denture base resin is very important in prosthodontics, this seminar is about different denture base resins, its properties and uses.

1. Denture base resin
By Dr. Hileri Mori (Part 1 PG)
Creator of youtube channel: Dentowoman

2. Content
 Introduction
 History
 Dental polymers
 Classification
 Ideal requirements
 Heat cured denture base resin
 Light cure denture base resin
 Chemically cured denture base resin
 Properties of denture base resin
 Advancements
 Conclusion

3. The glossary of prosthodontics terms
defines complete denture,
 Complete denture as a
removable dental prosthesis
that replaces the entire
dentition and associated
structures of the maxilla or
mandible. Such a prosthesis is
composed of artificial teeth
attached to a denture base.
In turn, the denture base
derives its support through
contact with the oral tissues,
teeth or dental implants.

4. Denture base ?
 According to Gpt-8 (2005) a denture base may be defined as the part of the
denture that rests on the foundation and to which teeth are attached
 ADA sp. No. 12

6. Materials used before 18th century
wood
Bone
Ivory
The Journal of Indian Prosthodontic Society, Evolution of denture base materials; S.
K. Khindria, Sanjeev Mittal, Urvashi Sukhija

7. Materials used in 18th century
Gold
Porcelain

8. Materials used in the 19th century
 1. Tortoise Shell (1850
 2. Gutta Percha (1851)
 3. Vulcanite (1851)
 4. Cheoplastic (1856)
 5. Rose Pearl (1860)
 6. Aluminum (1867)
 7. Celluloid (1870)

9. Materials used in 20th century
 1. Bakelite (1909): Its advantage was easy availability but its drawbacks were lack
of uniformity, poor color quality and repair difficulties.
 2. Stainless steel (1921):
 3. Cobalt Chromium (1930)
 4. Vinyl Resin (1932)
 5. Acrylic Resin (1937)
 6. Self cure Acrylic Resin
 7. Epoxy Resin (1951)
 8. Polystyrene (1951)
 9. Nylon (1955)
 10. Polycarbonates (1967)
 11. High impact acrylic (1967)
 12. Polysulphones (1981)
 13. Visible L.C (1947)Acrylic (1986)
 14. Pure Titanium (1998

12. Dental polymers
Condensation
polymerization
Addition
polymerization

15. Heat/light
/chemical
process
initiator
Propogation
Benzoyl peroxide
Chain transfer and
termination (exchange
of hydrogen atom or
coupling)

16. Copolymerization : improves physical
properties

17. Cross linking : improves strength,
decrease solubility & water sorption
Formation of chemical bonds or bridges
between the linear polymers

18. Ideal requirements
• Be radio-opaque
• Bond to artificial teeth
• Be rigid enough
• Be easy to process, adjust and
repair
• Have color stability
• biocompatible
• Satisfy aesthetic demands
• Have sufficient mechanical strength
• Be dimensionally stable to maintain
fit and occlusion
• Resist abrasion and erosion

19. Principal
ingredients of
heat cure
denture base
resin

21. Commercial names

22.  Impact failure and fatigue failure
transverse deflection and transverse strength of four commercial brands of
heat cure acrylic resin (Stellon, Acrylin-H, Trevalon and Trevalon-HI).
The heat cure denture base material
(Trevalon "HI") was the strongest and
Trevalon was the weakest among all
materials used in this study.

23. Compression molding technique
flasking
Dewaxing
Packing
under
pressure and
curing

24. Polymer to monomer ratio ?
 Volumetric and linear shrinkage
 21% decrease in the volume of material
 Pre polymerize = pre shrinking (powder)
 Non polymerized section = monomer
M
P
P
P
Dough
like mass
Shrinkage 7%

25. Despite of 7% volumetric shrinkage why
clinically acceptable result?
 Shrinkage is distributed uniformly to all the surfaces
 Adaptation of denture base is not significantly affected.

26. Linear shrinkage: effect on denture base
adaptation !
 2% linear shrinkage ( most commercial products 0.69%)
 Thermal shrinkage of resin is the reason
 During cooling process
 Chemical cured dentures have better fit due to less linear shrinkage

27. Why laboratory remount?

28. Polymer to monomer interaction
 Sandy : no interaction at molecular level, polymer beads
remain unaltered
 Stringy : monomer attacks the surface of polymer beads
 Dough: increased number of polymer chain enter the
solution. No longer tacky and do not adhere with the
surfaces
 Rubbery: monomer is dissipated by evaporation. mass
rebounds when compressed or stretched
 Stiff: continued evaporation of monomer

29. Dough forming time
 According to American national standards institute : this consistency br
attained in less then 40 min. from start of the mixing process.
 In clinical use this stage is attained within 10 mins.
 Working time: it is defined as a time a denture base material remains in a
dough like stage.
 Critical to compression molding
 5 mins
 Can be extended via refrigeration

30. Errors in packing
 Too much material: excessive thickness of denture base and relative
malpositioning of prosthetic teeth.
 Too little material: denture base voids or porosities

31. Temperature rise
• Decomposition of benzoyl
peroxide.
• Increased polymerization
• Increased exothermic
reaction.
• Boiling of monomer-
porosity
• Internal porosity: poorly
controlled temp.

