Biocompatibilty of dental materials

1. BIOCOMPATIBILITY OF
DENTAL MATERIAL
PRESENTED BY
DR ARUN KUMAR C S

2. INTRODUCTION

3. BIOCOMPATIBILITY
• Biocompatibility is “the ability of a material to elicit
an appropriate biological response in a given
application in the body”.
• Capable of material to exist in harmony with the
surrounding biologic environment.
-Kenneth J. Anusavice
-GPT, 9TH Edition

4. REQUIREMENTS OF A BIOCOMPATIBLE
MATERIAL
Should not
harmful to pulp & soft tissues.
contain toxic diffusable substance.
have carcinogenic potential.
 cause allergy.
Applied Dental Materials, 9th edition John F. McCabe & Angus W.G. Walls

5. Evaluation of Biocompatibility
 Biocompatibility tests are classified on three
levels (tiers) :-
1. Group I : Primary tests
2. Group II : Secondary tests
3. Group III : Usage tests
Craig’s Restorative Dental Materials, 12th edition
Usage
Secondary
Primary
Number of materials
Progressoftesting

6. PRIMARY TESTS
• invitro in nature.
• Carried outside (test tubes, cell culture dish, flask).
• Placed in contact directly or by means of a barrier.
These are done to evaluate
• Invitro cytotoxicity.
• Mutagenecity.
• Systemic toxicity.
In vitro tests
Direct
tests
Indirect
tests

7. Cytotoxicity Tests
placed directly on tissue culture cells / membranes
overlying them.
Craig’s Restorative Dental Materials, 12th edition
Genotoxicity Tests
Determines carcinogenic/mutagenic potential.
On mammalian or non-mammalian cells .
Evaluates gene mutations, chromosomal
structure .

8. PRIMARY TESTS
• Direct Cell culture test
• Membrane integrity assay
• Barrier screening test
• Agar diffusion test
• Filter diffusion testing method
• Dentin barrier test
• Tooth slice culture assay
• Ame’s test
• Style’s test

9. DIRECT CELL CULTURE
• Mouse fibroblasts or human epithelial cells used.
• culture dishes placed until a mono-layer of cells are formed.
• The tested material is added to the culture and placed for 3
days.
Murray PE, et al. Med Oral Patol Oral Cir Bucal. 2007 May 1;12(3):E258-66

10. AGAR OVERLAY METHOD(leach)
AGAR

11. DENTIN BARRIER TESTS

12. AMES TEST (Genotoxicity Test)

13. SECONDARY TESTS
Mostly conducted on animals(Mice, rats, hamsters, or
guinea pigs ).
• Inhalational Toxicity
• Skin Irritation
• Sensitization
• Maximization test
• Implantation Responses.
• Buehler’s test
Murray PE, et al. Med Oral Patol Oral Cir Bucal. 2007 May 1;12(3):E258-66

14. ANIMAL TESTS
Advantage :
• biological responses more comprehensive
• More relevant than in vitro tests
Disadvantages :
• Difficult to interpret and control
• Expensive
• Time consuming
• Ethical concerns .

15. MUCOUS MEMBRANE
IRRITATION TEST

16. SKIN SENSITIZATION TEST
Dermal patch will be
used after injection

17. IMPLANTATION TEST
Polyethylene tubes Test material
SHORT TERM 1 – 11 weeks
LONG TERM 1 – 2 years

18. USAGE TESTS
• Performed on animals and humans.
• To test both pulpal and bone response.
• On humans – clinical trial .
Various tests are
• Pulp-dentin test for restorative materials
• Pulp-capping and pulpotomy material test
• Mucosal damage and mucosa usage test
• Gingival usage test.
Murray PE, et al. Med Oral Patol Oral Cir Bucal. 2007 May 1;12(3):E258-66

19. • Pulp is merely exposed & partially removed for pulpotomy
assessment.
• Application of particular cement is done.
• Dentinal Bridge Formation is observed.
PULP CAPPING AND PULPOTOMY
USAGE TEST :

20. STANDARDS THAT REGULATE THE
MEASUREMENT OF BIOCOMPATIBILITY:
The first efforts of the ADA to establish guidelines for dental
a materials came in 1926 .
ANSI/ ADA specification 41: Three categories are
described in the 1982: initial, secondary and usage tests
ISO 10993
• International efforts were initiated by several
organisations to developed international standards for
biomedical materials and devices.

21. • Standard organisation (ISO) published the final
document in 1992.
• It contained 12 parts
• The ANSI/ ADA specification from council on scientific
affairs, American dental association .

22. US FDA
(FOOD AND DRUG ADMINISTRATION)
• ANSI results are send to FDA for approval.
• Product is approved by FDA if it passes the primary &
secondary tests.
• For dental material manufacturers a period of 7 years is
given to prove efficacy.

