Graduate Institute of Clinical Dentistry and School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC.

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1 Patients with discolored and malaligned anterior teeth able to obtain significant esthetic improvement after restoration with CAD/CAM (Cerec 3D) porcelain veneers case report CHIA-YUNG LIN BOR-SHIUNN LEE MING-SHU LEE MIN-HUEY CHEN 1 Graduate Institute of Clinical Dentistry and School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC. 2 Division of Operative and Esthetic Dentistry, National Taiwan University Hospital, Taipei, Taiwan, ROC. The use of porcelain and other all-ceramic veneers to restore discolored or malformed anterior teeth has become a significant component of esthetic dentistry over the past decade. CAD/CAM (Cerec 3D) is a sophisticated clinical restorative method capable of creating complex ceramic restorations including porcelain veneers and full-coverage crowns. We report a case of discolored and malaligned anterior teeth in a 26-year-old male patient who obtained significant esthetic improvement in the appearance of the anterior teeth after restoration with CAD/CAM (CEREC 3D) porcelain veneers. Our patient had suffered from discolored teeth since childhood and came to the Operative and Esthetic Dentistry Department of National Taiwan University Hospital (NTUH) seeking treatment. A clinical examination revealed that the patient had severe brown discoloration with band formation on all teeth, developmental enamel defects with drug-induced discoloration, and anterior teeth malalignment. The patient s discolored and malaligned anterior teeth (#14~#24 and #34~#44) were restored with CAD/CAM (CEREC 3D) porcelain veneers. This dental work resulted in significant esthetic improvement in the appearance of the patient s anterior teeth, and the patient was satisfied with the final prosthetic restorations. We concluded that patients with discolored and malaligned anterior teeth can obtain significant esthetic improvement by restoration with CAD/CAM (CEREC 3D) porcelain veneers. (J Dent Sci, 1(2):88-93, 2006) Key words: developmental enamel defect, tooth discoloration, CAD/CAM porcelain veneer. During the past 20 years, dentists have applied veneers to teeth using various techniques to correct esthetic problems. Veneers can be divided into 3 categories: free-hand-placed direct composite resins, preformed acrylic laminates, and laboratory-fabricated acrylic resins, composite resins, porcelains, and glass ceramic veneers 1,2. Porcelain and other all-ceramic veneers are rated as the best veneer restorations3. The use of porcelain and other all-ceramic veneers to restore discolored or malformed anterior teeth has become a significant component of esthetic dentistry in the past decade 3. Received: March 15, 2006 Accepted: May 28, 2006 Reprint requests to:dr. Min-Huey Chen, Department of Dentistry, National Taiwan University Hospital, 1 Chang-Te Street, Taipei, Taiwan 10048, ROC. 88 The most limiting factor in the choice of materials for dental restorations is the restricted range of fabrication technologies. The ability to fabricate a restoration outside the mouth and subsequently integrate it with a tooth extends the range of materials available to dentists 4. An indirect approach also enables the possibility of further optimizing the physical properties of the restoration by widening the choice of materials. The CEREC method (Sirona A.G., Bensheim, Germany) for restoring teeth by CAD/CAM is now over 10 years old 5. It is the ingenious result of a sophisticated analysis of the requirements of a dental restorative system and the application of logical problem-reduction in cavity design. In its infancy, it was limited to the fabrication of simple inlays only. From those beginnings, it has matured into a sophisticated clinical restorative method, CEREC 3D, capable of creating complex J Dent Sci 2006 Vol 1 No 2

2 CAD/CAM porcelain veneers Figure 1. Frontal view of the anterior teeth discoloration before porcelain veneer treatment. Figure 2. Ovoid form of the upper arch. There were brownish linear grooves on the palatal sides of #16 and #26. No attrition or abrasion was present. ceramic restorations and full-coverage crowns at the chair side. CASE PRESENTATION A 26-year-old male patient came to the Operative and Esthetic Dentistry Department of National Taiwan University Hospital with the chief complaint of discolored teeth (Figure 1). He asked for full-mouth veneer restorations. He denied having any systemic diseases, as well as any food or drug allergies. The patient had smoked for several years but had no parafunctional habits like clenching or bruxism (Figures 2, 3). According to the patient, he had had frequent illnesses and had taken long-term medication