Steps in bridge construction- power point

Steps
Stepsin
inbridge
bridgeconstruction
construction


abutment:thatpartofastructurethatdirectlyreceivesthrustorpressureandit saportionofatooth,orthatportionofadentalimplantthatsupportsand/orretainsaprosthesis.

Ante sLaw:[ByIrvinH.Ante,Toronto,OntarioCanada,dentist]aneponyminfixedpartialprosthodonticsfortheobservationthatthecombinedpericementalareaofallabutmentteethsupportingafixedpartialdentureshouldbeequaltoorgreaterinpericementalareathanthetoothorteethtobereplaced;asformulatedforremovablepartialprosthodontics,
thecombinedpericementalareaoftheabutmentteethplusthemucosaareaofthedenturebaseshouldbeequaltoorgreaterthanthepericementalareaofthemissingteeth.

artificialcrown:ametal,plastic,orceramicrestorationthatcoversthreeormoreaxialsurfacesandtheocclusalsurfaceorincisaledgeofatooth.


buccolingual relationship: any position of reference relative to the tongue and
cheeks.

cantilever: a projecting beam or member supported on one end.

cantilever fixed partial denture: a fixed partial denture in which the pontic is
cantilevered, (i.e., retained and supported only on one end by one or more abutments).

clinical crown: the portion of a tooth that extends from the occlusal table or incisal
edge to the free gingival margin.

complete crown: a restoration that covers all the coronal tooth surfaces (mesial,
distal, facial, lingual, and occlusal).


connector:ninfixedprosthodontics,theportionofafixedpartialdenturethatunitestheretainer(s)andpontics.

crown:thehighestpart,asthetopmostpartoftheskull,headortooth;thesummit;thatportionofatoothocclusaltothedentinoenameljunctionoranartificialreplacementthatrestoresmissingtoothstructurebysurroundingpartoralloftheremainingstructurewithamaterialsuchascastmetal,porcelain,oracombinationofmaterialssuchasmetalandporcelain.Toplaceonthehead,astoplaceacrownonatooth,dentalimplant,ortoothsubstitute-usage:impliesfabricationofarestorationforatoothonanaturaltoothordentalimplant.

crownfracture:micro-ormacroscopiccleavageinthecoronalportionofatooth.


crown-rootratio:thephysicalrelationshipbetweentheportionofthetoothwithinalveolarbonecomparedwiththeportionnotwithinthealveolarbone,asdeterminedbyradiograph.

extracoronalretainer:thatpartofafixedpartialdentureunitingtheabutmenttotheotherelementsofafixedpartialdenturethatsurroundsallorpartofthepreparedcrown.

fixedpartialdenture:apartialdenturethatislutedorotherwisesecurelyretainedtonaturalteeth,toothroots,and/ordentalimplantabutmentsthatfurnishtheprimarysupportfortheprosthesis-usage:withrespecttoafixedpartialdentureretainedondentalimplants,adjectivesmaybeusedtodescribethemeansofattachment,suchasscrewretained,cementretainedalsocalledfixedprosthesis.


fixedpartialdentureretainer:thepartofafixedpartialdenturethatunitestheabutment(s)totheremainderoftherestoration.

residualbone:thatcomponentofmaxillaryormandibularbone,onceusedtosupporttherootsoftheteeth,thatremainaftertheteetharelost.

residualridge:theportionoftheresidualboneanditssofttissuecoveringthatremainsaftertheremovalofteeth.

spanlength:thelengthofabeambetweentwosupports.


Stepsinbridgeconstruction:

1-Diagnosis:firststepmustbediagnosistheabutmentteethandsurroundingoraltissues.

a-periodontalexamination:properoralhygienemustbefoundtopreventplaqueaccumulationontoothandcrownmargins,whichleadtocaries.

b-Dentionexamination:

i-Visual:Theocclusion,toothcrowding,spacingandtoothrotationmustexaminedandfuturetreatmentwillanalyzed.

ii-Radiographic:Thiswillrevealtheshapeandconditionoftoothrootandsurroundingstructures.

3-Finalimpression.

4-Teamporaryrestoration(provitionalrestoration).

5-Constructionofworkingmodel.

6-Waxing.

7-Investing.

8-Waxelimination.

9-Casting.

10-Finshingandpolishing.

11-Tray-inandfinalcementationofbridge.


Ceramic:Ceramicsarecompoundsthatinvolveacombinationofmetallicandnonmetallicelements,creatingstrengthandaesthetics.

DentalCeramics:Becauseofthewidevarietyofporcelainproductsavailableinthemarket,itisvirtuallyimpossibletoprovideasinglecompositionforthemall.
Traditionally,porcelainsweremanufacturedfromamineralcalledfeldspar.Theseporcelainsarereferredtoasfeldspathicporcelains.Asporcelaintechnologyimprovedotherspecializedporcelainswereintroduced,likereinforcedcoreporcelains,opaquerporcelains,glassceramics,glazes,etc.Obviouslytheircompositionwouldcertainlydifferfromthetraditionalfeldspathicporcelains.


