N L Y A L S O N F E S SI O O R T A L P N E D PUBLISHED IN DUBAI www.dental-tribune.me January-February 2020 | No. 1, Vol. 10 The gold standard: IPS e.max Press – one material for virtually all indications?! Posterior occlusal veneers in the dental practice By Dr Diether Reusch and Jan Strüder, Germany The book titled “Porcelain Laminate Veneers” by David A. Garber, Ron- ald E. Goldstein and Ronald A. Fein- mann has had a great influence on the prosthetic and restorative meth- ods developed by the authors. Based on the resounding success of the adhesive technique, a minimally invasive approach evolved for the reconstruction of teeth. In 1990 “Westerburger Kontakte”, a private postgraduate dental train- ing institute, offered the first course on ceramic crowns, inlays and ve- neers. Today, as was the case almost 30 years ago, it is still considered quite an amazing feat that ceram- ics can be used in the same way as gold alloys. A study conducted by A. Krummel, A. Garling, M. Sasse and M. Kern at the Christian-Albre- chts-Universitaet Kiel (University of Kiel) showed that occlusal ve- neers in the posterior region with a minimum thickness of 0.3 to 0.6 mm offer a very promising treat- ment solution. In our dental prac- tice, we restore posterior teeth with occlusal veneers or partial crowns. These restorations measur- ing 0.5 to 7.0 mm in thickness are made of monolithic IPS Empress or LS2 and they are cemented with the adhesive technique. In anterior teeth, we use adhesively bonded monolithic 360° veneers, partial crowns or laminate veneers meas- uring 0.3 to 0.5 mm in thickness. In contrast to gold, which deforms quite easily and metal-ceramic solu- tions, which can fracture, most all- ceramic materials are virtually inde- structible. Therefore, these materials fulfil exceptionally high standards in terms of the static and the dynamic occlusion. Diagnosis and treatment planning As a result of parafunctional habits and biocorrosion the front teeth of our 23-year-old patient showed considerable attrition. The palatal enamel in the upper jaw had been completely worn away (Figs 1 and 2). Hardly any of the occlusal enamel remained on the posterior teeth. Functional analysis, wax-up and preparation planning The upper jaw model was articu- lated according to skull-related ori- entation principles. The joint-related orientation was used for the lower jaw. The lower jaw movements were recorded in order to program the ar- ticulator. A diagnostic wax-up was produced on the duplicate models (Fig. 3). The aim was to raise the ver- tical height to the level required for the reconstruction of the front teeth (“logical” tooth shape). The length of AD the anterior teeth was established with a mock-up, which was used to test the phonetic, functional and es- thetic parameters. As far as the later- al movements were concerned, our objective was to achieve immediate disclusion of the posterior teeth. Any interfering cusps were relocated. As a guide for the appropriate functional preparation, the dental technician marked the original location of the working cusps (red lines) and the non-supporting cusps (green lines) on the buccal surface of the teeth. Markings were made on the gingiva of the model to indicate the new position of the cusps and spaces. A mould of the duplicate wax-ups was made using a thermoforming pro- cess. A temporary composite resin was filled in the moulds, which were placed on the teeth. Once the materi- al had set, the moulds were removed. Together with the patient we were then able to evaluate the planned changes in terms of phonetics, func- tion and esthetics (Fig. 4) before the teeth were actually prepared. 1st treatment phase: tem- porary upper posterior restoration and perma- nent lower posterior restoration The posterior teeth in the upper and lower jaw were prepared, and the models (Fig. 5) were mounted in the articulator on the basis of the ob- tained facebow and centric relation data. The support pin was adjusted in accordance with the planned ver- tical dimension. The lower posterior teeth were waxed up with the help of an occlusal plane plate. Next, the wax crowns were invested and re- produced with ceramic. The crowns were placed using an adhesive ce- mentation technique (self-etch tech- nique, Adhese Universal, Variolink and Monobond Etch & Prime). We placed an indirect temporary res- toration made of composite resin in the upper posterior jaw. The unpre- pared anterior teeth were provision- ally treated with an adhesively bond- ed composite resin mock-up (Fig. 6). The upper dental arch was slightly expanded towards the buccal aspect and the anterior teeth were length- ened. The restorations featured the vertical dimension and cusp positions that were determined by means of the mock-up. Small adjustments were made in the upper temporary restora- tion by means of splint therapy. 2nd treatment phase: per- manent upper and lower anterior restorations Preparation and fabrication of the temporary restorations The upper and lower anterior teeth were prepared on the basis of mini- mally invasive principles (Figs 7 and 8). Step 1: A “dual-grit” diamond was used to mark the depth to which the incisal edge needed to be removed through the adhesively bonded mock-up (generally 1.0 to 1.5 mm). Step 2: A special grinder was used to apply 0.5 mm horizontal depth markings on the facial surface of the teeth through the mock-up. The grooves were marked with an insolu- ble fine liner. Step 3: The incisal edges were re- moved. For this purpose, the “ dual- grit” diamond was inclined towards the palatal aspect at an angle of about 30° Step 4: The proximal parts of the teeth were removed with a “dual- grit” diamond (0.3 mm) or a flame- shaped bur (014). Step 5: The mock-up was removed and the labial enamel was cut away until the markings were no longer visible. The cervical areas of the teeth were prepared along the gingival margin. The palatal preparation depth was between 0.3 and 0.5 mm. In the areas where the enamel loss on the palatal surface extended beyond the tuber- cle, we prepared the teeth for a 360° veneer. This was done to prevent pala- tal fractures from occurring. Step 6: Before we finely contoured the margins, we placed a #000 re- traction cord. The teeth were pre- pared with a red contra-angle hand- piece at reduced speed (40,000 rpm) up to the level of the retracted gingi- va. This preparation step can be done with air cooling. A silicone matrix, which was pro- duced on the basis of the diagnostic wax-up, was filled with hydrocolloid. Alternatively, the thermoforming method could have been used to make a mould of the wax-up, which would have been filled with silicone impression material. This enabled us to check whether or not we had removed enough of the tooth struc- ture (Fig. 9). If the hydrocolloid is less than 0.3 mm thick, the tooth struc- ture that needs to be further reduced is marked with a wax pencil. After this impression step, a model was produced with a fast-setting stone (Whip Mix Snap-Stone) in or- der to check the prepared surfaces. The silicone matrix (diagnostic wax- up) was given to a specialized dental assistant who fabricated the indirect provisional restorations. Preparation of the lower front teeth and fabrication of the model The lower front teeth were prepared and checked in the same way as the upper front teeth. The preparation depth was not to exceed 0.3 mm. Before the impressions were taken, a #0 cord (soaked with ViscoStat Clear, Ultradent) was placed over the #000 cord. It was removed shortly before the impression material was ÿPage B2