during his childhood. The initial clinical impression was a full mouth of yellowish-brown teeth. Small asymmetrical white opacities were found on his incisors, and banded discoloration was found on the incisal 1/3 of the anterior teeth (Figure 1). There was linear grooving with discoloration on the middle 1/3 of his first molars and anterior teeth. The lower left canine (#33) was fractured above the groove. Enamel wearing and defects accompanied by brown stains were observed on the 4 canines (Figures 4, 5). The anterior teeth were also malaligned, and the marginal gingival lines were unsymmetrical at the upper central incisors. There was spacing at the interproximal area from the upper right central incisor (#11) to the left lateral incisor (#22). The right molar relationship was a class III Figure 3. Ovoid form of the lower arch. There were brownish linear grooves on the buccal sides of #36 and #46.. malocclusion. From an esthetic viewpoint, his upper right central incisor (#11) was too wide and left central incisor (#21) was too long compared with the standard width-length ratio of 0.75~0.8, the incisal curve was too straight, and a crossbite was evident at teeth #22 and #32. The patient selected CAD/CAM (CEREC 3D) porcelain veneers for the upper and lower anterior region (#14~#24 and #34~#44) to improve the esthetics and mask the malalignment, after he was informed about other possible choices, including veneering with direct light-curing composite resin, J Dent Sci 2006 Vol 1 No 2 89

3 C.Y. Lin, B.S. Lee, B. S. Lee, M. S. Lee, et al. Figure 4. Left buccal view before porcelain veneer treatment. Spacing was observed in the interproximal area between #21 and #22. technique described by Christensen 6. The labial enamel was reduced by approximately 0.75 mm in the incisal 1/3 of the crown, decreasing gradually to 0.3 mm in the cervical region to create space for the veneer. The initial edge reduction was about 0.7 mm. No overlap preparation was made in the incisal edge. If a tooth was worn short incisally, it was veneered labially and extended palatally with the veneer, without overlapping onto the palatal surface. The proximal preparation ended at the contact area, except teeth #21 and #22 which required an alignment change (Figure 6). 3. After preparation, impressions were taken, poured in die stone, and sent to the laboratory for fabrication of the restorations. 4. The patient was recalled when the veneers were ready. Before luting, the inner surfaces of the veneers were treated with 0.4% hydrofluoric acid for 4 minutes and rinsed with water. After drying in air, a silane-coupling and bonding agent was applied. After cleaning, teeth were etched with a 37% phosphoric acid solution, rinsed with water and dried with compressed air. Excite DSC (Ivoclar- Vivadent, NY, USA) bonding agent was then applied to both the etched enamel and dentin surfaces. The luting composite, Variolink II Esthetic Cementation System (Ivoclar-Vivadent, NY, USA), was evenly placed over the veneer s bonding surface before it was placed onto the tooth surface. The veneer was then lightly pressed into place with finger pressure. Dental floss was used to remove Figure 5. Right buccal view before porcelain veneer treatment. The right molar relationship was a class III malocclusion. indirect composite resin, and bleaching the teeth. The procedure we followed for fitting the CAD/CAM (CEREC 3D) porcelain veneers is as follows. 1. His teeth were cleaned to remove extrinsic stains and dental calculus at the first appointment. He was informed about the need for good gingival health and educated in effective plaque control. Both preoperative and postoperative photographs were taken in order to evaluate the change in appearance. 2. The preparation of the teeth was based on a Figure 6. Frontal view of #14~#24 after the preparation. The contact points of the teeth were preserved, except for #11 and #21 due to the alignment change. 90 J Dent Sci 2006 Vol 1 No 2

4 CAD/CAM porcelain veneers Figure 7. Frontal view after porcelain veneer treatment. The width-length ratios of #11 and #21 were changed. Figure 9. Right buccal view after porcelain veneer treatment. between #21 and #22 was closed, and the #22~#32 crossbite was camouflaged. The width-length ratios of #11 and #21 were changed to 0.81 and 0.74, which are closer to standard values, and the incisal curve was more harmonious (Figures 7-9). After restoration with CAD/CAM (CEREC 3D) porcelain veneers, the patient s discolored and malaligned anterior teeth exhibited significant esthetic improvement, and the patient was satisfied with the final prosthetic restorations. Figure 8. Left buccal view after porcelain veneer treatment. The space between #21 and #22 was closed. excess luting material from the veneer s interproximal area. After removing the excessive cement, the veneers were light-cured with a light-curing unit (L.E.Demetron I, Kerr Corporation, city?, CA, USA) at an intensity of 1000 MW/cm 2 for 20 seconds in both the labial and marginal areas. 