23. USFDA classified the materials into 3 group
based on relative risk factors.
• Class I Low risk
• Class II Required to meet FDA
performance standards
• Class III Most stringent category, needs
approval for safety & effectiveness before marketing.

24. PHYSICAL FACTORS AFFECTING
PULP HEALTH

25. Microleakage
 Penetration of fluids along interface between
restoration & tooth
 It can result in :-
1. Secondary/Recurrent caries pulpitis, pulp
abscess, etc.
2. Staining or discoloration
3. Sensitivity due to continuing Pulpal irritation

26. Nanoleakage vs Microleakage
NANOLEKAGE IDEAL MICROLEKAGE

27. Thermal Changes
Temperature fluctuations may crack restorative material
Microleakage
Metals are good conductors of heat, causing sensitivity
with large metallic restorations
eg. Amalgam or gold inlays

28. Galvanism
Flow of current when two
dissimilar metallic
restorations
Due to different
electromotive potentials
Saliva acts as electrolyte
Contact Short-circuit
current flows through pulp
Pain & Discomfort

29. Estrogenicity
• chemical act similar to estrogen.
• Bisphenol A –on estrogenic receptors in cells.
• E-screen assay –growth response of breast cancer
cells that are estrogen sensitive .

30. Biocompatibility of dental materials
in oral environment

31. LATEX
• Latex from rubber tree.
• Ammonia is added as preservative,
(vulcanization)allergy.
• Angioneurotic allergic reactions oedema, chest pain, and
a rash on the neck and chest of severely allergic persons
• Skin irritation test (epinephrine)
Koh D, Ng V, Leow YH, Goh CL. Br J Dermatol. 2005 Nov;153(5):954-9

32. CASTING ALLOYS
• Alloy is any mixture of 2 or more metals
• Element is released from an alloy to cause allergy
• (mucous irritation test)
John M.Powers ,Criag’s , Restorative dental materials, 11TH edition , Elsevier PG 98- 126

33. BERYLLIUM
• In Ni-Cr alloys to increase the castability of these
alloys.
• Chemical bonding of porcelain .
• Documented carcinogen in metallic or ionic state.
• Berylliosis (inhalation test).

34. NICKEL
• Most allergic
• Palladium
• F>M
• Rakesh G.makwana reported that Ni
is a allergen by patch testing .

35. Wataha JC, et al. Dent Clin North Am. 2004 Apr;48(2):vii-viii, 499-512
METAL IN ALLOYS EFFECT ON TISSUE
Beryllium Carcinogenic
Cadmium Carcinogenic
Chromium Carcinogenic
Cobalt Carcinogenic
Copper Mutagenic
Gallium not mutagenic in vitro
studies
Nickel Carcinogenic (NiS)
Palladium mutagenic Low risk
Tin Mutagenic
Zinc Not mutagenic
Iron Mutagenic

36. AMALGAM
• Determined largely by corrosion products released
• Unreacted mercury from amalgam is toxic
• Copper.
• into the gingival crevice causes inflammation of the
gingiva
Mahler DB. J Dent Res. 1997Jan;76(1):537-41.

37. Amalgam & Mercury
Mercury itself has no effect on pulp
Acute mercury poisoning :-
Chronic mercury poisoning :-
Weakness, anorexia, wt. loss, insomnia, irritability,
dizziness & tremors .
Methyl mercury poisoning :-
Paresthesia , ataxia ,Tunnel Vision
Biocompatibility of Dental Materials - Gottfried Schmalz, Dorthe
Metallic
Inorganic
Organic

38. AMALGAM (miracle mix)
• The cavities, depths of about 2 mm, were between
the CEJ and the root tip.
• The teeth reimplanted after restoration
• The animals were sacrificed at 6 months.
• Result suggests that resin composites and amalgam
release cytotoxic materials

39. CEMENTS

40. ZINC PHOSPHATE
In Vitro screening test strong to moderate reactions.
• Usage test in deep cavity preparation moderate to severe
localized pulpal damage in 3 days.
• Toxic reactions were observed in a permanent growing cell
line
• The PH of the set cement is 2
John M.Powers, Criag’s, Restorative dental materials, 11TH edition , Elsevier PG 98- 126

41. ZINC POLYACRYLATE
In short tissue culture test, the release of zinc and
fluoride ions in reduced PH .
• After 3 days. Pulpal response of poly acrylate
cements is same as ZOE,
John M.Powers, Criag’s, Restorative dental materials, 11TH edition , Elsevier PG 98- 126

42. ZOE CEMENTS
In vitro test ,depresses cell respiration, and reduces nerve
transmission with direct contact.
• In usage tests ,slight to moderate inflammation within
the first week.
• Reduced to mild chronic inflammatory
• Reparative dentin formation( within 5 to 8 weeks),
John M.Powers, Criag’s, Restorative dental materials, 11TH edition , Elsevier PG 98- 126

