Aesthetic Veneers: What They Are and How to Handle Them PDF

667 17 Aesthetic Veneers: What Are They and How to Handle Them? Maria Filomena Rocha Lima Huhtala, Clovis Pagani, Carlos Rocha Gomes Torres, Pekka Kalevi Vallittu, and Jukka Pekka Matinlinna 17.1 In...

667 17 Aesthetic Veneers: What Are They and How to Handle Them? Maria Filomena Rocha Lima Huhtala, Clovis Pagani, Carlos Rocha Gomes Torres, Pekka Kalevi Vallittu, and Jukka Pekka Matinlinna 17.1 Introduction – 668 17.2 Basic Principles for Veneer Preparation – 669 17.3 Sequence of Tooth Preparation – 673 17.4 Direct Veneer Restoration – 678 17.5 Indirect Veneers – 681 17.5.1 Dental Ceramics – 681 17.5.2 Impression/Scanning of the Tooth Preparation – 682 17.5.3 Provisional Restoration – 682 17.5.4 Extraoral Phase for Indirect Restoration – 682 17.5.5 Try-in Procedure – 683 17.5.6 Pretreatment of Veneers – 683 17.5.7 Cementation of Indirect Veneers – 686 17.5.8 Finishing and Polishing – 686 17.6 Changes of the Apparent Tooth Dimension by Optical Illusions – 686 17.6.1 Flat Area – 686 17.6.2 Embrasures – 688 References – 689 © Springer Nature Switzerland AG 2020 C. R. G. Torres (ed.), Modern Operative Dentistry, Textbooks in Contemporary Dentistry, https://doi.org/10.1007/978-3-030-31772-0_17  668 M. F. R. L. Huhtala et al. Learning Objectives ative materials (of which the laminate is prepared). Adhesion The learning objectives of this chapter are related to the fol- can be of chemical or retentive nature (macromechanical or lowing topics: micromechanical retention). Chemical adhesion takes place 5 Indications and contraindications for veneers when the two dissimilar materials are close in a molecular 5 Clinical steps for tooth preparation level and contact to form chemical bonds [7, 8]. Dentin 5 Direct resin composite veneers bonding is understood to be based predominantly on micro- 5 Mock-ups and impressions for indirect veneers mechanical retention and is beyond the scope of this chapter 5 Ceramics used as an indirect veneering material [9, 10]. 5 Pretreatment, silanization of veneers, and luting At the chairside, the preparation for laminate veneers 5 Changes of the apparent tooth dimension by optical starts with structural reduction of facial surfaces and must illusions generally be made only on enamel, even though in several situations, they also involve the superficial layer of dentin. However, those preparations must avoid unnecessary 17.1 Introduction removal of dentin, not only due to pulpal damage but also because the bonding to etched enamel is always better than Facial aesthetics plays an important role on an individual’s to dentin. Aesthetic results with this technique are very good, well-being, self-esteem, emotional condition, social success, due to the reproduction of the original shade and translu- and even chances to get a job. The smile is primordial in the cency [11, 12]. search for an optimum dentofacial aesthetic standard. An The concept of coverage of the labial surface of anterior aesthetic smile depends on the harmony of shapes and shades teeth due to aesthetic reasons started back in the 1930s, of anterior teeth. In addition, the alignment of these teeth when Dr. Charles Pincus introduced the technique of and their harmonic positioning on the arch are the basics to ceramic veneers, to attend aesthetic demands of Hollywood obtain this aesthetic balance [1–3]. However, teeth are not artists. It is well-known that the American cinema always distributed on a harmonic way on the dental arch. played an important role on culture and people behavior This lack of harmony may have different origins, such as worldwide, and this demand had the merit to call the atten- genetic or developmental tooth anomalies, structural changes tion of dentists, who until then had the aim to restore mainly caused by caries, and chromatic changes or injuries in the function and occlusion of teeth than to restore the aesthet- dental structure due to traumas. ics. However, those labial surface coverages with a very thin When these alterations take place on the labial surface of layer of ceramic bonded to teeth were very expensive, and anterior teeth, or even on the buccal surface of premolars, only a few people had access to it. On an attempt to reduce one treatment option can be the total covering of the surface cost, clinicians start to cover the labial surfaces of teeth with using a restoration called a laminate, veneer, or facet. This direct composite resin veneers. However, results were lim- restoration is used to cover an unsightly area by bonding to ited due to the aesthetic quality of restorative materials avail- the facial surface of the prepared tooth. able at that time and the little retention that adhesive systems By and large, veneers can be made either by a direct tech- provided. After the 1980s, the development led to new bond- nique, using resin composite, or by an indirect technique ing techniques, including the so-called adhesive resin com- using composite or dental ceramic. In dentistry, composites posite cements [14, 15]. The further development on the are indicated for direct and indirect restorations or as a luting composite sicience become possible to obtain direct restora- cement, due to its light-curing of self-curing mechanism, tions that are very similar to tooth structure with esthetic 17 while ceramics are used to prepare indirect restorations, results close to those obtained with the ceramics, leading to because require a laboratorial firing step for its manufactur- a even broader use of the technique of labial coverage of ing. Resin composite materials consist of five key compo- teeth [2, 16, 17]. nents: (a) organic monomer (resinous) matrix, (b) Si-based Direct aesthetic veneers can be a very practical interven- glass fillers (for strength and X-ray opacity), (c) a silane cou- tion and the tooth preparation is usually limited to the labial pling agent (for adhesion promotion), (d) pigments (for aes- surface of the teeth. However, for indirect veneers, the prepa- thetics), and (e) activators, inhibitors, and stabilizers (for ration generally goes further than this surface and additional setting reactions) [5, 6]. steps are necessary, such as impression of the prepared area, Veneering doesn’t aim only aesthetic recovery but also temporary restorations, and laboratorial procedures [1, 18]. preservation of tooth structure, limiting the periodontal and The tooth preparation for direct venners is generally more pulp involvement that may result from more invasive proce- conservative and, in some specific situations, the restorations dures, such as full crown preparations. However, the clinical can be done even without the need of any preparation, e.g., success of a dental restorations will depend on several clini- lingually positioned teeth in relation to the adjacent ones. cal steps, such as the tooth preparation, bonding procedures Direct veneer restoration is therefore a faster technique and and cementation (for the indirect ones). It is noteworthy that can be finished in a single appointment. adhesion takes places (at least) in two levels: on the one hand, Among the indications for veneers are the teeth with dis- between prepared tooth tissue and, on the other hand, coloration, such as those affected by amelogenesis imperfecta, between resin composite cement and dental indirect restor- physiological aging, trauma, fluorosis, or stains caused by Aesthetic Veneers: What Are They and How to Handle Them? 669 17 tetracycline intake. However, it is vital to note that dental size, position within the arch, and surface characteristics can bleaching should always be the first treatment choice in those be modified. Before that, a treatment simulation can be per- cases, because it is much more conservative and does not formed with a diagnostic wax-up in a plaster model, quickly require any cutting of tooth structure. Therefore, only teeth previewing the effects