Esthetic Principles PDF

Esthetic Principles  II-Esthetic Principles Metal - Partial Ceramic Coverage restorations restorations Metal- ceramic Restorations  Metal- Ceramic Restorations The poor appearance may be a result of: ▪ Insufficient tooth preparation that will lead to...

Esthetic Principles  II-Esthetic Principles Metal - Partial Ceramic Coverage restorations restorations Metal- ceramic Restorations  Metal- Ceramic Restorations The poor appearance may be a result of: ▪ Insufficient tooth preparation that will lead to insufficient room for porcelain thickness. ▪ Inaccurate placement of the labial margin of a metal-ceramic crown. Metal- Ceramic Restorations Tooth Reduction Margin Placement  1-Tooth Reduction (a) Facial tooth reduction : ▪ Amount of reduction: Adequate reduction of the facial surface(minimum reduction of 1.5mm) Alloy ------as substructure. Porcelain-----sense of color depth& translucency. ▪ Direction of preparation : two distinct planes Adequate porcelain thickness Metal substructure. Opaque Porcelain. Dentin Porcelain. Enamel Porcelain. Labial surface should be prepared in two distinct planes. A) Labial surface should be prepared in two distinct planes: One cervically // to path of insertion, other // to incisal 2/3 of labial surface  B) Labial surface prepared in one plane // to path of insertion, result in insufficient space for porcelain in incisal 1/3 of labial surface Under reduction facially leads to over-contoured restoration C) Labial surface prepared in one plane with more than sufficient space , will endanger the pulp & produced over tapered prepration (b) Incisal reduction: ▪Amount of reduction: 2 mm is recommended for good esthetics. ▪No metal backing at the incisal edge of a metal- ceramic restoration for translucency similar to that of natural tooth structure. ▪Avoid excessive incisal reduction ----- it reduce the resistance and retention form of the preparation.  2mm 2mm (c) Proximal Reduction : ▪ No metal backing , as the incisal edges for look most natural without metal backing. ▪ This will allow some light to pass through the restoration in a manner similar to what occurs on a natural both. ▪Amount of reduction in CMR ▪Amount of reduction in CMR  2-Margin Placement ▪ Subgingival margins may be indicated for aesthetic reasons. ▪ BUT ,,It depends on the lip line: The position of the inferior border of the upper lip during smile formation. (Amount of Gingival Display)  ▪Low lip line. ▪High lip line ▪ Patients with high lip line, subgingival porcelain- labial margin. ▪Patient with low lip line, a metal supragingival collar may be placed because the metal is not seen during normal function. Replace the metal margin labially with shoulder porcelain ▪ Margins should NOT be placed so far apically that they encroach on the attachment. ▪Margins should follow the contour of the free gingival. Veneered restoration : Facial F L: Shoulder with bevel Lingual F L : Chamfer WHY ????? Metal Collar.. WHY??  Metal margins generally have a more accurate fit than porcelain margins. Partial Coverage Restorations Partial Coverage Restorations Proximal Margin Facial Margin  1-Proximal Margin The proximal margin should be placed just lingual to the facio- proximal line angle, (Just buccal to the proximal contact) where metal will be hidden.  HOW?? ▪ Posterior teeth : ▪ Anterior teeth : proximal groove // to proximal groove // incisal long axes of teeth two thirds of the facial surface of anterior.  2-Facial Margin Maxillary partial-coverage restoration should be extended just before the occluso-facial line angle ▪Mandibular partial coverage crowns-----metal display. ▪Chamfer & bevel is recommended for the buccal margin to provide a greater bulk of metal around the centric cusp. ▪Anterior partial-coverage restorations ---no metal display. The facial margin is extended just beyond the highest contour of the incisal edge.