Biocompatibility of dental materials /endodontic courses

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.com

Contents
• Introduction
•Relevance to dentists
•Tests for evaluation of biocompatibility.
-Group I → Primary tests
-Group II → Secondary test
-Group III → Pre – clinical usage tests
•Craigs classification of tests.
•Advantages – disadvantages of tests.
•Standards that regulate the measurement of biocompatibility.
•Allergic responses to Dental Materials.www.indiandentalacademy.com

•Pulpal responses to specific agents and techniques.
-Amalgam
-Chemical and light cured resin composites
-Zinc phosphate cement.
-GIC
-Resin based composite cements
-Etching agents
-Bonding Agents.
-Liners varnishes
-Bleaching Agents
•Reaction of oral soft tissues to restorative materials
-Denture base material.
-Soft Denture liners.
•Reaction of bone and soft tissues to implant material
•Conclusion
•References www.indiandentalacademy.com

Biocompatibility is formally defined “as the ability of a material to
elicit an appropriate biological response in a given application in the body”.
The term “Biocompatible” is defined in Dorland’s Illustrated
Medical Dictionary” as being harmonious with life and not having toxic or
injurious effects on biologic function”.
In general, biocompatibility is measured on the basis of localized
cytotoxicity [such as pulp and mucosal response], systemic responses,
allergenicity and carcinogenicity.

In broad sense, a biomaterial can be defined as
any substance, other than a drug, that can be used for
any period as part of a system that treats, augments or
replaces any tissue, organ or Function of the body.
The science of dental biomaterials must be based
on a broad information base of certain biologic
considerations that are associated with the use of
materials designed for the oral cavity.

Based on these criteria, the requirements for dental material
biocompatibility include the following:
•It should not be harmful to the pulp and soft tissues.
•It should not contain toxic diffusible substances that can be released and
absorbed into the circulatory system to cause a systemic toxic response..
•It should be free of potentially sensitizing agents that are likely to cause an
allergic response.
• It should have no carcinogenic potential.
Whether a material is biocompatible or not is therefore dependent on
what physical function we ask of the material and what biological response we
require from it www.indiandentalacademy.com

Biocompatibility is a property of a material and its environment.
In this sense, biocompatibility is much like color. Color is a property
of a material interacting with its environment (light) and the colour of a
material depends on the light source and observer of light.

Biocompatibility is a dynamic process, ongoing process not a static one.
Eg:- Dental implant that is Osseointegrated today may or may not be
osseointegrated in the future. The response of body to a materials is dynamic
because the body may change through disease or aging, the material may
change through corrosion or fatigue, or the loads placed on material may
change through change in occlusion or diet.

Relevance to Dentists.
Dentists potential concerns about biocompatibility can be
organized in to 4 areas :
1)     Safety of the patient.
One of the primary concern of any dental practitioner is to avoid
harming the patient. Evidence has shown that, although adverse reactions to
dental materials are not common, they can occur for many types of
materials, including alloys, resins and cements.
2)     Safety of Dental staff
In many situations, the risk of adverse effects of biomaterials is
much higher for dental staff than for the patient. The staff may be
chronically exposed to materials when they are being manipulated or setting.
Eg:- 1) Amalgam – Mercury vapour.
      2)  Chronic exposure to latex and resin based materials.
        3) Regulatory compliance issues.

Biocompatibility issues are closely linked to regulations that affect dental
practice.
Ex: Dental amalgam.
Because of the biologic concerns about mercury, regulators have
considered monitoring and restricting amount of mercury in waste water for
dental practice.
2) Legal Liability.
Biocompatibility issues also influence liability issues that affect
dental practitioners. Because dental materials can affect the well-being of
patients and dental auxillaries, practitioners assume a legal risk when using
these materials.