5. The margins of the veneers were then finished with a super-fine polishing diamond bur and checked with a dental probe to ensure that there was no excess cement along the veneer s labial margin. The occlusion was checked and adjusted. 6. The patient was recalled after 1 week to re-check the occlusion, proximal contact relationships, marginal integrity, and gingival health. Teeth discolorations were covered by veneer, the space DISCUSSION During enamel formation, ameloblasts are susceptible to various external factors, like metabolic injury, which may cause defects in the quantity and shape of the enamel or in the quality and color of the enamel 7. Quantitatively defective enamel, known as enamel hypoplasia, produces teeth with insufficient amounts of enamel, ranging from pits and grooves to a complete absence (aplasia). Stain engagement can be found with this type tooth. Qualitatively defective enamel, known as enamel hypocalcification, means that the quantity of enamel is normal but it is soft and friable, so that it easily fractures and wears readily. The color of this type of tooth varies from white opaque to yellow to brown. Teeth also tend to darken with age as a result of exogenous staining. In this case, a white spot may be the result of enamel hypomaturation, while easily wearing enamel may be the result of hypomineralization and linear grooving J Dent Sci 2006 Vol 1 No 2 91

5 C.Y. Lin, B.S. Lee, B. S. Lee, M. S. Lee, et al. with discoloration may be the result of hypoplasia. Factors associated with enamel defects may occur locally or systemically. Most enamel defects affect the anterior teeth and first molars, and the affected teeth may have coronal discoloration or actual pits and irregularities. The specific causes of systemically induced enamel defects are often obscure but are usually attributed to childhood infectious diseases. The patient stated that he had had several illnesses and had undergone long-term medical therapy during childhood. In this case, systemic factors from infectious illnesses were suspected. Tetracyclines can cause discoloration and enamel hypoplasia of both the primary and permanent dentitions if administered during the period of tooth development 8. The discoloration, which is permanent, varies from yellow or gray to brown 9. The labial surfaces of yellow-stained anterior teeth darken in time, while the palatal surfaces and buccal surfaces of posterior teeth remain yellow 10. Calcification of the permanent teeth begins after birth and is completed at 7~8 years of age, with the exception of the third molar 11. Therefore, administration of tetracycline to children under 8 years of age should be avoided as it may result in tooth discoloration and enamel hypoplasia 12. There is a possible association between staining and enamel hypoplasia as a result of the high-dosage intake of tetracycline during tooth calcification 13. In our case, the yellow to brownish discoloration could have been drug-induced, and extrinsic smoking stains on the canines may have been a result of enamel hypoplasia. Treatment for this kind of patient may include vital or nonvital teeth bleaching, which will lighten the discoloration but may leave a translucent appearance 14. As tetracycline staining is intrinsic, the bleaching technique is most often only partially successful. There are 3 other options, including placing composite resins, porcelain laminate veneers, or full-coverage porcelain crowns 15,16, to physically cover the teeth. The advantages and disadvantages of each of these options are described below. Patients demand for treatment of unesthetic anterior teeth is steadily growing. Full crowns are the most predictable and durable but undoubtedly most invasive, with substantial removal of large amounts of sound tooth substance and possible adverse effects on the adjacent pulp and periodontal tissues 3. Resin composite veneers can be used to mask tooth discolorations and correct unaesthetic tooth forms or positions. However, such restorations suffer from a limited longevity because resin composites remain susceptible to discoloration, wear, and marginal fractures. Glazed porcelain veneers were proposed as being durable anterior restorations with superior esthetics. Simonsen and Calamia 17 introduced special acid etching procedures that substantially improved long-term porcelain veneer retention. They demonstrated that the bond strength of a hydrofluoric acid-etched and silanated veneer to a luting resin composite is routinely greater than the bond strength of the