The document discusses different types of denture bases used in dentistry. Temporary denture bases include materials like autopolymerizing resins, shellac, thermoplastics, and wax. These provide rigidity, stability, and allow for setting teeth and recording jaw relationships. Permanent denture bases primarily use acrylic resin due to its strength, stability, and compatibility. The document outlines the history of denture materials from early natural materials to modern resins, and evaluates different temporary base materials and their advantages for uses like diagnostic trials.

1. INDIAN DENTAL ACADEMY
Leader in continuing Dental Education

2.  Definition
 History
 CLASSIFICATION
 TEMPORARY DENTURE BASES
 ACRLIC RESIN
 SHELLAC
 WAX
 THERMOPLASTIC SHEETS
 STABILIZED DENTURE BASES

3. WHAT IS A DENTURE BASE ?
Denture base: The part of a denture that rests on the
foundation tissues and to which teeth are attached.

4. HISTORY
Carved by direct observations of ridge contours
 hard shell of a coconut
 ox femur
 hard fruitwood such as teak
 hippopotamus tusk

5. 1711 Purman in Poland made the first
recorded impression of the jaw using
bees wax. His cast was also of wax,
probably as a model for fitting by bone
or ivory craftsman.
1756 Pfaff, in Germany, formed the first
plaster cast, described “taking the bite,”
and made and used the first recorded
articulator.

8. Having a working model was a tremendous advance in dentistry
and provided the possibility of
swagging gold denture bases (Bourdet, France 1757)
molding or fusing of porcelain dentures (Delabarre,
France, 1800)
Tin (Hudson, 1820)
Tin with silver or gold plating (Royce, 1836)
Compression molded tortoise shell (Harrington 1847)
A form of Gutta Purcha
Tried as denture bases without much success.

10. 1854 Hard rubber (Vulcanite) was introduced by Evans
in England.
The process for making this material was patented by Nelson
Goodyear in the United States in 1851.
Hard rubber was the first really acceptable denture base
material, or the first one that could be molded by a dentist for a
patient at a reasonable cost.
For the next 80 years, no material displaced vulcanite as the
preferred denture base material.

13. ADVANTAGES
 Dimensionally stable.
 Adequate strength.
 Normally compatible with the tissues.
 Possessed a somewhat wettable surface (Some
dentists thought that it produced good retention, others
thought it caused a slight fouling of the denture).

14. SHORTCOMINGS
Poor esthetic property.
Lack of abrasion resistance (loss of polish)
Difficulty encountered in rebasing or relining

15. Many other materials were tried unsuccessfully during this
period.
They included
 Platinum
 Swagged aluminum (1867)
 Cast gold
 Celluloid
 Phenol formaldehyde resins
 Gyptal resins
 Polyvinyl acetate-chloride

17. The next milestone was the introduction of acrylic resin to the
dental profession in the year 1936.
For the next 6 years both vulcanite and acrylic resin were
used as denture bases with the later replacing hard rubber.
VULCANITE ACRYLIC RESIN
By 1942, acrylic resin with its copolymers was considered the
best available denture base material.

19. At a special workshop of Academy of Denture Prosthetics, the
prime clinical requirements of the ideal denture base material
were studied and a list of 58 desirable qualities was
suggested.
Acrylic resin meets 47 of the 58 requirements
Fails in area such as
Instantaneous temperature conductivity
Wettable surface
Easy sterilization
Resistance to abrasion and stain
Choice of hardness and softness
Unbreakability

20. It is estimated that 99% of all complete dentures are fabricated
with one of the acrylic resins.
However, other materials are occasionally used as denture
bases to meet the requirements in certain cases.