of the laminates, allowing the analysis that do not show a satisfactory response to bleaching should of the intended treatment by the patient. Another option is to receive veneers. Other indications include teeth with exten- perform a digital smile design, using a picture of the patient’s sive caries lesions or fractures, presence of multiple restora- teeth or a previous intraoral scanning. In the latter case, a 3D tions with unsatisfactory shade, rotated or inclined teeth, printing can be performed, obtaining a resin model which is necessity of reduction and closing of diastemas, short teeth shown to the patient. which require increasing of its length, misshapen peg-shaped Using the wax-up or 3D model of the proposed treat- maxillary lateral incisor, microdontia and Hutchinson’s inci- ment, an intraoral mock-up can be produced. For that a tray- sors, aesthetic transformation (canines into lateral incisors less impression of the wax-up or resin model is performed and lateral into central incisors), alignment of teeth on the using a putty silicone impression material. The labial side of dental arch, and, finally, anterior or premolar teeth with the matrix is trimmed in the interproximal regions to allow extensive non-carious lesions. The contraindications for the excess material overflow. A bis-acryl composite is applied veneers are patients with bruxism, parafunctional oral habit, inside the matrix and seated. After curing, an intraoral mock- edge-to-edge occlusion of the anterior teeth, anterior teeth up will allow the patient previewing of the final treatment with large destruction of the crown, when there is not enough outcome. That can also be used as a guide during the tooth remaining tooth structure to support the veneer, high car- preparation [21, 22]. ies disease activity associated with bad oral hygiene, peri- > It is necessary for the clinician to identify when direct odontal disease, and teeth with excessive labial inclination. In resin composite veneers are the option and when this last situation, a preparation would likely result in expo- indirect ceramic veneers are preferable. This should be sure of the pulp. based on a comprehensive evaluation of the patient, Veneers allow very good aesthetical results because the bearing in mind indications and contraindications and entire coverage of the tooth labial surface produces harmony the anticipated aesthetic outcome. of shade and shape of the teeth. Veneers also allow the adjust- ment of individual aesthetic parameters using characteriza- tion colored materials. The large variety of resin composites and resin cements, with different shades and 17.2 Basic Principles for Veneer Preparation translucency, allow to achieve adequate aesthetic standards in relation to the adjacent teeth [1, 11, 16, 19, 20]. The preparation for direct veneers is very conservative as Indirect ceramic veneers have greater durability and only a thin layer of the labial tooth surface is removed. The color stability and do not suffer abrasion or discoloration. depth of the preparation will depend on the area of the tooth, Conversely, for direct resin composite veneers, this color sta- intensity of chromatic alteration, shape, and position. In rela- bility depends on factors inherent not only to the composite tion to the area of the tooth, because the preparation should used but also to some patient’s habits. Frequent consump- be preferably performed only on enamel, it should be kept in tion of food and/or beverages with dyes, as well as smoking mind the enamel thickness on each part of the crown, thus habit diminishes the veneer durability. Another disadvan- avoiding reaching dentin. It is known that the thickness of tage of the direct veneers is the need of the clinician’s skills to the enamel in the cervical region on the upper central inci- create the aesthetic characteristics, such as shape, texture, sors ranges from 0.5 to 0.7 mm, on the medium third from contour, and shade. Thus, direct procedure takes more time 1.1 to 1.4 mm, and from 1.2 to 1.8 mm on the incisal third. and is less indicated when all anterior teeth need to be cov- The thickness of the enamel on upper and lower anterior ered by a veneer. There is also the possibility of incorpora- teeth can be observed in. Figs. 6.11a–i and 6.12a–i. tion of air bubbles during the composite layer application, Therefore, the rotary instrument used for the preparation therefore creating areas even more susceptible to staining should have a diameter compatible with the enamel thickness and degradation. of each area. In relation to the intensity of chromatic altera- In the case of highly discolored teeth, it is hard to obtain tions, for mild ones, a 0.4-mm-deep preparation on enamel is adequate color match and natural translucency with direct done on the cervical third and 0.5 mm on the medium and veneers, because the slight depth of tooth preparation does incisal thirds. For teeth with more severe discoloration, a not allow enough composite thickness to mask the dark 0.5-mm-deep preparation on enamel could be performed on background. Opaque masking agents can be used to hide the the cervical region and 0.7–1 mm on the medium and incisal dark background under the restoration. However, the thick- thirds. Concerning the tooth’s shape, small or peg-shaped ness of the composite layer applied over it will hardly be teeth will require less removal of tooth structure to cover the enough to allow recovering the natural translucence of the surface with restorative material, aiming to obtain the neces- tooth. sary material thickness and good aesthetic results. In the A complete cosmetic change of all anterior teeth can be same way, lingually inclined teeth may require minimum or accomplished using veneers. Not only the color but the shape, no preparation of the labial surface.  670 M. F. R. L. Huhtala et al. In order to control the preparation depth and guarantee faces of the tooth that will be prepared and neighbour ones the ideal amount of tooth structure removal, two prepara- (. Fig. 17.1b). After setting, the first impression is gently tion guides (or reduction guides) can be produced with a removed, and a new impression is taken. One of impres- putty viscosity silicone impression material. This technique sions will be cut perpendicularly to the long axis of the is shown in. Fig. 17.1a–l. For taking the trayless impres- tooth, at the center of the crown, and on the mesiodistal sion, a putty silicone base and catalyst are mixed uniformly direction (. Fig. 17.1c–i). The second one will be cut paral- before being placed by hand on the labial and lingual sur- lel to the long axis of the tooth, at the center of the crown on a b c d e f 17. Fig. 17.1 Preparation guides made with silicone impression tooth to be prepared; g, h testing of the preparation guide. i evaluating material. a Two portions of heavy putty silicone must be used; b after the tooth structure removal after preparation; j to evaluate the amount mixing with the catalyst, it is applied over the teeth before preparation; of tooth structure removal on the cervicoincisal direction, the second c–f to see the amount of tooth structure removal on the mesiodistal guide must be cut at the region corresponding to the center of labial direction, two parallel longitudinal cuts are performed on the first surface, parallel to the long axis of the prepared tooth; k testing of the guide, on the area that corresponds to half of the crown of the guide; l evaluation of the structure removal after the preparation adjacent teeth, followed by one perpendicular to the long axis of the Aesthetic Veneers: What Are They and How to Handle Them? 671 17 g h i j k l. Fig. 17.1 (continued) the cervicoincisal direction (. Fig. 17.1j–l). Those prepara- The outline form of the veneer tooth preparation is deter- tion guides are placed over the tooth during the preparation mined by the surrounding structures, i.e., gingiva