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HELLO!
Presented by:
Abdullah Ahmad 5210039
Assem Awad 5211149
“Some journeys don't have
endings, they lead to new
beginnings. These are the
journeys that lead to great
adventures!”
Alex Haditaghi,
Let’s Start our Journey
INTRODUCTION
• To date the most commonly used denture base
materials are the conventional heat-cured
acrylic resins.
• Its popularity originated from its:
High aesthetic
quality
Ease in
manipulation
Stability in
the oral
conditions
Ease in
finishing and
polishing
Inexpensive
equipment.
Methacrylate-based polymers are polymerized by different
methods
Heat
curing.
Chemical
curing.
Light
curing.
Microwave
curing.
INTRODUCTION
• These processing methods can affect resin physical properties
mainly related to the degree of monomer conversion and
porosity, which in turn may impact surface characteristics and
prosthesis survival.
INTRODUCTION
Dimensional changes
• An acceptable polymerization method is the one
which is capable of achieving the best properties of
acrylic resin as fracture toughness, static strength,
flexural modulus , and dimensional stability, in short
possible time.
INTRODUCTION
The fracture resistance of polymethylmethacrylate (PMMA) IS NOT
SATISFACTORY. Different factors can be involved in denture fracture.
Among them, flexural fatigue and impact are the most common failure
mechanisms of an acrylic denture base
INTRODUCTION
Unfortunately
• Many approaches have been used to
strengthen acrylic denture base resins.
• These approaches involved the use of metal
wires or plates, fibers, metal powder or
rubber toughening agents.
INTRODUCTION
FURTHER MORE
• Conventional heat cured acrylic
resin is cured either by short curing
cycle (2 hours) or Long curing
cycle for more than 9 hours
INTRODUCTION
Advantages of microwave curing
Concept
Less time consuming
Less internal stress
Less procedures.
Good polymerization
Equal heat distribution
Ease of manipulation
INTRODUCTION
In expensive equipment
Human nature is complex. Even if we
do have inclinations toward violence,
we also have inclination to empathy,
to cooperation and to self-control.
Steven Pinker
•PUT HERE the
method of curing of
this type of resin
• Any studied prosthetic material has to
withstand repeated disinfection.
• Prosthetic materials sent from dental clinics to
the dental laboratories may be contaminated
by pathogenic bacteria, which can be
transferred to the prosthetic lab technicians
and cross transferred to other patients.
INTRODUCTION
In Addition
AND
• At home, denture DISINFECTION is necessary to remove oral
microorganisms, odor-causing particles and food debris.
• Denture disinfection should be carried out through a safe and simple technique
to ensure patient compliance for proper disinfection.
INTRODUCTION
BUT HOW TO DO
THAT?
INTRODUCTION
WE HAVE TWO
POSSIBLE
WAYS
INTRODUCTION
FIRST METHOD BY CHEMICAL DISINFECTION
• Using solutions of glutaraldehyde,
sodium hypochlorite, iodoform,
chlorine dioxide or alcohol
• But, chemical disinfection may
present disadvantages, such as
denture staining & oral tissue
reactions.
INTRODUCTION
What about
the second
way?
INTRODUCTION
SECOND WAY: MICROWAVE ENERGY
• Microwave energy has been indicated as a
simple, practical & low-cost
alternative to overcome the shortcomings
of chemical disinfection methods.
• It provides mechanical displacement to
bacterial colony all around the denture due
to orbiting of the microwave oven disc
INTRODUCTION
Is it mechanically safe to
microwave cure denture base
material, and to further disinfect
by microwave?
AIM OF THE
WORK
The aim of the present study was to compare between glass-
fiber-reinforced microwave-cured and conventional heat
cured acrylic denture base resin in regard to:
 Dimensional changes,
 Impact strength
 Flexural strength
Hardness,
Before and after repeated microwave disinfections.