Test for evaluation of Biocompatibility
The purpose of biocompatibility tests is to eliminate any potential product or
component of a product that can cause harm or damage to oral and maxillofacial
tissues.
Biocompatibility tests are classified on three levels, with the most rapid and
economical occurring at primary level.
Group I : PRIMARY TESTS.
Group II: SECONDARY TESTS.
Group III: PRE – CLINICAL USAGE TESTS

Group I : PRIMARY TESTS.
The primary tests consist of cytotoxic evaluations in which
dental materials in a fresh or a cured state are placed directly on
tissue culture cells or on membranes (barriers such as dentin disks)
overlying tissue culture cells that react to the effects of products or
components that leach through the barriers.
Genotoxicity Test
Mammalian or non mammalian cells, bacteria, yeasts or
fungi are used to determine whether gene mutations, changes in
chromosomal structures or other deoxyribo nucleic acid or genetic
changes are caused by the test materials, devices and extracts from
materials. www.indiandentalacademy.com

Group II: SECONDARY TESTS.
At this level the product is evaluated for its potential to create
systemic toxicity, inhalation toxicity, skin irritation and
sensitization and implantation responses.
In systemic toxicity tests such as oral median lethal
dose test, test sample is administered daily to rats for 14 days
either by oral gavage or by dietary inclusion. If 50% of
animals survive, the product has passed the test.

The inhalation toxicity tests are performed on rats,
rabbits or guinea pigs in an exposure chamber with aerosol
preparations by releasing the spray material around head and
upper trunk of animals. The animals are subjected to 30
seconds of continuous spray released at 30 minute interval.
After 10 consecutive exposures, the animals are observed
over a 14 day period. If any animal dies within 2-3 minutes,
the agent is considered very toxic.

Implantation tests
The use of invivo implantation techniques also takes into consideration
the physical characteristics of the product such as form, density, hardness and
surface finish that can influence the character of the tissue response.
The animal species is selected according to the size of the implant test
specimen and the intended duration of the test in relation to the life span of animal.
Short term tests ( ≤ 12 weeks) → Mice, rats, guinea pigs
Long term tests ( ≥ Weeks) → dogs, rabbits, sheep, goats.

For bone implantation, lateral cortex of a femur or a
tibia or both are exposed, and holes are drilled using low –
speed, intermittent cutting under profuse irrigation with
physiologic saline solution to prevent overheating of bone.
Cylinders of test implant material are inserted in to the drilled
holes by finger pressure to allow a tight press fit.
Histopathologically, one evaluates the formation of new bone
onto the surface of test implant material without intervening
connective tissue.

Group III PRE – CLINICAL USAGE TESTS
Pulp and Dentin Usage test.
This test is designed to assess the biocompatibility of
dental materials placed in dentin adjacent to the dental pulp.
Nonrodent mammals are selected. Class V cavity preparations
are done to leave 1mm or less of tubular dentin between the
floor of cavity preparation and pulp.
The appropriate number of cavities are restored, and
some are retained for control specimens. For a positive
control, a restorative material is selected that consistently
induces a moderate to severe pulp response.

The animals are sacrificed after 7 days, 28 ± 3 days
and 70 ± 5 days. After routine histopathologic processing,
specimens are graded for degree of inflammatory response
to prevalence of reparative dentin formation in pulp and the
number of microorganisms (microleakage) entrapped in the
surrounding cavity walls and cut dentinal tubules.
Promising test materials induce the least
inflammatory response in the pulp, and if a response is
produced, the time required to disappear is also measured.

The testing procedures here
are similar to above except that pulp is
merely exposed for the pulp capping
evaluation and is partially removed
for pulpotomy assessment. A ca(OH)2
product is used as a negative control.
The animals are sacrificed after 7 ± 2
days 70 ± 5 days.
Observations are made of
dentinal bridge formation adjacent to
or sub adjacent to the applied
material.
Pulp Capping and Pulpotomy Usage test

Endodontic usage test
For this test the same types of animals are used but the pulp is
completely or almost completely removed from pulp chamber and root
canals are replaced by obturating test material and control material. ZOE
alone or ZOE combined with a sealer is used as control material.
The animals are sacrificed after 28 ± 3 days and 13 ± Weeks. The
teeth are removed together with their surrounding apical periodontal
tissues in a single block for evaluation of inflammation.
For a biocompatible material, one should observe minimal or no
response and should have the shortest resolution time if a response is
detected.

