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Dental Tribune Asia Pacific Edition No. 12, 2016

Stability, function and aesthetics— in fabricating complete dentures, optimum results can only be achieved if the individual details are successfully combined. In addi- tion to the rehabilitation of func- tional aspects, the aesthetic recon- struction of the teeth and soft oral tissue can considerably enhance a patient’s self-confidence. Treating edentulous patients using conventional complete den- tures continues to be a frequently applied therapy option. Yet, re- storing the edentulous jaw with denture teeth to achieve a func- tional and aesthetic rehabilitation poses a tough challenge to the treatment team. Biomechanical, physiological and geriatric con- cerns must be considered. True- to-nature replication of teeth and soft oral tissue is fundamental too. The objective is to restore pa- tients’ appearance and confidence by providing them with natu- ral-looking dentures. Initial situation A 58-year-old female patient presented with an edentulous upper jaw. She wore a complete denture in the maxillary arch and defective metal–ceramic restora- tions in the mandibular arch. Her existing teeth were damaged and could not be used as abutments for new restorations. They had to be extracted. The patient was diagnosed with Angle Class III malocclusion. There was a severe anteroposterior discrepancy be- tween the upper and lower arches. Seen in profile, the patient showed a prominently jutting chin and a protruding lower lip (Fig. 1). Her aesthetic appearance was im- paired. In addition, the patient complained about the poor func- tion and high mobility of the maxillary denture. A flabby ridge and severe bone resorption were present in the anterior part of the maxilla (Fig. 2). The alveolar ridge showed an asymmetrical progres- sion in the mandibular arch (Fig. 3). After the initial assessment of the patient’s oral condition and consultation on the treatment op- tions available to her, we decided to create new dentures for the maxilla and mandible. Conven- tional complete dentures were se- lected as the treatment option. Model analysis We began by taking a closed- mouth impression to create a pri- mary record of the jaw relations. Accurate model analysis provided important information in prepa- ration for the individual func- tional impression. These steps es- tablished the basis for a statically and functionally correct design of the dentures. The median palatine raphe, incisive papilla, first large palatine rugae, tuber maxillae and crest of the alveolar ridge were marked on the maxillary model. On the mandibular model, the crest of the alveolar ridge, Pound’s line and the tuberculum alveolaremandibulaeweremarked as landmarks. The mucobuccal fold was determined on both models. The Angle Class III mal- occlusion can be clearly seen on the articulated models (Fig. 4). High demands are placed on custom trays, because the func- tional impression is pivotal in achieving precisely fitting den- tures. The objective is to max- imise the supporting area of the denture base while taking into account the movements of the muscles. A suction effect must be established between the mucous membrane and denture base. For this purpose, the functional mar- gins need to be fully contoured. The area of the flabby ridge was marked on the model and covered with a spacer to ease the pressure. Subsequently, customised trays were fabricated. In order to pre- vent the denture shifting upwards and forwards, a wide labial rim was created in the maxillary ante- rior vestibule. Dorsally, the tray ended at the vibrating line. The custom tray should also provide a suction effect in the mandible. Relatively voluminous margins were created to achieve this. Suffi- cient tongue space was provided and the anterior area was given a slightly concave contour. The retromolar pad was only thinly covered and a concave buccal shelf was created. A rim was placed on the crest of the alveolar ridge to provide a support surface for the placement of Gnathometer “M” (Ivoclar Vivadent) used for record- ing the jaw-to-jaw relation (intra- oral needle-point tracing). The bite rims of Gnathometer “M” acted as the preliminary vertical dimen- sion. An assembly of custom tray and registration device was used to take an impression of the oral situation (Virtual Heavy Body, Ivoclar Vivadent) and to record the jaw-to-jaw relation (Fig. 5). Set-up and try-in Designed for classic occlusal schemes,theSRPhonaresIImoulds (IvoclarVivadent)areideallysuited for complete dentures. The facial meter (alameter) integrated into the SR Phonares II FormSelector assisted in selecting the moulds that were best suited for our pa- tient. The teeth were set up in line with the set-up criteria for the clas- sic occlusion. In order to prevent the flabby ridge from allowing the denture to move, the maxillary premolars were positioned