Metallic denture base materials new1/endodontic courses

METALLIC DENTUREMETALLIC DENTURE
BASE MATERIALSBASE MATERIALS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

IntroductionIntroduction
DefinitionsDefinitions
Brief History.Brief History.
ClassificationClassification ofof denture base materialsdenture base materials
Ideal requirementsIdeal requirements
Advantages and disadvantages of metallic denture bases .Advantages and disadvantages of metallic denture bases .
Different metallic denture basesDifferent metallic denture bases

 Review of literatureReview of literature
 SummarySummary andand conclusionconclusion
 ReferencesReferences

introductionintroduction
In the space age , there is a belief prevalent thatIn the space age , there is a belief prevalent that
modernmodern technologytechnology can be put to use to solve anycan be put to use to solve any
scientific problem, if the problem can be clearlyscientific problem, if the problem can be clearly
defined .defined .
All through the history of making dentures we find aAll through the history of making dentures we find a
constant struggle of the dentist to find a suitableconstant struggle of the dentist to find a suitable
denture base.denture base.

DEFINITIONSDEFINITIONS
 Denture base :Denture base :
““That part of a complete or removable partial dentureThat part of a complete or removable partial denture
which rests uponwhich rests upon thethe basal seat and to which the teethbasal seat and to which the teeth
are attached. ”are attached. ”-- GPTGPT
 METAL BASE :METAL BASE :
The metallic portion of the denture base forming aThe metallic portion of the denture base forming a
part or all of the basal surface of the denture .It servespart or all of the basal surface of the denture .It serves
as a base for the attachment of the resin portion of theas a base for the attachment of the resin portion of the
denture base and the teeth.denture base and the teeth.

Brief history ofBrief history of
denture base materialsdenture base materials
 Various types of materials have been used in the pastVarious types of materials have been used in the past
for fabrication of denture bases.for fabrication of denture bases.
 Wood, ivory, baked porcelain, gold,silver,Wood, ivory, baked porcelain, gold,silver,
cheoplastic metal and celluloid were used.cheoplastic metal and celluloid were used.
 Of the metals used gold and silver were the best , butOf the metals used gold and silver were the best , but
their cost was too great for the average patient.their cost was too great for the average patient.

Brief history ofBrief history of
denture base materialsdenture base materials
 In 1839, Charles GoodyearIn 1839, Charles Goodyear discovereddiscovered a method ofa method of
producing rubber, and in 1851,Nelson Goodyearproducing rubber, and in 1851,Nelson Goodyear
invented a process for making hard rubber orinvented a process for making hard rubber or
vulcanite.vulcanite.
 In 1937, methyl methacrylate was found to be usefulIn 1937, methyl methacrylate was found to be useful
as a denture base.as a denture base.
 The first know casting of an aluminium completeThe first know casting of an aluminium complete
denture base in the United States was done in 1867 bydenture base in the United States was done in 1867 by
BEAN.BEAN.

 Chromium-cobalt –base alloys wereChromium-cobalt –base alloys were
introduced forintroduced for useuse in dentistry in 1933 byin dentistry in 1933 by
Erdle and Prange.Erdle and Prange.

CLASSIFICATION OF DENTURECLASSIFICATION OF DENTURE
BASE MATERIALSBASE MATERIALS
1.Metallic denture base materials1.Metallic denture base materials
example : Cobalt-chromiumexample : Cobalt-chromium
Gold, titanium…Gold, titanium…
2. Non Metallic denture base materials :2. Non Metallic denture base materials :
example :Acrylic resinsexample :Acrylic resins
3.COMBINATION3.COMBINATION

 Bio-compatibleBio-compatible
 Adequate physical and mechanical properties:Adequate physical and mechanical properties:
- High flexure and impact strength- High flexure and impact strength
- Long fatigue life- Long fatigue life
- High abrasion resistance- High abrasion resistance
- High thermal conductivity- High thermal conductivity
- Low density- Low density
- Low solubility and sorption to oral fluids- Low solubility and sorption to oral fluids
Ideal requirements of a dentureIdeal requirements of a denture
base materialbase material

- Dimensionally stable and accurate- Dimensionally stable and accurate
- Superior esthetics and color stability- Superior esthetics and color stability
- Radio-opacity- Radio-opacity
- Good adhesion with denture teeth and liners- Good adhesion with denture teeth and liners
- Ease of fabrication with minimum expense- Ease of fabrication with minimum expense
- Easy To repair- Easy To repair
- Readily cleansable- Readily cleansable

