Dental Tribune Asia Pacific No. 6, 2016

In the restoration of anterior teeth, clinicians have to select the most appropriate material for the case at hand on the basis of specific crite- ria. Recently developed restorative materials have opened up a myriad of exciting possibilities. In situa- tions in which teeth show signs of erosion, abrasion, abfraction or a combination of these phenomena, practitioners will tend towards using ceramics or composite resins, depending on how much intact tooth structure remains. Traditionally, composites are used for Class III, IV and V defects; however, ceramic veneers are pre- ferred in cases in which a large amount of tooth structure is miss- ing or a major change is planned (e.g. a smile makeover). When two central incisors need aesthetic enhancement, the choice of ap- proach is not as clear. Irrespective of the material used, a minimally invasive approach involving very little preparation of the tooth structure can be taken nowadays owing to the high strength of modern materials (e.g. lithium disilicate glass-ceramic). Never- theless, it is important to remem- ber that minimal preparation is an option only if the teeth are properly aligned. As long as the desired changes to the tooth shape and shade are small, the preparation can be limited to the enamel. In many cases, however, orthodontic treatment is needed before the tooth position and/or shape can be optimised by means of restorative procedures. This minimally invasive approach re- quires the dental practitioner to convince the patient of the neces- sity of undergoing preliminary orthodontic treatment. It is our aim to remove as little of the tooth structure as possible in every case that we treat. With modern materials such as lithium disilicate and leucite-reinforced ceramics, we can press or mill ve- neers that are as thin as 0.6 mm and even 0.3 mm with confidence. Only a few years ago, treatment with indirect restorations still required at least two appoint- ments. Ceramic materials such as IPSEmpressCAD(IvoclarVivadent) allow clinicians to produce poly- chromatic monolithic veneers and crowns in less than one hour and without having to glaze them. Nonetheless, many dentists still believe that dental technicians with their well-honed manual skills produce better aesthetic re- sults than a machine does, and they do not see the need to em- brace digital technology. As a re- sult, some clinicians are reluctant to invest in this technology be- cause of the high acquisition costs of the milling machines. Through the clinical case study presented here, we want to focus on aspects like the importance of having a suitable treatment plan, the possi- bilities currently available for the fabrication of veneers, the poten- tial of the press and CAD/CAM techniques, as well as the latest im- provements made in the field of cementation. Clinical case A 31-year-old female patient presented to our office because she was dissatisfied with her ante- rior teeth. She complained about the malalignment of the maxil- lary and mandibular central in- cisors (Fig. 1). A detailed clinical examination established that the composite restorations in these teeth were defective. As a result of erosion, a considerable amount of tooth structure had been lost. In addition, malalignment of teeth #21 and #41 was quite obvious. The treatment plan we pre- sented to the patient included ini- tial orthodontic treatment fol- lowed by minimal preparation of the two central incisors for two ce- ramic veneers. The patient was re- ferred to an orthodontist for treat- ment. Unfortunately, it took more than a year before she presented to the practice again and we were quite surprised to find that the two central incisors had been re- stored with poorly finished direct composite veneers (Fig. 2). In ad- dition to preventing any conta- mination of the working field, the clinician must accomplish the ar- duous task of creating an appro- priate emergence profile, proper contours and contact areas, and producing a suitable micro- and macro-texture, and all this within a single appointment. Many sim- ply underestimate the challeng- ing nature of this type of restora- tion, and this was a case in point. Owing to the poor preparation, the composite veneers had to be removed and replaced with new ones. In this particular case, the advantages of using the indirect technique were obvious. The pa- tient agreed to have two ceramic veneers made for her. For this purpose, impressions were taken and a master cast was produced. This working model provides the dental technician with the oppor- tunity to evaluate the situation in detail. He or she has the time to think about possible ways of cor- recting the malalignment. Dentists do not have this lux- ury of time when they are treating a patient in the dental chair, as they have to finish the restora- tions as quickly as possible in order to prevent contamination of the treatment area and keep chair time to a minimum for the com- fort of the patient. In the present case, another hurdle had to be overcome: any composite mate- rial that might have remained on the tooth structure had to be clearly identified using trans- illumination with white light- emitting diode light (Fig. 3) and 10 Dental Tribune Asia Pacific Edition | 6/2016 TRENDS & APPLICATIONS Two approaches, one goal Digital expertise versus manual skill in the fabrication of ceramic veneers By Dr Eduardo Mahn, Chile Figs. 8a & b: Try-in of the veneers with a light try-in paste (Light+). — Figs. 9a & b: Try-in of the veneers with a dark try-in paste (Warm+). — Fig. 10: Enamel etching with phosphoric acid. — Fig. 11: Application of a single-component adhesive (Adhese Universal). — Fig. 12: Removal of excess composite cement. — Fig. 13: Light curing with Bluephase Style polymerisation lights. 10 11 9a 9b 12 13 8a 8b Fig. 1: Initial situation. — Fig. 2: When the patient returned to the practice after a year, her teeth showed unsatisfactory composite veneers. — Fig. 3: The old veneers were removed and the teeth were transilluminated to identify any composite residue. — Fig. 4: The two-cord technique was used for the impression. The retraction cords remained in the sulcus. — Fig. 5: Temporary restoration. — Fig. 6: Try-in of the IPS e.max Press HT A1 veneers (fabricated in the laboratory). — Fig. 7: Try-in of the polished IPS Empress CAD Multi A1 veneers (fabricated in the dental office). 4 5 3 1 2 6 7 1011 1213 45 12 67

Dental Tribune Asia Pacific No. 6, 2016

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