Ceramic veneers II Flashcards
What does veneer prep depend on?
Method of fabrication Occlusion Desired aesthetics Any parafunction Presence of enamel at all proposed margins
What can make up a veneer?
Resin composite
Porcelain (ceramic)
Indications for direct composite veneers?
Extensive damage to incisal or buccal surface
Defective restoration
Discolouration not amendable to bleaching
Malaligned teeth - pt does not want ortho
Congenitally deformed teeth
Pt not have time or finances for indirect porcelain veneer
Where indirect porcelain veneer would require excessive tooth structure removal
Contraindications of direct composite veneers?
Inability to obtain correct shades to blend with adjacent teeth
Inability to obtain correct contours or surface characteristics
No proper isolation
Multiple teeth - difficulty in achieving consistent shade, contours and surface characteristics
Advantages of direct composite veneers?
Very little/no tooth prep
Composite can wear similarly to natural tooth and do not cause iatrogenic wear of opposing dentition
Chairside repairs
Can be made chairside or in lab
Disadvantages of direct composite veneers?
Colour stability - composite takes stain from environment
Not as long lasting as porcelain alternative
Not as strong as ceramic
Wears more compared to ceramic
What is the direct technique? What is required?
Veneers are made by dentist chairside
One appointment only
Minimal/no prep
Colour modifiers and resin composite (microfilled, hybrid) required
Indirect composite technique features?
Minimal prep 0.25-0.5mm tooth reduction Resin cement for cementation Bonding procedure similar to porcelain veneers Variety of systems: - Artglass - Belleglass - Sculpture
Advantages of indirect over direct composite veneers?
Reduced polymerisation shrinkage = smaller marginal gap
Reduced marginal leakage, sensitivity, recurrent caries and staining
Physical properties of composite can improve with additional curing
Better control over interproximal contours and contacts
Less technique sensitive than direct one
Done in lab for you
Porcelain laminate veneer components?
Porcelain veneer
Acid etched enamel surface
Silane coupling agent
Resin cement
Advantages of porcelain laminate veneers?
Superior aesthetics Long term durability Strength Marginal integrity Soft tissue compatibility Minimal tooth reduction
Disadvantages of porcelain laminate veneers?
Time consuming - multiple appointments Fragility Repair difficult Colour matching challenging Irreversibility Inability to trial cement the restoration
What materials are used for porcelain technology?
Lithium disilicate
Feldspathic
Glass infused
Negatives of not prepping the veneer tooth?
pain, overcontoured margins, hygiene, gingival inflam, high failure rates
Positives and negatives of veneer prepping a tooth?
Stress conc is less on veneers fitted to prepared teeth
Prep removes aprismatic and hypermineralised enamel layers = more resistant to acid etching
Should aim for prep to be completely in enamel to maximise resin bond strength and reduce tensile stress in the porcelain
What does veneer tooth prep involve?
Minimal prep 0.5-0.5 mini chamfer 0.6 to 0.8 for incisal and buccal reduction Facial reduction in 2 planes Special bur kits Depth grooves/pits
Veneer prep types?
Window preparation
Long bevel - done in IRS
Complete veneer coverage
Why extend the preparation over the incisal edge?
To increase strength of veneer-tooth
When is intra-labial/window veneer prep useful?
Useful in canine guidance, class II div II and class III incisor relationships
- Contained within labial surfaces
- No temp restoration needed
- Minimal prep - does not involve the incisal edge so not involved in occlusion BUT join between veneer and tooth can be visible
Why do a temporary veneer?
Aesthetics
Reduce sensitivity
Diagnostic - contour, shape, length
Types of temporary veneers?
When are temps necessary?
Direct composite build up with spot etching of enamel (used for 1 or 2 preps)
Chairside - clear matrix made on diagnostic wax up, then spot etch and protemp/composite in matrix and placed over multiple preps
Indirectly made temps in labs
Not always necessary - needed when more aggressive and dentine exposed - sensitivity, aesthetics
Can serve as provisionals
Why cement the veneer in place?
Veneer becomes integral part of tooth structure
Share part of loading stresses during mastication
Light cured composite luting agent (for thin veneers)
What cement use for the try in stage of the veneer? Why do this?
Resin luting agent
Veneers tried before cementation to assess fit and aesthetics
Try in paste - water soluble, optical contact
Handle veneer with care
Use of veneer carrier
How to prepare the veneer for cementation?
Veneer surface treated with HF acid
Clean fitting surface of veneer with acetone (40ml) to remove try in paste
Treating the surface with phosphoric acid can improve bonding
Rinse and dry
Silane application and keep away from light
How does silane coupling agent work?
Apply to internal etched surface
Chemically bonds to ceramic
Makes ceramic surface hydrophobic
Features of cementation?
Variety of resin cements - Variolink II, nexus, calibra
Standard material - translucent
Can get more opaque ones for darker teeth
Etch tooth
Bonding agent
Resin cement
Veneer carrier avoids handling and too much pressure - can crack veneer
Veneer must be held in 2 planes during initial palatal polymerisation
If veneer not held firmly during initial polymerisation = suck back occurs = gaps in margins
Resin spaces can be caused by insufficient luting resin and incorrect sequence of seating multiple veneers
Remove excess cement with floss, finishing burs and check occlusion, finish with polishing points
What can cause resin spaces?
Insufficient luting resin
Incorrect sequence of seating multiple veneers
How can veneers fail?
Fracture - especially with unfavourable occlusion, parafunction, bonding to existing restorations Types of fracture - Static - Cohesive - Adhesive Microleakage/marginal staining Debonding
What is a static fracture?
When segment of veneer fractures but remains on tooth
Due to excess loading or polymerisation shrinkage
What is a cohesive fracture?
Within body of porcelain due to tensile load from excessive functional or parafunctional loading
Results in loss of fragment
What is an adhesive fracture?
Failure of bonding interface
Due to weak bond or severe occlusal loading
