PORCELAIN LAMINATE VENEERS

Porcelain Laminate Veneers (PLV) or Bonded Artificial enamel. Laminate Veneers is 'a thin sheet of material usually used to finish'. It is conservative method to aesthetically restore appearance of discolored or deformed tooth. A thin ceramic laminate is bonded onto the facial surface of the affected tooth. PVL first used by Charles Pincus between 1930's and 1940's. Laminate veneers evolved with introduction of acide etch technique, BIS-GMA and bonding agents. Early composite resins were directly added to facial surface by process called Bonding. Later preformed veneers were bonded onto etched surface by process called Laminating. Preformed veneers were replaced by glazed ceramic as they improved color stability, abrasion resistance and was well tolerated by the gingiva.
Indications -
Discolored teeth, teeth with intrinsic staining eg. tetracycline stains, enamel hypoplasia, mild diastema closure, mild malformed teeth such as peg shaped lateral incisors.
Contraindications -
Poor oral hygiene, high caries index, parafunctional habits, extensive restored tooth, actively erupting tooth, mouth breather, insufficient tooth structure
Case selection -
evaluation of static and dynamic occlusal relationship, degree of discoloration, patient attitude and motivation
Types of preparation -
Type I - Contact lens preparation in which preparation do not cover incisal edges
Type II - Classic or conventional preparation - prep. covers incisal edges and terminates lingually
Type III - Wrap around prep. - almost similar to full coverage.
Steps in preparation -
1. Labial reduction - 0.3 - 0.5 mm enamel reduction using diamond depth cutter (1.6mm) and round end tapered diamond. Finish line - slight chamfer at level of gingiva
2. Proximal reduction - labial preparation extended proximally using thinner round end tapered diamond. Contact area should be left intact and it should just stop short of breaking contact.
3. Incisal reduction - depends on choice of type of preparation. Round end tapered diamond used to make cuts in enamel of depth 0.5mm. Reduction done using wheel shaped diamond palatally.
4. Lingual reduction - round end tapered diamond used to create lingual finish line. It should be at least 1 mm away from the centric contact.
Finishing - preparation is smoothened and all sharp line angles are rounded using fine and ultrafine abrasives.
Veneer Try in -
i). Dry try in - each veneer tried on dry tooth surface to check marginal accuracy
ii). Wet try in - water soluble glycerine or try in paste is used to minimize vertical dislodgement. used to check proximal fit.
iii). Resin cement - to check color matching
Cementation -
Hydrofluoric acid is applied on internal surface of veneer for 4 -  10 seconds. It increased bond strength at least 4 times.
Silane coupling agent is applied next which also improves shear bond strength.
Tooth surface is etched and bonded but not cured. Next light cured resin cement is mixed and applied on the internal surface of veneer. The loaded veneer is carefully picked and seated over prepared tooth. In  cases of incisally wrapped veneers require first gingival and then facial directed pressure for complete seating. Excess cement is removed and the veneer is cured for at least 45sec on all surfaces.
Maintenance -
- avoid ultasonic scaling on veneer margin
- avoid abrasives of highly fluoridated pastes
- avoid excess biting force
- soft acrylic mouth guards can be used during contact sports.
Video links to refer for -
1. Step by step veneer preparation - PORCELAIN LAMINATE VENEER IN FIXED PR...
2. Gingival retraction method - METHODS OF GINGIVAL RETRACTION IN FIX...