https://userupload.net/g0cao5wc6biu Ideally, a dental material that is to be used in the oral cavity should be harmless to all oral tissues—gingiva, mucosa, pulp, and bone. Furthermore, it should contain no toxic, leachable, or diffusible substance that can be absorbed into the circulatory system, causing systemic toxic responses, including teratogenic or carcinogenic effects. The material also should be free of agents that could elicit sensitization or an allergic response in a sensitized patient. Rarely, unintended side effects may be caused by dental restorative materials as a result of toxic, irritative, or allergic reactions. They may be local and/or systemic. Local reactions involve the gingiva, mucosal tissues, pulp, and hard tooth tissues, including excessive wear on opposing teeth from restorative materials. Systemic reactions are expressed generally as allergic skin reactions. Side effects may be classified as acute or chronic.

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2. OUTLINE
 Introduction
 Definition
 Requirements of dental materials
 Tests for evaluation of biocompatibility
 Allergic responses to dental materials
 Minimizing dental iatrogenesis
 Standards that regulate the measurement of
biocompatibility
 Biocompatibility of dental materials

3.  Reaction of other oral soft tissues to restorative
materials
 Reaction of bone & soft tissues to implant materials
 References
 Conclusion

4. INTRODUCTION

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6. DEFINITION
‘It is the ability of a material to elicit an appropriate
biological response in a specific application’
William D,F 1987
The term biocompatible is defined as being
harmonious with life & not having toxic or injurious
effects on biologic function
Dorland’s illustrated Medical Dictionary

7. REQUIREMENTS
Shouldn’t be harmful to the pulp and soft tissues.
Shouldn’t contain toxic diffusible substances.
Should be free of potentially sensitizing agent.
Should have no carcinogenic potential

8. TESTS FOR EVALUATION OF
BIOCOMPATIBILITY
Group 1: PRIMARY TESTS
Group 2: SECONDARY TESTS
Group 3: PRECLINICAL USAGE TESTS

9. GROUP 1: Consists of cytotoxic evaluation

10. GENIOTOXICITY TEST-Used to determine whether
gene mutations, changes in chromosomal structure
or other genetic changes are caused by the test
materials.
AAMI Standards,1994

11. GROUP 2:The product is evaluated for its potential
to create: Systemic toxicity
Inhalation toxicity
Skin irritation
Sensitization
Implantation responses

12. Implantation Tests-For short term tests <12 weeks
For long term tests>12 weeks

13. GROUP 3
a)Pulp & dentin usage tests-Non rodent mammals are
selected.
The less reparative dentin formed the better.
b)Pulp capping & pulpotomy usage tests-Observations
are made of dentinal bridge formation.
.

14. c) Endodontic usage tests-Degree of inflammation is
evaluated in the periapical areas

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16. CORRELATION AMONG IN
VITRO,ANIMAL & USAGE TESTS
In vitro & animal tests measure aspects of biological
response that are more subtle than in a material’s
clinical usage.
Barriers between the material & tissues exist in
usage tests
Best barrier is dentin,which is not present in vitro.

17. ALLERGIC RESPONSES TO
DENTAL MATERIALS
a) ALLERGIC CONTACT DERMATITIS-
 Most common
 Interval between exposure & clinical
manifestations varies between 12 & 48 hrs.
 Primary irritant dermatitis
 Highest incidence in personnel & patients involved
in orthodontics & pediatric dentistry.

18. b) ALLERGY TO LATEX PRODUCTS-
Rubber has been identified as a cause of contact
sensitivity since mid 1940s,Malten & Associates
reported an increasing incidence in 1976.

19. It may represent a true latex allergy or a reaction to
accelerators & antioxidants used in latex
processing
Rankin et al 1993
Thiuram also causes allergic reactions.

20. March (1988) suggested that the polyether
components in latex rubber gloves was the causative
agent.
FDI(1991) estimated that about 6% to 7% of surgical
personnel may be allergic to latex.
Reactions:
Dermatitis of the hands(eczema) is the most common
adverse reaction
Rankin et al,1993

21. c) ALLERGIC CONTACT STOMATITIS-
Most common adverse reaction to dental materials.
May be local or contact type lesions.
Patch test

22. Common allergens:
People who are sensitive to formaldehyde may develop
enhanced tissue responses under this condition.
Free residual methyl methacrylate monomer in acrylic
dentures can cause allergic reactions.

23. MERCURY CONTROVERSY-
MINIMATA Disaster of early 1970s in Japan

24. Headache is not a symptom of mercury poisoning
Symptoms of chronic Hg poisoning:
Symptoms of elemental Hg poisoning:

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26. Lowest level of total blood Hg at which earliest non
specific symptoms occur is 35ng/ml.
 Allergy to Nickel-About 10% of the females & only 1%
male.
Only about 30% of the patients having nickel allergy
develop a reaction to an intra oral nickel chromium
dental alloy.

