LABIAL VEEER LAM FREE

Dimples are depth pits prepared on the surface of the tooth using a 1 mm diameter round bur sunk to half its diameter to attain 0.5 mm depth. An alternative is to use depth grooves or dimples. Burs that are specially constructed to provide graded depth cuts are then reduced together with a chamfer bur ( Figures 7.2.2 and 7.2.3). The use of depth cutters or grooves and dimples has been recommended to control tooth preparation, as standardised objects allow accurate judgement of depth. In short, the thickness of porcelain veneers is determined by the amount of desired shade change and the final tooth position, which is dictated by functional and aesthetic parameters.A porcelain veneer needs a minimum thickness of 0.2–0.3 mm for each shade improvement if discoloured, or alternatively a more opaque porcelain can be chosen.

Veneers may be used to mask discoloration.

2 All efforts should be made to keep preparation within the enamel for long-term adhesion and also to avoid any unnecessary tooth structure removal. The enamel thickness at the gingival third is 0.3–0.5 mm, up to 0.6–1 mm at the middle third and 1.0–2.1 mm at the incisal third.

Careful depth reduction of tooth structures is carried out to provide a minimum of 0.3 mm (feldspathic porcelain) or 0.6 mm (Empress, e.max) preparation.

The preparation of the labial contour of anterior teeth needs to be addressed in three planes: incisal, middle third and cervical ( Figure 7.2.1).

Provide definite seating landmarks, allowing proper seating of the veneer.

LABIAL VEEER LAM FREE

Provide a finished preparation that is smooth and free of any sharp internal line angles.Maintain the preparation within enamel wherever possible.Provide a definite margin, so that the ceramist has a finishing line, allowing correct emergence of the veneer from the gingival margin.Provide sufficient thickness for the porcelain for adequate fracture resistance and not to over-contour the final restoration.Meticulous tooth preparation is required with porcelain laminate veneers. 1Those veneers bonded to dentin and teeth with preparation margins in dentin were approximately 10 times more likely to fail than those bonded to enamel. In a 12-year study by Gurel of 583 veneers, 7.2% or 42 veneers failed. This puts the porcelain at risk of fracture when placed under tensile loading. Preparation into dentine should be avoided because of the less reliable bond to dentine and the difference in elastic modulus and flexibility between dentine and porcelain. Failure to do this may result in excessive and unnecessary removal of tooth enamel.Īll efforts should be made to contain the preparation within enamel, as this provides opportunity for a reliable and durable bond between restoration and remaining tooth tissue. It is important that whatever tooth reduction is required, it is based on the definitive wax-up/planned outcome and not the original tooth. The preparation for PLVs should be based on the final smile design, with the shade and position of the margin of the restorations being taken into consideration. Relative to crowns, porcelain laminate veneers (PLVs) are a conservative treatment option to improve anterior aesthetics and have a long history of documented success.

Labial veeer lam