In vivo testsIn vitro tests Usage tests
Direct Indirect
Material in contact Material extra in contact
Biocompatibility Test
Craig classification

Standards that regulate the measurement of Biocompatibility.
The first efforts of ADA to establish guidelines for dental
materials came in 1926. One of early attempts to develop a
uniform test for all materials was the study by DIXON and
RICKERT in 1933, in which toxicity of most dental materials in
use at that time was investigated by implanting the materials into
pockets in subdermal tissue.
In 1972 the council on Dental materials, instruments, and
equipment of ANSI / ADA approved Document No. 41 for
recommended standard practices for biological evaluation of
Dental materials

ANSI / ADA Document 41
Three categories of tests are described in the 1982
ANSI / ADA document: initial, secondary and usage tests.
Usage
Secondary
Primary
No of tests
Progress
Of testing

Initial tests include invitro assays for cytotoxicity, red
blood cell membrane lysis (bemolysis) mutagenesis and
carcinogenesis at the cellular level.
Based on the results of these initial tests, promising
materials are tested by one or more secondary tests in small
animals (invivo) for inflammatory or immunogenic potential
Finally, materials that pass secondary tests and still
hold potential are subjected to one or more in vivo usage tests.

ISO 1993
It contains 12 parts, each dealing with a different aspect
of biological testing. For example part 2 addresses animal
welfare requirements, part 3 addresses test for genotoxicity,
carcinogenicity and reproductive toxicity, and part 4 deals with
tests for interactions with blood.
This standard divides tests into “initial” and
“supplementary” tests to assess the biological reaction to
materials.
-Initial tests for cytotoxicity, sensitization, systemic
toxicity.
-Supplementary tests are tests such as chronic toxicity,
carcinogenicity and biodegradation.

Allergic responses to Dental materials:
Allergic contact Dermatitis
Allergy to Latex Products
Allergic contact stomatitis

Allergic contact Dermatitis.
It is most common occupational disease. The
incubation period is 2 days to several years. Dermatitis
occurs where the body surface makes direct contact with
the allergen.
An allergic contact dermatitis associated with the
monomers of bonding agents frequently involves the distal
parts of fingers and the palmar aspects of the finger tips.

Allergy to Latex Porducts:
Hypersensitivity to latex containing products may
represent a true latex allergy or a reaction to accelators
and antioxidants used in latex processing. (Rankin et al,
1993).
Thiuram a chemical used in fabrication of latex
articles and polyether component of latex rubber gloves
worn by dentists were the causes of allergic reactions.

Processing of latex :
Natural rubber products
While milky sap from tropical trees
.
Ammonia is added to pressure.
hydrolyzes and degrades the sap proteins to
produce allergens.
Vulcanization
Sulfur chemicals + heat
Rubber +
Leached out allergens on
surface
Liquid latex

Reactions vary from simple types such as localized rashes
and swelling to more serious types such as wheezing and
anaphylaxis.
-Rankin et al, 1993 stated that Dermatitis of hands is the
most common adverse reaction.
-In 1984, Blinkhorn and Leggate described generalised
angioneurotic edema, chest pains and a rah on the neck and chest
of a 15 years old boy as a reaction to a dental rubber dam.
To avoid these allergic reactions non latex gloves were
introduced their composition is elastyrene (block copolymer),
neolon, tactylon, Qualitoch (corn starch)

Allergic contact stomatitis:
Most common adverse reaction to dental materials. The long
term reactions are dependent on the composition of the materials,
the toxic components, the degradation products, the concentration of
absorbed and accumulated components, and other factors associated
with substances leached from these materials.
The most definitive diagnostic test for allergic contact
dermatitis or stomatitis is the patch test. The suspected allergen is
applied to the skin with the intent to produce a small area of allergic
contact dermatitis. This test generally takes from 48 –96 hours,
although a reaction may appear after 24 hours.

Dental materials contain many components known to be
common allergens, such as chromium, cobalt, mercury, eugenol,
components of resin – based materials and formaldehyde.
Minute amounts of formaldehyde may be released as a
degradation product of unreacted monomers in dentures made
from resin based composite materials.
BAKER and COWORKERS 1988, demonstrated that
free residual methyl methacrylate monomer in autopolymerized
acrylic dentures or appliances can cause allergic reactions. To
avoid this, authors recommended that autopolymerized
appliances and denture should be immersed in water for 24 hrs
before being worn.

