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PORCELAIN LAMINATES
INDIAN DENTAL ACADEMY
Leader in continuing dental education www.indiandentalacademy.com
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Contents
Introduction Tooth preparation Laboratory procedures Placement of veenersConclusion References
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INTRODUCTION
A captivating smile showing an even row of natural gleaming white teeth is a major factor in achieving that elusive dominant characteristic known as personality. Dr.charles pincus in the early 1930 developed thin facing made of air fired porcelain which were temporally held in place with adhesive denture powder and created the Hollywood smile for actors,which was an integral part of image personality and opinion
Since then the art of veneering teeth has progressed over 30 yrs to current generation of concepts and materials www.indiandentalacademy.com
Types of Veneers
Directly fabricated veneers
Indirectly fabricated veneers
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Porcelain Laminates
They can be considered to be very much the state of art in cosmetic dentistry. They are wafer thin shells of porcelain like custom made artificial fingernails
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Advantages
Color Bond strengthResistance to abrasion Periodontal health Inherent porcelain strengthResistance to fluid absorptionEsthetics
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Indications
DiscolorationEnamel defectsDiastema Malpositioned teethMalocclusionPoor restorationsAgeingWear patternsAgenesis of lateral incisor
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Contraindications
Available enamel Ability to etch enamel Oral habitsPeriodontally compromised
teeth
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Tooth Preparation
There are different schools of thought for tooth preparation for porcelain laminates some clinicians are of the school of thought that little or no tooth reduction is required while the opposite end of spectrum advocate a full deep chamfer preparation
If it is possible to place veneers without tooth preparation and still develop a good esthetic form, no subsequent periodontal changes then it is obviously the ideal if not some form of enamel reduction becomes essential
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Biological and technical factors for tooth preparation
EstheticsRelative tooth positionMasking of tetracycline stainsMarginal placement Age Potential for periodontal changes
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Rationale for Enamel Preparation
To provide for an adequate dimension of available space for porcelain material
To remove convexities and provide for a path of insertion in those situations where either the incisal or interproximal areas are to be included in the veneers
To provide space for adequate opaquing where necessary and for composite resin luting agent www.indiandentalacademy.com
To provide definite seal to help position the laminate during placement
To prepare receptive enamel for etching and bonding the laminate
To facilitate sulcular margin placement in severally discolored teeth
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Enamel Reduction
Labial reduction Inter proximal extensionSulcular extensionIncisal or occlusal modificationLingual reduction
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Labial Reduction
The preparation should remain within the enamel wherever possible and most certainly at all the peripheral marginal areas to ensure an adequate seal to enamel
A general rule may well be to ensure that over 50 % of preparation is on enamel
In general 0.3 to 0.6 mm or about half thickness of available enamel
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Depth Guide
Is one of the method to gauge the amount of enamel removed
The LVS depth cutter diamond will create horizontal striations or depth cut grooves on the labial aspect of tooth
An alternative method for gauging the amount of enamel reduction is use of a no 1 round bur
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The problem with this approach is that these depth cuts can vary depending on the angle the bur is held at and the amount of time is considerably greater
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Reduction of remaining enamel
Following the creation of depth cut or striations the remaining enamel must be reduced to the depth of these initial cuts
Labial reduction should encompass 2 aspects
1) The bulk of reduction should be done with a coarse diamond to get added retention and better refraction of light
2) The marginal area it is desirable to use a fine grid diamond that will create a definitive, smooth finish line to enhance the peripheral seal
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Interproximal Extension
The margin should be generally hidden within embrasure area, extension of the laminate beyond the mesiobuccal and distobuccal line angle of the tooth gives a wraparound effect with etched resin bonds at right angles to the labial surface for increased bond strength
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Contact Areas
The contact points are modified by very fine one sided diamond abrasive strip through the adjacent teeth . the abrasive strip is used in an S configuration so that the abrasive side will reshape the contact areas rather than separate them
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Sulcular Extension
Preparation ends right at the gingival margin. Extension is carried out with a LVS diamond. A narrow gingival chord is placed to slightly displace the tissues for about 8 to10 minutes. This system of first developing the preparation confluent with the gingival and then placing the retraction chord prior to refining and extending into the sulcus ensures a) access for diamond b) less gingival trauma c) direct vision of margins during all procedures
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Sulcular Extension
Preparation ends right at the gingival margin. Extension is carried out with a LVS diamond. A narrow gingival chord is placed to slightly displace the tissues for about 8 to10 minutes. This system of first developing the preparation confluent with the gingival and then placing the retraction chord prior to refining and extending into the sulcus ensures a) access for diamond b) less gingival trauma c) direct vision of margins during all procedures www.indiandentalacademy.com