and neigh- procedure, to analyze if an adequate removal of the tooth bor teeth. Regarding the cervical cavosurface margin of the structure is being performed. preparation, the height of the lip line during the maximum smile is important to determine its limit. In other words, it is Tip important to know if the cervical tooth region will be visible or not during the smile. To obtain a completely hidden tooth- In order to control the preparation depth and guarantee restoration interface, the margin of the preparation has to be the ideal amount of tooth structure removal, preparation placed inside the gingival crevice. However, any defect inter- guides can be produced with a putty viscosity silicone facial defect of the restoration may promote biofilm deposi- impression material. tion in this area, leading to gingival inflammation, even though it might be mild. Thus, if the tooth-restoration inter-  672 M. F. R. L. Huhtala et al. face is prepared close to or slightly before the gingival mar- from a perpendicular direction (sight’s angle of 90 degrees) gin, it may contribute to the health of the surrounding soft in relation to the labial surface – a position that dentists tissues. However, this position of the margin can only be pos- generally use to evaluate the final preparation – there is a sible on patients that do not show gingival margin during poor vision of the gingival embrasure between contiguous maximum smile and present little or no color alteration of teeth. This viewing perspective is called “static area of visi- the tooth, or on the patients that do not mind having a less bility” and does not represent the actual viewing perspec- favorable aesthetics at this area, aiming to protect the gingi- tive that the patient could be seen by other people in daily val health. However, most people simply do not accept a vis- life. This may lead to insufficient preparation of some areas ible margin, even if it cannot be noticed during conversation of the facial surface of the crown. On the other hand, when on the social life situations. On these cases and on the situa- the tooth is observed from a lateral perspective, in a sight’s tions where the lip line shows the marginal gingiva, the cervi- angle smaller than 90 degrees, the gingival embrasure areas cal cavosurface angle of the preparation should be placed become more noticeable. If this is not taken into consider- 0.1–0.3 mm inside the gingival sulcus. ation, the aesthetic outcome of the veneer restoration may In relation to the proximal margins of the preparation, not be pleasant, due to the remaining of the discolored on teeth with slight color alterations, they should be placed areas of the tooth uncovered by the veneer. The dentist before the proximal contacts. However, on teeth with viewing perspective during preparation needs to change intense discoloration, the preparation must go further as constantly, to evaluate if the dark areas are not remaining half the contact area, in such a way that the dark back- unprepared and exposed, when the patient is observed ground would not be visible after the restoration. When from different angles. This active viewing perspective is there are diastemas, the preparation should extend to the called “dynamic area of visibility” and is necessary during interproximal surfaces, allowing the correct restoration of the preparation (. Fig. 17.2a–d) [16, 23]. the proximal contour. Another aspect regarding proximal In relation to outline in the incisal edge, there are three limits of the preparation is the sight’s angle (or viewing per- possibilities. The type I (or window preparation) has a feath- spective), when preparing the gingival embrasure areas, ered edge, while the type II has an incisal reduction and a below the interproximal contact. When teeth are observed butt joint; and the type III (or wrap preparation) has an inci- a b 17 c d. Fig. 17.2 Lateral view perspective of the embrasure area changing the sight’s angle. a–c Preparation without considering the dynamic area of visibility. b, d preparation considering dynamic area of visibility Aesthetic Veneers: What Are They and How to Handle Them? 673 17 sal reduction associated with a palatal chamfer. For 17.3 Sequence of Tooth Preparation direct composite veneer restoration on teeth with thick inci- sal edges, the feathered-edge preparation should be chosen. When a homogeneous reduction of the labial surface is However, on cases of patients with very thin incisal edges desired, the first step for the veneer preparation is to deter- that are susceptible to fractures, or when teeth need to be mine the maximum preparation depth, by making facial elongated, as well for all indirect veneers, an overlapped inci- depth cuts with known dimensions (. Fig. 17.3a–o). The sal edge preparation with butt joint or a palatal chamfer preparation is started with the peripheral depth cut following should be performed. These preparations provide proper the gingival contour, in a U shape (. Fig. 17.3b–d), with a thickness of the ceramic at the margin to prevent restoration round diamond point, with a diameter compatible with the fracture, restrict the angle fractures, and enhance the aesthet- size of the tooth and depth of aimed preparation, following ics of the laminate (. Fig. 17.5). the contour of the gingival margin [11, 16]. By knowing the As in most clinical cases, the direct veneer preparation is diameter of the diamond point, it is possible to standardize restricted to enamel, and it usually does not lead to postop- the depth of the preparation, by penetrating half of its diam- erative complications, from the pulpal or functional point of eter into the tooth surface. For instance, the No. 1011 dia- view. From the periodontal point of view, a correct cervical mond point has a 0.8 mm of diameter, while the No. 1012 one anatomy and the perfect fitting of the veneer to the prepara- has a 1.0 mm of diameter, and the No. 1013 one has a 1.2 mm tion, at this region, avoid alterations of the periodontal tis- diameter. As mentioned above, for teeth with small color sues. In some cases, veneers have shown to be a better alteration, a 0.4 mm reduction should be planned on the cer- choice than full crowns, in particular for patients with deep vical region, while for the ones with severe discoloration, this overbite, where there is usually not enough space on the lin- reduction should be 0.5 mm. For that, half of the diameter of gual tooth surface; or for the mandibular anterior teeth, the No. 1011 and No. 1012 burs, respectively, can be used as where it is easier to preserve the pulp integrity than on the references. During the preparation of the peripheral full crown preparation. depth cut on the cervical area, it should be performed first a b c d. Fig. 17.3 Direct veneer tooth preparation. a Initial aspect; distal half and finishing of the preparation margin using a gingival b–e preparation of peripheral depth cut. f–i preparation of the protector instrument; m analysis of the preparation on the mesiodistal cervicoincisal depth cut; j reduction of the mesial half of the labial direction. n analysis of the preparation on the cervicoincisal direction; surface; k analysis of the tooth structure reduction; l reduction of the o finished preparation with supragingival margin  674 M. F. R. L. Huhtala et al. e f g h i j 17 k l. Fig. 17.3 (continued) Aesthetic Veneers: What Are They and How to Handle Them? 675 17 m n o. Fig. 17.3 (continued) before the gingival margin, even if later the gingival cavosur- The following step is to connect the peripheral depth cut face margin will be placed inside the gingival sulcus. In doing to the cervicoincisal one, first on one-half of the tooth sur- so, subsequent corrections of the preparation can be per- face, following the mesiodistal contour of the surface formed without invasion of the biologic width. (. Fig. 17.3j, k). Then, the reduction should be performed Next, the peripheral