Porcelain Laminate Veneers: Handling and Definition

Laminate Veneer Definition

• It is a thin labial plate made of cosmetic material, either ceramic or composite.
• It affixes directly to the teeth using composite resin as a bonding cement to mask tooth structure.
• They are 0.3-0.8 mm thick, but may reach 1.5 mm at the incisal edge.
• They bond to the labial surface and are mainly used for esthetics.

Handling Porcelain Laminate Veneers

• Porcelain is brittle at thinness of 0.3-0.5 mm and needs careful handling during laminate veneer fabrication.
• Laminate veneer strength depends on bonding with the tooth structure, specifically enamel, using adhesive resin cement.
• This makes the veneer stronger because the veneer, cement, and tooth structure act as one.

Enamel

• The superficial layer exhibits acid resistance due to continuous deposition of calcium and fluoride.
• Topical fluoride must be applied during enameloplasty (enamel re-shaping) because abrasion of the superficial layer exposes enamel prisms and inter-prismatic substances, increasing caries.

Materials

• "Laminate" originally referred to thin ceramic labial plates, but now includes processed composites.
• Processed composite for laminate veneers is not cured with a standard light curing unit, but built up in layers like porcelain.
• It is heat-cured in a special oven under heat, pressure, and light.

Processed Composite Advantages

• Increases material strength.
• Minimizes irritation caused by free radicals of composite.

Laminate Veneer Advantages

• Minimal tooth preparation (conservative to tooth structure).
• High esthetics.
• High strength that depends on bonding with tooth structure.
• Long-lasting restoration with no color change.
• Soft tissue biocompatibility.
• Marginal integrity relies on bonding with tooth structure.
• No need for local anesthesia since all preparation is confined to enamel.
• Temporization is unnecessary if the patient is satisfied with the preparation's shape.
• No sensitivity because all preparation is confined to enamel.

Laminate Veneer Disadvantages

• High cost.
• Technique-sensitive procedure.
• Fragile material during handling.
• Multiple visits, needing a minimum of two.
• Cannot be repaired.
• Difficult to achieve restorations that are not over-contoured.
• Minimum thickness needed.
• Cannot be temporarily retained with provisional cement.

Cementation

• Cement the final restoration with temporary cement for 7-10 days. This allows patient to adjust to the restoration and orient well about discrepancies.
• Cement the final restoration with temporary cement for 7-10 days because patients become fatigued at a certain point of the occlusal adjustment and cannot distinguish between discrepancy and normal status.
• Glaze or polishing is needed after occlusal adjustment.
• Replace temporary cement with new temporary cement where intra-oral polishing needs to be done. The vibration of the handpiece causes cement to break down when using conventional temporary cement.
• Use permanent cement once the patient adapts to the restoration.

Laminate Veneer Indications

• Unsightly, stained, or defective restorations.
• At least 50% of prepared tooth must have sound, high-quality enamel because enamel bonding is relied on.
• Permanently stained or discolored teeth (heavy tetracycline stain).
• Short teeth from attrition, length can be added with laminates in anterior teeth.
• Minor mal-posed teeth.
• Peg-shaped laterals.
• Spaces between teeth (diastemas).
• Small fracture in the incisal third (small class IV).
• Cases of root exposure that need good analysis.
• Adolescent teeth with large pulp.
• Teeth suffering from erosion or abrasion.

Laminate Veneer Contraindications

• Para-functional habits like bruxism, as lateral forces may fracture the laminate.
• Edge-to-edge and crossbite occlusion.
• Insufficient sound enamel.
• Extensive discolored restoration.
• Fractured tooth with more than one-third of incisal third involved.
• High caries index.
• Bad oral hygiene.
• Endodontically treated teeth because brittle teeth have low moisture content, resulting in low dentin resiliency.
• Moderate to severe mal-position.
• Poor plaque control.
• Very short teeth with low enamel.

Classifications

• Direct - light-cured composite restoration with window preparation involving composite or acrylic resin.
• Indirect - custom-made processed composite (feldspatic porcelain/normal porcelain or empress E-max)
• Window preparation means the cavity has walls, and the incisal edge is intact, and can be used with indirect restoration.

Direct No Preparation

• No preparation is necessary.
• Intra-enamel preparation
• Enamel etching.
• Window preparation.
• Composite application extended from gingival crest to facioincisal line angle.