Laeijendecker and van Josst 1994, presented cases
of females wearing complete denture suffering from oral
lichen planus and “burning mouth syndrome”. When patch
testing was done they developed papula reactions. Clinical
improvement occurred when gold in dentures was replaced.
Chemicals that may produce allergic contact
stomatitis on a short – term basis can be found also in
mouthwashes, dentifrices, and topical medications such as
lozenges and cough drops. They can cause burning, swelling
and ulcerations of oral tissues.

Pulpal Responses to specific Agents and Techniques:
1) AMALGAM
Conventional amalgam restorations have generally been
considered to be either inert or mildly irritating to the pulp.
Pulpal response to amalgam placement is related to
condensation pressure. Little inflammatory response is elicited
when a cavity is cut using a high speed air water spray
technique. While placing a conventional amalgam restoration,
pressure of condensation will intensify the initial minimal
inflammatory response and it will subsequently increase the
formation of reparative dentin.

In 1968 SOREMARK and associates showed that
radioactive mercury reached pulp in humans after 6 days if
no cavity liner was used. They also stated that “rate of
diffusion into enamel and dentin was inversely related to the
degree of mineralization”.
KUROSAKI and FUSAYAMA (1973) showed that
mercury from amalgam restorations in humans and dogs did
not reach pulp. In fact, it did not penetrate dentin that was
demineralised intentionally.

VAN Der LINDEN and VAN AKEN 1973, studying
on human teeth found no mercury in more radiopaque dentin
beneath amalgam restorations. Previously, it had been thought
that this layer was prominent because of mercury diffusion.
J.H.ENGLE,J.L FERRACANE 1992 stated that
greatest amount of mercury was released during dry polishing
of an amalgam restoration[44 micro grams].Total amount of
mercury generated during placement [6-8micro grams],wet
polishing[2-4 micrograms] and trituration[1-2 micrograms] was
also measured.

II Chemically Cured Resin Composites.
The addition of mineral fillers to the direct filling chemically cured resin
composites in 1960’s and 1970’s did not reduce their potential for creating severe
pulp responses. If not lined properly, they cause chronic pulpitis that persists for an
indefinite time.

III Visible light Cured Resin composites.
Level of pulp response to resin composite
restorations is especially intensified in deep cavities
when an incomplete curing of resin permits an higher
concentration of residual unpolymerized monomer to
reach the pulp.
Precautions:
1) Use twice the recommended time exposure
2) Cure in increments.

IV Zinc phosphate cement
When used as a base, it is not a highly toxic substance.
However, if a thin mix of Zinc phosphate cement is used to
cement a crown or inlay, a strikingly different response occurs.
When patient bites down on a tongue blade to seat restoration, the
phosphoric acid within the mix of zinc phosphate cement is forced
into the dentinal tubules in such a quantity that it creates, after 3
or 4 days a widespread three – dimensional lesion involving all
the coronal pulp tissue.
A young tooth with wide open dentinal tubules is more
susceptible to such an intense inflammatory response than in older
tooth.
The best protection against phosphoric acid penetration is
provided by coating the dentin with two coats of an appropriate
varnish, dentin bonding agent, liner, or a thin wash of calcium
hydroxide. www.indiandentalacademy.com

V Glass lonomer cement
When first introduced, pulp responses were classified
as bland, moderate and less irritating than other cements. The
blandness of GIC was attributed to absence of strong acids
and toxic monomers. Polyacrylic acid and related poly acid
are much weaker than phosphoric acid, as polymers, they
possess higher molecular weights that may limit their
diffusion through the dentinal tubules to the pulp.

PAMEIJER and STANLEY 1984, permitted an anhydrous
GIC to set under continuous pressure (Simulating Crown
cementation), pulp abscesses and intense (severe)
haemorrhage occurred when the reparative dentin thickness
was 0.5 mm or less. Therefore, it is recommended to use a
small dab of calciumhydroxide only to areas of extensive
crown preparation; when it is within 1 mm of pulp before the
cementation procedure.