same luting resin to the etched enamel surface 18. Further, porcelain retains less plaque than other restorative materials or enamel, and the plaque is removed more rapidly, which causes no or a minimal periodontal response. The CEREC method (Sirona, Bensheim, Germany) for restoring teeth by CAD/CAM is now over 10 years old 5. Technological improvements have increased the range of restorations capable of being milled 19, to the extent that virtually any shape can now be made. Machinable ceramics as used by the CEREC system provide a useful restoration with high success rates 4. ProCAD (Ivoclar-Vivadent, city?, NY, USA) with leucite-reinforced porcelain blocks was used in our case. Tooth preparation for CAD/CAM (CEREC 3D) porcelain veneers is the same as that for veneers fabricated from conventional low-fusing feldspathic porcelain. ProCAD 100/I12 was selected according the shade and shape of this patient s teeth; a more-opaque color was needed to cover his severe tetracycline staining. Standardized data are calculated for individual cases. The anatomy, occlusal morphology, and color stability of CAD/CAMgenerated ProCAD block restorations were satisfactory in a 3-year clinical performance study 20. CEREC 3D is the name of the software used in the CEREC 3 system. While a light-cured luting composite is preferred for bonding conventional porcelain veneers, a dual-cured or self-curing luting composite is used for CAD/CAM porcelain veneers. When the luting space was set to 30 µm, crowns with a good fit could be fabricated on the Cerec 3 system 21. These restorations are color stable and wear at a clinically acceptable rate, and they can compete with the layering technique crowns in aesthetic value 22. The marginal fit of restorations milled by CEREC 3 was within the ADA specifications of 50 µm 23. However, there are no long-term reports about CEREC J Dent Sci 2006 Vol 1 No 2

6 CAD/CAM porcelain veneers Further, caution should be exercised when using this system for restoring non-vital teeth, as a higher fracture incidence has been noted 4. REFERENCES 1. Christensen GJ. A veneering of teeth: state of the art. Dent Clin North Am, 29: , Meijering AG, Creugers NHJ, Roters FJM, Mulder J. Survival of three types of veneer restorations in a clinical trial: a 2.5 year interim evaluation. J Dent, 26: , Peumans M, Meerbeek BV, Lambrechts P, Vanherle G. Porcelain veneers: a review of the literature. J Dent, 28: , Martina N, Jedynakiewicza NM. Clinical performance of CEREC ceramic inlays: a systematic review. Dent Mater J, 15: 54-61, Mormann WH, Brandestini M, Lutz F, Barbakow F. Chairside computer aided direct ceramic inlays. Quintessence Int, 20: , Christensen GJ. Have porcelain veneers arrived? J Am Dent Assoc, 122: 81, Joseph A, James J, Richard CK. Abnormalities of Teeth. In Oral Pathology-Clinical Pathologic Correlations 4th ed, Penny Rudolph, St. Louis, USA, pp , Cohlan SQ. Tetracycline staining of teeth. Teratology, 15: , Van der Bijl P, Pitigoi-Aron G. Tetracyclines and calcified tissues. Ann Dent, 54: 69-72, Mello HS. The mechanism of tetracycline staining in primary and permanent teeth. J Dent Child, 34: , Jackson R. Tetracycline staining of wisdom teeth. Cutis, 23: , Conchie JM, Munroe JD, Anderson DD. The incidence of staining of permanent teeth by the tetracyclines. Can Med Assoc J, 103: , Bevelander G, Rolle GK, Cohlan SG. The effect of the administration of tetracycline on the development of teeth. J Dent Res, 40: , Livingston HM, Dellinger TM. Intrinsic staining of teeth secondary to tetracycline. Ann Pharmacotherapy, 32: , Sadan A, Lemon RR. Combining treatment modalities for tetracycline-discolored teeth. Int J Periodont Rest Dent, 18: , Wragg PF, Tulloch EN. A rationale for treating tetracycline discoloured teeth. Restorative Dent, 3: 28-34, Simonsen RJ, Calamia JR. Tensile bond strength of etched porcelain. J Dent Res, 62: 297 (Abstract 1154), Calamia JR, Simonsen RJ. Effect of coupling agents on bond strength of etched porcelain. J Dent Res, 63:179 (Abstract 79), Mömann WH, Brandestini M. The fundamental inventive principles of CEREC CAD/CIM and other CAD/CAM methods. In CAD/CIM in Aesthetic Dentistry Mörmann WH ed, Chicago, USA, pp , Reich SM, Wichmann M, Shortall AC. Clinical performance of large, all-ceramic CAD/CAM-generated restorations after three years: A pilot study. J Am Dent Assoc, 135: , Nakamura T, Dei N, Kojima T, Wakabayashi K. Marginal and internal fit of Cerec 3 CAD/CAM all ceramic crowns. Int J Prosthodont,16(3): , Herrguth M, Wichmann M, Reich SM. The aesthetics of all-ceramic veneered and monolithic CAD/CAM crowns. J Oral Rehabil, 32: , Estefan D, Dussetschleger F, Agosta C, Reich S. Scanning electron microscope evaluation of CEREC 2 and CEREC 3 inlays. Gen Dent, 51: 53, J Dent Sci 2006 Vol 1 No 2 93