Indirect

• Processed composite – etched composite veneer through window preparation.
• Porcelain veneer – etched porcelain veneer with or without incisal lapping preparation.
• Other ceramic veneer – same as porcelain veneer with or without incisal lapping preparation.

Porcelain Veneer shade selection

• Polish the tooth before selecting shade.
• Use neighboring, collateral, or opposing teeth when there is internal staining.
• Have the patient sign consent for approval of treatment.

Porcelain Veneer Tooth Preparation

• Preparation thickness of 0.3 mm obtained by first placing depth grooves of 0.3 mm using diamond depth cutter.
• A 1.6 diameter wheel: the shank has a diameter of 1 mm; the circle around the shank has a diameter of 1.6 mm (0.3 mm inside the tooth, 0.3 mm outside, on a shank of 1 mm = 1.6 mm).

Facial Reduction

• The facial surface is reduced in two planes.
• A 1.6 mm diameter wheel mounted on a 1 mm diameter noncutting shaft diamond depth cutter to achieve the desired reduction in the gingival half of the labial surface.
• The desired reduction made in the incisal half with 2 mm diameter depth cutter.
• Remove tooth structure islands to establish a chamfer finish line of 0.3 mm width using a rounded-end diamond.
• It is better to prepare half of the facial surface vertically during facial surface preparation.

Proximal Reduction

• Reduction extends proximally just short of the breaking line.
• Avoid breaking.
• Breaking the contact results in food impaction, and increases caries.
• Some cases may need the preparation to extend to include the full contact area.
• Example: Proximal restoration, proximal lesion, discoloration, adjacent ceramic crown, multiple veneers and black spaces, changing tooth form

Incisal Reduction

• Factors affecting design include facio-lingual thickness, need for esthetic lengthening, and occlusal considerations.
• .5 mm depth grooves with a 45° orientation.
• Remove the island of tooth structure in between grooves.
• Use rounded end diamond parallel to the incisal edge.

Centric And Eccentric Occlusion

• Perform a good evaluation of centric and eccentric occlusion where the patient is asked to bite edge-to-edge, to avoid subsequent fractures of the restoration.

When To Wrap

• In teeth which need esthetic lengthening or increase surface area for bonding.
• Fractured incisal edge (if the fracture is limited, 1-2 mm broken).
• Cases of increased functional stresses on incisal edge, such as in lower anteriors.
• Wrapping stops just away from the centric and eccentric contact.

Thickness Of Ceramics

• The thickness of ceramics at the incisal edge to not exceed 2 mm to avoid introducing porcelain to many firing processes to avoid devitrification.

Devitrification

• Devitrification occurs when there are numerous firing processes of ceramics.

When Not To Wrap

• If the path of insertion is prevented.
• If thinning the incisal edge requires excessive shortening of the tooth to reach proper incisal edge thickness.
• If patient centric contact has a bite more inside to avoid biting on joint between ceramic tooth and the palatal.

Lingual Reduction

• To increase surface area & enhance mechanical retention.
• Use 0.5 mm chamfer finish line paralleled to lingual surface.
• Finish line located down lingual surface by 1/4 and 1 mm from centric contact connecting proximal finish lines.

Laminate Veneer Preparation

• Do not stop the laminate preparation on the incisal edge, and extend to incisal fourth of palatal surface/according to the centric & eccentric occlusion to prevent fracture.
• Incisal wrapping is preferred where lower anterior teeth are stained. It occurs with lower anterior teeth under heavy occlusion to make it more esthetic, and increases the surface area for bonding, improving longevity.

Wrapping

• Do not wrap when that will prevent undercuts which will prevent proper seating of the laminate, but if any area of dentin is exposed, it is okay only if that area was in the center of the preparation, in other words; the periphery of the preparation must rely on ENAMEL.

Finishing the preparation

• Round all sharp line angles with round-ended tapered diamond.
• Smooth sharp corners with composite polishing disks (red/yellow color).

Veneer classifications

• Types based on incisal preparation: window, feather, bevel, incisal overlap.
• Window preparations are used with composite; the other three are for ceramic.

Incisal Overlap

• Incisal overlap is preferred esthetically to avoid lines forming between veneers and teeth.
• Type of ceramic used depends on the amount of discoloration.

Incisal Overlap Example

• Where there is severe discoloration, and an all-ceramic restoration is undesirable.

No Preparation

• For small teeth with multiple diastemas.
• 2 Choices: Etching with abrasion/direct etching based on enamel quality.
• Advantages: no preparation is necessary, so anesthesia is not needed.
• Disadvantages: no finish line means the restoration has slight over-contouring.