27.  Toxicity & allergenicity of beryillium-
Berylliosis
Beryllium containing alloys should be ground with
adequate ventilation.

28. MINIMIZING DENTAL
IATROGENESIS

29. MINIMIZING DENTAL
IATROGENESIS
Iatros-physician & genesis - to produce
It is defined as the creation of side effects, problems or
complications resulting from treatment by a
physician or dentist.
Parameters for assessment

30. Cavity preparation:
Low speed(6000 to 20,000 rpm)- minimal pulpal
response
High speed(>50,000 rpm)- pulpal response is greatly
reduced.
Inflammatory response is significant in the first 24 hrs.

31. First effort of ADA to establish guidelines for dental
materials came in 1926 at NIST.
One of the early attempts to develop a uniform test
for all materials by Dixon & Rickert in 1933.
Other attempts were carried out by Mitchell(1959)
on connective tissue & by Massler(1958) on tooth
pulp.
STANDARDS THAT REGULATE THE
MEASUREMENT OF BIOCOMPATIBILITY

32. 1. ANSI/ADA Document 41-Three categories
described in the 1982.
Initial
Secondary
Usage tests

33. Initial tests:1) In vitro assays for cytotoxicity
2)RBC membrane lysis
3)Mutagenesis & Carcinogenesis at the
cellular level
4)In vivo acute physiological distress
5)Death of the whole organism

34. Secondary tests: Inflammatory or immunogenic
potential
Usage tests

35. 2.Iso 10993-The final document ISO 10993 was
published in 1992 .
ISO 10993 contains 12 parts.
Initial tests are for cytotoxicity, sensitization &
systemic toxicity

36. Supplementary tests are- Chronic toxicity
Carcinogenecity
Biodegradation

37. BIOCOMPATIBILITY OF
DENTAL MATERIALS

38. REACTIONS OF PULP-
Microleakage: If a bond doesn’t form between the
tooth and the restorative material or debonding
occurs, bacteria, food debris or saliva may be drawn
into the gap by capillary action. this effect has been
termed microleakage.

39. Nanoleakage:It refers to the leakage of saliva,bacteria
or material components through the interface
between a material & a tooth structure.
It can occur even when the bond between the material
& dentin is intact.
Hydrolytic degrading of the dentin material bond.

40. DENTIN BONDING-
Smear layer

41. Numerous studies have shown removal of the smear
layer improves the strength of the bond between
dentin & restorative materials.
Hybrid layer
Removal of smear layer poses threat to pulpal tissues
for 3 reasons:

42. DENTIN BONDING AGENTS-
 Causes suppression of cellular metabolism for upto
4 weeks.
HEMA is atleast 100 times less cytotoxic in tissue
culture than BIS-GMA.
If the dentin is <0.1mm, HEMA may be cytotoxic in
vivo
HEMA and other resins may act synergistically to
cause cytotoxic effects in vitro.

43. RESIN BASED MATERIALS-
Light cured resins are less cytotoxic than chemically
cured systems.
Pulpal response is low to moderate after 3 days when
RDT is 0.5mm.
With a protective liner or bonding agent reaction of
the pulp is minimal.

44. AMALGAM & CASTING ALLOYS-
Biocompatibility of amalgam is determined largely
by corrosion products released.
With the addition of copper ,amalgams become toxic
to cells in culture.
Implantation tests show that low copper amalgams
are well tolerated,but high copper cause severe
reactions.

45. Gallium alloys are no more toxic than high copper
alloys in cell culture.
• Cast alloys contain several noble & non noble metals
but the pulp is more likely to be affected by the luting
cement.

46. GLASS IONOMERS-
In screening tests, freshly prepared ionomer is
mildly toxic, reduces with time.
Fluoride release may cause cytotoxicity.
Histological studies show any inflammatory
infiltrate is minimal or absent after 1 month.
Several reports of pulpal hyperalgesia for short
periods .

47. LINERS,VARNISHES & NON-RESIN
CEMENTS-
CALCIUM HYDROXIDE-
High pH in suspension leads to extreme cytotoxicity in
screening tests.
Calcium hydroxide containing resins causes mild to
moderate cytotoxic effects in both freshly set & long term
set conditions.
Inhibition of cell metabolism is reversible.
Coagulates any hemorrhagic exudate of the superficial
pulp

48. Resins in Ca(OH)2 stimulate reparative dentin
formation more quickly & with no zone of necrosis.
Resin containing Ca (OH)2 pulp capping agents are
the most effective liners now available for treating
pulp exposures.
Initial response of exposed pulpal tissue is
necrosis to a depth of 1 mm or more

49. ZINC PHOSPHATE-
Strong to moderate cytotoxic reaction that decrease
with time.
Focal necrosis
Initial low pH on setting-4.2 at 3 mins
Placement of a protective layer indicated.