Advantages of cast metal dentureAdvantages of cast metal denture
bases over acrylic basesbases over acrylic bases
 Lack of bulk with more strengthLack of bulk with more strength
 The metal base prevents warpage during processing.The metal base prevents warpage during processing.
 Stronger and are less subject toStronger and are less subject to breakabgebreakabge..
 More accurate fit and more faithful reproduction ofMore accurate fit and more faithful reproduction of
tissue details.tissue details.
 Less tissue changes occur under metal bases.Less tissue changes occur under metal bases.
 Dimesional accuracy.Dimesional accuracy.
 Less porous.Less porous.
 Better thermal conductivityBetter thermal conductivity
 Show less lateral deformation in function.Show less lateral deformation in function.

Disadvatages of metal basesDisadvatages of metal bases
 Greater technical costs.Greater technical costs.
 Difficulty of rebasing and reliningDifficulty of rebasing and relining
 Less margin forLess margin for errorerror permissible in thepermissible in the
posterior palate seal areaposterior palate seal area
 Increased weight for a maxillary dentureIncreased weight for a maxillary denture

 Despite the popularity of PMMA as a dentureDespite the popularity of PMMA as a denture
base there are various situations where abase there are various situations where a
metallic denture base can be used :metallic denture base can be used :
- Single- Single maxillarymaxillary complete denture opposing acomplete denture opposing a
natural mandibular dentitionnatural mandibular dentition
- Unfavourable occlusal plane- Unfavourable occlusal plane
- Heavy anterior contacts- Heavy anterior contacts
- Heavy masticatory forces- Heavy masticatory forces

Different metallic dentureDifferent metallic denture
base materials:base materials:
 Cobalt-chromium alloys :Cobalt-chromium alloys :
 As early as 1949 it was estimated that nearly 80% ofAs early as 1949 it was estimated that nearly 80% of
all partial denture appliances were cast from co-crall partial denture appliances were cast from co-cr
alloys.alloys.
composition :composition :
Principle elementsPrinciple elements (approx. 90%)(approx. 90%)
Cobalt 60%Cobalt 60%
Chromium 25% to 30%Chromium 25% to 30%


Other componentsOther components ::
MMolybdenum siliconeolybdenum silicone
Aluminium nitrogenAluminium nitrogen
Berylium carbon & manganeseBerylium carbon & manganese
Nickel chromium alloys :Nickel chromium alloys :
 Nickel 70%Nickel 70%
 Chromium 16%Chromium 16%
 Other constituentsOther constituents

1.Chromium :1.Chromium :
Responsible for the tarnish resistance and stainlessResponsible for the tarnish resistance and stainless
properties.properties.
When the chromium content of an alloy is more thanWhen the chromium content of an alloy is more than
30% it is more difficult to cast ; and therefore dental30% it is more difficult to cast ; and therefore dental
alloys should not contain more than 28% or 29%alloys should not contain more than 28% or 29%
chromium.chromium.
These alloys are considered to beThese alloys are considered to be techniquetechnique
sensitivesensitive

 Cobalt and nickel :Cobalt and nickel :
 In generalIn general cobaltcobalt and nickel areand nickel are
interchangeable .interchangeable .
 Cobalt increases the elastic modulus ,strengthCobalt increases the elastic modulus ,strength
and hardness more than Nickel does.and hardness more than Nickel does.

 Other alloying components :Other alloying components :
CARBON : Increase in carbon content increases theCARBON : Increase in carbon content increases the
hardness of Co-based alloyshardness of Co-based alloys
If the carbon content is increased by 0.2% more thanIf the carbon content is increased by 0.2% more than
the desired amount –results in a too hard and toothe desired amount –results in a too hard and too
brittle alloy not suitable for dental appliances .brittle alloy not suitable for dental appliances .
whereas a decrease of 0.2% will decrease the tensilewhereas a decrease of 0.2% will decrease the tensile
and the yield strengthand the yield strength