32. Polymerization cycle
1.Constant temp. water
bath at 74 C for 8hrs.
2.74C for 8hrs and
increasing temp. to
100C for 1hr.
3.74C for approx. 2 hrs.
increasing the temp.
to 100C and
processing for 1hr.

33. Porosity
 Likely to develop in thicker portions
 Vaporization of unreacted monomer
 Position of the denture base
 Unequal mixing
Inadequate pressure
Air entrapement

34. Injection molding technique

35. Advantages Disadvantages
Good dimensional accuracy High cost
Less free monomer Mold design
Good impact strength Less craze resistant
Less creep resistant

36. What literature says? Injection molding
vs. compression molding
 injection molding techniques exhibited less processing errors as compared to
compression molding technique with statistical significance.
 The injection molding method produced a significantly smaller incisal pin
opening over the standard compression molding technique when PMMA resin
was used.
 The injection molding system was the more accurate method for processing
dentures
 Dimensional changes?
However, in terms of clinical significance, there appears to be little
advantage in selecting injection molded acrylic, although time
savings at the laboratory remount and occlusal correction stage may
be made.

38. Microwave dentures
 Methyl methacrylate molecule is asymmetric.
 Specially formulated resin and a nonmetallic flask.
 Overheating: thick sections, porosities
 Better fit then conventional compression molding

39. owing to the forces of mastication,
denture bases may flex close to
500,000 times per year!!!

40. Causes of breakage !
 Deep notching at the mid-line labial fraenum
 opposing natural teeth
 occlusal discrepancies,
 inaccurate fit,
 prominent tori,
 differential hardness of the supporting tissues,
 excessively thin sections of acrylic and
 processing errors.

41. High impact denture base resin
 Rubber-modified PMMA is known as ‘highimpact acrylic’
 cracks in the material are difficult to initiate and their propagation is slow

42.  high aesthetic demands, and
denture base resin systems
are available which
facilitate a closer match to
patients’ oral tissues than a
‘monoblock’ of conventional
pink.
 Enigma Colour Tone Kit,
Schottlander

43. Fibers reinforced acrylic
Carbon Fibers Polyester fiber (PE).
Highly drawn linear polyethylene
fibers.
Organophilic montmorillonite
(Claytone).
Glass fiber reinforcement. Methacrylated
polyhedralsilsesquioxanes (POSS).
Kevlar (Synthetic Aramid Fiber Silica-glass fiber reinforced
polymeric materials
Ultra high modulus polyethylene
fibers.

45. Anti fungal agents
 Polymeric biocides are polymers
made up of bioactive monomers.
 These polymers consist of multiple
interconnected biocides which are
incorporated into PMMA through
surface modification or
copolymerization
 silver zeolites, silver
nanoparticles and
platinum nanoparticles
 Nano titanium dioxide particles and
powdered titanium dioxide
have been reported as effective
antifungal and antibacterial agents

46. Chemically activated denture base resin
 Cold cure, self cure, auto polymerizing resin
 Activator: tertiary amine
 Degree of polymerization is not that complete as heat polymerized denture
base resin
 Greater amount of unreacted monomer – tissue irritant, decreased trasverse
strength
 Less shrinkage then heat activated denture base resin
 Inferior color stability (tertiary amine)

48. Most recent generation of light
activated denture base resin
 a base forming resin
 A tooth setting resin
 A countering resin

50. Fluid resin technique
 Low viscosity resin
Advantages Disadvantages
Adaptation Shifting of prosthetic teeth
Decreased damage to teeth and
denture base during processing
Air entrapment
Reduced material cost Poor bonding between denture base
and teeth
Simplification of flasking, deflasking
and finishing
Technique sensitive

51. Thermoplastic resin
 Softened by heat without chemical change
 thermoplastic nylon resin that is ultra thin, very flexible (think more
comfortable for chewing and speaking) and is so durable
 that one company – Valplast – offers a lifetime warranty for fractures or
breaks.
 excellent transitional restoration during the healing period on implant cases.

52. Polyether ether ketone

54. The denture
base is milled
from
preformed
acrylic resin
blocks,
CAD CAM Denture base resin

55. Polymerization shrinkage is not an
issue

56. Digitally designed occlusion

57. References
 Evaluation of Three Different Processing Techniques in the Fabrication of
Complete Dentures Vamsi Krishna Chintalacheruvu,1 Rajasekaran Uttukuli
Balraj,2 Lavanya Sireesha Putchala,3 and Sreelekha Pachalla4
 Dental materials; Philips 12th edition
 1.Computer aided technology for fabricating complete dentures: systematic
review of historical background, current status and future prospectives. J
Prosthet Dent 2013; Bindra AS, et al
 2. Comparision of treatment outcomes in digital vs. conventional complete
removable dental prosthesis fabrications in a predoctoral setting, J prosthrt
Dent, 2015; Kattadiyill MY,et al

58. Thank you!
dentowoman03@gmail.com