TITLE OF THE TOPIC:“ TO COMPARE THE FLEXURAL STRENTGTH OF
HEAT POLYMERISED METHYL METHACRYLATE DENTURE BASE ACRYLIC
RESIN REINFORCED WITH KEVLAR FIBERS, GLASS FIBERS AND NYLON
FIBERS WITH THAT OF A COMMONLY USED HIGH IMPACT HEAT
POLYMERISED DENTURE BASE RESIN" AN IN-VITRO STUDY
6 BRIEF RESUME OF THE INTENDED STUDY:
6.1) NEED FOR THE STUDY:
Polymethyl methacrylate (PMMA) was introduced as a denture base material by
Dr. Walter Wright in 1937. Presently it is the most widely used material because of its
favorable working characteristics, superior esthetics, stability in oral environment,
processing ease and use with inexpensive equipments. The inherent disadvantage of it is
low strength, causes an acrylic denture to fracture during service as a result of fatigue due
to usage or impact due to fall. Some of the factors responsible for denture fracture also
include low strength, flexibility of the material, induced processing stresses and high
However, it has been shown to improve the flexural strength by adding rubber
phase in polymer pearls and the resultant material known as high impact strength resin23.
Moreover, various approaches to strengthen the acrylic resin have been suggested,
including metallic reinforcement, wire mesh and synthetic fibers reinforcement by nylon,
aramid, glass, polyethylene and carbon fibers13.
The purpose of this study is to evaluate whether or not reinforcement of normal heat
polymerizing resin with kevlar fibers, glass fibers and or nylon fibers increases the
To compare the results with that of a commercially available High Impact heat
polymerizing resin to determine a better and stronger material.
6.2 REVIEW OF LITERATURE:
D. C . Jagger , A. Harrrison and K. D. Jandt, authors review the attempts to improve
the mechanical properties of denture base materials takes account of papers published
during the last 30 years. Author has discussed about chemical modification of PMMA by
the addition of rubber graft copolymers and the reinforcement of PPMA with other
materials such as carbon fibers, glass fibers and ultra - high modulus polyethelen3.
Gulay Uzun, Nur Hersek, and Teomam Tincer, conducted a study which measured
the effect of 5 fiber strengtheners on the impact strength, deflection, transverse strength
and elasticity modulus of heat polymerized denture base resin. Specimens were
reinforced with glass, carbon, thin kevlar, thick kevlar and polyethylene fibers in the
woven form. It concluded that polyethylene and glass fibers are more resistant to impact
strength, fiber reinforcement had no significant effect on the transverse strength.
Polyethylene reinforcement significantly raised deflection value. Carbon , thick kevlar and
polyethylene reinforced specimen showed significantly higher elasticity modulus values4.
Jacob john, Shivaputrapppa A. Ganagadhar, Shah I, conducted a study to evaluate
reinforcing a conventional acrylic resin with glass fibers, aramid , or nylon fibers .Ten
specimens of similar dimensions were prepared for each of the 4 experimental group:
conventional acrylic resin and the same resin reinforced with 3 different fibers. All the test
specimens were subjected to 3- point bending test. It was concluded that specimens
showed better flexural strength than the conventional acrylic resin. Specimens reinforce
with glass fibers showed the highest flexural strength, followed by aramid and nylon1.
Orhan Murat Dogan et.al conducted a study to observe changes in impact resistance of
a denture base reinforced with five types of fibers . E- glass , polyester, rayon, and nylon
fibers were cut in 2,4,6 mm length and added into the resin at concentration of 3% by
weight, additionally impact sections were observed under a scanning electron microscope.
It was concluded that impact energy increased with fiber length and the highest value was
recorded for rayon fiber - reinforcement of 6mm length. E - glass fiber reinforcement
produced relatively stable, high values for each length, good interfacial strength between
polymer matrix and glass fibers was confirmed by scanning electron microscope analysis5.
D. Vojvodic et.al conducted a study to determine the flexural strength of E - glasss fiber
reinforced dental polymer and dental high impact strength resin. Specimens were tested
after polymerization and after artificial ageing performed by storage at 37°c for 28 days
and thermo cycling. Author concluded that there was significantly higher values of
flexural strength of glass reinforced specimens compared to the unreinforced specimens.
Between groups of samples tested after polymerization and storage in water there was no
statistically significant difference while samples tested after thermo cycling revealed
6.3 AIM AND OBJECTIVES OF THE STUDY:
1. To evaluate the flexural strength of a high impact denture base resin material
2. To evaluate the flexural strength of a commonly available heat cure denture base
material reinforced with kevlar fibers ( Dupont).
3. To evaluate the flexural strength of a commonly available heat cure denture base
material reinforced with glass fibers.
4. To evaluate the flexural strength of a commonly available heat cure denture base
material reinforced with nylon fiber.
5. To compare the flexural strength of the above mentioned materials and evaluate to
know which material has a superior flexural property.
MATERIALS AND METHODS
Preformed stainless steel metal dies of 65x10x3mm in size will be fabricated. 12
specimens fabricated in each of the experimental group and total sample size of 48
specimens. Control group test specimens were made with high impact heat cure denture
base resin. Remaining three experimental groups consisted of a commonly available
PPMA resin specimen of the same dimensions reinforced glass, kevlar, nylon fibers.
Fibers have thickness of 10 to 15µm and were cut to 5mm length , the cut fibers were
soaked in monomer for 10 minutes for better bonding with acrylic resin. The resin and
fibers ( 2% by weight ) were mixed thoroughly to dispense the fibers. All specimens are
subjected to polymerization cycle. Specimens were retrieved, trimmed with diamond bur.
All the specimens were stored in water at room temperature for 1 week before testing. All
the samples were subjected to three- point bending test on a universal testing machine at
across head speed of 2mm/min. Data got was statistically analyzed with a one-way
analysis of variance.
Control group: lucitone 199 and / or Acrylyn H heat cure material
Study group: DPI heat cure material
Group 1: high impact denture base resin
Group 2: Commonly available heat cure resin reinforced with kevlar fibers
( Dupont, India)
Group 3: Commonly available heat cure resin reinforced with glass fibers
Group4: Commonly available heat cure resin reinforced with nylon fibers
7.3 DOES THE STUDY REQUIRE ANY INVESTIGATIONS OR
INTERVENTIONS TO BE CONDUCTED IN PATIENTS OR OTHER HUMANS
7.4 HAS ETHICAL CLEARANCE BEEN OBTAINED FROM YOUR
8. 8.1 LIST OF REFERENCES
1. Jacob john, Shivaputtrappa A, Gangadhar, Shah I. Flexural strength of heat
polymerized PMMA denture resin reinforced with glass, aramid or nylon fibers. J
Prosthet Dent 2001; 86: 424-427.
2. D. Vojvodic , F Matejicek, Z Schauperl, K Mehulic, Ivana B and Sanja S.
Flexural strength of E - Glass fiber reinforced dental polymer and dental high
impact strength resin. Strojarstvo 2008;50(4):221-230.
3. D. C . Jagger , A. Harrrison and K. D. Jandt. The reinforcement of dentures.
Journal of oral rehabilitation 1999;26: 185-194.
4. Gulay Uzun, Nur Hersek, and Teomam Tincer. Effect of five woven
reinforcements on the impact and transverse strength of denture base resin. J
Prosthet Dent 1999;81:612-620
5. Orhan Murat Dogan, Giray Bolayir, Selda Keskin, Arife Dogan. The effect of
esthetic fibers on the impact resistance of a conventional heat - cured denture base
resin. Dental Materials Journal 2007;26(2):232-239.