 MOLYBDENUM :MOLYBDENUM : (3% to 6% )(3% to 6% )
-Contributes to the-Contributes to the strengthstrength of the alloy.of the alloy.
-Initially tungsten was used , but it reduced the-Initially tungsten was used , but it reduced the
elongation ,was therefore replaced by other hardeningelongation ,was therefore replaced by other hardening
elements like molybdenum .elements like molybdenum .
 ALUMINIUM :ALUMINIUM :
-Forms a compound with Ni and Al (Ni3Al) which-Forms a compound with Ni and Al (Ni3Al) which
increases the tensile and the yield strength of theincreases the tensile and the yield strength of the
alloysalloys

 BERYLIUMBERYLIUM ::
About 1% lowers the fusion temperature range of theAbout 1% lowers the fusion temperature range of the
alloy by about 100 degrees C.alloy by about 100 degrees C.
 SILICONE AND MANGANESESILICONE AND MANGANESE ::
Increase the fluidity and castability of these alloys.Increase the fluidity and castability of these alloys.
 NITROGEN :NITROGEN :
If present contributes to the brittle qualities of theseIf present contributes to the brittle qualities of these
alloys .alloys .

titaniumtitanium
 Ti was developed byTi was developed by William GregorWilliam Gregor of Englandof England
in 1791,and was named by Martin H. Kalproth ofin 1791,and was named by Martin H. Kalproth of
Germany in 1795.Germany in 1795.
 Welhelm KrollWelhelm Kroll1930 invented useful metallurgical1930 invented useful metallurgical
processes for Ti and isprocesses for Ti and is consideredconsidered to be theto be the
FATHER of Ti dentistry.FATHER of Ti dentistry.
 In the recent years ,the attention of Ti has switchedIn the recent years ,the attention of Ti has switched
from its previous attention with jet engines,from its previous attention with jet engines,
mammoth aircraft frames to prosthetic limbs ,dentalmammoth aircraft frames to prosthetic limbs ,dental
implants….implants….


Ores of TiOres of Ti : Rutile: Rutile
IlmeniteIlmenite

Ti processingTi processing ::
1.Reduction process1.Reduction process
2.Melting the2.Melting the spongesponge
3.Primary ingot formation3.Primary ingot formation
4.Secondary ingot formation4.Secondary ingot formation

 Types of Ti :Types of Ti :
Ti and Ti alloys exist in 3 majorTi and Ti alloys exist in 3 major categoriescategories accordingaccording
to predominant phases present as :alphato predominant phases present as :alpha
- Beta and- Beta and
- Alpha-beta forms- Alpha-beta forms
 When pure Ti is heated at 882+/- 2degrees C theWhen pure Ti is heated at 882+/- 2degrees C the
metal exhibits an allotrophic phase transformation inmetal exhibits an allotrophic phase transformation in
which a hexagonal close-packed alpha phasewhich a hexagonal close-packed alpha phase
structure is transformed into a body centered cubicstructure is transformed into a body centered cubic
structure as the temperature is raised above thatstructure as the temperature is raised above that
temperature.temperature.
 Even a rapid quenching does not suppress the alpha –Even a rapid quenching does not suppress the alpha –
beta phase transformation .Thus a pure Ti casting hasbeta phase transformation .Thus a pure Ti casting has
a alpha hcp structure near room temperature .a alpha hcp structure near room temperature .

 Forms and sizesForms and sizes :Alloyed and unalloyed:Alloyed and unalloyed
Ti is available in differentTi is available in different formsforms and sizes likeand sizes like
: plates , bar ,rod, wire, sheet, strip, powder..: plates , bar ,rod, wire, sheet, strip, powder..
 Commercially pure Ti:Commercially pure Ti: available in 4available in 4
different grades(ASTM-Grade1-4)different grades(ASTM-Grade1-4)

 Dental Ti castingDental Ti casting ::
Because of the inherent properties of Ti that made itBecause of the inherent properties of Ti that made it
difficult to melt and cast, traditional casting machinesdifficult to melt and cast, traditional casting machines
that cast in air with conventional ceramic crucible andthat cast in air with conventional ceramic crucible and
investment materials could not be used .investment materials could not be used .
 More specialized casting equipment and moldMore specialized casting equipment and mold
materials developed solely for this purpose werematerials developed solely for this purpose were
developed.developed.

