Download - Complex Amalgam Restoration(Final)
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Complex AmalgamRestoration
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Complex Amalgam Restoration
Complex amalgam restorationsinvolve replacement of missing toothstructure because of teeth have beenfractured or involved with caries orexisting restorations. It involvesreplacement of one or more missing
cusps, and often requires bondingtechniques.
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INDICATIONS
Large amounts of tooth structure are missing One or more cusps need capping Increased resistance and retention forms are needed
Pins, slots, grooves and boxlike forms provideresistance form
Used as control restorations in teeth ith pulpal orperiodontal prognosis
Used as control restorations in teeth ith caries Used as definitive restorations Used as build up or foundation
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FACTORS
Resistance and retention forms
Status and prognosis of tooth
Role of the tooth in overalltreatment plan
Occlusion
Esthetics Economics
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Resistance and retention forms
Retention features depend on amount ofremaining tooth structure and the toothbeing restored
!ore tooth structure is lost " moreauxiliar# retention is needed
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Status and prognosis of tooth
Caries activit#, endodontic therap#
Control restoration$ %& Protects pulp from oral cavit# and insults
'& Provides anatomic contour
(& )acilitates control of caries and pla*ue
+& Provides resistance against fracture
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Role of the tooth in overalltreatment plan
x- Choice for tooth is influenced b# itsrole in overall tx- Plan
Remember$ in the clinic do not .ust look
at the tooth but consider its role andfunction
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Occlusion
Interim restorations for teeth thatre*uire occlusal alterations
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Esthetics
!etallic appearance
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Economics
Less expensive and less timeconsuming than cast restoration
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CONTRAINDICATIONS
Patient has significant occlusalproblems
ooth cannot be restored ith directrestoration because ofanatomic/functional considerations
0sthetics
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ADVANTAGES 1Conserves
tooth structure1Appointment time$
one appointment 1Resistance and
retention formsincreased
1Cost
DISADVANTAGES1Pinholes and pinplacement$ 2entinalmicrofractures
1!icroleakage 3fromcavit# varnish& 12ecreased strength 1Resistance form is
harder to achieve 1Penetration into pulp
and perforation intoexternal toothstructure
1Anatom#
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CLINICAL TECHNIQUES
Pin-retained amalgam restratins "any restoration requiring placement of one or more
pins in the dentin for resistance and retention forms Pins are used hen resistance and retention forms
cannot be achieved ith slots/locks/or undercuts Pins have greater retention
Pins for Class I4 restorations rare$ small si5e ofanterior teeth 6oever, can be considered for Class I4 on the distal
surface 3distoincisal corner& of canine hen restoredith amalgam
Alternative to pin$ Lingual dovetail
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Slt-retained amalgam restratins
" retention groove in dentin whose
length is in horizontal plane Prepared ith (( 7 or 8 round bur
!a# be used as an alternative to pin1retained or in con.unction ith pin1retained
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Retention differences beteen pins and slots are not significant
Pin 1Pin is usuall# used in
preparations ith feor no vertical alls
Slt 19lots are usuall#
indicated in shortclinical crons and
cusps that have beenreduced '1( mm foramalgam
1!ore tooth structureis removed
1Less likel# to create
microfractures indentin
1Less likel# toperforate/penetrate
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Amaglam !"ndatins
"an initial restoration of severely
involved tooth; tooth is restored sorestorative material serves in lieu oftooth structure to provide retentionand resistance during final cast
restoration
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TOOTH PREPARATION
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Pin-retained amalgamrestratins
2evelopment of resistance form depth cuts Cusp reduction )inal restoration
If the cusp to be capped is located at correct occlusal heightbefore preparation, depth cuts should be made on existingocclusal surface of cusp to be capped Carbide fissure bur 2epth of cuts should be a minimum of ' mm deep for functional cusps
and %-: mm deep for nonfunctional cusps 3p ;%+& If unreduced cusp is at less than correct height, then cuts ill be less- he goal is to have at least ' mm of amalgam thickness for functional
cusps and %-: mm of amalgam for nonfunctional cusps during finalrestoration-
Rounded internal angles
Opposing vertical alls should converge occlusall# to enhance retentionform
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Remove infected carious dentin CaO6 liner and resin1modified glass ionomer base can
be applied It should not extend closer than % mm to slot or pin
Pin t#pes 9elf threading pin is most commonl# used pin and most
retentive of the three t#pes of pins 3self1threadings,cemented pins, friction locked pins& Cemented pin is the least retentive
Pin hole$ =-==%: to =-==+ in- smaller than diameter of
pin Pin drilled into dentin> ma# generate stress heninserted
See powerpoint for factors affecting retention of pin indentin and amalgam
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Pr#lems and !ail"res ! $in-retained restratins
)ailure can occur ithin the restoration At the interface beteen pin and restorative material ?ithin the pin At the interface beteen pin and dentin
?ithin the dentin Pin ma# break during bending if not careful
Choose an alternate location at least %-: mm remotefrom broken pin to prepare another hole
Removal is difficult Loose pin 3example$ as in self1threading pins
sometimes do not engage in dentin> duringpreparation&
Penetration into pulp and perforation of externaltooth surface
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Slt-retained amalgamrestratins
9lots are usuall# placed on facial/lingual/mesial/distalaspects of preparation
he# ma# be continuous or segmented It depends on amount of missing tooth structure and
here pins are used 9horter slots " more resistance to hori5ontal forces @o- (( 7 bur used to place slot in gingival floor and
@o- %BL bur =-: mm axial of 20 2epth is at least =-: mm Length is at least % mm or more
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Amalgam !"ndatins
ooth preparation depends on t#pe ofretention selectedDpin retention> slotretention or chamber retention3endodontic therap#&
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Pin retentin )or broken don teeth ith fe or no
vertical alls
)or foundations, pinholes are furtherdistancefrom external surface of tooth>this is the main difference beteen useof pins for foundation and use of pins fordefinitive restorations
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Slt retentin Placed in gingival floor of preparation
ith @o- (( 7 bur
Placed farther inside 20 than forconventional amalgam preparations
2epth is usuall# =-:1%-= mm and '-= E
+-= mm long
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C%am#er retentin his is recommended hen$
2imension to pulp chamber is sufficient to
give retention and bulk amalgam 2entin thickness in region of pulp chamber
is enough to provide rigidit# and strength
here is an extension into root canal
space '1+ mm 3hen pulp chamberheight is ' mm or less> an#thing greatergives no advantage&
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he end