is
difficult –
composition, wetness, lo
w minerals
 Smear layer formation &
remo...
 Dentine bonding agents :
 HEMA is 100 times less cytotoxic in tissue culture
than Bis – GMA
 Bis – GMA, TEGDMA, UDMA
w...
Amalgam
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 Dental amalgam :
 Toxic or not ?
 In usage test response of
pulp to amalgam in shallow
or deep lined cavities
 Galliu...
 Dental cements
 Resin based materials :
 Resin composites –
luting or restorative
 Light cured < cytotoxic
than chemi...
 Glass ionomers :
 Luting agent &
restorative material
 Weaker polyacrylic acid
 Fluoride release
 Histological studi...
 Zinc phosphate :
 Luting agent & base
 Thermal conductivity closer
to enamel
 Pulpal damage in first 3
days due to in...
 Calcium hydroxide :
Suspension form Resin containing
Highly cytotoxic Mild to moderate cytotoxic
Necrosis 1mm or > No ne...
 Zinc oxide eugenol :
 Suppresses the nerve transmission
 Inhibit synthesis of Prostaglandins & Leukotriens
 Hammesfah...
Soft tissue response to the
luting cements
 Apply petroleum jelly
 Clean the excess
 Any residues of cement
www.indiand...
 Bleaching agents :
 Usually contain some form of peroxide
 In-Vitro – traverses the dentine & in sufficient
conc. can ...
Latex
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 Latex :
 6% to 7% of surgical personnel may be allergic
 42% adverse reactions to occupational materials
 Hypersensit...
Liquid vulcanization solid
latex sulphur + heat rubber
 Soaked in hot water leaches out allergens
 Allergenicity depends...
Impression materials
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 Impression materials :
 Price & Whitehead
(1972) – Allergic
contact stomatitis &
Foreign body response
 Sydiskis & Ger...
Casting alloys
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 Dental casting alloys :
 John c. Wataha 2000
 Release of elements is essential for adverse effects
 Identifying & qua...
 b) Systemic toxicity
 Released metals may not be inside the body
 Route of access – I.V < Peritoneal < Oral
 Distribu...
 d) Allergy to dental casting alloys
 Elemental release is essential for allergy
 Metal ions – Haptens
 Allergy & Toxi...
 Patch test for metals – controversial
 Application of metal ion to skin in the form of patch
 Injecting small amount o...
 Nickel :
 Common component
 Incidence of allergy 10% – 20%
 Cross reactivity between nickel & palladium (33%
& 100%)
...
 Beryllium :
 Used in Ni-Cr alloys in conc. of 1 – 2 wt%
 Forms thin adherent oxides
 Documented carcinogen
 Beryllio...
Reaction of other oral soft tissues
 a) Denture base
materials
 Methacrylates
 Greatest potential for
hyper sensitizati...
 True allergy of oral mucosa to denture base
material is very rare
 Residual monomer (methyl methacrylate)
 Allergic ac...
 b) Soft denture liners &
adhesives
 Release of plasticizers
 Extremely cytotoxic
 Effects are masked by
the inflammat...
Denture cleansers
 Used to cleanse the prosthesis
 Eg : Hypochlorite, mild acids, etc.
 Biocompatible & cause no harm t...
Artificial teeth
 Acrylic & Porcelain teeth
 Acrylic teeth is preferred in poor ridges
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Implants
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Reaction of bone & soft
tissues to implant material
 Materials – Ceramics, Metals, Carbons & Polymers
 a) Reaction to ce...
 d) Reaction to pure metals & alloys
 „Metal‟ oldest type of oral implant material
 Shares the quality of „strength‟
 ...
 Soft tissue :
 Epithelium forms bond
with implant similar to
that of tooth
 C.T apparently does not
bond to the titani...
Conclusion
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List of references
 Restorative dental materials by Craig & Powers
 Phillips‟ Science of dental materials
 Chemistry of...
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Precautions to be taken in the
Lab
 Make certain the ventilation system in room is
properly functioning
 During operatio...