depth cut should be extended along the on the other side (. Fig. 17.3l). The depth and homogeneity mesial and distal embrasures until the incisal edge (. Fig. 17.3e). of the reduction can be evaluated with the preparation This proximal extension of the preparation should be guided by guides (. Fig. 17.3m, n). Then, the improvement of the aesthetics, reaching areas where the tooth/restoration interface preparation margins can be performed, placing the gingival could not be seen, taking into consideration the dynamic area margin 0.2 mm inside the gingival sulcus, if there is an aes- of visibility (. Fig. 17.2a–d). The more compromised in terms thetic issue. Such procedure can be done using a No. 2135 of color alteration is the tooth structure, the larger the extension tapered diamond point, for a chamfer finish line. The of the preparation toward the proximal surfaces should be – gingival tissue can be protected from the rotary instrument which can even involve half of the proximal contacts. In this using a metallic gingival retraction/protection instrument case, when performing the proximal reduction, the adjacent (. Fig. 17.3l). teeth should be protected with a steel strip. Another option to control the depth of the facial reduc- Next, a cervicoincisal depth cut should be prepared in the tion is to use depth-limiting diamond points, available in center of the labial surface with a No. 2135 tapered diamond two different diameters. The No. 4141 three-wheeled dia- point with a rounded tip, for teeth with slight discoloration, mond depth cutter creates mesiodistal depth of cuts or with a No. 4138 point for darker teeth. However, to obtain 0.3 mm deep, while the No. 4142 performs depth cuts of a homogeneous reduction of the entire labial surface, the 0.4 mm deep (. Fig. 17.4a). Between the wheels covered by cervical-incisal depth cut should be prepared in three planes, diamonds, there are inactive areas, which will touch the following the convexity of the labial tooth surface intact tooth structure and control the tooth removal. Even (. Fig. 17.3f–i). This way, the reduction will be performed when the depth-limiting diamond points are applied, the evenly over the tooth surface, allowing the application of a previous peripheral depth of cut can be performed first, to homogeneous thickness of the restorative material over the facilitate the preparation (. Fig. 17.4b). Then, the depth- prepared area. limiting diamond point is to be used, followed by the  676 M. F. R. L. Huhtala et al. a b c d e f 17. Fig. 17.4 Preparation using depth-limiting diamond point. with No. 4141 point; e connection of all depth cuts to create a a Three-wheeled diamond depth cutter points with different diam- homogeneous enamel reduction; f finished preparation with eters; b peripheral depth cut; c, d mesiodistal depth cuts prepared intrasulcular gingival margin No. 2135 tapered point to connect to the peripheral depth area, due to inter-incisor contacts during protrusive move- of cut (. Fig. 17.4c–f). ment of the mandible, allowing a safe incisal disocclusion For indirect veneers, overlapped incisal edge preparation guide. This design also provides a definite seat during cemen- needs to be performed to avoid fractures of the restoration. tation. That can be done by a butt joint (. Fig. 17.5e, f) or a wrap Before preparing the palatal chamfer, an incisal reduction preparation (. Fig. 17.5i, k). In the first case, just an incisal of about 1 mm must be done. For that, three incisal depth reduction is performed, while on the latter, it is followed by cuts are performed by placing a No. 2135 diamond point per- an additional palatal chamfer. There is a discussion in the lit- pendicular to the long axis of the tooth (. Fig. 17.5c). They erature about which would be the best design for the incisal are then connected, as shown in. Fig. 17.5d–f. Then, a edge of ceramic veneer preparations. However, the pala- 0.5–1-mm-long palatal chamfer is prepared. The palatal tal chamfer effectively counteracts shear stress in the incisal depth of cuts is done with the No. 2135 diamond point posi- Aesthetic Veneers: What Are They and How to Handle Them? 677 17 a b c d e f g h. Fig. 17.5 Overlapped incisal edge preparation with a palatal chamfer. a, b Preparation restricted to the labial surface; c incisal depths of cuts; d–f incisal reduction; g, h palatal depth of cuts. i–l palatal chamfer concluded  678 M. F. R. L. Huhtala et al. i j k l. Fig. 17.5 (continued) tioned parallel to the long axis of the tooth, which are then restoration mock-up is evaluated, and if it is not the one connected to one another, including the proximal surfaces desired, it can be easily removed by pulling out the veneer by (. Figs. 17.5g–l and 17.7c). its margin, with the aid of an exploratory probe. Then a new composite mock-up can be placed and evaluated. This will Tip also allow the dentist to evaluate whether the depth of the preparation performed, when associated to characterization It is important to familiarize oneself with the detailed material and composites, is enough to hide any altered back- steps in tooth preparation. One needs to have a clear ground color the tooth may present. If necessary, a deeper 17 anatomical picture of teeth in mind during the preparation can still be done. preparation. Selection of appropriate burs or points is Isolation of the operating field can be performed with vital for the success of tooth preparation, because it is a gingival retraction cord and cotton rolls, or with a rubber matter of tenths of millimeters. dam associated with clamps to expose the margin of the preparation. In those cases, the No. 210 or 211 clamps pres- ent the ideal shape, allowing adequate displacement of the gingival tissue. If the preparation is restricted to enamel, after 17.4 Direct Veneer Restoration acid etching (with phosphoric acid gel) and rinsing, the sur- face can be dried with air stream, resulting in a opaque To restore the labial surfaces of teeth after veneer prepara- chalky-white appearance. In this case, if the dentist is using tions, a resin composite material with excellent polishing an adhesive system with separate primer and bonding bot- characteristics should be selected. Those recommended tles, the primer does not need to be applied. However, if there include microhybrid, nanohybrid, and nanoparticle compos- are areas of exposed dentin on the prepared surface, after ites, to recover the dental aesthetics. Before performing the rinsing the acid gel, the surface should be blot dried. This will final veneer, a restoration mock-up can be done, using the leave the surface visibly moist (glossy), followed by an appli- same composite, shades, and thickness layers of the final res- cation of a primer/bond adhesive system or a single bottle toration. The materials should be applied over the teeth with- adhesive system. Due to the abundant enamel availability on out any previous adhesive treatment. After curing, the this kind of preparation, the acid etching technique should Aesthetic Veneers: What Are They and How to Handle Them? 679 17 be preferred in relation to the self-etching approach, result- to mask the intense opacity of the tint, followed by a final ing in higher bond strength values. layer of more translucent enamel shade composite, to repro- In the case of heavily discolored teeth or when there are duce enamel characteristics (. Fig. 17.6a–o). If the adjacent several shades on tooth surface after preparation, due to sev- tooth has a labial surface rich on macro and micro textures, eral previous restorations, a thin layer of opaque light-curing they should be reproduced over the restoration according to viscous liquid characterization material, also known as color what was described in 7 Chap. 14. When the tooth that will modifier, tint, or masking agent, can be used to create a receive the veneer has Class III or IV restorations that require whiter homogeneous surface