 Casting problems were due to-Casting problems were due to-
1. The high melting point of Ti (1670 degrees1. The high melting point of Ti (1670 degrees
C),Murray 1987.C),Murray 1987.
2. The strong chemical affinity of Ti with2. The strong chemical affinity of Ti with
gases viz.gases viz. O2,H2,N2..O2,H2,N2..
3.3. High reducing ability of TiHigh reducing ability of Ti
4.4. High solubility of the same gases in TiHigh solubility of the same gases in Ti
5.5. Low density of TiLow density of Ti

 Thus, improvements in the conventional castingThus, improvements in the conventional casting
methods were required viz:methods were required viz:
1. Selecting heat sources high1. Selecting heat sources high enoughenough for fusing Ti.for fusing Ti.
2. Isolating the molten metal from air.2. Isolating the molten metal from air.
3. Developing a container which reacts with very little3. Developing a container which reacts with very little
or does not react at all with the molten Ti.or does not react at all with the molten Ti.
4. Finding new ideas for delivering the molten metal in4. Finding new ideas for delivering the molten metal in
the mold at desired velocity .the mold at desired velocity .

 Ti casting equipment :Ti casting equipment :
Inorder to cope with the high fusion temperature of TiInorder to cope with the high fusion temperature of Ti
alloys , 2 melting methods are used -alloys , 2 melting methods are used -
1. Argon/arc melting with a non-consumable tungsten1. Argon/arc melting with a non-consumable tungsten
electrode.electrode.
2.High frequency induction melting2.High frequency induction melting

MeltingMelting CastingCasting EquipmentEquipment
1.Electric arc1.Electric arc A. Gas PressureA. Gas Pressure
B. Centrifugal ForceB. Centrifugal Force
Casmatic (Iwatani, Osaka, Japan)Casmatic (Iwatani, Osaka, Japan)
Cyclarc Manita ( Tokyo , Japan)Cyclarc Manita ( Tokyo , Japan)
Titaniumer Ohera (Osaka,Japan)Titaniumer Ohera (Osaka,Japan)
Ti cast Super C (Selec , Japan)Ti cast Super C (Selec , Japan)
2.High frequency2.High frequency A. Gas pressureA. Gas pressure
B. Centrifugal forceB. Centrifugal force
Arvatroa (Kyato , Japan)Arvatroa (Kyato , Japan)
Titanus (Bego, Germany)Titanus (Bego, Germany)

ALUMINIUMALUMINIUM
 Basically produced by the electrolysis of bauxite oreBasically produced by the electrolysis of bauxite ore
in a molten cryolite bath.in a molten cryolite bath.
BACKGROUNDBACKGROUND
 The first know casting of an aluminium completeThe first know casting of an aluminium complete
denture base in the US was done in 1867.denture base in the US was done in 1867.
 Carroll presented a method for casting the aluminiumCarroll presented a method for casting the aluminium
bases under pressure.bases under pressure.

ALUMINIUMALUMINIUM
 Prothero detailed some of the advantages ofProthero detailed some of the advantages of
Aluminium as thermal conductivity, malleability, andAluminium as thermal conductivity, malleability, and
rigidity; and disadvantages as warpage and imperfectrigidity; and disadvantages as warpage and imperfect
density of the castingdensity of the casting
 Campbell suggested that aluminiums thermalCampbell suggested that aluminiums thermal
conductivity not only elicits a favourable patientconductivity not only elicits a favourable patient
response , but also promotes a normal pink,response , but also promotes a normal pink,
physiologic condition of the mouth.physiologic condition of the mouth.

 Sizeland –Coe was the first to discuss the use of aSizeland –Coe was the first to discuss the use of a
super pure alluminium alloy for the construction ofsuper pure alluminium alloy for the construction of
denture bases, as it eliminated much of the intra-oraldenture bases, as it eliminated much of the intra-oral
corrosion that existed.corrosion that existed.
 Lundquist felt that the primary dis -advantage of theLundquist felt that the primary dis -advantage of the
alloy was its discoloration .alloy was its discoloration .
 Barsoum et al evaluated the accuracy of fit of AlBarsoum et al evaluated the accuracy of fit of Al
bases as compared to heat and cold cured resins-Albases as compared to heat and cold cured resins-Al
had a better fit.had a better fit.

