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1. Cytotoxicity of denture base acrylic resins
INDIAN DENTAL ACADEMY
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2.  INTRODUCTION
 EFFECT
OF POLYMER TO MONOMER RATIO
 EFFECT OF STORAGE TIME AND WATER
IMMERSION
 EFFECT OF POLYMERIZATION CYCLE
 EFFECT OF POLYMERIZATION METHOD
 SUMMARY AND CONCLUSION
 REFERENCES
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3. Cytotoxicity of denture base
acrylic resins:A literature
review.
Janaina Habi Jorge, Eunice Teresinha
Giampaolo,DDS, PhD, Ana Lucia Machado, DDS,
PhD, and Carlos Eduardo Vergani, DDS, PhD.
Araraquara Dental School, Sao Paulo State
University, Araraquara, Sao Paulo, Brazil.
(J Prosthet Dent 2003;90: 2,190-193.)
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4. Acrylic resins are widely used in the fabrication of
denture bases and have been shown to be cytotoxic
as a result of substances that leach from the resin.
The primary eluate is residual monomer. It has the
potential to cause irritation, inflammation, and an
allergic response to the oral mucosa. Clinical signs
include crythema, erosion of oral mucosa, and a
burning sensation on the mucosa and tongue.
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5. Resins used for the manufacture of denture bases
have displayed various degrees of in vitro
cytotoxicity and in vivo allergic responses.
Residual monomer concentration varies with the
methods and the conditions of polymerization.
The variations in chemical composition and purity
of the commercially available resin systems, the
degree of conversion of their constituent
monomers, and manipulative variables may all
affect the biologic and physical properties of the
acrylic resins. This article reviews the literature
published from 1973 to 2000, selected by use of a
Medline search (U.S. National Library of
Medicine).
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6. EFFECT OF POLYMER TO MONOMER
RATIO
 According
to Kedjarune et al, the more monomer
added to the mixture, the greater the amount of
residual monomer and, therefore, the more
potential for cytotoxicity.
 Lamb et al observed that resins prepared with a
high proportion of polymer (5:3) resulted in
significantly lower levels of residual monomer, as
compared to those prepared with a lower
ratio(4:3).
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7. EFFECT OF STORAGE TIME AND
WATER IMMERSION


Sheridan et al reported that the cytotoxic effect
of acrylic resins was greater in the first 24 hours
after polymerization and decreased with time.
The authors concluded the longer prosthesis is
soaked, the less cytotoxic effect it is likely to
have.
Lefebvre et al observed that the effect of
substances released from 4 light – polymerizing
denture base resins on epithelial cells is greater
in initial 24 hours period.
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8.  Different
substances can be released in different
concentrations changing the physical and chemical
properties of the materials.
 The cytotoxic effect may occur for several days but it
can be minimized if prostheses are stored in water for
24 hours.
 Weaver and Goebel reported that the immersion of
prosthesis in heated water decreased the
hypersensitivity reaction in the examined patients.
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9. EFFECT OF POLYMERIZATION CYCLE
 Kedjarune
et al observed a reduced amount of
residual monomer when the polymerization time
was extended, thus resulting in less cytotoxic
effects.
 Harrison and Huggett conducted a study wherein
23 heat – polymerized denture base polymers were
subjected to various polymerization cycles. The
results of this investigation showed that a 7 – hour
incubation in water at 70 C followed by 1 hour at
0
100 C was ideal.
0
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10.  Vallitty
et al performed a study with 2
autopolymerized resins in which the reaction was
initiated by barbituric acid and 2 heat-polymerized
resins activated by benzoyl peroxide. The results
showed that the autopolymerized resins exhibited
higher contents of residual monomers than the heat
polymerized resins.
 Lamb et al observed that levels of residual monomers
in autopolymerized resins were higher for specimens
polymerized at 22 C, as compared with those
0
polymerized at 55 C.
0
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11. EFFECT OF POLYMERIZATION
METHOD

The cytotoxic effects of heat – activated, chemically –
activated, and microwave – activated acrylic resins on
gingival fibroblasts were also reported by Sheridan et
al, who observed that, among the tested materials, the
greatest cytotoxic effect was produced by chemically
activated acrylic resins.
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12.  According
to Hensten – Pettersen and Wictorin, the
cytotoxic effect is greater in autopolymerized resins
than in heat polymerized resins.
 Similar findings were observed by other researchers
as Yunus et al, Blagojevic & Murphy, De Clerk,
Truong and Thomasz and others.
 Visible light – polymerized denture base resins have
been claimed to be nontoxic after polymerization.
However, several studies have shown that these
materials have varying levels of cytotoxicity. The
extent of their toxic effect appears to be related to the
specific formulation of the material and
polymerization time.
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13.  To
summarize, the reviewed studies indicated that
autopolymerized resins are more cytotoxic than
the heat – polymerized denture base resins, which
in turn are more cytotoxic than the microwave –
polymerized resins.
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14. SUMMARY
&
CONCLUSION
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15. REFERENCES






Weaver RE, Goebel WM, Reactions to acrylic resin dental prostheses.
J Prosthet Dent 1980;48:138-42.
Tucker TN. Allergy to acrylic resin denture base. J Prosthet Dent
1981;16:602.
Kallus T. Evaluation of the toxicity of denture base polymers after
subcutaneous implantation in guinea pigs. J Prosthet Dent
1984;52:126-34.
Nakamura M, Kawahara H. Long-term biocompatibility test of denture
base resins in vitro. J Prosthet Dent 1984;52:694-9.
Lefebvre CA, Schuster GS Caughman GB, Caughman WF. Effects of
denture base resins on oral epithelial cells. Int J Prosthodont
1991;4:371-6.
Okita N, Hensten-Pettersen A. In vitro cytotoxicity of tissue
conditioners. J Prosthet Dent 1991;66:656-9.
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