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Thank you
For more details please visit
www.indiandentalacademy.com
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Biological properties of dental materials 1 /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Biological properties of dental materials 1 /certified fixed orthodontic courses by Indian dental academy

  1. 1. SRI GANESH INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. www.indiandentalacademy.com
  3. 3. Biological properties of Dental materials. www.indiandentalacademy.com
  4. 4. Contents  Introduction  Biocompatibility v/s Biological properties  Components of biocompatibility  Adverse effects of dental materials  Toxicity  Inflammation  Allergy  Mutagenicity  Carcinogenicity  Local & Systemic effects of materials  Key principles that determine adverse effects from materials  Concept of Immunotoxicity  Oral anatomy that influences the biological response  Enamel  Dentine & Pulp  Bone  Measuring the biocompatibility  Invitro tests  Animal tests  Usage tests  Clinical trials www.indiandentalacademy.com
  5. 5.  Advantages & disadvantages of biocompatibility tests  Correlation among the tests  How tests are used together ?  Regulatory standards for measurement of biocompatibility  Current biocompatibility issues in dentistry  Reaction of pulp to different materials  Dentine bonding & Dentine bonding agents  Dental amalgam  Dental cements  Bleaching agents  Latex  Impression materials  Biocompatibility of metals  Reaction of other oral soft tissues to restorative materials  Denture base material  Soft denture liner & adhesives  Reactions of bone & soft tissues to Implant materials  Conclusion  List of references www.indiandentalacademy.com
  6. 6. Introduction www.indiandentalacademy.com
  7. 7. Biological properties of Dental materials  Biocompatibility = Lack of interaction  Biocompatible material = list of negatives  Non degradable  Non irritant  Non toxic  Non allergic  Non carcinogenic  Non mutagenic  Total inactivity = Passive ignorance ?  More appropriate – active acceptance  Biocompatibility : ability of a material to perform with an appropriate host response, in a specific application. www.indiandentalacademy.com
  8. 8. Components  Initial Physiochemical interaction  Effect of the tissue environment  Local host response  Transport of products – Systemic effects  Establishment of solid-liquid interface as any material is implanted into the tissue  Protein absorption is the first event  Immediate response to injury is inflammation  Very few is know about the factors  Condition of the host  Properties of the material  Context in which the material is used Eg: Biocompatible as Crown & Bridge but not as an implant material www.indiandentalacademy.com
  9. 9. Adverse effects from Dental materials www.indiandentalacademy.com
  10. 10. Toxicity  Placement of a foreign material in the body carries the possibility of toxicity  Toxicity can be of 2 types  Acute toxicity.  Chronic toxicity.  Type 1: requires prolonged or repeated administration  Type 2: requires very few or one dose but long lasting effects  Type 1 chronic toxicity is a possibility with “Biomaterials” Eg: metal ions released by gradual corrosion of an implant  According to J.J.Jacobs et al (1991)  Vanadium – lungs  Aluminium – surrounding tissues  Fortunately, materials causing over toxicity are no longer used in dentistry. www.indiandentalacademy.com
  11. 11. Inflammation  May result from toxicity or allergy and often it precedes toxicity.  Oedema, inflammatory cell infiltrate  Current biocompatibility researchwww.indiandentalacademy.com
  12. 12. Allergy www.indiandentalacademy.com
  13. 13. Allergy  Body specifically recognizes material as foreign & reacts disproportional to the amount of material  Gell & Coomb‟s classification of immune responses  Type 1: Atopic or anaphylactic reaction  Type 2: Cytotoxic hypersensitivity reaction  Type 3: Immune complex disease  Type 4: Delayed or cell mediated hypersensitivity  Type 5: Stimulating antibody reaction  Type 6: antibody dependent, cell mediated Cytotoxic reaction www.indiandentalacademy.com
  14. 14.  Type 1, 2, 3 – quickly. Eosinophils, Mast cells & B lymphocytes  Type 4 – delayed. Monocytes & T cells  Allergic response – individual‟s immune system recognizes a substance as foreign  Allergic reactions – initially dose independent, disproportionate  Toxic / inflammatory reactions – dose dependant, proportionate www.indiandentalacademy.com