 IndicationsIndications of an aluminium denture base:of an aluminium denture base:
1. Is an excellent choice when the natural mandibular1. Is an excellent choice when the natural mandibular
dentition opposes the edentulous maxillary arch.dentition opposes the edentulous maxillary arch.
2.patients who have undergone maxillary and2.patients who have undergone maxillary and
mandibular atrophy through years of CD use willmandibular atrophy through years of CD use will
benefit .benefit .
3. Patients who have had fracture problems with resin3. Patients who have had fracture problems with resin
denture bases.denture bases.
 Contraindications :Contraindications :
1.Following recent extractions.1.Following recent extractions.
2.Systemic problems2.Systemic problems
3.Severe undercuts3.Severe undercutswww.indiandentalacademy.comwww.indiandentalacademy.com

 Advantages :Advantages :
1.Accurate fit .1.Accurate fit .
2.Greater accuracy and added retention2.Greater accuracy and added retention
3.Good thermal conductivity, malleability.3.Good thermal conductivity, malleability.
4.Interocclusal record making is more accurately4.Interocclusal record making is more accurately
reproduced.reproduced.
5.Less bulk with more strength.5.Less bulk with more strength.
6.Inexpensive6.Inexpensive

Technique for castingTechnique for casting
aluminiumaluminium
1. Duplicate master cast1. Duplicate master cast
with reversiblewith reversible
hydrocolloid.hydrocolloid.
2. Pour refractory cast,2. Pour refractory cast,
remove and place in aremove and place in a
drying oven at 190drying oven at 190
degree C for 30min .degree C for 30min .

3. Trim the refractory cast
4. Immerse the refractory cast in bees wax at 290
degrees F
5. Place one thickness baseplate wax over entire
tissue bearing surface of the cast.
6. Coat the cast with Ti seal. Place retention beads
7. Place the main sprue as well as the auxillary
sprue.

 Induction casting is recommended forInduction casting is recommended for
aluminium denture base.aluminium denture base.
 Fill the crucible with Al pellets & push theFill the crucible with Al pellets & push the
start button.start button.
 Keep the arm spinning for 4 minutes non stop.Keep the arm spinning for 4 minutes non stop.
 Alloy the casting to bench cure for atleast 45Alloy the casting to bench cure for atleast 45
minutesminutes
 Final cleaning and anodization may be done ifFinal cleaning and anodization may be done if
required.required.

STAINLESS STEEL DENTURE BASESTAINLESS STEEL DENTURE BASE
When approximately 12% to 30% chromium is addedWhen approximately 12% to 30% chromium is added
to iron ,the alloy is called STAINLESS-STEEL .to iron ,the alloy is called STAINLESS-STEEL .
Types of stainless steelTypes of stainless steel
(crystal structure formed(crystal structure formed
by iron atoms )by iron atoms )
chromiumchromium nickelnickel carboncarbon
FerriticFerritic 11.5-2711.5-27 00 0.20max0.20max
AustenticAustentic 16-2616-26 7-227-22 0.25max0.25max
MartensiticMartensitic 11.5-1711.5-17 0-2.50-2.5 0.15-1200.15-120

PROPERTIES :PROPERTIES :
Despite the difficulties in swaging ,stainless steelDespite the difficulties in swaging ,stainless steel
has some merits as a denture base material :has some merits as a denture base material :
1.Very thin denture base can be produced –figures as1.Very thin denture base can be produced –figures as
low as as 0.11mmlow as as 0.11mm
2. The steel is fracture2. The steel is fracture resistantresistant..
3. Not heavy due to the thinness .3. Not heavy due to the thinness .
4.The corrosion resistance is good .4.The corrosion resistance is good .
5. Good thermal conductivity.5. Good thermal conductivity.

 Methods of swaging :Methods of swaging :
1.Conventional method1.Conventional method
2.Newer methods :2.Newer methods :
a. Explosion forminga. Explosion forming
b. Explosion hydraulic formingb. Explosion hydraulic forming
c. Hydraulic formingc. Hydraulic forming

Gold alloysGold alloys
 Gold alloys of types 3 and 4 areGold alloys of types 3 and 4 are
sufficiently rigid for use as a cast metalsufficiently rigid for use as a cast metal
base.base.
 casting with gypsum bonded investmentscasting with gypsum bonded investments
with a uniform thickness as thin as 28with a uniform thickness as thin as 28
gauge is easy.gauge is easy.