color. Either white or VITA™ replacement, this should be made on a previous dental shade opaque characterization materials can be used. After appointment. This would simplify the veneer preparation that, a thin layer of dentin shade composite should be used, procedure. a b c d e f. Fig. 17.6 Direct veneer restoration. a Tooth-shade evaluation; light-curing color modifier shade A1 (Kolor + Plus – Kerr); j application b, c application of gingival retraction cord size No. 000; d protection of of dentin shade composite layer (Z350, 3 M/Espe); k, l application of neighbor teeth with a Mylar strip and acid etching. e, f application of enamel opacity composite. m enamel shade composite applied; the adhesive system; g light-curing; h, i application of opaque n, o final result  680 M. F. R. L. Huhtala et al. g h i j k l 17 m n. Fig. 17.6 (continued) Aesthetic Veneers: What Are They and How to Handle Them? 681 17 o 17.5 Indirect Veneers The indirect veneers can be performed with composites or ceramics. As the restoration is prepared outside the mouth, an impression or scanning of the preparation is necessary, in order to create the restoration over a cast or milling it in CAD/CAM machine. Before luting, a pretreatment of the restoration is required, to improve its bonding to the tooth structure. Those procedures are presented in the following sentences. 17.5.1 Dental Ceramics. Fig. 17.6 (continued) Ceramic is defined as something made from nonmetallic material by firing at high temperature. The dental ceramics When the teeth present only chromatic alteration and the are widely used biomaterials in prosthetic dentistry, because labial shape is intact, a custom-made matrix can be created of their attractive and well-studied clinical properties. They before the tooth preparation, copying the surface shape and have basically three indications in dentistry: (a) ceramic- texture. It can be used later to restore the exact original anat- metal crowns (porcelain fused to metal, PFM) and fixed par- omy, thus saving clinical time. That matrix can be cre- tial dentures; (b) all-ceramic restorations consisting of ated in two different ways. In the first, an impression can be crowns, inlays, onlays, indirect laminates (veneers), and taken, and a plaster model obtained on a previous dental short-span anterior bridges; and (c) ceramic denture teeth. visit. Over the model a matrix can be produced using a ther- Ceramics for dentistry are aesthetically pleasing by their moplastic material, such as low-density polyethylene sheet, color, shade, and luster and are chemically stable. and a vacuum thermoforming machine. It follows the same A dental ceramic is best described as a complex multi- technique applied to produce dental bleaching trays. Another phase system. It comprises a dispersed crystalline phase possibility is to create the matrix immediately before the which is surrounded by a glassy phase, actually a continuous preparation, using self-curing acrylic resin. In this case, after amorphous phase. The crystalline phase is mainly responsi- application of a retraction cord into the gingival sulcus, a ble for its physical properties, while the glassy phase gives its thin film of liquid petroleum jelly is applied over the tooth aesthetic characteristics. Traditional feldspar-based ceramics surface, followed by the placement of acrylic resin, picking are also referred to as “porcelain.” They are silicon (Si) based up powder particles on wet brush, and applying over the sur- and made of aluminosilicate minerals, such as quartz (SiO2), face. It must be applied over the labial surface of the treated feldspar (KAlSi3O8–NaAlSi3O8–CaAl2Si2O8), and kaolin tooth, incisal edge, and part of the labial surface of the adja- (Al2Si2O5(OH)4). Typically, dental porcelain is composed of cent teeth. A handle made of acrylic is created over the exter- ca. 73–75% feldspar and ca. 22–25% quartz. To increase the nal surface of the acrylic matrix to simplify its placement. workability of the unfired porcelain, and to impart X-ray After curing, the margins of the matrix need to be finished contrast, some kaolin needs to be added. Pigments are with an abrasive mounted stone. The acrylic matrix should important to provide the required aesthetic shade and hue be tested in the position before and after the operating field. It is noteworthy that there is a crucial difference between isolation. a regular ceramic (such as your coffee mug) and a dental por- After the preparation, adhesive procedures are per- celain, which is related to the proportion of quartz, feldspar, formed, and the dentin shade composite applied. Before and silica (SiO2) contained in the ceramic matrix. Dental light-curing of each resin composite layer, the matrix should porcelains (feldspathic-, leucite-, or fluorapatite-based) can be placed in the position to evaluate if there still is space left meet the highest aesthetic standards but have limitations: to apply the enamel shade composite. The matrix must be they are brittle, with low fracture toughness and flexural isolated internally with liquid petroleum jelly. The enamel strength. This is a consequence of their very high glass con- shade composite is then placed inside the matrix and taken tent. Due to the limited thickness in indirect laminates and in the position. The excess of material is removed, and the the material’s properties, the clinical success of porcelain restoration is light-cured for only 10 s. The matrix is veneers relies on reinforcement of the restorations by adhe- removed, and the finishing of the margins should be per- sive cementation. formed with a scalpel blade, followed by the final light-cur- The new glass ceramics have improved mechanical prop- ing. The labial surface of the restoration will have the same erties due to a higher proportion of the crystalline phase that shape of the natural tooth, and just a polishing will be gener- strengthen the material. As they possess higher fracture ally necessary. strength and increased toughness, when compared to the  682 M. F. R. L. Huhtala et al. porcelain, they also have a wider application field. To the However, when the final restoration will be prepared by an group of glass ceramics belong the leucite-based and lithium external laboratory, an interim restoration will be required. disilicate-based (LiSi2O5) ceramics, as well the new zirconia- When a single tooth will receive the provisional restora- reinforced glass ceramic. The stronger materials avail- tion, a plastic clear crown form (. Fig. 8.13a) can be used as a able are the so-called high crystalline ceramics, mainly the matrix to restore the external anatomy of the tooth. The crown Y-TZP zirconia-based ones. However, most are highly form is placed on the tooth and the excess is trimmed. A direct opaque and have low aesthetics, not being generally recom- composite or a bis-acryl composite is applied inside the form, mended for indirect veneers. which is taken in position. The excess is removed with a sable brush or disposable applicator moistened with bonding agent. > Identifying various dental ceramics and their correct After light-curing the matrix is removed, while the composite indications will guarantee success to the dental stays in place. The margins are checked, and any excess can be treatment. One should never underestimate the removed with a scalpel blade. Generally, the temporary resto- significance of etching, not only of the tooth structure ration remains in place without any adhesive application, but also of the ceramic. In cementation it is vital to solely through mechanical retention. The occlusion can be carefully adhere to the luting protocol. adjusted with diamond finishing points. Any adjustments of the interim restoration must not change the previous tooth preparation. If the restoration dislodges, a temporary aesthetic 17.5.2 Impression/Scanning of the Tooth cement can be used (e.g., Bifix Temp, Voco; ClearTemp