  15. 15. Mutagenic reactions  Alteration in base pair sequence (mutation)  2 types  Alteration in cellular process that maintain DNA integrity  Direct interaction  Can occur from radiations, chemicals, errors in DNA replication process  Examples  Metal ions – nickel, copper, beryllium  Few components of root canal sealers  Resin based materials to some extent www.indiandentalacademy.com
  16. 16. Carcinogenic response  Currently no dental material has been shown to be carcinogenic for dental applications in patients  However, carcinogenesis is often exceedingly difficult to prove or disprove conclusively www.indiandentalacademy.com
  17. 17. Local & Systemic effects of materials  Local effects  Pulp  Periodontium  Root apex  Oral tissues – buccal mucosa, tongue  Systemic effects  Function of the distribution of substances released from the materials  Simple diffusion  Lymphatics  Blood vessels  Access to the body by  Ingestion & absorption in gut  Inhalation  Release at tooth apex  Absorption into mucosa  Systemic response depends on  Duration & concentration of the exposure  Excretion rate of the substance  Site of the exposure www.indiandentalacademy.com
  18. 18. Key principles that determine adverse effects from materials  A) various types of metal corrosion & other types of material degradation :  Biocompatibility depends on the degradation process  Corrosion is determined not only by material composition but also by the biological environment  Many ways for release of products in host  Metal prosthesis – releases metal ions by  Electrochemical force  Particles dislodged by mechanical forces  Resin composites  Cyclic stresses  Salivary esterases www.indiandentalacademy.com
  19. 19.  B) Surface characteristics :  Surface is quite different from interior  Examples  Dental casting alloy containing 70% gold may have 95% gold at its surface  Relative unpolymerized state of a sealant at its surface  The surface composition, roughness, mechanical & chemical properties are critical to the biocompatibility www.indiandentalacademy.com
  20. 20. Concept of Immunotoxicity www.indiandentalacademy.com
  21. 21. Concept of Immunotoxicity “ Based on the principle that small alteration in the cells of immune systems by materials can have significant biological consequences ”  Examples:  Mercury ions increase the Glutathione but Palladium decreases Glutathione content of Monocytes  HEMA may change the ability of Monocytes to direct an immune response once challenged by plaque or others agents www.indiandentalacademy.com
  22. 22. Oral anatomy that influences the Biological response  Enamel : “seals” the tooth  Peroxides permeate intact enamel  Dentine & Pulp :  Smear layer  Effective in reducing the hydrostatic pressure but not diffusion  Acid etching www.indiandentalacademy.com
  23. 23.  Bone : Osseointegration & Biointegration  Osseointegration  Implant & bone closely approximate to each other  Approximation less than 100 A  No fibrous tissue in intervening space  Titanium alloys  Biointegration  Implant & bone are fused to one another & are continuous  Occurs with Ceramic & Ceramic coated metal implants Eg: Calcium & Tri calcium phosphate, Hydroxyapatite, Bioglass www.indiandentalacademy.com
  24. 24. Measuring the Biocompatibility  Is not simple and methods of measurement are evolving rapidly as more is know about the interactions between dental materials and oral tissues & as technologies for testing improves  Classified as  In Vitro test  Animal test  Usage test  Clinical trial – special case of a usage test in humans www.indiandentalacademy.com
  25. 25. In Vitro test  Placement of a material or component of it in contact with cell, enzyme or some other isolated biological system  Direct  Material in contact  Physically present or extract from material  Indirect  Some sort of barrier www.indiandentalacademy.com
  26. 26. Types of cells used in In-vitro assays  Primary cells :  Directly from an animal into culture  Grows for only a limited time  Continuous cells :  Primary cells transformed to allow them to grow indefinitely www.indiandentalacademy.com
  27. 27. Testing procedures & extent of testing  Manufacturer‟s responsibility to test new material  A) Initial tests :deals with general biocompatibility & systemic effects of a material  Short term systemic toxicity test  Short time oral administration  Toxicity profile  Acute systemic toxicity test  I.V administration  Inhalation toxicity test  Dental remedies that have significant volatility under usage condition  Hemolysis test  In vitro evaluation of hemolytic activity of materials intended for prolonged tissue contact  Emes mutagenicity & the dominant lethal test  To asses the potential carcinogenic activitywww.indiandentalacademy.com
