hesham porcelain laminate veneers

8/4/2019 Hesham Porcelain Laminate Veneers

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They are thin plates of ceramicmaterial retained by adhesivecement through etching andbonding mechanisms

Their use is Considered

conservative and aesthetictechnique that can be appliedwhen restoring the mouth for improved aesthetics.

The longevity of the veneers isgood and they aredurable,especially if the rightindications are in place and thecorrect techniques are applied.



1. Stained / defective restoration.2. Diastema Closure.

3. Fractures.

4. Young aged patients where fullcoverage is contraindicated.

5. Slight malposition.

6. Craze lines within enamel.7. Mild Attrition /erosion / abrasion.

8. Root Exposure.



Excellent esthetics.

Long term durability due to high abrasionresistance, color stability and bio compatibility ofporcelain.

Inherent porcelain strength.

Good marginal integrity.

Minimal tissue reduction (only 0.5 mm withinenamel).

Excellent bio compatibility of the highly glazedceramics.

No need for anaesthesia.

Usually do not require temporization.



Multiple visits are required.

High cost.

Fragility during try-in and cementation.

Lack of repairability. Difficult color matching.

Shade alteration is impossible after cementation.

Irreversibility although tooth reduction isminimal.

Can’t be temporarily cemented for evaluation.



Bruxism with tooth wear.

Very Short tooth.

Tooth with inadequate enamel for retention (severe abrasion).

Endodontically treated tooth with little

remaining tooth structure. Patient with parafunctional activity e.g.

nail biting bruxism, clenching.



The facial view : When the smile is analysed from a full-face

perspective, only mesio-distal or verticalproblems can be dealt with.

In the illustrated case it is evident that thecentralsoverlap, causing a vertical cantingof the mid-line that is visible

even to people with no dental knowledge.

Proportionally speaking, the existing teethare short for the face.

The golden proportion is evident from thisaspect. (1:1.618)



45º angle view (checking buccal-lingualdimension):

This angle allows the dentist to check thecrowding in a more reliable manner.

In this case it is evident that themesialincisal tip of upper right 1 is morebuccally placed relative to the upper left 1.



Aesthetic occlusal plane (AOP):

The third dimension to be checked in theaesthetic evaluation is the AOP, whichcan simply be done from a saggital

view. In this case, a deciduous canine exists

(tooth c ), which creates a problem

related to the AOP since it is too short. Also the upper centrals appear from this

aspect to be tilted a bit palatally whichwanst evident from other views.



When Seeking the best results and in order to make sure that going for tooth

preparation to receive a laminateveneer is the treatment of choice , andthat it would satisfy the patient’s needsyou would better follow the following

steps :



1. Take a primary impression and construct

study casts .

2. Prepare the teeth on the model if needed.

3. Wax the teeth on the model up so that you

can reach a close form of the restoration

you are intending to construct.4. Evaluate the results and discuss with the

patient in order to put the final treatmentplan.

5. Take an impression of the waxed up model

and get the second cast poured.



The next step would be the constructionof a vaccuum transparent sheet on the

poured model and loading it withflowable composite or temporary crownmaterial and placing it into the patient’smouth and curing .

Also the direct method can be usedwhich is building freehand light curedcomposite on the teeth to be veneered.



Tooth preparation:

1. Facial and interproximal Reduction :

The procedure should begin with the use of adepth cutter which indicates the exact depth thatis to be prepared which should be minimal, limitedto enamel if possible but sufficient to providecorrect contour of restoration (approx. 0.5 mm

while 0.3 mm cervically). Followed by the use of a round end fissure or

tapered stone to finalize the facial reductionpreferably having an end with a finer grid.

Once this reduction has been performed, thepreparation is finished at the gingival margin andthen extended towards the papilla to finish theinterproximal elbow preparation.



Although the previous procedure in preparation ofthe laminate veneer is the most widely used

method, it did not promote optimal preservation ofenamel.



The simplest and most important tool for enamelreduction is a well-adapted, horizontally sectioned

silicon index from the wax-up.



Recommended preparation procedure:

Initial control with silicon index.

Axial reduction I: interdental preparation using

ultrasonic osscilllating instrument



The amount of interdental preparation depends onthe type of interdental contact.



In cases of multiple neighboring teeth , wrappingof old class III restorations and reduction of

diastema, extensive interdental preparation will berequired.



2. incisal preparation and palatal wrap around:

The incisal edge might not be included as in Window andfeather preparations however each has its disadvantages .

Minimal incisal beveling can be done in Beveled type ofpreparation.

The incisal preparation ideally must not be less than 0.5 to0.75 mm for strength.