These are indicated for all – ceramic
crowns, metal ceramic crowns, ceramic
veneers, and porcelain inlays.
In 1992, PAMEIJER and
STANLEY compared pulp responses to
dual – cured resin – based cementation
agents. They observed that only when
dual – cure resin cement received no
visible light energy average pulp response
levels exceed the accepted level of
biocompatibility.
VI Resin based composite cements (Dual cure)

VII Conditioning (etching) Agents.
Conditioning procedures are used with both resin composite
systems and GIC’s.
BRANNSTROM 1981 showed that conditioning of dentin and
removal of the smear unit allows the ingress of bacteria and outward flow
of dentinal fluid and possibly contributes to formation of a biofilm that
interferes with adhesion.
Conditioning techniques that are associated with weaker acids,
shorter periods of application, and elimination of subbing and scrubbing
procedures produce a minimal pulp response.

VIII Bonding Agents
A variety of dentin bonding agents have developed and
are applied to cut dentin during restoration of teeth.
Many of these reagents are cytotoxic to cells invitro if
tested alone. However, when placed on dentin and rinsed with
tap water between applications of subsequent reagents,
cytotoxicity is decreased. Long term invitro studies suggest
however that sufficient components of many bonding agents
permeate up to 0.5 mm of dentin to cause significant suppression
of cellular metabolism for up to 4 weeks after their application.

Hydroxy ethyl methacrylate (HEMA) is at least 100 times less
cytotoxic in tissue culture than Bis – GMA.
DOUGLAS.K.RANICH,JOHN.C.WATAHA1999 Stated that
major components of DBA like Bis-GMA,UDMA suppress
mitochondria enzymes such as succinic dehydrognase indicating
that at sufficient concentrations these components alter
macrophage function.

Calcium hydroxide cavity liners come in many forms,
ranging from saline suspensions with a very alkaline pH
(above 12) to modified forms containing zinc oxide, titanium
dioxide and resins.
IX Liners, Varnishes and Non-resin Cements

Necrosis to a depth of 1mm
Neutrophil infiltration.
Coagulation of hemorrhagic exudates of superficial pulp.
after 5-8 weeks only slight inflammation remains.
Necrotic zone Dystrophic calcification
Stimulus for dentin bridge
formation
The initial response of exposed pulpal tissue to highly alkaline
aqueous pulp – capping agents.

When resins are
incorporated into the formulae,
these calcium hydroxide compounds
become less irritating and are able
to stimulate reparative dentin bridge
formation more quickly than ca
(OH)2
with no zone of necrosis.

X Zinc oxide eugenol cement
It has been used for many
years. In vitro, eugenol from ZOE,
depresses cell respiration and reduces
nerve transmission with direct contact.
The concentration of eugenol in cavity
preparation just below ZOE has been
reported to be 10 –2
M (bactericidal), the
concentration on the pulpal side of
dentin may be 10 –4
M or less. This
lower concentration reportedly
suppresses nerve transmission and
inhibits synthesis of prosta glandins and
leukotrienes. [ anti inflammatory ]

XI Bleaching Agents
Bleaching agents have been used on nonvital and vital
teeth for many years, but their use on vital teeth has increased
astronomically in recent years. These agents usually contain
some form of peroxide (generally carbamide peroxide).
Invitro studies have shown that peroxides can rapidly
traverse the dentin in sufficient concentrations to be cytotoxic.
The cytotoxicity depends to a large extent on the concentration
of peroxide in bleaching agent.
Few clinical studies show that peroxides rapidly even
penetrate intact enamel and reach the pulp in a few minutes and
occurrence of tooth sensitivity is very common.

Reaction of other Oral soft tissues to restorative materials.
Restorative materials may cause reactions in the oral
soft tissues such as gingiva.
In general, conditions that promote retention of plaque,
such as rough surfaces or open margins, increase inflammatory
reactions in gingiva around these materials. However, released
products of restorative materials also contribute either directly
or indirectly to this inflammation, particularly in areas where
the washing effects of saliva are less, such as in interproximal
areas, in deep gingival pockets or under removable appliances.www.indiandentalacademy.com

Cements exhibit some cytotoxicity in the freshly set
state, but this decreases substantially with time. The buffering
and protein – binding effects of saliva appear to mitigate
against cytotoxic effects.
Composites are initially very cytotoxic in invitro tests
of direct contact with fibroblasts. The cytotoxicity is most
probably primarily from unpolymerized components in the air
– inhibited layer that leach out from the materials.
Amalgam restorations carried in to gingival crevice
may cause inflammation of gingiva because of products of
corrosion or bacterial plaque.