  28. 28. Cytotoxicity tests  Measures cell count or growth after exposure to a material  Method 1 :  Place the cells in the well of a cell culture dish  If Cytotoxic - cell may stop growing, exhibit cytopathic features or detach from the cell  Method 2 :  Measurement of cytotoxicity by a change in membrane permeability  Loss in membrane permeability is equivalent or very nearly equivalent to cell death  Identifies the cells that are alive or dead www.indiandentalacademy.com
  29. 29. Tests  Sensitization test  Oral mucous membrane irritation test  Subcutaneous implant test  Bone implant test www.indiandentalacademy.com
  30. 30. Usage tests  Pulp &Dentine test  Response of dentine & pulp  Minimum experimental variables  Pulp capping & Pulpotomy test  Endodontic usage test  Assess response of the pulp wound & the periapical tissue  Influenced by – level at which the pulp tissue is cut off & total removal of pulp tissue  Bone implant usage test  To evaluate all materials that, during their intended use, penetrate the oral mucosa and the adjacent bone www.indiandentalacademy.com
  31. 31. Correlation among the tests  Lack of correlation  Less prominent biological response  Barriers may exist  Measure different aspects of the biological response to the material www.indiandentalacademy.com
  32. 32. Advantages & disadvantages of Biocompatibility tests  In-Vitro test  Advantages  Quick to perform  Least expensive  Standardized  Large scale screening  Excellent for mechanisms of interaction  Disadvantages  Relevance to In-Vivo questionable www.indiandentalacademy.com
  33. 33.  In- Vivo test  Advantages  Allows complex systemic interactions  More comprehensive  More relevant  Disadvantages  Relevance to use ?  Expensive  Time consuming  Ethical concern  Difficult to control  Difficult to interpret & quantify www.indiandentalacademy.com
  34. 34.  Usage test  Advantages  Relevance to use of material is assured  Disadvantages  Very expensive  Time consuming  Major legal / ethical www.indiandentalacademy.com
  35. 35. usage progression secondary of primary testing  Linear paradigm, relies on the accuracy of the primary tests (challenged by Major et al 1977)  No prediction of results in usage tests  Lack of correlation in In-Vitro tests How the tests are used together to measure the Biocompatibility www.indiandentalacademy.com
  36. 36.  Non linear thinking U Progression S of P Testing  All the 3 tests are done  As test progresses Usage test predominates www.indiandentalacademy.com
  37. 37.  Most common progression Usage „Recognizes Primary Secondary complexity‟ www.indiandentalacademy.com
  38. 38. Standards that regulate the measurement of Biocompatibility  ANSI / ADA : earliest attempt in 1933  1972 – The Council on dental material, instruments & equipment of ANSI / ADA approved document no. 41 for recommended standard practices for biological evaluation of dental materials  In 1982 updated to include test for mutagenicity  Uses linear paradigm www.indiandentalacademy.com
  39. 39.  ISO Standard 10993 :  Not restricted to dental materials only  First published in 1992  In 2002 ISO 10993 consisted of 16 parts  2 types of tests –  Initial – Cytotoxicity, sensitization & systemic toxicity. In – Vitro / animal test  Supplementary – chronic toxicity, carcinogenicity & bio-degradation. Animals / Humans  Specialized tests – Eg: dentine barrier test www.indiandentalacademy.com
  40. 40. Current Biocompatibility issues in dentistry www.indiandentalacademy.com
  41. 41.  Reactions of pulp to different materials  Micro leakage :  If a material does not bond or debonds at enamel or dentine  Previous belief  Concept of nano leakage  Between mineralized dentine & bonded material. In very small spaces of demineralized matrix into which material did not penetrate  Hydrolytic degradation of dentine – material bond www.indiandentalacademy.com
  42. 42.  Dentine bonding :  Bonding to dentine is difficult – composition, wetness, lo w minerals  Smear layer formation & removal  Many studies have shown  0.5mm of RDT is adequate  Dentine is a buffers of protons  Penetration of acids < 100 micrometers www.indiandentalacademy.com