MATERIAL
AND
METHODS
Conventional Heat Cured
Polymethyle Methacrylate
Acrylic Resin (Acrostone
Egypt)
MATERIALS & METHODS
Materials
Glass fibers reinforced
microwave cured acrylic
resin (conventional PMMA
reinforced by 5% e-glass
fibers)
MATERIALS & METHODS
Materials
MATERIALS & METHODS
Specimens preparation
A- CONVENTIONAL HEAT CURED ACRYLIC RESIN
(ACROSTONE)
MATERIALS & METHODS
MATERIALS & METHODS
SPECIMENS PREPARATION OF CONVENTIONAL
HEAT CURED ACRYLIC RESIN (ACROSTONE)
MATERIALS & METHODS
Specimens preparation
B- GLASS FIBERS REINFORCED MICROWAVE CURED
ACRYLIC RESIN
GLASS FIBERS REINFORCED MICROWAVE CURED
ACRYLIC RESIN
We kindly asked our partners at Pavia University, Italy to help us and to
fabricate the specimens with the same specifications as conventional
heat cured resin .
MATERIALS & METHODS
Specimens Groups
Group A: conventional heat
cured acrylic resin, N= 30
Group B: microwaved-cured glass
fiber reinforced acrylic resin, N=30
Impact
strength. N=10
Flexural
strength, n=10
Hardness, n=10
Impact
strength, n=10
Flexural
strength, n=10
Hardness, n=10
Half the specimens of each subgroup were tested before microwave disinfection.
Half the specimens of each subgroup were tested after repeated microwave disinfection
DIMENSIONAL CHANGES
MATERIALS & METHODS
• A digital caliber was used to measure the distance between the indentations on the surface
of the specimens of each type of acrylic resin used before being fractured by mechanical
testing.
• Measurements was made on specimens not subjected to microwave disinfection ( N=30)
• Measurements was made on specimens subjected to microwave disinfection ( N=30)
IMPACT STRENGTH
Is a standardized high strain-rate test
which determines the amount of
energy absorbed by a material during
fracture.
MATERIALS & METHODS
Specimens were subjected to an impact
strength test in the Charpy system (XJJ
Charpy impact tester, United, China) with
40 kpcm impact load.
FLEXURAL STRENGTH
Test provides values for the modulus of
elasticity in bending , flexural stress ,
flexural strain and the flexural stress-
strain response of the material.
MATERIALS & METHODS
Specimens were subjected to a 3-point bending test in a
universal testing machine (Digital display hydraulic UTM ,
WES 100, United, China) running at a crosshead speed
of 5 mm/min until failure.
KNOOP HARDNESS TEST
“Micro hardness test” a test for
mechanical hardness used
particularly for very brittle materials or
thin sheets, where only a small
indentation may be made for testing
purposes.
MATERIALS & METHODS
Specimens were subjected to Knoop hardness test in a
microindenter (United HV-1000; Chaina) calibrated with 25
g load during 10 s.
MATERIAL AND METHODS
DISINFICTION
The specimens were subjected to a 3-min microwaving cycle at 600 Watt in a
domestic microwave oven.
MATERIALS & METHODS
For this procedure, the specimens were immersed in glass bowls containing 150
mL of distilled water. Each specimen was subjected to 5 simulated disinfections,
being 1 per day
MATERIALS & METHODS
RESULTS
DIMENSIONAL CHANGES
Samples Dimensions before
disinfection
Dimensions after
disinfection
tuky’s test
Acrostone "G1" 18.16 18.06 (p>0.05)
Acrostone "G2" 18.18 18.8 (p>0.05)
Acrostone "G3" 18.22 18.12 (p>0.05)
Acron MC 18.20 18.12 (p>0.05)
Acrylic resin No disinfection
Simulated microwave
disinfection
Conventional resin 7.72 +- 0.41A 9.25 +- 0.09B
Arcon MC 7.88 +/- 0.19A 6.25 +/- 0.09A
Impact Strength
0
1
2
3
4
5
6
7
8
9
10
acrostone acron mc
before after
Acrylic resin No disinfection
Simulated microwave
disinfection
Acrostone 5.78 +- 0.40A 5.66 +- 0.07B
Acron MC 6.06 +/- 0.27A 5.78 +/- 0.10A
Flexural Strength
5.4
5.5
5.6
5.7
5.8
5.9
6
6.1
acrostone acron mc
Chart Title
before after
Acrylic resin No disinfection
Simulated microwave
disinfection
Acrostone 15.67 +- 0.90A 10.07 +- 0.28B
Acron MC 17.02 +/- 0.20A 16.16 +/- 0.17A
Knoop Hardness
0
2
4
6
8
10
12
14
16
18
acrostone acron mc
Chart Title
before after
CONCLUSIONS
CONCLUSIONS
Within the scope of this study, it was concluded that:
• Repeated microwave disinfection at 600 Watt, did not affect the
dimensional changes of acrylic resin denture base .
