Bio compatibility testing of dental materials

1. BIOCOMPATIBILITY
OF
DENTAL MATERIALS
DR. MANJIRI HONAP
DEPARTMENT OF CONSERVATIVE DENTISTRY &
ENDODONTICS

2. CONTENTS
• Introduction
• requirements
• Definition
• Evaluation of biocompatibility
• Primary (in-vitro) test
• Animal (in-vivo) test
• Usage test
• Conclusion
• references

3. 3
Dental materials of various kinds are used in
dentistry, of which some are left in contact with
oral hard and soft tissues for number of years
( e. g. restorations and appliances)
While others are used temporarily during the
course of treatment
(e.g. impression materials, waxes, abrasives,
polishing agents etc.)
INTRODUCTION

4. 4
BIOCOMPATIBILITY REQUIREMENTS:
Ideally, a dental material that is to be used in the oral cavity, should be
 Harmless to all oral tissues
 Free of agents that could elicit sensitization or an allergic response
 Contain no toxic, leachable, or diffusible substance that can be absorbed
into the circulatory system, causing systemic toxic responses, including
teratogenic or carcinogenic effects.

5. 5
Biocompatibility is defined as “Being harmonious with life and not having toxic
or injurious effect on biologic functions”.
Or
Ability of a material to perform with an appropriate biological response when
applied as intended.
Definition

6. Host response :
Response of living
tissues to the
material.
Material response:
Response of the
material to the
living systems.
Biologic response

8. EVALUATION OF BIOCOMPATIBILITY
In vitro test Animal test Usage test
1.Mucous membrane
irritation test
2. Skin sensitization test.
3. Implantation test.
4. Systemic toxicity test.
5. Inhalation test.
1. Dental pulp
irritation test
2. Pulp capping and
pulpotomy test.
3. Endodontic usage
test.
Cytotoxicity test
Cell metabolism test
Mutagenic test

9. LEVEL I : PRIMARY OR
IN-VITRO TEST
Test tube
Cell culture dish
Outside living organism

10. Quick to perform.
 Less expensive than animal and usage test.
 Can be standardized.
 Well suited to Large scale screening.
 Good experimental control.
 Can be tightly controlled to address specific scientific questions.
Advantages of in vitro test

11. These tests assess cell death caused by a material by measuring
Cell number or growth, before and after exposure to the test
material.
Cytotoxicity tests

12. • 1. Direct contact test

13. The test is used on the basis that a loss in membrane
permeability is equivalent to or nearly equivalent to cell
death.
Membrane permeability test

14. In vivo, direct contact often does not exist between cells and
materials. Separation of cells and materials may occur from
keratinized epithelium, dentin or extracellular matrix.
Thus several in vitro barrier tests have been developed to mimic
in vivo conditions.
2. indirect contact tests
(Tests that use barriers)

15. Dentin forms a barrier through
which toxic materials must diffuse
to reach the pulp.
2. Dentin barrier test

16. Questionable relevance to the final in vivo use of the material.
Lack of inflammatory and other tissue-protective mechanisms in
the in vitro environment.
Note: In vitro study alone cannot entirely predict the overall
biocompatibility of the material.
Disadvantages of
in vitro test

17. 17
Level II: Screening tests
or secondary tests
Or animal tests

18. These tests are usually done in mammals such as mice,
rats, hamsters, or guinea pigs.
The biologic responses in animal tests are more
comprehensive.
Relevant than in vitro test and these features are major
advantages of this test.
Animal tests are distinct from usage tests in that the
material is not placed in an animal with regard to its final use.

19. They can be difficult to interpret and control,
are expensive, may be time consuming.
And often involve significant ethical
concerns.
Disadvantages

20. This test determines if a material causes inflammation to the
mucous membranes or abraded skin.
During this test, test materials are placed into contact with
hamster cheek-pouch tissue or rabbit oral tissue.
1. Mucous membrane
irritation test

21. In guinea pigs, the test materials are injected intradermally
to test the development of skin hypersensitivity reactions.
Freund’s adjuvant can be used to augment the reaction.
Allergy test on a guinea pig;
the redness of the back skin is
typical of an allergenic material.
2. Skin sensitization test

22. These tests are used to evaluate materials that will contact
subcutaneous tissue or bone.
The location of the implant site is determined by the use of
the material and may include connective tissue, bone or
muscle.
3. Implantation test

23. To determine systemic toxicity, the test substances can
be administered to experimental animals in various
ways.
In dentistry, most substances or materials are
administered orally (feeding of an extract of the test
material, mostly finely ground).
Previously, the acute LD50 was determined as routine.
4. Systemic toxicity test

24. An aerosol of the test material is sprayed around the
head of experimental animal in a chamber periodically.
If the animal dies in a few minutes, or hours, the
materials are considered toxic.
5. Inhalation test

25. Level III: usage test

26. Can be done in animals or human volunteers.
usage tests in animals employ larger animals that have similar
environments to humans, such as dogs and monkeys.
Usage test
 Test material is placed in a situation identical to its
intended clinical use.

27. ADVANTAGES:
 They are totally relevant.
 These tests are the gold standard and give the
ultimate answer to whether or not a material will
be biocompatible.
DISADVANTAGES:
 Are extremely expensive.
 Last for longer periods.
 Involve many ethical and often legal concerns.
Usage test

28. Pulp compatibility of dental materials is of great importance
to the dentist.
It is investigated on teeth of experimental animals or on
human teeth that have to be extracted for orthodontic
reasons.
In both cases, class V cavities are prepared as
atraumatically as possible and are then filled with the test
material.
1.Pulp and dentin usage test

29. After a period of days to several months, the teeth are
removed and histologically prepared, and the pulps are
microscopically evaluated for signs of acute or chronic
inflammation and odontoblast reaction (including dentin
neogenesis)
In addition, the space between test material and the
cavity wall is investigated for bacterial penetration.

30. These methods can be modified in such a way that the
pulp is exposed or part of the pulp is removed before
the material is applied.
In this way, materials and methods intended for direct
(vital) pulp cappings or pulpotomies can be assessed.
2. Pulp capping and pulpotomy
usage test:

31. Minor irritations can stimulate present odontoblasts to form
tertiary dentin (“reactive dentin”) in the pulp combined with an
obliteration of dentin tubules.
3. Tertiary dentin formation

32. Animal models (e.g., primates, dogs) are used and
application of a given material into the root canal is
done according to endodontic techniques after a usual
root canal preparation.
Compatibility is assessed by histologic evaluation of
the peri apical tissues.
4. Periapical Tissue Damage
and Endodontic Usage Test

33. Conclusion
For a biocompatible material one should observe minimal or no
response and the shortest resolution time of a response.

34. References
Biocompatibility of Dental Materials by Gottfried Schmalz,
Dorthe Arenholt-Bindslev.
Craig’s restorative dental materials 12th edition.