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Dental Tribune Middle East & Africa No. 4, 2017

Dental Tribune Middle East & Africa Edition | 4/2017 RESTORATIVE 25 ◊Page 24 Fig. 6. Saliva isolation (other patient) Fig. 7. Margin draw Fig. 8. First crown proposal models with the software, the edge of preparation is drawn (Fig. 7) and after defining the insertion axis, the crown is designed. MyCrown Design software calculates the first proposal based on the sur- rounding teeth and gives a patient- specific and aesthetic restoration proposal. A quick adjustment was re- quired due to a small improvement of contact points with neighbouring teeth. (Fig. 8) After crown modelling, contact points and occlusal contact points satisfaction, we went to the next step - Manufacture (Milling pro- cess). Once the milling was over, we polished the tooth and sat it on the preparation. After checking the points of contact and occlusion, the crown could be cemented. Cementa- tion was done by Variolink by Ivoclar due to its great cementation shade/ opacity control and adhesive attrib- utes. Result The colour of the crown seems to be darker after cementation. Lighter shade of the neighbouring teeth is caused by loss of moistness due to the length of the procedure. (Fig. 9) We asked the patient to come in several hours or the next morning to check the colour. She called only to say everything is perfect and she is very satisfied with this restoration. We have to rely on her judgment and believe that the colour really is satis- fying. Conclusion This clinical example demonstrates, that if we have sufficient knowledge of latest dental trends and suitable equipment, we can help the patient in one session, even in more com- plicated cases that would otherwise require multiple appointments. MyCrown allowed to create a per- fectly fitting restoration within one visit. The initial software proposal of the crown design was approved al- Fig. 9. Aesthetic final result and happy patient lowing to place the restoration into the patient mouth within minutes of its completion. We should always consider every pa- tient is different and should be treat- ed with a unique approach, based on the indication. MyCrown illustrated the benefit of being able to offer re- storative treatment in a single visit. Aesthetic rehabilitation and tissue preservation in the anterior region By Dr Jan-Frederik Güth & Hans- Jürgen Stecher, Germany While there are often several ad- equate prosthetic treatment options to choose from for one single case, there are some cases where none of the proven solutions seems to be perfectly suitable. The prosthodon- tist and his team have to balance the pros and cons for each available option – they have to decide which treatment is best suited to fulfil the needs of the specific patient. This was the case with a 16-year-old fe- male patient who presented at the Department of Prosthodontics of the Ludwig Maximilians University of Munich, Germany in 2015. An or- thodontic treatment had just been completed and a further prosthetic rehabilitation was required. Background At the age of 10, the patient had suffered an anterior tooth trauma with avulsion and replantation of the maxillary central incisors (teeth 11 and 21, FDI notation). Despite all efforts, it had not been possible to preserve tooth 21. The former den- tist had replaced it with a four-unit metal-ceramic adhesive bridge (Mar- yland bridge) (Figs. 1 & 2). Unfortunately, the dismal progno- sis for tooth 11 was confirmed in the course of treatment: it had to be ex- tracted during orthodontic therapy. In order to replace both central inci- sors for the duration of this therapy, a provisional bridge with artificial gingiva was manufactured and at- tached to the fixed orthodontic ap- pliances (Fig. 3). Prosthetic treatment plant At the patient’s first visit in the pri- vate dental office of the LMU Mu- nich, the lateral incisors had large composite restorations not only on the vestibular surfaces, but – due to the previous rehabilitation with an adhesive bridge – also on the palatal surfaces (Fig. 4). Tooth 22 had received an endodon- tic treatment. This fact significantly limited the prosthetic options and had a negative effect on the progno- sis of this tooth. The developmental stage of the cervical vertebrae as- sessed by the orthodontist using lateral cephalometric radiographs revealed that only minimal transver- sal and horizontal growth was still to be expected for this patient. Due to this fact and the unfavourable pros- thetic value of the abutment teeth, the prosthodontic team – in consul- tation with the patient – decided to place an all-ceramic adhesive bridge with two wings bonded to teeth 12 and 22. The aim of this treatment was to postpone the placement of implants as long as possible in order to ensure that the patient was fully grown when this intervention was carried out. By use of a fixed resto- ration, the team strived for the best possible support and preservation of the surrounding soft and hard tis- sues. First steps After removal of the fixed orthodon- tic appliances, the direct restorations of the maxillary lateral incisors were replaced by new composite restora- tions. Tooth preparation had already been carried out on these teeth to place the former metal-ceramic bridge. Hence, it was not necessary to remove large amounts of additional tooth structure, however, the exist- ing palatal preparations required refinement. Subsequently, gingiva management was carried out with retraction paste. An impression was taken with the 3M True Definition Scanner and uploaded to the 3M Connection Center. The patient re- ceived a removable interim prosthe- sis (Fig. 5). Fig. 1: Situation prior to the orthodontic treatment with an adhesive bridge used to replace tooth 21. Fig. 2: The adhesive bridge shows a compro- mised fit after repeated removal and place- ment. Fig. 3: Snapshot during orthodontic treat- ment with temporarily replaced central incisors. (Image 1–3 courtesy of Prof. A. Wichelhaus) Fig. 4: Situation at the first visit of the young female patient at the LMU Munich private dental office. Fig. 5: Patient with interim prosthesis after removal of the orthodontic appliances, re- placement of the fillings and palatal tooth preparation. Fig. 6: Computer-aided framework design starting from the anatomical tooth shapes using the Zfx CAD Software. Fig. 7: Precise fit of the sintered framework on the model. Fig. 8: Try-in of the restoration in its fired, unglazed state. Fig. 9: Precise fit of the wings in the palatal area. Laboratory procedure In the dental laboratory, the digital impression file was downloaded, a physical model ordered and the data set imported into the Zfx CAD-Soft- ware for the design of the adhesive bridge framework. The bridge was designed in full con- tour. The recommended parameters (minimum wall thickness, connector strength etc.) for the selected materi- al – 3M Lava Plus High-Translucency Zirconia – were entered into the soft- ware. Then, the bridge was automati- cally reduced to the framework (Fig. 6). before the porcelain layering was performed (Fig. 7). Figure 8 shows the situation at the biscuit-bake try-in. This procedure is beneficial in that it provides for a uniform strength and optimal support of the veneer- ing porcelain. The framework was milled, thinned out at the margins using a fine diamond rubber pol- isher, individualised with dyeing liquids, and sintered. The precise fit of the wings to the palatal tooth sur- faces was confirmed on the model Finally, the adhesive bridge was finished and glazed. On the model, a highly accurate fit was obtained (Fig. 9), and the restoration showed a natural appearance (Fig. 10). This is in part due to the high translucency of the framework material (Fig. 11). ÿPage 26

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