TYPETYPE %Au%Au %Cu%Cu %Ag%Ag %Pd%Pd %Pt%Pt %In,Sn,Fe,Zn,Ga%In,Sn,Fe,Zn,Ga
II 8383 66 1010 0.50.5 -- BalanceBalance
IIII 7777 77 1414 11 -- BalanceBalance
IIIIII 7575 99 1111 3.53.5 -- BalanceBalance
IVIV 6969 1010 12.512.5 3.53.5 33 BalanceBalance

Procedure for gold alloy cast base :Procedure for gold alloy cast base :
 Wax block out of the master cast is done.Wax block out of the master cast is done.
 Place the cast in a slurry water preheated toPlace the cast in a slurry water preheated to
38degrees C for 20 min.38degrees C for 20 min.
 Duplicate the cast using a duplicating colloid.Duplicate the cast using a duplicating colloid.
 Dry the refractory cast ,then pour and trim theDry the refractory cast ,then pour and trim the
cast.cast.
 Selection of he size of the plastic pattern us aSelection of he size of the plastic pattern us a
clinical decision (18 gauge generally)clinical decision (18 gauge generally)

 Add retention beads for the resin.Add retention beads for the resin.
 Attach the sprues.Attach the sprues.
 Invest the cast.Invest the cast.
 Burn out the wax.Burn out the wax.
 Induction casting may be used .Induction casting may be used .

Metal TypeMetal Type YeildYeild
StrengthStrength
(Mpa/Ksi)(Mpa/Ksi)
TensileTensile
StrengthStrength
(Mpa/Ksi)(Mpa/Ksi)
ElongationElongation
(%)(%)
HardnessHardness
(HV)(HV)
ElasticElastic
ModulusModulus
(GPa/Ksi x(GPa/Ksi x
101033
))
Co- Cr (A )Co- Cr (A ) 710/103710/103 870/120870/120 1.61.6 432432 224/32.4224/32.4
Ni – Cr (B)Ni – Cr (B) 690/100690/100 800/116800/116 3.83.8 300300 182/26.4182/26.4
Co – Cr – Ni (c)Co – Cr – Ni (c) 470/68470/68 685/99685/99 8.08.0 264264 198/28.7198/28.7
Fe – Cr ( D)Fe – Cr ( D) 703/102703/102 841/122841/122 99 309309 202/29.3202/29.3
Type IV GoldType IV Gold 493/71.5493/71.5 776/112776/112 77 264264 90/1390/13
CP TiCP Ti 344/50344/50 345/50345/50 1313 210210 103/14.9103/14.9
Ti – 6V- 4 AlTi – 6V- 4 Al 870/126870/126 925/134925/134 55 320320 117/17117/17

REVIEW OF LITERATUREREVIEW OF LITERATURE
1. WATANABE et al in 1997 tested the1. WATANABE et al in 1997 tested the
hypothesis that differences in pressurehypothesis that differences in pressure
produceproduce castingscastings with various amounts ofwith various amounts of
porosities values. This study suggestedporosities values. This study suggested
castings which have adequate mechanicalcastings which have adequate mechanical
properties and low porosities can beproperties and low porosities can be
obtained by choosing an argon pressureobtained by choosing an argon pressure
difference.difference.

Hamda et al in 1999 conducted a study withHamda et al in 1999 conducted a study with
an objective to produce complete, void freean objective to produce complete, void free
castings of removable partial denturecastings of removable partial denture
frameworks made from commercially pure Ti.frameworks made from commercially pure Ti.
The ball sprueThe ball sprue designdesign produced the mostproduced the most
complete castings for the removable partialcomplete castings for the removable partial
denture denture Ti frameworks.denture denture Ti frameworks.

 Moore and White K.C. in 1986 describedMoore and White K.C. in 1986 described
materials and technique for applying gingivalmaterials and technique for applying gingival
color to aluminium when it is used as acolor to aluminium when it is used as a
 They concluded that abrasion of anodizedThey concluded that abrasion of anodized
surface may release dye inclusions.surface may release dye inclusions.

 Anthony De Furio and Daniel H. Gehl (1970)Anthony De Furio and Daniel H. Gehl (1970)
conducted a study to determine the amount of forceconducted a study to determine the amount of force
required to dislodge maxillary dentures made fromrequired to dislodge maxillary dentures made from
aluminium , gold and acrylic resin. He used aaluminium , gold and acrylic resin. He used a
precision machine toprecision machine to measuremeasure the force necessary tothe force necessary to
dislodge a maxillary denture base from its basal seat.dislodge a maxillary denture base from its basal seat.
He concluded that the chrome cobalt and aluminiumHe concluded that the chrome cobalt and aluminium
alloy bases gave retention values which werealloy bases gave retention values which were
significantly higher than those obtained with thesignificantly higher than those obtained with the
acrylic resins and gold alloy bases .acrylic resins and gold alloy bases .

