Dental Tribune Nordic Edition No.4, 2016

10 Dental Tribune Nordic Edition | 4/2016 TRENDS & APPLICATIONS Digitally designed, meticulously implemented Maxillary and mandibular all-ceramic restorations after loss of occlusal vertical dimension By Prof. Petra Gierthmühlen & Udo Plaster, Germany The problem of worn and eroded teeth is becoming more prevalent. The pathological loss of tooth substance can result from erosion (acid-related tooth damage), attrition (tooth-to-tooth wear) or abrasion (mechanical processes). In most cases, a number of factors contrib- ute to the clinical situation. Once the causes have been established, suitable therapeutic measures can be planned. In modern den- tistry, the removal of considerable amounts of tooth structure for the preparation of a restoration is re- garded very critically. A more appro- priate solution is to find a minimally invasive or non-invasive means of restoring the teeth using adhesively bonded restorations. This type of approach is described on the basis of the following case study. Preoperative situation When the patient consulted our practice, he complained about restricted masticatory function and tooth hypersensitivity. In ad- dition, he was dissatisfied with the appearance of his teeth. The dental examination revealed large cari- ous lesions and various defective fillings. All of the teeth showed severe signs of erosion (Fig. 1). Sub- stantial loss of tooth structure was evident in the anterior teeth in par- ticular. The analysis of the smile line established that the length-to- width ratio had been negatively af- fected. In the relaxed smiling posi- tion, the teeth were hardly visible. In addition, the discrepancy be- tween the smile line and the mid- line was very pronounced. The patient showed consid- erable loss of occlusal vertical dimension. A functional disorder (e.g. craniomandibular dysfunction) was not diagnosed. The aim of the extensive treatment was to recon- struct the proportions, function and aesthetics of the teeth. There- fore, the occlusion was to be rede- fined and the vertical dimension adjusted. Creation of the mock-up In order to obtain a sound basis for the treatment planning process, the Face Hunter scanner (Zirkonzahn) was used to produce a digitalised image of the patient’s face. The 3-D view of the preopera- tive situation offers an advantage over conventional photographs in that it enables the envisaged situation to be examined from dif- ferent aspects, thereby providing a realistic overall picture. A digital wax-up with a height- ened occlusal plane was created with the PlaneSystem (Zirkon- zahn). In this step, the tooth posi- tions, lengths, sizes and shapes were determined on the basis of functional and aesthetic criteria. The Digital Articulator module was used to check the static and dynamic occlusion. The digitally calculated movement paths cor- related with the guiding surfaces of the teeth. In the process, the extra-oral aesthetic parameters were checked too. The segments designed with the Zirkonzahn software were used to construct a PMMA mock-up by means of CAD/CAM fabrication methods. The mock-up was tried in and deemed to be satisfactory in terms ofitsfunctionandaesthetics (Fig.2). The patient accepted the new sit- uation and the raised vertical dimension (Figs. 3a & b). Therefore, the mock-up served as a template for the remainder of the treatment process (Figs. 4 & 5). First, the digi- tal design was used in the creation of the provisional restorations. Tooth preparation and provisionalisation The restorative procedure in- volved the entire dental arch in both jaws. The defective restora- tions were replaced and the teeth were prepared according to defect- oriented principles (Figs. 6a & b). A minimally invasive approach was taken to prepare the maxillary anterior teeth for the crowns, the mandibular anterior teeth for the veneers, and the molars for the crowns and onlays. The digitally designed final situation was super- Fig.1: Substantial loss of tooth structure, particularly in the anterior region.—Fig.2: A digital wax-up served as the basis for the creation of the PMMA mock-ups.—Figs.3a & b: Try-in of the mock-up in the mouth.—Figs. 4 & 5: Comparison of the aesthetic analysis of the initial and target situations.—Figs. 6a & b: Defect-oriented preparation in both of the jaws. Figs. 7a & b: Transfer of the situation by means of conventional impressions.—Fig. 8: The digital design of the mock-up for the provisional restorations.—Fig. 9: The patient quickly became accustomed to the CAD/CAM- fabricated provisionals.—Fig. 10: Construction of the permanent restorations with the help of the initial facial scan and the mock-up.—Fig. 11: The individual restorations were machined in wax, pressed with lithium disilicate glass-ceramic and subsequently finished.—Fig. 12: The maxillary anterior teeth were cut back and then veneered. The veneers, the onlays and crowns for the molars were manufactured in monolithic form. 1 2 3a 5 4 3b 6a 6b 7a 7b 8 9 12 11 10 12 3a 7a 7b 89

Dental Tribune Nordic Edition No.4, 2016

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