LC, Preparation Ultradent). Another option is to etch a 1 mm diameter area on the center of the preparation and cement the temporary resto- The first step to obtain a proper impression is to perform the ration with a flowable composite. gingival displacement. For that, a retraction cord is gently When the original labial surface has appropriate shape, placed inside the sulcus using a retraction cord packer. The and the veneer indication is only related to color alteration, a cord must be placed beneath the finishing line to avoid inter- matrix can be prepared with a putty silicone material inside ferences during the impression, for capturing the details of the mouth, previously the tooth preparation. A trayless the gingival cavosurface margin. After that a low viscosity impression is performed, by applying the material covering elastomeric impression material (addition silicones and poly- the labial and lingual surface of the anterior and some poste- ethers) is applied over the preparation, followed by the putty rior teeth. Interproximal slits are cut on the buccal areas of the material previously loaded inside an impression tray. The matrix, which serve as vents through which the excess of the retraction cord can be left in place during impressioning, provisional material will flow. An appropriate amount of the being generally removed in the mold. The gingival displace- bis-acryl composite is applied in the matrix, which is taken in ment can also be performed with the double-cord technique. place until the initial cure of the material. The marginal fit is A thin retraction cord (000) embedded in hemostatic solu- analyzed, and finishing is performed. If the restoration is dis- tion is placed inside the gingival sulcus, and over it a thicker lodged, it can be cemented as described above. When the one (00). The one step putty-wash silicone impression tech- teeth shape will be changed by the veneers, a diagnostic wax- nique can be used. For that, immediately before the impres- up can be used to prepare the silicone matrix, which will sion, the thicker cord is removed, and the low viscosity guide the production of the temporary veneers. The patient material injected around the tooth preparation. The putty should always be informed about the low retention and fragile impression material is mixed, applied inside metal trays and characteristics of the provisional restoration. 17 immediately placed intraorally, letting the materials to polym- erize simultaneously. A high-accuracy type IV dental stone is poured into the mold. After its hardening, a replica is 17.5.4 Extraoral Phase for Indirect obtained, which is positive reproduction of the soft tissues Restoration and teeth. The cast is then sent to the dental technician to prepare the laminate. In modern dental laboratories, the ceramic veneers may be Another option is to perform a 3D digital impression, prepared using various approaches. The first and oldest scanning the tooth preparation using an optical intraoral method is the sintering, which consists in application of an scanner. The information is digitalized, and a virtual 3D aqueous slurry of ceramic particles on a refractory cast. A model is created. A dedicated software is used for restoration sintering is performed over the cast at a temperature above design process. The milling unit is used to mill the laminated the softening points of the ceramic, whereby the matrix par- from ceramic or composite blocks. ticles melt and the particles coalesce. Different layers of ceramics, of different shades and opacities, are incrementally applied, creating a polychromatic and natural look for the 17.5.3 Provisional Restoration final restoration. This method is used for feldspar and leucite- reinforced veneers [21, 28]. Some indirect restorations are performed chairside, such as A second option is the direct casting or hot-pressing. In when a CAD/CAM system is available in the dental office. this case a waxing of the restoration is performed that is Aesthetic Veneers: What Are They and How to Handle Them? 683 17 embedded in a refractory material. The lost wax technique is thickness and high translucency of the laminates, an incor- applied, creating a refractory mold. In this case a ceramic rect selection of the cement shade can jeopardize the aes- ingot is softened by heating and can be pressed or injected thetic outcome of the whole treatment. The try-in paste is into the mold, creating monolithic and monochromatic lam- applied in the internal side of the restoration, which is placed inate. It can be used for lithium disilicate glass ceramic and in position like will be performed during the final luting. The leucite-containing glass ceramic [21, 28]. test should start with an untinted and transparent try-in The last method is based on the use of a CAD/CAM sys- paste. If the first shade is not adequate, the laminate and the tem. In this case an intraoral scanning or a scanning of a preparation are washed, and a new shade is tested, until stone model is performed, creating a virtual cast of the teeth. defining the correct one for that clinical case. Different The restoration design is done in the dedicated software, and options of cements/try-in pastes shades are available, e.g., the milling is performed on a ceramic bloc, also creating transparent, opaque white, bleach, yellow, brown, or follow- monolithic and monochromatic laminates [21, 28]. The mill- ing the Vita Classical shade guide. After that, the dentist must ing can take place chairside or in the dental laboratory. This thoroughly remove the try-in paste with water spray and dry method can be applied for ceramic blocs made of feldspar the restoration with water- and oil-free air. No occlusal eval- and leucite or lithium disilicate-reinforced glass ceramics, uation should be performed before the cementation, to pre- zirconia-reinforced glass ceramic, and hybrid dental ceramic vent unforeseen fracture of the fragile laminate. (ceramic network structure reinforced by a polymer net- work). Recently high-translucent zirconia has been proposed for veneer restoration, although not providing yet the best 17.5.6 Pretreatment of Veneers aesthetic outcome in relation to the other options. Feldspar and leucite are milled from fully sintered blocs. The Obviously, tooth tissues do not possess any natural affinity to restoration is polished or glazed in a small ceramic furnace. dental ceramics. This explains why pretreatment of tooth tis- Lithium disilicate glass ceramic, zirconia-reinforced glass sues and a ceramic restoration, in association with adhesive ceramic, and Y-TZP monolithic zirconia are milled from system and a resin cement, are vital. Veneers as well other oversized dimension from partly sintered blocs (precrystal- dental indirect restorations require a surface pretreatment lized state). That initial lower strength allows the milling pro- for durable adhesion. This step is also called surface condi- cess. They are then fully sintered in a furnace, shrinking to tioning. It is defined as one or a series of steps, including (but the required size, reaching its final translucency and maxi- not limited to) cleansing, removal of debris, and modifica- mum flexural strength. The restoration with hybrid ceramic, tion of internal restoration surface, over which a silane cou- like a composite block, is just milled and polished. pling agent and adhesive will be applied, chemically bonding A monolithic restoration means that the final shape of the to the resinous cement [3, 8, 31]. restoration was obtained with a single material, which lacks The surface treatment will prevent the formation of (or the polychromatic characteristic of a natural tooth, such as remove) any weak surface layer on the substrate (debris, the translucent incisal edge, opalescence, counter- grease, oil, contaminants). That will increase the surface free opalescence, and defined dentin mamelons. Those are energy