21. DENTURE BASES
TEMPORARY PERMANENT
DENTURE BASE DENTURE BASE

22. TEMPORARY DENTURE BASES
Record base: an interim denture base used to support the
record rim material for recording maxillomandibular records,
arranging artificial teeth, or trial placement in the mouth.
Synonyms:
Base plate
Record base
Temporary base
Trial base
Interim denture base

23. PURPOSES OF BASE PLATES:PURPOSES OF BASE PLATES:
KEYWORTHKEYWORTH(1929)(1929)
CARRIERCARRIER
HOLDHOLD
CHECKCHECK

24. REQUIREMENTS OF BASE PLATES:REQUIREMENTS OF BASE PLATES:
ELDERELDER(1955)(1955)
AAdaptationdaptation
AAllow setting of teethllow setting of teeth
BBorder formorder form
CConstructiononstruction
CColorolor
DDimensional stabilityimensional stability
RRigidityigidity

25. TUCKERTUCKER (1966)(1966)
NotNot abrade the cast during removal &abrade the cast during removal &
replacement.replacement.
Take advantageTake advantage of desirable undercuts.of desirable undercuts.
Be of a material thatBe of a material that bondsbonds with that usedwith that used
to block out undercuts on the cast so thatto block out undercuts on the cast so that
it becomes a part of the base plate.it becomes a part of the base plate.

26. Other Requirements for a denture base:
Stable, both on the cast and in the mouth, to ensure the
securing of accurate jaw relation records and the transfer
of these records to the articulator.
Free of voids or projections on the surface that contacts
that contacts the oral mucosa.
Easily removed from the cast.
Reproduce both the contours and the dimensions of the
reflections of the final cast.
Failure to meet these criteria will permit the movement of
the bases in the mouth and result in inaccurate jaw
relationship records.

27. IMPORTANCE OF DENTURE BASES:
Diagnostic use:
The presence of over or underextended borders of the final
impression.
The presence of compression of the mucosa of the residual
ridge, hard palate or soft tissues approximating the borders
of the base.
An indication of the patient’s acceptance of the final denture,
by his early response to the presence of ‘denture-like’ forms
and materials.
The existence of gag reflex that could inhibit adaptation to or
acceptance of the final denture.

28. Therapeutic role:
Aid in recording of maxillomandibular relationship.
Allow the transfer of accurate jaw relationships to an
articulator.
Enabling the setting of artificial teeth for the trial denture.
Reduced or inadequate salivary flow, which may
adversely affect denture retention.
Observation of tongue positions or habits, which would be
unfavorable to the stability of the mandibular prosthesis.

29. CRITERIA FOR THE MATERIAL:
Be readily adapted to the required shape and contours
with a minimum of time, expense and technical skills.
Be rigid and strong in relatively thin sections.
Not exhibit flow at mouth temperature.
Not warp or distort appreciably during the procedures
required for denture fabrication.
Exhibit a color that will not distract from viewing the
arrangement of the teeth of the trial denture as they will
appear in the completed denture.

30. MATERIALS USED:MATERIALS USED:
Autopolymerizing resinsAutopolymerizing resins
Shellac base plateShellac base plate
Thermoplastic resinsThermoplastic resins
Base plate waxBase plate wax

31. STABILIZED BASE PLATESSTABILIZED BASE PLATES
An interim denture base lined with plastic, or
other material, to improve its adaptation and
stability.
Zinc oxide eugenol impression paste.Zinc oxide eugenol impression paste.
Elastomeric impression materials.Elastomeric impression materials.
Hard or soft curing resins.Hard or soft curing resins.

32. AUTOPOLYMERIZING RESIN BASE PLATESAUTOPOLYMERIZING RESIN BASE PLATES
Require an activator and catalyst.Require an activator and catalyst.
No external heat required.No external heat required.
ADVANTAGES:ADVANTAGES:
Readily availableReadily available
Reasonable costReasonable cost
Set hard and rigid or soft and flexible.Set hard and rigid or soft and flexible.
Ease of use.Ease of use.