A study which was conducted in dept ofA study which was conducted in dept of
prosthodontics by Dr.Gautam Shetty under theprosthodontics by Dr.Gautam Shetty under the
guidance of DR. N.P.PATIL in sdm dentalguidance of DR. N.P.PATIL in sdm dental
college.college.
The main objective of the study were :The main objective of the study were :
1. To compare the fit of Al alloy (7010)denture base1. To compare the fit of Al alloy (7010)denture base
with acrylic denture base and base metal alloywith acrylic denture base and base metal alloy
2. To study the effect of anodization and2. To study the effect of anodization and
electroplating on the resistance to corrosion.electroplating on the resistance to corrosion.
3. To compare the flexure strenght of aluminium3. To compare the flexure strenght of aluminium
alloy wih that of resin and base metal alloy .alloy wih that of resin and base metal alloy .www.indiandentalacademy.comwww.indiandentalacademy.com

RESULTS :RESULTS :
 The results indicated the accuracy of fit of aluminiumThe results indicated the accuracy of fit of aluminium
was better than base metal alloy and superior thanwas better than base metal alloy and superior than
acrylic resinacrylic resin
 Anodized Al showed better resistance to corrosionAnodized Al showed better resistance to corrosion
resistance than that electroplated and that without anyresistance than that electroplated and that without any
surface treatment.surface treatment.

SUMMARY ANDSUMMARY AND
CONCLUSIONCONCLUSION
 The dentist shouldThe dentist should possesspossess sufficientsufficient
knowledge of the properties of differentknowledge of the properties of different
Prosthodontics materials they deal with ,soProsthodontics materials they deal with ,so
that they can exercise prudent judgment inthat they can exercise prudent judgment in
their selection, which in turn will ensuretheir selection, which in turn will ensure
treatment efficacy and effectiveness.treatment efficacy and effectiveness.

REFERENCESREFERENCES
 Anusavice Kenneith. J :Philips science of DentalAnusavice Kenneith. J :Philips science of Dental
materials .11materials .11thth
edition 2003edition 2003
 Atwood D.A : FinalAtwood D.A : Final reportreport on the clinicalon the clinical
requirement of ideal denture base materials .JPDrequirement of ideal denture base materials .JPD
1968,20 :1011968,20 :101
 Baraco M.T and Dember M.L:Cast AluminiumBaraco M.T and Dember M.L:Cast Aluminium
denture base,JPD 1987,58:179denture base,JPD 1987,58:179
 Combe E.C : Notes on dental materials 6Combe E.C : Notes on dental materials 6thth
editionedition
1992 Churchill Livingstone1992 Churchill Livingstone

REFERENCESREFERENCES
 Craig R.G :Restorative dental materials 8th editionCraig R.G :Restorative dental materials 8th edition
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retention of maxillary complete denture with differentretention of maxillary complete denture with different
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 Faber B. L: Lower cast metal base JPD1957 51 :7Faber B. L: Lower cast metal base JPD1957 51 :7
 Grundwald A.H:Gold base lower denture ,JPD 1964,Grundwald A.H:Gold base lower denture ,JPD 1964,
14:43214:432
 Johnson W.W :The history of ProstheticJohnson W.W :The history of Prosthetic
dentistry,JPD 1959,9:841dentistry,JPD 1959,9:841
 Lundquist Do :Lundquist Do :AnAn Al alloy as a denture base, JPDAl alloy as a denture base, JPD
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 Moore F.D :Organic or metal bases for dentures , JPDMoore F.D :Organic or metal bases for dentures , JPD
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 Morrow R.M RUDD K.D :Dental Lab procedures CDMorrow R.M RUDD K.D :Dental Lab procedures CD
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 Wang Russel .R : Titanium for complete dentureWang Russel .R : Titanium for complete denture
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 Winkler Sheldon :Winkler Sheldon : EsssentialsEsssentials Of Complete DentureOf Complete Denture
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