and maximize the molecular interaction at the inter- obtained when the hot-pressing and CAD/CAM methods facial layer, between the laminate and resin cement, optimiz- are employed. In this case the restoration can be character- ing the adhesion at the interface. It can also create special ized either externally, through glazing (staining), or alterna- surface micro-features for micromechanical retention [7, tively cut-back and covered with layers of compatible sintered 31]. Sufficient adhesive strength can be provided and main- ceramic. tain a long service time. Porcelains and the new glass dental ceramics are pre- treated by acid etching using hydrofluoric acid, which is a 17.5.5 Try-in Procedure very corrosive and toxic agent. Great caution and care must be exercised when using it. Acid etching is considered the Each laminated must be tested into the preparation for fitting. most effective procedure in enhancing adhesion between For that the provisional restoration is removed with an instru- feldspar-based and glass ceramic laminates and resin cement. ment. The preparation is cleaned with pumice and a prophy- By etching the ceramic surface, a partial dissolution of the laxis rubber cup or brush, followed by washing and drying. ceramic glass content occurs, creating a porous topography Any residues of temporary cement must be removed that produces micromechanical retention between the lami- (. Fig. 17.7c). The internal area of the laminate is moistened nate surface and resin cement (. Fig. 17.7g, h). Acid with water or glycerin and the restoration is placed. Inadequate etching is normally performed using ca. 5–10% gel-like seating can be diagnosed by using a low viscosity silicone hydrofluoric acid. Nowadays, the use of that acid etching is material (Fit Test C & B, Voco). The internal adjustments can unanimously recommended. For lithium disilicate and be performed with small round fine diamond points. zirconia-reinforced glass ceramic veneers, a 5% hydrofluoric To verify the shade of the restoration, water-soluble try-in acid is applied for 20 seconds. For leucite-reinforced glass pastes that simulate the optical characteristics of the resin ceramic and feldspar ceramic restorations, the recommended cements can be used to select its color. Due to the small etching time is around 60 seconds.  684 M. F. R. L. Huhtala et al. A mandatory application of a silane coupling agent is around 1 minute, the adhesive and resin cement can be needed to chemically bond the inorganic material (silica) of applied for final cementation of laminate (. Fig. 17.7i) [7, 8, ceramic structure to the resinous monomers in the adhesive 31, 34, 35]. Some manufactures recommend the application system and resin cement. The silane also allows the resin to of the adhesive over the silanized surface, which is not better wet the ceramic surface that may easily penetrate into light-cured before the cementation (. Fig. 17.7j). Others the porous structure [32, 33]. After silane solution dries for recommend the application of the cement directly over the a b c d e f 17. Fig. 17.7 Indirect veneer restoration. a Color alteration on with a clear strip and acid etching; e application of the adhesive nonvitalized central incisors; b internal and external dental bleaching system; f glass ceramic veneers etching of the internal surface with procedure did not significantly improve the aesthetics of the smile. The hydrofluoric acid gel; h etched surface after washing and drying, initial uneven gingival zenith position of the right central incisor in showing a frosty appearance due to the surface roughness created by relation to the left incisor was corrected by a gingival surgery; the dissolution of the glassy phase. i application of the silane coupling c preparations with incisal reduction and palatal chamfer; d placement agent; j application of the adhesive system; k luting of the veneers with of a retraction cord into the crevice, protection of the neighbor teeth a light-curing resin cement; l final result Aesthetic Veneers: What Are They and How to Handle Them? 685 17 g h i j k l. Fig. 17.7 (continued) silanized surface. Each manufacturer instruction must be Tip followed. For indirect composite veneers, the internal surface of the Understanding the various steps and rationale in ceramic restoration must receive sandblasting (air abrasion). This veneer pretreatment is important. The try-in must be procedure increases the surface roughness to provide micro- performed before the acid etching. After etching the mechanical retention. After that the surface is cleaned with internal must not be contaminated. If any contamination spray of air/water or ultrasonic bath. Some manufacturers occurs, the surface needs to be cleansed with acetone or recommend the application of silane to promote bonding to ethanol or re-etched with phosphoric acid, followed by the inorganic matrix of the composite, exposed by the sand- rinsing with water. blasting procedure.  686 M. F. R. L. Huhtala et al. 17.5.7 Cementation of Indirect Veneers 17.5.8 Finishing and Polishing The rubber dam isolation can be performed, in association After cementation, the dynamic occlusion contacts must be with clamps for anterior teeth, although it is not always evaluated with a thin articulating paper. The anterior disoc- feasible or possible. Another possibility is to apply a clusion guide must occur without excessive stress concen- lip and check retractor to create a soft tissue displacement. tration in just one tooth. The canine disocclusion guide The neighbor teeth surfaces are protected with a clear must also be evaluated. Any adjustment can be performed mylar strip or a polytetrafluorethylene (PTFE) tape with a fine-grit diamond points or 30-flutted carbide bur. (. Fig. 17.7d). The tooth preparation surface is etched The finished areas must be properly polished using abrasive with phosphoric acid gel for 15 second (. Fig. 17.7d). If no rubbers, disks, or polishing pastes with felt disks, using pro- dentin was exposed during the preparation, the surface is gressively finer abrasives (. Figs. 4.29a–d and 4.31b). The completely air dried, leaving a frosty-white appearance. whole margin must be evaluated with an exploratory probe. However, if any dentin was prepared, the blot drying tech- Any excess must be removed using a very thin grit needle nique is used, and the excess of moisture is removed with shaped diamond point. Any excess in the interproximal a cotton pellet, leaving a visible moistened surface. The area must be detected with dental floss and removed with selected adhesive system is applied, and the excess is abrasive strips. The margins of the restorations should be removed with air stream (. Fig. 17.7e). No light-curing is reevaluated in the next dental appointment to detect any performed. remaining discrepancy. The internal area of the restoration is etched with hydro- fluoric acid, and the silane coupling agent is applied, as previ- ously described. According to the manufacturer’s instruction, 17.6 Changes of the Apparent Tooth the adhesive system can be applied over the silanized surface Dimension by Optical Illusions (. Fig. 17.7j). The excess is removed with an air stream, but no light-curing is performed. In some patients, changes in the clinical width or length of a The resin cement of choice is the light-curing one, which certain teeth are desired for aesthetic improvement. For allows a better color stability over time. The veneers are that, orthodontic treatment or gingival surgery is usually held with a placement instrument that features a flexible required. However, some patients might not desire to receive adhesive tip (OptraStick, Ivoclar Vivadent), charged with such an invasive or prolonged treatment. For those cases, the resin cement on the internal surface and then posi- some superficial morphology changes can be performed on tioned with continuous digital pressure in the tooth. Excess the labial surface, making the tooth look larger or shorter, of cement can be removed with a brush. The proximal area thereby creating an optical (and aesthetic) illusion. The art can be cleaned with dental floss. A light-curing is per- of creating illusions consists of changing perceptions, caus- formed for 10 seconds, to ensure the positioning and fitting ing an object to appear different from what it actually is. of the laminate. After the cementation of the last restora- This is performed by changing the so-called tooth face, tion, a layer of glycerin gel is placed over the interphase which is a flat area on the labial surface. In the same between tooth and restoration, to eliminate the oxygen way, the size of incisal and cervical embrasures determines inhibition layer of the cement, and the light-curing is per- the youth aspect of teeth and can be shaped when making formed again for 60 second on every side of the tooth. Any the restoration. additional excess can be removed with a No.11 scalpel 17 blade. In the interproximal area, a serrated separating strip can be employed (. Fig. 15.18f). 