164
T. Chandran et al.
time. The acrylic resins used in dentistry like any other dental biomaterial not fully
inert and can occasionally cause local or systemic toxicity. All dental products should
be certified by International Organization for Standardization for its safe use [33].
The monomer methyl methacrylate is supplied as liquid and it is mixed with
the polymer which is in powder form. When mixed, the polymer gets partially
dissolved in the monomer to form a plastic dough. This dough is packed into
the moulds and it gets polymerized. This polymer has very good stability, doesn’t
undergo discolouration easily, has good ageing properties and hence is widely used
in dentistry.
The polymerization of acrylic monomers is often incomplete. The rate of polymerization largely depends on the mode of polymerization. Heat cured products
often leave less unpolymerized resin than self-cured polymerization. The residual
monomers left leached out of the dental products. They dissolve in saliva and get
absorbed into the oral mucosa, skin and can also reach the gastrointestinal system. The
health hazards caused by these materials are often due to their cytotoxicity. Residual
MMA gets hydrolysed and forms methacrylic acid which is a proved allergen and
tissue irritant. EGDM is identified as the strongest allergen in acrylic materials [27].
To reduce the amount of residual polymers released polymerization at hightemperature close to the glass transition temperature of the materials used is recommended. Microwave and light-curing releases less volume of residual monomers
but their use in denture bases is complicated and expensive. The residual monomer
release should be in the range of 1–3%. Microwave post-polymerization as well as
immersing the dentures in a water bath for about 1–7 days before inserting into the
oral cavity can significantly decrease the release of residual monomers [54].
The localized manifestation of the effects of acrylics include stomatitis, cheilitis,
candidiasis, and painful sensations, diffused erythema and urticaria. The allergy to
the acrylics can also be in an extensive form as in Erythema multiforme. Most of
the cases report an acute form of irritation to dental resins and they subside once
the irritant is removed. In contrast chronic denture wearers who are elderly people
report chronic form of tissue irritation as in fibrous hyperplasia [19]. Orthodontic
patients and prosthesis wearers gradually ingest the residual monomers and this
require special attention in the context of systemic toxicity though systemic toxicity
is rarely reported [24].
Occupational hazards associated with the use of dental monomers and polymers
is a matter of major concern. Dental technicians often fall prey to this. In order
to achieve greater precision, they often avoid the use of gloves. This can cause
contact dermatitis and eczema of skin of distal phalange and palmar surface of
finger tips. The affected parts experience dryness, itching, cracking, peeling, and
swelling. The inhalation of the polymer can cause asthma, anorexia, decreased gastric
motor activity, headache, and drowsiness. In severe cases can also cause neurological
dysfunctions like paraesthesia and neuropathy [34]. Hence dentists and auxiliaries
should avoid direct contact with the polymers by practicing no touch techniques,
avoid inhalation by using protective masks while working with these materials and
ensure that the operatory is well ventilated.
T. Chandran et al.
time. The acrylic resins used in dentistry like any other dental biomaterial not fully
inert and can occasionally cause local or systemic toxicity. All dental products should
be certified by International Organization for Standardization for its safe use [33].
The monomer methyl methacrylate is supplied as liquid and it is mixed with
the polymer which is in powder form. When mixed, the polymer gets partially
dissolved in the monomer to form a plastic dough. This dough is packed into
the moulds and it gets polymerized. This polymer has very good stability, doesn’t
undergo discolouration easily, has good ageing properties and hence is widely used
in dentistry.
The polymerization of acrylic monomers is often incomplete. The rate of polymerization largely depends on the mode of polymerization. Heat cured products
often leave less unpolymerized resin than self-cured polymerization. The residual
monomers left leached out of the dental products. They dissolve in saliva and get
absorbed into the oral mucosa, skin and can also reach the gastrointestinal system. The
health hazards caused by these materials are often due to their cytotoxicity. Residual
MMA gets hydrolysed and forms methacrylic acid which is a proved allergen and
tissue irritant. EGDM is identified as the strongest allergen in acrylic materials [27].
To reduce the amount of residual polymers released polymerization at hightemperature close to the glass transition temperature of the materials used is recommended. Microwave and light-curing releases less volume of residual monomers
but their use in denture bases is complicated and expensive. The residual monomer
release should be in the range of 1–3%. Microwave post-polymerization as well as
immersing the dentures in a water bath for about 1–7 days before inserting into the
oral cavity can significantly decrease the release of residual monomers [54].
The localized manifestation of the effects of acrylics include stomatitis, cheilitis,
candidiasis, and painful sensations, diffused erythema and urticaria. The allergy to
the acrylics can also be in an extensive form as in Erythema multiforme. Most of
the cases report an acute form of irritation to dental resins and they subside once
the irritant is removed. In contrast chronic denture wearers who are elderly people
report chronic form of tissue irritation as in fibrous hyperplasia [19]. Orthodontic
patients and prosthesis wearers gradually ingest the residual monomers and this
require special attention in the context of systemic toxicity though systemic toxicity
is rarely reported [24].
Occupational hazards associated with the use of dental monomers and polymers
is a matter of major concern. Dental technicians often fall prey to this. In order
to achieve greater precision, they often avoid the use of gloves. This can cause
contact dermatitis and eczema of skin of distal phalange and palmar surface of
finger tips. The affected parts experience dryness, itching, cracking, peeling, and
swelling. The inhalation of the polymer can cause asthma, anorexia, decreased gastric
motor activity, headache, and drowsiness. In severe cases can also cause neurological
dysfunctions like paraesthesia and neuropathy [34]. Hence dentists and auxiliaries
should avoid direct contact with the polymers by practicing no touch techniques,
avoid inhalation by using protective masks while working with these materials and
ensure that the operatory is well ventilated.