Denture base material
Denture base materials, especially methacrylates, have
been associated with immune hypersensitivity reactions of gingiva
and mucosa probably more than any other dental material.
The greatest potential for hypersensitization is for dental
and laboratory personnel who are exposed repeatedly to a variety
of unreacted components.
Hypersensitivity has been documented to the acrylic and
diacrylic monomers, certain curing agents, antioxidants, amines
and formaldehyde

Soft denture liners
Soft tissue responses to soft denture liners and
adhesives are of concern because of intimate contact between
these materials and gingiva. Plasticizers., which are
incorporated into some materials to make them soft and
flexible, are released in vivo and invitro.
In animal tests, several of these materials have caused
significant epithelial changes, presumably from the released
plasticizess.

Reaction of Bone and soft tissues to implant materials.
These are four basic materials used in implant
fabrication : ceramics, carbon, metals and polymers Interest in
biocompatibility of implant materials has grown as the use of
implants in clinical practice has increased dramatically in the
past 10 yrs.

Reactions to Ceramic Implant Materials
Most ceramic implant materials have very low toxic
effects on tissues, either because they are in an oxidized state
or are corrosion resistant. These are toxic and are non
imunogenic and non carcinogenic. These are brittle and lack
impact and shear strength, and therefore have been used as
porous or dense coatings on metals or other materials.
If root surface porosities are more than 150 mm in
diameter, the implants often become firmly bound to bone. If
porosities are smaller, the tissue usually forms only fibrous in
growth.

Reactions to pure Metals and Alloys
A variety of implant materials has been used, including
stainless steel, chromium cobalt – molybdenum and titanium and
its alloys. In dentistry the only metallic implant materials in
common use today are titanium alloys.
Titanium is a pure metal which forms a thin film of
various titanium oxides, which is corrosion resistant and allows
bone to osseointregrate in the soft tissue, the bond epithelium
forms with titanium is morphologically similar to that formed
with the tooth.
Peri-implantitis is now a documented disease around
implants and involves many of same bacteria as periodontitis.

BIOCOMPATABILITY OF METALS
Laboratory techniques performed with metals may expose us
occasionally or routinely to excessively high concentrations of
beryllium and nickel dust and beryllium vapor.
Beryllium
Although the beryllium concentration in dental alloys rarely
exceeds 2 wt % the amount of beryllium vapor released in to the
breathing space during melting of Ni-Cr-Be alloys may be
significant over an extended period.

• The risk of beryllium vapor exposure is greatest for dental
technicians during alloy melting especially in the absence of an
adequate exhaust and filtration system.
• High levels of beryllium have been measured during finishing
and polishing when a local exhaust system was not used. They
were reduced to levels considered safe when exhaust fan was
used.
• Exposure of beryllium may result in acute and chronic forms of
beryllium disease – BERYLLIOSISwww.indiandentalacademy.com

Clinical features
Symptoms range from coughing, chest pain and
general weakness to pulmonary dysfunction.
- Contact dermatitis
- Chemical pneumonitis

NICKEL
•It is a great concern to dental patients with a known allergy to
this element.
•Dermatitis resulting from contact with nickel solutions
was described as early as 1989.
•Inhalation, ingestion and dermal contact of nickel or
nickel containing alloys are common because nickel is found in
environmental sources such as air, soil and food as well as in
synthetic objects such as coins, kitchen utensils, and jewellery.