Minimal Preparation

• Involves minimal tooth preparation to allow for a thin layer of ceramic.
• Ceramic requires only 0.3-0.5 mm thickness, needing minimal tooth removal.
• Light chamfer margin will satisfy requirements and give labs greater control.

Moderate Preparation

• Pressed ceramics, use IPS Empress or Cerpress (ceramics with low strength).
• The recommended is 0.5-0.6 mm.
• If for dark/discolored natural dentition is preferred, 0.8-1.0 mm is preferred.
• Incisal thickness is recommended to be 1.5 mm for pressed ceramic with rounded shoulder/deep chamfer margin.
• Faulty teeth brushing of the patient can cause enamel wearing.

Laminate Veneer examples

Classifications: technique, material of fabrication, proximal extension, incisal preparation, preparation techniques

Impressions

• With silicon on a special silicon using CAD/CAM.
• Full arch with silicon (polyvinyl) for Incisal lapping or polyether.
• Subgingival or Equigingival finish lines use Gingival retraction with cord.
• Check and disinfect the impression and its removal.
• Laminate impression is double mix, one step; both bodies happen at one time.
• Scan with special powder inside the intra-oral camera.

More on Impressions

• In conventional porcelain fused metal bridge impression happens in 2 steps.
• The light and heavy body that means materials shouldn't be applied onto the area of interest due to the dis-balanced force.
• It done will lead to rocking issues during the try in with metal.

Provisional Restorations

• Are normally unnecessary, and if it is needed you can use plastic sheet and specialized vacuum machine. Then put cast target sheet for proper dimension and teeth saving.

Impression Finish Line

• The finish line mustn't touch the tissue, and is done with spot etch for a nice bonding.
• Avoid using acrylic resin, instead temporary cementing the process with a probe to secure the margin.
• Finally bond it with cement when they are ready.

Tooth Preparation

• When there are broken teeth/teeth needing temporization, create with wax, impress with rubber base cast with alginate and put on the cast. In case of rubber use temp directly, alg-cast then use the sheet, wax sheets melting in time, and distort the crown.
• Avoid etching everything at the whole surface, as it may cause deterioration.
• Prolonged etching affects the enamel quality, the quality of bonding.
• Handle that laminate with care for a nice try in, with stains and lutings that are correct can be used with cements in case of sub-structure discoloration.

Trial Pastes tips

• With the lute cements trials and the paste should be the same in terms of color but don't create the bond, they exist only for testing.
• Use ultrasonic cleaning/original lute color stains.
• Where composite/PFM exist bond with the PFM as it is harder to get the color/shade and use that for other.

Try In Checkpoints

• Check the restoration borders, contour, shade and discrepancies (occlusal if found).

Cementation Of Laminate Veneer

• Where there are 2 things (laminate and tooth structure); cementation happens for those structures so clean laminate using ultrasonic cleanser or alcohol in an ultrasonic process.
• After cleaning etching where 10% hydrofluoric acid happened with Feldspatic Porcelain is 10$ ammonium bi fluoride with glass, acid-Etching results in irregularities.
• In etchable ceramics (Zirconium), they don't contain non-silica and the acid touching isn't that of concern in that type of case.

Cementation

• Air based is performed using sand, silica or alumina.
• Use alcohol to avoid oil and issues in production, be in order when applying, so that there are no misplaces because you can't remove those when already cemented. All veneers are applied separately.
• Followed by application surface use silane which results effective between resin adhesion and silica (drying is optional).

For structure of the tooth

• At 37% with phosphoric acid to apply and after this chalky appearance.
• Then add Bonding structure agent with chemicals/one layer and apply with vibration.

Tooth Laminate Placement Advice

• Add low based cement and place with pressure, start with the farthest to avoid facture/failure and be sure to remove all extra cement/finishing and clean the edges as normal.

Lumeeners

• Are extra ceramic made thin that are glued only to the front without touching the teeth or touching enamel 0.3mm
• Very effective with cosmetic users because not that difficult to place.

Lumeener Advantages

• Fast, easy impressions, and teeth are not needing grinding etc so it is not painful/less harmful. Finally gives enamel that is not staining.
• Patients are accepting and for cosmetic reasons great.

Lumeener Disadvantages

• Bulky at times, for periodontal reasons and the width/edges are difficult to alter. Also can't cover the stains to the extreme.