Finish Line Configurations
Feather or knife edge is most conservative form of preparation
There is difficulty in fabricating thin porcelain margins so invariably a poor marginal fit occurs
Inevitable increased thickness subgingivaly and resultant gingival problems
Laboratory problems in delineating the exact end of the preparation line
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Modified Chamfer Finish
This provides increased bulk of porcelain at margins so increased strength
Correct enamel preparation is achieved for increased bond strength
Laboratory procedures are easy with better fit of porcelain
Greater ease for dentist to obtain correct gingival finish line
A definitive stop to aid in seating the laminate to correct position
A sound marginal seal www.indiandentalacademy.com
Incisal Reduction
Fabrication of porcelain lapping the incisal edge makes the placement of restoration much easier by virtue of having a definitive stop
However when added length is needed it is necessary to actually prepare the incisal aspect
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Lingual Reduction
Reduction of the incisal edge may require reduction of lingual surface so that there is no butt joint at this incisal/lingual junction but rather a rounded chamfer
This ensures increased thickness of porcelain, enamel bonds at right angles to those at incisal edge, and increased strength
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Impression Technique
Tissue management tissue displacement is achieved by retraction cord
Impression
Elastomers –light material and tray material
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Temporization
Direct composite veneer Direct composite resin veneer utilizing
vacuum formed matrix Indirect composite resin/acrylic resin
veneer
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Laboratory Procedures
The refractory investment technique
The platinum foil technique
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The refractory investment technique
Fabrication of master cast Application of die spacer Fabrication of refractory model Preparation of refractory model Degassing the refractory investment Sealant application Removal of veneers from refractory material
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Platinum Foil Technique
Choosing the foilModel and die preparationPlatinum matrix placementRemoval of foil
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Porcelain application First application of 0.3 to 0.4 thick is made.
Esthetic results of finished veneers are enhanced if the porcelain mix is applied in four stages-gingival third, body, incisal third, enamel shading
Finishing and contouring-microfine diamonds & sandpaper discs are used
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Glazing – seals any microporosities & gives more natural luster. Stains can be applied to add chroma
Adjustment and placement on the master modelEtching – 7.5% hydrofluoric acid is etchant,10%
of baking soda is neutralizer, surface is air abraded and washed in detergent in ultra sonic bath
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Placement of Veneers
Three stage porcelain veneer try inStage 1: check for individual fitStage 2: collective fit try inStage 3: color check
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Procedure of Placement
Tissue management Retraction cords Local anesthesia
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It is important to realize that no modification for shape is done until the final seating and curing are completed
The bonding of porcelain laminate is in fact a series of links : etched enamel- to enamel/dentin bonding agent- to luting composite resin- to unfilled resin- to hydrolyzed saline – to etched porcelain
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Silanation
The etched surface is treated with silane coupling agent to enhance adhesive properties
Pre activated silane or hydrolyzed form Non hydrolyzed form
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Enamel Activation
To remove all surface coatings
Slurry of fine pumice and water with a non webbed rubber cup or brush
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Enamel Etching
30 to 37 % of phosphoric acid solution 15 to 20 seconds
30 seconds Wash with water
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Application of dental bonding agent
Apply evenly on the etched enamel and on the internal aspect of the veneer
All excess bonding agent has to be removed
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Seating Sequence
It is best to seat one laminate at a timeIn multi unit cases start with the distal
most toothCentrals should always be seated together
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Placement
Pulsing or gentle rocking motionPrevent suck backThe matrix strip must be reinserted
between the teeth to prevent them from bonding to one another
Curing should be complete for at least 2 minutes each for various areas
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Finishing
Magnification and LVS kit finishing instrument
Load should be distributed over as many teeth as possible so that any one veneer extension is not responsible for withstanding the entire load
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Cosmetic Contouring
Is done after several days for esthetic harmony
Fine diamonds, micro fine LVS no. 6 or 7 are used
Finishing is done with porcelain polishing wheels and/or diamond polishing paste
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Cast Ceramic Laminates
2 distinct systems are present
Castable ceramic(dicor)
Castable apatite (cerapearl)
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Conclusion
Dentistry has long sought for the ideal restorative material to esthetically alter unattractive smile
A major breakthrough that facilitated predictable retention of porcelain to tooth structure has added a new dimension to esthetic dentistry.The strength of porcelain laminates will continue to be assessed although relatively technique sensitive the surface texture ,color, fluorescence & overall esthetics have been regarded as exceptional.
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REFERENCES
David A garber-porcelain laminate veenersKenneth J Anusavice-phillips science of
dental materialsWunder R et al in vitro effect of fluroide
on porcelain J.Prosthe.Dent 55.[385] 1986
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