• Impact strength of conventional resin increased after repeated microwave
disinfection while that of the reinforced resin decreased
• Glass fiber reinforced microwave cured acrylic resin showed higher
flexural strength than conventional resin before and after repeated
microwave disinfection. Flexural strength is important to resist fracture
under masticatory loads on dentures.
CONCLUSION
Continue:
• Hardness of conventional resin was higher than
microwaved cured resin.
• After microwave treatment conventional resin hardness
decreased but microwaved cured remained stable.
RECOMMENDATIONS
RECOMMENDATIONS
• Further studies are recommended to clarify the results of this
study.
• Studies on reinforced resin with variable percent of glass fibers
and the study of its effect on mechanical properties and
survival of acrylic resin are needed.
• Microwave is a simple and reliable method for disinfection of
acrylic dentures.
REFERENCES
REFERENCES
1. Kahn RC, Lancaster MV, Kate W. The microbiologic cross-contamination
of dental prostheses. J Prosthet Dent 1982;47:556-559.
2. Sanitá PV, Vergani CE, Giampaolo ET, Pavarina AC, Machado AL.
Growth of Candida species on complete dentures: effect of microwave
disinfection. Mycoses 2009;52:154-160.
3. olyzois GL, Zissis AJ, Yannikakis SA. The effect of glutaraldehyde and
microwave disinfection on some properties of acrylic denture resin. Int J
Prosthodont 1995;8:150-154.
4. Consani RLX, Vieira EB, Mesquita MF, Mendes WB, Arioli-Filho JN.
Effect of microwave disinfection on physical and mechanical properties of
acrylic resins. Braz Dent J 2008;19:348-353.
Thank
You

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Effect of Microwave Disinfection on Acrylic Denture Base Materials

  • 2.
  • 3. Presented by: Abdullah Ahmad 5210039 Assem Awad 5211149
  • 4. “Some journeys don't have endings, they lead to new beginnings. These are the journeys that lead to great adventures!” Alex Haditaghi,
  • 6. INTRODUCTION • To date the most commonly used denture base materials are the conventional heat-cured acrylic resins. • Its popularity originated from its: High aesthetic quality Ease in manipulation Stability in the oral conditions Ease in finishing and polishing Inexpensive equipment.
  • 7. Methacrylate-based polymers are polymerized by different methods Heat curing. Chemical curing. Light curing. Microwave curing. INTRODUCTION
  • 8. • These processing methods can affect resin physical properties mainly related to the degree of monomer conversion and porosity, which in turn may impact surface characteristics and prosthesis survival. INTRODUCTION Dimensional changes
  • 9. • An acceptable polymerization method is the one which is capable of achieving the best properties of acrylic resin as fracture toughness, static strength, flexural modulus , and dimensional stability, in short possible time. INTRODUCTION
  • 10. The fracture resistance of polymethylmethacrylate (PMMA) IS NOT SATISFACTORY. Different factors can be involved in denture fracture. Among them, flexural fatigue and impact are the most common failure mechanisms of an acrylic denture base INTRODUCTION Unfortunately
  • 11. • Many approaches have been used to strengthen acrylic denture base resins. • These approaches involved the use of metal wires or plates, fibers, metal powder or rubber toughening agents. INTRODUCTION
  • 12. FURTHER MORE • Conventional heat cured acrylic resin is cured either by short curing cycle (2 hours) or Long curing cycle for more than 9 hours INTRODUCTION
  • 13. Advantages of microwave curing Concept Less time consuming Less internal stress Less procedures. Good polymerization Equal heat distribution Ease of manipulation INTRODUCTION In expensive equipment
  • 14. Human nature is complex. Even if we do have inclinations toward violence, we also have inclination to empathy, to cooperation and to self-control. Steven Pinker
  • 15.
  • 16.