  43. 43.  Dentine bonding agents :  HEMA is 100 times less cytotoxic in tissue culture than Bis – GMA  Bis – GMA, TEGDMA, UDMA www.indiandentalacademy.com
  44. 44. Amalgam www.indiandentalacademy.com
  45. 45.  Dental amalgam :  Toxic or not ?  In usage test response of pulp to amalgam in shallow or deep lined cavities  Gallium based amalgam  Excessive gallium release, roughness, discolor  Significant foreign body reaction  Absorption : 1 – 3 micrograms / day  Minimum dose to produce observable toxic effect is 3 micrograms / kg body weight www.indiandentalacademy.com
  46. 46.  Dental cements  Resin based materials :  Resin composites – luting or restorative  Light cured < cytotoxic than chemically cured  Pulpal reaction diminishes after 5 – 8 weeks  Protective liner or bonding agent minimizes Pulpal reaction www.indiandentalacademy.com
  47. 47.  Glass ionomers :  Luting agent & restorative material  Weaker polyacrylic acid  Fluoride release  Histological studies in usage test shows that any inflammatory infiltrate to ionomer is minimal or absent after 1 month www.indiandentalacademy.com
  48. 48.  Zinc phosphate :  Luting agent & base  Thermal conductivity closer to enamel  Pulpal damage in first 3 days due to initial low PH(4.2), reaches neutrality in 48 hours  When placed in deep cavities ?  Inclusion of Ca- OH to the powder or lowering the concentration of phosphoric acid www.indiandentalacademy.com
  49. 49.  Calcium hydroxide : Suspension form Resin containing Highly cytotoxic Mild to moderate cytotoxic Necrosis 1mm or > No necrotic zone shortly Neutrophil infiltration Dentine bridge formation 5 to 8 weeks is quick Slight inflammatory response wks - months Dystrophic calcification Dentine bridge www.indiandentalacademy.com
  50. 50.  Zinc oxide eugenol :  Suppresses the nerve transmission  Inhibit synthesis of Prostaglandins & Leukotriens  Hammesfahr 1987, initiated the search for a biocompatible resin base system incorporating Calcium hydroxide “ PRISM VLC DYCAL” www.indiandentalacademy.com
  51. 51. Soft tissue response to the luting cements  Apply petroleum jelly  Clean the excess  Any residues of cement www.indiandentalacademy.com
  52. 52.  Bleaching agents :  Usually contain some form of peroxide  In-Vitro – traverses the dentine & in sufficient conc. can be cytotoxic  Penetrates intact enamel & reaches the pulp in few min.  May burn gingiva www.indiandentalacademy.com
  53. 53. Latex www.indiandentalacademy.com
  54. 54.  Latex :  6% to 7% of surgical personnel may be allergic  42% adverse reactions to occupational materials  Hypersensitivity may be due to true latex allergy or reaction to accelerator & antioxidants White, milky sap Addition of ammonia Hydrolyses & degrades the sap proteins to produce allergens www.indiandentalacademy.com
  55. 55. Liquid vulcanization solid latex sulphur + heat rubber  Soaked in hot water leaches out allergens  Allergenicity depends on collecting, preservation & processing www.indiandentalacademy.com
  56. 56. Impression materials www.indiandentalacademy.com
  57. 57.  Impression materials :  Price & Whitehead (1972) – Allergic contact stomatitis & Foreign body response  Sydiskis & Gerhardt (1993) – some degree of toxicity in cell culture  Gabriela Mazzanti et al (2005) – no significant evidence of diffuse inflammation or local skin reaction www.indiandentalacademy.com
  58. 58. Casting alloys www.indiandentalacademy.com
  59. 59.  Dental casting alloys :  John c. Wataha 2000  Release of elements is essential for adverse effects  Identifying & quantifying the elements that are released is most relevant measure from stand point of Biocompatibility  a) Release of elements from casting alloys  Multiple phases  Inherent tendency to release elements – lability Eg: Cu, Ni, Cd, Zn & Ga – highly labile  Environmental conditions - PH www.indiandentalacademy.com
  60. 60.  b) Systemic toxicity  Released metals may not be inside the body  Route of access – I.V < Peritoneal < Oral  Distribution – there is no documented proof that these material cause „Systemic toxicity‟  c) Local toxicity  Micro environment exists around casting alloys  Metal ions can cause local toxicity  Increased exposure causes increased toxicity www.indiandentalacademy.com
  61. 61.  d) Allergy to dental casting alloys  Elemental release is essential for allergy  Metal ions – Haptens  Allergy & Toxic reaction – difficult to distinguish www.indiandentalacademy.com