The extent of wrapping is dependant on the initial situation

and the prosthetic objective. Establishment of interproximal and incisal wrap around offers

many advantages:i. it facilitates the esthetic definition of the laminate veneer inthe incisal zone.ii. It enhances form and emergence profileof the restoration.

iii. It facilitates the placement and stabilization of the finalrestoration. Moreover it facilitates easy access to all marginsduring bonding.iv. Better stress distribution and superior intrinsic resistance inthe restoration itself.



For moderate crown fractures (incisal one third) or moderate wear, the palatal finish line is localised in

the zone of maximum tensile stresses. A butt margin is indicated.



Ideal levels of palatal margins:



I. thin versus thick teeth.



II.Existing class III restorations:

Veneering teeth with pre-existing class III compositerestorations arises the problem of interdental

penetration and positioning of the margin.Moreover additional factor that must beconsidered in this situation is the curing contractionof the luting composite and the extremes of

thermal changes.



Any Suitable impression material for fixedprosthodontics can be used .

Example : polyvinyl siloxane or polyether

can be used.

Gingival retraction is necessary in manycases specially if slightly subgingival

finishline is prepared. Casts should be full arch and articulated

to preserve the anterior occlusalguidances.



Choice of fabrication technique:

I. Refractory die technique:

ceramic fired over refractory die is the oldest

and most widespread method for fabricating aporcelain piece.



II. Platinum foil technique:

superior marginal fidelity of platinum foil veneers has beenrecorded .

III. Cast glass-ceramic restorations (Dicor):

IV. Pressed ceramic (Empress):

this offers two modalities: the reinforced pressed porcelain isused to fabricate either an entire restoration or only a core.

V. Slip casting (Inceram ):

It can generate restorations with higher intrinsic strengthcompared to other systems.

VI. Machined ceramics (Cerec, Celay):



Try in of the laminate veneers is a critical

step and influences the success of thefinal restoration.

Try in shade kits are available that mimic

the colour and appearance of differentshades of luting resin cement.



Etching of the enamel surface using 37%orthophosphoric acid or laser etching.

Etching of the laminate surface byhydrofluoric acid.

Silanization of the laminate fitting surface. Placing the preselected cement shade

on the laminate’s fitting surface.

Removal of excess using a brushmoistened with bonding agent.

Curing.



Finishing is performed using finishingstones with fine grit .

Followed by polishing paste with 2-5micron particle size

Interproximal abrasive strips.

Evaluate the contact with unwaxeddental floss.

Check occlusion by articulating paper.



Special effects:

I. Shape effects:



II. Masking effects:

Superficial and localized defects can be removedmechanically during tooth preparation.

The discolored substrate is maintained, andmasking is obtained by integrating a certaindegree of opacity into the ceramic work piece.



Glassceramics

Oxideceramics



Feldspathic porcelain Leucite re-inforced (Empress)

Lithium disilicate (emax)



Aluminium oxide ceramics1. Inceram alumina

2. Inceram spinelle

3. Inceram zirconia (67%)4. Procera all ceram

Zirconium oxide ceramics



This requires that we havesimple classification of the

cases first :

Type 1 patients : in thesecases the veneers are not

exposed to functionalloading, and are referred to

as simple esthetic facets.

Type 2 patients : in thesecases the veneers areexposed to functional

loading, and are referred toas functional esthetic

facets.



Type 1: is further subdivided accordingto optical characteristics to:

•Type 1-A : these are subjects

programmed to receive simple estheticfacets where the substrate teethpresent no color alterations.

•Type 1-B : these patients are likewise

programmed to receive simple estheticfacets, though in this case the substrateteeth present color alterations.



Since these are patients with facets that will not be

subjected to functional loading and present a clear substrate, the material used only aims to solveproblems relating to tooth shape. These areconsequently favorable cases, since moreover only a

small ceramic material thickness is required. In these situations we therefore recommend the use

of conventional feldspathic ceramics, in view of their excellent optic characteristics that afford optimumesthetic results. The absence of occlusal stress in thesecases, and the use of the currently availableadhesion techniques (which improve resistance tofracture of these ceramics) contribute to ensureprolonged restoration survival.



These patients present facets that will not

bear functional loading but which showmoderate to severe alterations in dental

color that must be effectively masked bythe restoration. In these situations boththe porcelain and cement must present

various degrees of opacity in order tohide the color alterations .



Restored with empress (leucite reinforced)opacity grade II



They are contact lens thin kind of laminate

veneers around 0.3 mm thick. They require no preparation.

They are helpful for phobic patients.

They are reversible as there is no tooth

destruction. It is alledged that they do not pose a

problem for the emergence profile thoughstill questionable.

They r not tolerated by some patients.

They might cause discomfort and gingivalinflammations.



Fracture / chipping. Impaired esthetics.

Gingival inflammation. Mrginal discoloration and decreased marginal

integrity. Incomplete fit of laminate. Debonding. Patient discomfort. Hypersensitivity. Caries.

hesham porcelain laminate veneers

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