Basic Structure:Basically porcelain is a type of glass. Therefore its
basic structure is similar to that of glass. The basic structure therefore
consists:

A-dimensional network of silica (silica tetrahedra).

B-Pure glass melts at too high a temperature for dental use.

C-Adding certain chemicals lowers the melting temperature by disrupting
the silica network. The glass obtains porcelain like qualities when the silica
network is broken by alkalies like sodium and potassium. This also lowers the
fusion temperature. These chemicals are therefore known as glass modifiers
or fluxes. Other substances which act like glass modifiers are alumina (Al,03)
and boric oxide (B,03)·Boric oxide forms its own separate network in
between the silica network. Adding certain opacifiers reduces the
transparency and completes the transformation to dental porcelain.


Micro structural classification:At the micro structural level, we can
define ceramics by the nature of their composition of glass-to-crystalline
ratio. There can be infinite variability of the microstructures of materials, but
they can be broken down into four basic compositional categories, with a
few subgroups:composition category:

1 –glass-based systems (mainly silica),composition category.

2 –glass-based systems (mainly silica) with fillers, usually crystalline
(typically leucite or, more recently, lithium disilicate),composition category.

3 –crystalline-based systems with glass fillers (mainly alumina)
andcomposition category.

4 –polycrystalline solids (alumina and zirconia).

Dental porcelain is generally regarded as biologically inert. However,
other toxicities may exist fromsome of the accessory materials, and the
fillings may increase wear on opposing teeth.


Classification and description of ceramic systems:

The ceramic restorations available today may be metal bonded or
made completely of ceramic. Based on the substructure or core material
used we have two basic groups. They are further divided based on the
fabrication method:

A-Metal-ceramic (metal bonded or PFM) restorations:

1-Cast metal ceramic restorations:

-Cast noble metal alloys.

-Cast base metal alloys.

-Cast titanium (ultra low fusing porcelain).

2-Swaged metal ceramic restorations:

-Gold alloy foil coping (Renaissance, Captek).

-Bonded platinum foil coping.


Classification and description of ceramic systems:

B-All ceramic restorations:

1. Platinum foil matrix constructed porcelains

-Conventional porcelain jacket crown

-Porcelain jacket crown with aluminous core

-Ceramic jacket crown with leucite reinforced core (Optec HSP)

2-Castable glass ceramics (Dicor)

3-Injection moulded (leucite reinforced) glass ceramics (IPS Empress)

4-Glass infiltrated core porcelains

-Glass infiltrated aluminous core (Inceram)

Glass infiltrated spinell core (Inceram spinel\)

5-Ceramic restoration with CAD-CAM ceramic core

-Glass ceramic blocks

-Feldspathic porcelain blocks Ceramic

6-restoration with copy milled ceramic core. (Celay)

1-Alumina blocks (Celay inceram)

2-MgAI20, (Inceram spinell).


Surface Staining, Characterization and Effects:Natural teeth come
in variety of hues and colors. Some of them are present at the time of
eruption (intrinsic, e.g. white fluorosis stains), while others are acquired over
a period of time from the environment (extrinsic, e.g. cervical stains).
Staining and characterization helps make the restoration look natural and
helps it to blend in with the adjacent teeth . The stain powders are mixed
with a special liquid, applied and blended with a brush. With more and more
emphasis on recreating the natural look, effects are created using special
techniques. This includes defects, cracks or other anomalies within the
enamel.

Glazing:Before final glazing, the restoration is tried in the mouth by the
dentist. The occlusion is checked and adjusted by grinding. Final alterations
can be made to the shape of the restoration by the dentist. The restoration is
now ready for the final step which is the glazing. The restoration is smoothed
with a stone prior to glazing. Glazing is the process by which the restoration
is given a smooth glossy surface.


Objectives of glazing:

1-Glazing enhances esthetics

2-Enhances hygiene

3-Improves the strength. Glazed porcelain is much stronger that unglazed
ceramic. The glaze inhibits crack propagation.

4-Reduces the wear of opposing teeth. Unglazed porcelain can accelerate
wear of the opposing natural teeth.


Use and application:

1-Inlays and onlays

2-Esthetic laminates (veneers) over natural teeth

3-Single (all ceramic) crowns

4-Short span (all ceramic) bridges

5-As veneer fore cast metal crowns and bridges (metal ceramics)

6-Artificial denture teeth (for complete denture and partial denture
use)

7-Ceramic orthodontic brackets.

Classification according to fairing temperatures:

1-High fusing 1300°(for denture teeth)

2-Medium fusing 1101 to 1300°(for denture teeth)

3-Low fusing 850 to 1100°(for crown and bridge use)

4-Ultra low fusing less than 850 (used with titanium)


Classification according to Type:

1-Feldspathic or conventional porcelain

2-Aluminous porcelain

3-Leucite reinforced

4-porcelain Glass infiltrated alumina

5-Glass infiltrated spinell

6-Glass ceramic

Classification according to Use

1-Porcelain for artifical denture teeth

2-Jacket crown, veneer and inlay porcelain

3-Metal ceramics

4-Anterior bridge porcelain.

Classification according to Processing Method

1-Sintered porcelain

2-Cast porcelain

3-Machined porcelain.


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