  62. 62.  Patch test for metals – controversial  Application of metal ion to skin in the form of patch  Injecting small amount of ion below the skin  Assessment of the response is difficult  Salt of metal ions important for response Eg: chloride, sulphate, nitrate salts  Vehicle – whether its water, oil or petrolatum can vary the response  Grimaudo N.J 2001 – true allergic hypersensitivity to dental casting alloys is rare www.indiandentalacademy.com
  63. 63.  Nickel :  Common component  Incidence of allergy 10% – 20%  Cross reactivity between nickel & palladium (33% & 100%)  Nickel ions induces ICAM‟s in the endothelium – release of cytokines  It may contribute to any intraoral inflammation around nickel containing crowns www.indiandentalacademy.com
  64. 64.  Beryllium :  Used in Ni-Cr alloys in conc. of 1 – 2 wt%  Forms thin adherent oxides  Documented carcinogen  Berylliosis  Individual is hypersensitive  Inhalation of beryllium dust, salts, fumes www.indiandentalacademy.com
  65. 65. Reaction of other oral soft tissues  a) Denture base materials  Methacrylates  Greatest potential for hyper sensitization  Acrylic & diacrylic monomers, curing agents, antioxidants, ami nes, formaldehydes  For the patients most of these materials have been reacted in polymerization and thus less prone www.indiandentalacademy.com
  66. 66.  True allergy of oral mucosa to denture base material is very rare  Residual monomer (methyl methacrylate)  Allergic acrylic stomatitis  Heat cured is better www.indiandentalacademy.com
  67. 67.  b) Soft denture liners & adhesives  Release of plasticizers  Extremely cytotoxic  Effects are masked by the inflammation  Denture adhesives show severe cytotoxic reactions In-Vitro  Large amount of formaldehyde  Allowed significant microbial growth www.indiandentalacademy.com
  68. 68. Denture cleansers  Used to cleanse the prosthesis  Eg : Hypochlorite, mild acids, etc.  Biocompatible & cause no harm to the patient www.indiandentalacademy.com
  69. 69. Artificial teeth  Acrylic & Porcelain teeth  Acrylic teeth is preferred in poor ridges www.indiandentalacademy.com
  70. 70. Implants www.indiandentalacademy.com
  71. 71. Reaction of bone & soft tissues to implant material  Materials – Ceramics, Metals, Carbons & Polymers  a) Reaction to ceramic implant material  Very low toxic effects. Oxidized state, corrosion resistant  Used as a porous or dense coating  Root surface porosities > 100microns (firmly bound )  Root surface porosities < 100microns (fibrous ingrowth)  b) Hydroxyapatite  Relatively non resorbable form of calcium phosphate  Coating material & ridge augmentation material  c) Beta -Tricalcium phosphate  Another form of calcium phosphate, has been used in situations where resorption of the material is desirable www.indiandentalacademy.com
  72. 72.  d) Reaction to pure metals & alloys  „Metal‟ oldest type of oral implant material  Shares the quality of „strength‟  Initially selected on the basis of the „Ease of fabrication‟  Stainless Steel, Chromium-Cobalt- Molybdenum, Titanium and its alloys  Most commonly used is Titanium  Titanium‟s Biocompatibility is associated with its fast oxidizing capacity.  Corrosion resistant & allows Osseointegration www.indiandentalacademy.com
  73. 73.  Soft tissue :  Epithelium forms bond with implant similar to that of tooth  C.T apparently does not bond to the titanium, but forms a tight seal that seems to limits ingress of bacteria & its products www.indiandentalacademy.com
  74. 74. Conclusion www.indiandentalacademy.com
  75. 75. List of references  Restorative dental materials by Craig & Powers  Phillips‟ Science of dental materials  Chemistry of medical & dental materials by J.W.Nicholson  Concise Encyclopedia of medical & dental materials by David Williams  Dental biomaterials by Arturo N. Natali  Dent material 2005;21(4):371-74  JPD 2001 Aug;86(2):203-9  Gen Dent 2001 Sep-Oct;49(5):498-503  JPD 2000 Feb;83(2):223-34  JPD 1998 Sep;80(2):203-9  JPD 1993;69;431-5  J Biomater Appl 1987 Jan;1(3):373-81  BDJ 1972;133:9-14 www.indiandentalacademy.com
  76. 76. www.indiandentalacademy.com
  77. 77. Precautions to be taken in the Lab  Make certain the ventilation system in room is properly functioning  During operation of the dental lathe wear a protective eyewear & a mask  Clean & disinfect the dental lathe at least once daily  Use sterile rag wheels, stones & fresh pumice for each patient's prosthesis www.indiandentalacademy.com
  78. 78. www.indiandentalacademy.com Thank you For more details please visit www.indiandentalacademy.com

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