close to the centre of the alveolar ridge (Fig. 6). We decided to place premo- lars in the dorsal area of the man- dibular arch to achieve an external seal with the buccal mucous mem- brane and the lingual wall at closed-mouth position (Fig. 7). The requirements of function and sta- bility and patient-specific charac- teristics were considered in the tooth set-up. The patient was in the habit of chewing food with her an- terior teeth because of her Angle Class III malocclusion. This was to be avoided in the new dentures by providing enough freeway space between the anterior maxillary and mandibular teeth at the set-up. A great deal of attention was given to faithfully mimicking the natu- ral oral soft tissue, as we wished to provide a maximum level of aes- thetics already at the try-in stage. Five different shades of wax were used for characterisation. By creat- ing vestibular gingival portions that have a delicate, yet effective, appearance, the customised look can be accentuated. Aesthetics, phonetics, occlusal vertical dimen- sion and centric relation were as- sessed at the try-in of the wax-up and rated as good. Completion The wax-up was converted to resin using a proven method. We focused particularly on creating natural-looking soft tissue to enable the dentures to integrate unobtrusively into the oral sur- roundings. Accurately designed as they were, the dentures and prosthetic gingiva were converted to a PMMA resin (IvoBase High Impact, Ivoclar Vivadent) using the IvoBase system. As polymerisa- tion shrinkage was fully compen- sated for, one-to-one replications of the wax-ups were attained. The denture wax-ups were flasked and sprued (Fig. 8). Once the moulds had been created and the wax boiled out, the flasks and teeth were prepared for the injec- tion moulding process. The pre- dosed denture base material was mixed, and the capsules contain- ing the mixed material and the flask were mounted on the in- jection device (IvoBase Injector). Once the appropriate programme had been selected, the injection process started. The result after divesting matched the require- ments. Even fine details of the wax-up were exactly reproduced (Fig. 9). The dentures fitted the models accurately and required only minimal reworking. Customised soft-tissue reconstruction using SR Nexco The 3-D soft-tissue contours should be customised with shade characterisations. In the same way as different shades of wax are used for the try-in, different shades of resin should be used to reproduce the colour variations found in the natural gingiva. The light-curing laboratory composite SR Nexco (Ivoclar Vivadent) is ide- ally suited for this purpose. This material is available in a compre- hensive range of gingival shades, including intensive shade vari- ants. Natural-looking soft-tissue aesthetics can be reproduced using a straightforward method. Given its non-sticky consistency, the composite is easy to apply and does not need to be warmed up prior to application. The labora- tory composite offers vast scope for individualised soft-tissue crea- tions, as it is available in a broad spectrum of SR Nexco Stains and SR Nexco Paste Effect materials. Variations in the degree of soft- tissue thickness, blood vessel den- sity and pigmentation can be easily replicated to resemble the characteristics of the natural gin- giva. The veneering material is optimally coordinated with the IvoBase denture base material. We began by applying SR Nexco Paste Basic Gingiva BG34 extensively on to the denture base. A natural depth effect was produced with intensive SR Nexco shades, that is SR Nexco Paste Intensive Gingiva. Papillae and alveolar spaces were faithfully replicated using these materials. Next, the lighter and more transparent SR Nexco Paste Transpa was applied to enhance the optical colour depth effect. This method resulted in a natural- looking appearance. The interplay of different shades, convex and 14 Dental Tribune Asia Pacific Edition | 12/2016 TRENDS & APPLICATIONS Enhanced gingival aesthetics Optimising conventional dentures with an innovative veneering material By Dr Jiro Abe & Kyoko Kokubo, Japan Fig. 1: Profile photograph of the initial situation (Angle Class III).—Fig. 2: Edentulous upper jaw with a flabby ridge in the anterior region and advanced bone resorption.— Fig. 3: Asymmetrical alveolar ridge progression in the man- dibular arch.—Fig. 4: Articu- lated models: Angle Class III malocclusion with anterior open bite is clearly visible.— Fig. 5: A customised impression tray and registration device form a unit.—Fig. 6: Setting up the maxilla: the premolars were positioned close to the alveolar crest.—Fig. 7: Setting up the mandible: premolars were also used in the dorsal area.—Fig. 8: Converting the wax-up to PMMA material (IvoBase system).—Fig. 9: The dentures prior to soft-tissue customisation. 9 8 7 6 2 4 3 5 1 24 35

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