  • 17. •PUT HERE the method of curing of this type of resin
  • 18. • Any studied prosthetic material has to withstand repeated disinfection. • Prosthetic materials sent from dental clinics to the dental laboratories may be contaminated by pathogenic bacteria, which can be transferred to the prosthetic lab technicians and cross transferred to other patients. INTRODUCTION In Addition
  • 19. AND • At home, denture DISINFECTION is necessary to remove oral microorganisms, odor-causing particles and food debris. • Denture disinfection should be carried out through a safe and simple technique to ensure patient compliance for proper disinfection. INTRODUCTION
  • 20. BUT HOW TO DO THAT? INTRODUCTION
  • 22. FIRST METHOD BY CHEMICAL DISINFECTION • Using solutions of glutaraldehyde, sodium hypochlorite, iodoform, chlorine dioxide or alcohol • But, chemical disinfection may present disadvantages, such as denture staining & oral tissue reactions. INTRODUCTION
  • 24. SECOND WAY: MICROWAVE ENERGY • Microwave energy has been indicated as a simple, practical & low-cost alternative to overcome the shortcomings of chemical disinfection methods. • It provides mechanical displacement to bacterial colony all around the denture due to orbiting of the microwave oven disc INTRODUCTION
  • 25. Is it mechanically safe to microwave cure denture base material, and to further disinfect by microwave?
  • 27. The aim of the present study was to compare between glass- fiber-reinforced microwave-cured and conventional heat cured acrylic denture base resin in regard to:  Dimensional changes,  Impact strength  Flexural strength Hardness, Before and after repeated microwave disinfections.
  • 29. Conventional Heat Cured Polymethyle Methacrylate Acrylic Resin (Acrostone Egypt) MATERIALS & METHODS Materials
  • 30. Glass fibers reinforced microwave cured acrylic resin (conventional PMMA reinforced by 5% e-glass fibers) MATERIALS & METHODS Materials
  • 31. MATERIALS & METHODS Specimens preparation A- CONVENTIONAL HEAT CURED ACRYLIC RESIN (ACROSTONE)
  • 34. SPECIMENS PREPARATION OF CONVENTIONAL HEAT CURED ACRYLIC RESIN (ACROSTONE)
  • 35. MATERIALS & METHODS Specimens preparation B- GLASS FIBERS REINFORCED MICROWAVE CURED ACRYLIC RESIN
  • 36. GLASS FIBERS REINFORCED MICROWAVE CURED ACRYLIC RESIN We kindly asked our partners at Pavia University, Italy to help us and to fabricate the specimens with the same specifications as conventional heat cured resin .
  • 37. MATERIALS & METHODS Specimens Groups Group A: conventional heat cured acrylic resin, N= 30 Group B: microwaved-cured glass fiber reinforced acrylic resin, N=30 Impact strength. N=10 Flexural strength, n=10 Hardness, n=10 Impact strength, n=10 Flexural strength, n=10 Hardness, n=10 Half the specimens of each subgroup were tested before microwave disinfection. Half the specimens of each subgroup were tested after repeated microwave disinfection
  • 38. DIMENSIONAL CHANGES MATERIALS & METHODS • A digital caliber was used to measure the distance between the indentations on the surface of the specimens of each type of acrylic resin used before being fractured by mechanical testing. • Measurements was made on specimens not subjected to microwave disinfection ( N=30) • Measurements was made on specimens subjected to microwave disinfection ( N=30)
  • 39. IMPACT STRENGTH Is a standardized high strain-rate test which determines the amount of energy absorbed by a material during fracture. MATERIALS & METHODS Specimens were subjected to an impact strength test in the Charpy system (XJJ Charpy impact tester, United, China) with 40 kpcm impact load.
  • 40. FLEXURAL STRENGTH Test provides values for the modulus of elasticity in bending , flexural stress , flexural strain and the flexural stress- strain response of the material. MATERIALS & METHODS Specimens were subjected to a 3-point bending test in a universal testing machine (Digital display hydraulic UTM , WES 100, United, China) running at a crosshead speed of 5 mm/min until failure.
  • 41. KNOOP HARDNESS TEST “Micro hardness test” a test for mechanical hardness used particularly for very brittle materials or thin sheets, where only a small indentation may be made for testing purposes. MATERIALS & METHODS Specimens were subjected to Knoop hardness test in a microindenter (United HV-1000; Chaina) calibrated with 25 g load during 10 s.