Nickel allergy was determined by PATCH TEST LUIS-BLANCO-DALMAN 1982,
[JPD.1982: 48; 99-101] described a standard patch test consisting of 5% Nickel sulfate
solution or 5% Nickel sulfate solution on a petrolatum base, in centre portion of a square
band-aid of good quality. This is applied on medial aspect of upper arm, which was
cleaned with a alcohol swab. This is left in place for 48hr undisturbed. A band-aid with
out any reagent is placed adjacent to the first acts a control. After 48 hrs, band-aid is
removed and area is cleaned.
It is read after 20 min.
0  no reaction.
+  erythema is seen.
++  erythema, papules are seen.
+++  erythema, papules, vesicles are seen.
++++  edema with vesicles is seen.

Dimethyl glyoxine test
FEIGL and SHORE stated that few drops of 1% alcohol
solution of dimethyl glyoxime, few drops of ammonium
hydroxide added to a metallic object, skin on solution will
produce a strawberry red insoluble salt in prescence of nickel.
LAMSTER (1987), showed 2 cases demonstrating
Loss of alveolar bone about Ni rich nonprecious alloy and
porcelain crown with in 18 months of placement. Reason for
this was thought that the electrolysis of metal leading to
corrosion and bioviability of Nickel.

TIMOTHY. K. JAMES (1986) stated that incidence of
Ni hypersensitivity was more in women.(10 times more than
men). The reason was attributed to increased contact with
nickel plated objects at work and at home.
John. C. Wataha 1998 stated that transient exposure of
casting alloys to an acidic oral environment is likely to
significantly increase elemental release from Ni-based alloys,
but not from high noble alloys.

He also stated that brushing dental casting alloys may
increase their cytotoxicity in vitro, but the increase depends
heavily on the alloy type and brushing technique. He observed
that with tooth paste Nickel based alloys were significantly more
lost, Ni-Cr-Be was the worst, increasing more than 60% toxicity
over controls.
J. Geis-Gers 1993, stated that from point of corrosion
resistance Beryllium free Ni-Cr-Mo alloys should be preferred in
clinical use.
Kasl-Heinz et al 1991, stated that average substance loss
after 35 days for Ni-Cr-Mo alloys varies between 0.65 – 3.26
µg/cm2

Craig, Hanks in 1990 stated that of pure metals Au,
Pd, Ti were least cytotoxic. Followed by Ag, Ni, single phase
alloys with moderate copper.
Symptoms of sensitivity range from urticaria, pruritis,
Xerostomia, eczema or vesicular eruptions.
Release of Ni ions from dental alloys is high enough to
be clinically significant. If so as a result, of potential alteration
in endocrine functions, changes in vital functions such as blood
pressure, pulse, temperature may be expected. Ni containing
alloys have been linked to decrease in lymphocytes in human.

Conclusion
The biocompatibility of a dental material depends on its
composition, location and interactions with oral cavity.
Diverse biological responses to these materials depend on
whether they release their components and whether those
components are toxic, immunogenic, or mutagenic at released
concentrations.
The location of a material in the oral cavity partially

Today, in development of any biomaterial one must consider
not only strength, esthetics, or functional aspects of the
material, but its biocompatibility as well. Furthermore,
demands for appropriate biological responses are increasing as
we ask materials to per form more sophisticated functions in
body. Thus considerations of biocompatibility are important to
manufactures, practitioners, scientists and patients.

REFERENCE
1) Restorative Dental Materials; craig : 11th
ed.
2) Science of dental Materials ; Annusavice ; 10th
ed
3) JPD. 2001; 86 ; 203 – 209
4) JDR. 67 ; 1295, 1988.
6) JDR. 63 : 171, 1984.
7) JADA. 1990; 121 : 716 – 719
8) J. endo. 1999 ; 25 ; 2 : 114 – 117
9) JPD. 1985 – 54 : 127 – 136
10) JDR. 1988 : 67 : 9 ; 1235 – 1242
11) JPD. 2000 ; 83 : 223 – 234
12) JPD. 1982 ; 48 ; 99 – 101.
13) Dental Biomaterials – E.C. Coombe
14) J. Periodont.1987 ; 58 : 486 – 490
15) JPD. 1987 ; 85 : 1 – 5.

No man climbs a mountain alone. From the cradle to
the grave, we depend on the efforts of many other men and
women. We build on the past, and we are all the products
our parents, our teachers, our colleagues, and the talents,
and challenges that god provides us.

Biocompatibility of dental materials /endodontic courses

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