33. Most commonly used material.Most commonly used material.
METHODS OF CONSTRUCTION:METHODS OF CONSTRUCTION:
SPRINKLE-ON METHODSPRINKLE-ON METHOD
FINGER ADAPTED DOUGH METHODFINGER ADAPTED DOUGH METHOD
CONFINED DOUGH METHODCONFINED DOUGH METHOD
 STONE MOLD METHODSTONE MOLD METHOD
 WAX CONFINED METHODWAX CONFINED METHOD

34. SPRINKLE ON METHOD:SPRINKLE ON METHOD:

39. KEY POINTS:
 EXCELLENT
 Performed in an well ventilated area to
minimize exposure to resin fumes.
 Use nonfibered powder because it sifts more
readily than a powder with fibers, which will
obstruct the opening of the dispenser.
 Use a low speed lathe (1740 rpm) with plenty of pumice
slurry to prevent the build up of heat in the base plate
during polishing.

40. Reinforce base plates with flat ridges by a wire embedded
in resin.
To minimize porosity, keep all areas moist with
monomer to prevent drying when applying resin.

42. FINGER ADAPTED DOUGH METHOD
 FASTER
Unless using gloves, needless repeated contact with resin
during adaptation.
Exceedingly difficult to obtain uniform thickness.
Chances of rebound or lift-off of the resin.
Can displace the soft curing resin used to fill undercuts.

43. SWENSON 1970

47. Elder (1955) described application of pressure using
modelling plastic.
Assadzadik and Yarmond (1975) used the stone mold
method for applying pressure.
ADVANTAGES:
 Excellent control of thickness
 Reduced finishing time
 Minimal porosity
DISADVANTAGES:
Increase in time required to make a mold
Tendency to form voids in the base plate.

55. Described by Lavere and Freda in 1974.
Wax pattern assures the proper thickness of
the base plate throughout, especially in the
palate.
Outer surface of wax makes the record base
neat and pleasing in appearance.

59. Two problems unique to this method:
 Controlling the thickness of the resin layer.
 Keeping the wax exterior surface free of resin.

60. SHELLAC DENTURE BASE MATERIAL:
Shellac is a commonly used material for denture bases.
Derived from the resinous exudate of a scale insect.( Greener,
Harcourt, and Lautenschlager, 1972).
Powdered talc or mica serves as fillers to increase the strength.

61. The material is brown but can be dyed to a more acceptable
color.
It is supplied commercially in forms shaped to correspond to
the general shapes of the maxillary and mandibular arches.

62. Advantages:
 It is inexpensive.
 It can be easily and quickly adapted using readily available
laboratory equipment.
 If adapted accurately, strengthened, and handled carefully,
it can be effectively used for both mandibular and maxillary
arches.
Disadvantages:
If not adequately strengthened, it tends to warp when
subjected to repeated changes of temperature.
Being a brittle material, it is also subjected to breakage.
Chance of losing their initial adaptation

67. STABILIZED WITH ZINC OXIDE EUGENOL
Fletcher (1951), Jamieson ( 1956), Kapur & Yurkstas (1957)
Exhibits better adaptation and dimensional stability.
DISADVANTAGES:
Thicker base plates
Require additional time
Block-out of undercuts is essential.

72. BASEPLATES STABILIZED WITH ELASTOMERIC
MATERIAL
Freese (1956), Bodine ( 1964) & Malson (1964)
ADVANTAGES:
Inherent flexibility
Smooth surface
DISADVANTAGES:
Increased thickness
Increased cost and construction time

74. BASEPLATES STABILIZED WITH
AUTOPOLYMERISING RESIN
Boos (1956), Jamieson (1956), & Hall (1958).
DISADVANTAGES:
Possible warping of the base plate as the result of
internal stresses being released from the resin liner.
Additional time required.

77. ADVANTAGES:
Excellent thickness control
Reasonably good adaptation to the cast.
Simple technique
Minimal amount of time required.
Satisfactory rigidity.
DISADVANTAGES:
Expense of equipment
Difficulty in achieving intimate adaptation in deep recess
and border reflections.
Difficulty in obtaining smooth round borders.