17.6.1 Flat Area If more than one restoration will be cemented, the clini- cian must try in the restoration that will be luted next, On the mesiodistal direction, the flat area or tooth face is because even small excess of cement from the previous placed between the mesial and distal transitional line angles laminate will prevent the seating of the subsequent. The (. Fig. 17.8a, c). The transitional line angles on the labial laminates of both central incisors are simultaneously surface of neighboring teeth form the labial embrasures. cemented, i.e. both laminates are place in position first an Even though it may not be a perfectly flat surface, it is then light-curing is done simultaneously, following by the responsible for reflecting the visible light and for the appar- cementation on those teeth more distally located. If any ent dimensions of the anterior teeth. Light that reaches error occurs, they will be located far from the midline and the facial surface between the transitional line angles is will be less visible. reflected to the observer, while the mesial and distal areas to Aesthetic Veneers: What Are They and How to Handle Them? 687 17 a b c. Fig. 17.8 Location of the flat area (tooth face) on the labial surface the transition line between the middle and incisal third of the crown; of the central incisor. a On the mesiodistal direction, it is located b delimitation of the flat area from a proximal view; c delimitation of between the mesiolabial and distolabial transitional line angles. On the the flat area from an incisal view cervicoincisal direction, it is located between the high of curvature and those line angles deflect the light, making them appear sion. The changes that were planned are seen in. Fig. 17.9a darker and less observable and seen. Reallocating the posi- and performed in. Fig. 17.9b, c.. Figure 17.9d shows the tion of the transitional line angles, the area that reflects light result after polishing. When performing a direct veneer res- can be increased or reduced. The more the transitional toration, the flat area can be adapted according to the indi- line angles approach the center of the labial surface, the nar- vidual needs, either during the application of composite rower this flat area becomes. On the other hand, the more increments or during the finishing procedures. To reduce the displaced toward the proximal surfaces these transitional width of the flat area and create a narrowing illusion, the den- line angles are, the wider is the flat area. The increase of the tist should enlarge the mesial and distal embrasures, using a flat area width, on the mesiodistal direction, gives a widen- small diameter abrasive bur disk ing illusion to the tooth. Given that, teeth with the same On the cervicoincisal direction, the labial surface of ante- actual anatomical width can have different apparent dimen- rior teeth generally has three inclinations. The flat area is sion if they have different width of the flat areas. That then defined by those inclinations, located at the medium concept is described as the “law of the face,” which third of the crown, above the high of curvature, and below implies making dissimilar teeth appear similar by turning the transition line between the middle and incisal third the apparent faces equal. (. Fig. 17.8a, b). The larger the flat area on the cervicoincisal. Figure 17.9a–d shows resin composite replicas obtained direction, the larger will be the apparent height of the tooth. from the natural tooth shown in. Fig. 17.8a–c, where the. Figure 17.10a–d shows composite replicas obtained from width of the flat area was reduced to create a narrowing illu- the natural tooth, originally shown in. Fig. 17.8a–c. The  688 M. F. R. L. Huhtala et al. a b c d. Fig. 17.9 Effects of flat area width on the apparent width of the angles by wearing with abrasive disk; c transverse cross section crown using resin replicas of the same tooth. a Delimitation of the showing the changes performed; d original aspect of the light actual width of the flat area on the left and drawing of the new reflection on the left and after changes on the right, creating a dimension on the right; b changing the position of the transitional line narrowing illusion changes were planned in. Fig. 17.10a and performed in Tip. Fig. 17.10b, c through the cervical and incisal reduction of the flat central area, using an abrasive disk. Finally, in To reduce the apparent length of long teeth, the flat area. Fig. 17.10d is shown the result after polishing. should be reduced on the cervicoincisal direction and Based on the above presented explanations, to increase increased on the mesiodistal direction. 17 the apparent height of short teeth restored with veneers, the flat area should be enlarged in the cervicoincisal direction and reduced in the mesiodistal direction. Conversely, to reduce the apparent length of long teeth, the flat area should 17.6.2 Embrasures be reduced on the cervicoincisal direction and increased on the mesiodistal direction. The size and distribution of the embrasures directly influence smile aesthetic according to what was described in 7 Chap. 1 Tip (. Fig. 1.11a–d). Therefore, when making veneer restora- tions on several teeth, dentists can change the embrasures to To increase the apparent height of short teeth restored make the smile look younger. Changes in embrasure shape with veneers, the flat area should be enlarged in the can be performed at the moment of the composite applica- cervicoincisal direction and reduced in the mesiodistal tion or during the finishing of the restoration, using scalpel direction. blades and thin polishing disks with small diameter. Small or absent embrasures make the smile look older. Aesthetic Veneers: What Are They and How to Handle Them? 689 17 a b c d. Fig. 17.10 Effects of flat area length on the apparent height of the section showing the change performed; d original aspect of the light crown using resin replicas of the same tooth. a Delimitation of the reflection on the left and changes on the right, resulting in the actual flat area length on the left and drawing of the new dimension shortening of the apparent crown height on the right; b length reduction with abrasive disk; c longitudinal cross Conclusion References Aesthetic treatment decisions should be based on prevail- ing clinical conditions and the patient preferences and 1. Busato ALS, Hernandez PAG, Macedo RP. Dentística: restaurações anticipations, following the principles of maximum conser- estéticas. 1st ed. Artes Médicas: São Paulo; 2002. 2. Kina S, Bruguera A. Invisível. Restaurações Estéticas Cerâmicas. vation of the tooth structure. The veneers are restorations Artes Médicas: São Paulo; 2008. restricted to the labial surface of aesthetically compromised 3. 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