  • 43. The specimens were subjected to a 3-min microwaving cycle at 600 Watt in a domestic microwave oven. MATERIALS & METHODS
  • 44. For this procedure, the specimens were immersed in glass bowls containing 150 mL of distilled water. Each specimen was subjected to 5 simulated disinfections, being 1 per day MATERIALS & METHODS
  • 46. DIMENSIONAL CHANGES Samples Dimensions before disinfection Dimensions after disinfection tuky’s test Acrostone "G1" 18.16 18.06 (p>0.05) Acrostone "G2" 18.18 18.8 (p>0.05) Acrostone "G3" 18.22 18.12 (p>0.05) Acron MC 18.20 18.12 (p>0.05)
  • 47. Acrylic resin No disinfection Simulated microwave disinfection Conventional resin 7.72 +- 0.41A 9.25 +- 0.09B Arcon MC 7.88 +/- 0.19A 6.25 +/- 0.09A Impact Strength 0 1 2 3 4 5 6 7 8 9 10 acrostone acron mc before after
  • 48. Acrylic resin No disinfection Simulated microwave disinfection Acrostone 5.78 +- 0.40A 5.66 +- 0.07B Acron MC 6.06 +/- 0.27A 5.78 +/- 0.10A Flexural Strength 5.4 5.5 5.6 5.7 5.8 5.9 6 6.1 acrostone acron mc Chart Title before after
  • 49. Acrylic resin No disinfection Simulated microwave disinfection Acrostone 15.67 +- 0.90A 10.07 +- 0.28B Acron MC 17.02 +/- 0.20A 16.16 +/- 0.17A Knoop Hardness 0 2 4 6 8 10 12 14 16 18 acrostone acron mc Chart Title before after
  • 51. CONCLUSIONS Within the scope of this study, it was concluded that: • Repeated microwave disinfection at 600 Watt, did not affect the dimensional changes of acrylic resin denture base . • Impact strength of conventional resin increased after repeated microwave disinfection while that of the reinforced resin decreased • Glass fiber reinforced microwave cured acrylic resin showed higher flexural strength than conventional resin before and after repeated microwave disinfection. Flexural strength is important to resist fracture under masticatory loads on dentures.
  • 52. CONCLUSION Continue: • Hardness of conventional resin was higher than microwaved cured resin. • After microwave treatment conventional resin hardness decreased but microwaved cured remained stable.
  • 54. RECOMMENDATIONS • Further studies are recommended to clarify the results of this study. • Studies on reinforced resin with variable percent of glass fibers and the study of its effect on mechanical properties and survival of acrylic resin are needed. • Microwave is a simple and reliable method for disinfection of acrylic dentures.
  • 56. REFERENCES 1. Kahn RC, Lancaster MV, Kate W. The microbiologic cross-contamination of dental prostheses. J Prosthet Dent 1982;47:556-559. 2. Sanitá PV, Vergani CE, Giampaolo ET, Pavarina AC, Machado AL. Growth of Candida species on complete dentures: effect of microwave disinfection. Mycoses 2009;52:154-160. 3. olyzois GL, Zissis AJ, Yannikakis SA. The effect of glutaraldehyde and microwave disinfection on some properties of acrylic denture resin. Int J Prosthodont 1995;8:150-154. 4. Consani RLX, Vieira EB, Mesquita MF, Mendes WB, Arioli-Filho JN. Effect of microwave disinfection on physical and mechanical properties of acrylic resins. Braz Dent J 2008;19:348-353.

Editor's Notes

  1. Say something good to your listeners
  2. Cross-infection. We should think about prevention of spreads.
  3. Impact strength of reinforced resin was slightly higher than the conventional resin although not significant After microwave disinfection, impact strength of conventional resin increased while that of reinforced resin decreased
  4. Flexural strength of conventional resin was significantly less than reinforced resin. After microwave disinfection strength of both types of resins decreased but still the glass fiber reiforced resin was higher than the conventional one
  5. Knoop hardness of conventional resin was significantly high than the reinforced resin before and after microwave disinfection Hardness of conventional resin decreased significantly after subjecting to microwave energy While that of the reiforced resin remained stable