43. RESIN MODIFIED GIC
HEMA diffuses through the dentin to pulp .
• Persistent inflammation and allergic reactions .
• HEMA can penetrate latex cause contact dermatitis.
• Resin modified < conventional GIC
• John w. Nicholson, the biocompatibility of resin modified glass ionomer cements fro dentistry, dental materials 2008, 24, 1720-1708
• M.Ghavamnasari, A histopathological study on pulp responses to glass ionomer cements in human teeth., Journal OF Dentistry, Tehram University Of
Medical science2005, VOL 2, NUMBER 4

44. Impression Materials
Irreversible hydrocolloids :- Inhaling fine airborne
particles (dust) can cause silicosis & pulmonary
hypersensitivity.
Dustless/Dustfree alginate is preferred
Elastomers :- Cellular toxicity levels
Polyether > Addition Silicone > Polysulphide

45. IMPRESSION MATERIALS
Kanarek described a clinical case of polysulphide
impression material . Severe inflammatory reactions
Chiaro coppi did a study on toxicity of impression
materials using human fibroblast
• polyether materials are cytotoxic
• among poly vinylsiloxanes, only Light Body induces clear
inhibition of cellular viability tests

46. POLYSULFIDE RUBBER
IMPRESSION MATERIAL
• ADA measured toxicity by injecting material into
the oral mucosa of baboons for 48 h
• light-bodied materials were less toxic and
contained less lead. Lead peroxide (PbO2) are used
in materials for radiographic detection.
J Dent Res 62(5):548-55 1, May 1983
Spranley TJ, et al. J Dent Res. 1983 May;62(5):548-51

47. CERAMICS
• systemic toxicity extremely low
• silicosis(fibrotic pneumoconiosis)
• inflammation after implantation in muscle
• uranium oxide cause radioactivity

48. DENTURE BASE MATERIAL
• Heat polymerizing, light curing, or Chemically
• Methyl esters of methacrylic acid are the
basicmodules of PMMA
• cytotoxic to epithelial cells in culture.
• Initiator dibenzoyl peroxide, and the cross-linking
agent EGDMA are the most common allergens
• water (37°C) before insertion to remove the major
share of leachable substances.

49. DENTURE ADHESIVES AND SOFT
TISSUE LINERS
• Cell culture tests : extremely cytotoxic(CMC)
• In animal tests : caused significant epithelial
changes
• In usage : Mild cytotoxity
F Chen et al- Cytotoxic effects of denture adhesives on primary human oral keratinocytes, fibroblasts and permanent
L929 cell line (Gerodontology 2012; doi: 10.1111/j.1741-2358.2012.00681.x)

50. SILICONE MAXILLOFACIAL
ELASTOMER
• Silicones are most widely used .
• Study done on baboons -implantation
Subperiosteal , Submucosal , Intramuscular .
• study indicated that inflammatory response and
not capsule thickness is the indicator .
Wolfaardt JF, Cleaton-Jones P, Lownie J, Ackermann G Biocompatibility testing of a silicone
maxillofacial prosthetic elastomer, J Prosthet Dent. 1992 Aug;68(2):331-8.

51. SUMMARY
• The biocompatibility of a dental material depend
on its composition ,location, and interaction with
the oral cavity .
• Materials that appear biocompatible when in
contact with the oral mucosal surface may cause
adverse reactions if they are implanted beneath it .
• Interactions between the material and the body
influence the biocompatibility of the material.

52. REFERENCE
• Craig RG, Restorative dental materials, 10th ed.
• Gottfried schmalz, Biocompatibility of dental materials, 3rd
ed,2009.
• Anusavice , Phillip’ Science of Dental Materilals,11th edition
Elsevier
• Applied Dental Materials, 9th edition John F. McCabe &
Angus W.G. Walls
• Peter E.Murray Et Al , How Is The Biocompatibility Of Dental
Materials Evaluated, Med Oral Patol Cir Bucal 2007;12,258-
66.
• Koh D, Ng V, Leow Y-H, Goh CL. A study of natural rubber
latex allergens in gloves used by healthcare workers . Br J
Dermatol 2005; 153: 954–9
• Wataha JC: Biocompatibility of dental casting alloys: a
review, J Prosthet Dent 83:223, 2000.

53. • D.B. Mahler; The High-copper Dental Amalgam
Alloys; J Dent Res 76 (1) 1997
• Fujibayashi S, Biomaterials [2004, 25(3):443-45
• John w. Nicholson, the biocompatibility of resin
modified glass ionomer cements fro dentistry, dental
materials 2008, 24, 1720-1708
• F Chen et al- Cytotoxic effects of denture adhesives
on primary human oral keratinocytes, fibroblasts and
permanent L929 cell line(Gerodontology 2012; doi:
10.1111/j.1741-2358.2012.00681.x).
• T.J. Spranley, Acute Tissue Irritation of Polysulfide
Rubber Impression Materials, J DENT RES 1983 62:
548.

54. THANK YOU