50. ZINC POLYCARBOXYLATE-
Cytotoxicity correlated with the release of zinc &
fluorides into the culture medium & low pH.
Concentration of polyacrylic acid above 1% cytotoxic.
Reparative dentin formation is minimal
,recommended only in cavities with intact dentin in
the floor.

51. ZINC OXIDE EUGENOL-
In vitro,eugenol depresses cell respiration & reduces
nerve transmission with direct contact.
Effects of eugenol are dose dependent.
Conc. Of eugenol just below ZnOE has been reported to
be 10-2
M ,on the pulpal side 10-4
M or less.
Causes only a slight to moderate inflammatory reaction
Used as a negative control

52. BLEACHING AGENTS-
In vitro studies,show peroxides rapidly traverse the
dentin to be cytotoxic.
Cytotoxicity depends on concentration of peroxides.
Tooth sensitivity-cause unknown
Can chemically burn gingiva.

53. REACTION OF OTHER ORAL
SOFT TISUES TO RESTORATIVE
MATERIALS
Components from dental materials & plaque may
synergize to enhance inflammatory reactions.
Composites are initially very cytotoxic in vitro tests
of direct contact with fibroblasts
Newer composites with non-BISGMA,non-UDMA
have lower cytotoxicity

54. Polished composites show less cytotoxicity
Methacrylate based composites may cause
hypersensitivity.

55. Amalgam –
• Gingival inflammation
• Hydropic degeneration
• Copper – bactericidal
• Severe reactions to gallium based alloys
Nickel allergy
Palladium allergy
Patients with palladium allergy are always allergic to
nickel.

56. Denture base materials-
Immune hypersensitivity of gingiva & mucosa.
Denture liners & adhesives-
Release of plasticizers
Extremely cytotoxic
Microbial growth

57. REACTION OF BONE & SOFT TISSUES
TO IMPLANT MATERIALS
Four basic implant materials: Ceramics
Carbon
Metals & polymers

58. Reactions to ceramic implant materials-
Very low toxic effect
Hydroxyapatite -coating material for titanium
implants.
Biologic response of carbon coatings can be
favourable,they have been supplanted by
titanium,aluminium oxide& hydroxyapatite

59. Reactions to pure metals & alloys-
 Oldest type
 Most common-Titanium
 Ti6Al4V has been used successfully
In the soft tissue,bond epithelium that forms with
titanium is morphologically similar to that formed
with the tooth.

60. Connective tissue doesn’t bond to titanium , but forms
a tight seal that limits the ingress of bacteria &
bacterial products.

62. TESTS FOR EVALUATION OF
BIOCOMPATIBILITY

63. PRIMARY TESTS-

64. SECONDARY TESTS-

65. PRE CLINICAL USAGE TESTS-
“GOLD STANDARD”

66. CORRELATION AMONG IN
VITRO,ANIMAL & USAGE
TESTS

68. CORE MATERIALS-
1. SILVER CONES-

69. 2. GUTTA PERCHA-

70. Thermoplasticized guttapercha technique-

71. 3. RESILON-

72. “MONOBLOC”
FORMATION-

73. SEALERS AND CEMENTS-
1. ZINC OXIDE EUGENOL-

74. 2. CALCIUM HYDROXIDE CONTAINING SEALER-

75. 3. FORMALDEHYDE CONTAINING SEALER-

76. 4. CHLOROFORM BASED SEALERS-
Chloroform substitutes:

77. 5. POLYMERS-

78. 6. GLASS IONOMER SEALERS-
Ketac endo:

79. MINERAL TRIOXIDE AGGREGATE-

80. IRRIGANTS & INTRACANAL MEDICAMENTS-

81. 1. SODIUM HYPOCHLORITE-

82. 2. ETHYLENE DIAMINE TETRA ACETIC ACID-

83. 3. CHLORHEXIDINE-

84. 4. CALCIUM HYDROXIDE CONTAINING SEALER-

85. 5. ANTIBIOTICS & ANTI INFLAMMATORY DRUGS-

86. 6. PHENOL & PHENOL DERIVATIVES-
Pulpotomy:

88. REFERENCES
Science of dental materials-Philips,10th
edition
Restorative dental materials-G.Craig & John M.
Powers,11th
edition.
Notes on dental materials-Combe,5th
edition.
International web site: www.google.com

89. Pathways of pulp, Cohen
International endodontic journal 36,147-160,2003.
International endodontic journal,36,75-85,2003.

91. “ABSOLUTE BIOCOMPATIBILITY MAY BE
REGARDED AS UTOPIA,WHILE IN MORE
REALISTIC WAY WE HAVE TO CONSIDER THE
DEGREE OF BIOCOMPATIBILITY THAT WE FIND
IN PRACTICE”
-D.Williams