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to ensure that the ridge was provided with the natural roundness towards the adjacent tooth to subsequently allow for ossing. A special modelling spatula (Composite #4, American Eagle Instruments) was used for the relevant shaping (Fig. 5). In addition or alternatively, an 8A Carver modelling instrument from the same supplier or a 3A probe (HuFriedy) is suitable. Once the occlusal surface was built up, the matrix could be removed. e less few residual material was removed with a scaler, so that the lling could be nished and polished (Fig. 7). For the lling of tooth 26, an even thinner steel sectional matrix for molars (contoured matrix Quickmat Deluxe, 0.025 x 6.4 mm) was placed, which was rst xed cervically with a wedge and then with a tension ring (Palodent, Dentsply Sirona) (Fig. 8). After ow- and bulk- ll increments were applied using the tried and tested layering technique, the sectional matrix was removed. e removal achieved pull o resistance, thus indicating the presence of a strong proximal contact (Abb. 9). Finally, the 2nd lling was nished and polished as well (Fig. 10). e steps for pairs of interproximal adjacent llings are carried out according to the same principle for each lling, that is in the same way as the restoration of a tooth with a single tooth lling. If there is a pure proximal defect in the posterior region, it should be treated rst and only then should be started with the class II cavity (Denner, 2016). With two adjacent class II cavities, reconstruction of the rst marginal ridge can be rather di cult due to the lack of orientation to the adjacent tooth. If possible, the opposite side of the jaw should be used as a guide. In any case, the upper margin of the sectional matrix should be placed as low as possible so that the adjacent tooth substance can be more visible as a reference for the modellation (Fig. 5). For the application of a veneer in proximal cavities, prefabricated, contoured sectional matrices made of steel (Polydentia) are particularly suitable. ese are very thin, at the same time stable and can be easily cut to size like other steel matrices to create strong contact points. In addition, they are also relatively inexpensive compared to other products. What to watch out for when using tension rings Both teeth and cavities are very di erent in terms of size and anatomy. is is particularly evident in the position of the tooth equator and the shape of tooth tapering at cervical level. For this reason, multiple tension ring options fromdi erent suppliers should be available to achieve good results and to remove only minimal residual. In the case described above,

Fig. 06: The marginal ridge on tooth 27 was built up with a high-viscosity nano-hybrid bulk fill composite (GrandioSO x-tra, VOCO). The modelling of the rounded marginal ridge was achieved with a slightly elastic spatula.

Fig. 05: The marginal ridge on tooth 27 was built up with a high-viscosity nano-hybrid bulk fill composite (GrandioSO x-tra, VOCO). The modelling of the rounded marginal ridge was achieved with a slightly elastic spatula.

Fig. 08: Distally from tooth 26, a sectional matrix was wedged, and a tension ring was insterted. On the photo: it was possible to build up the distopalatal cusp slope and the proximal wall to the cavity floor.

Fig. 07: The buccal and palatal cusp slopes were also modelled step-by-step with the same bulk-fill composite. Before fitting the next matrix, the filling was further finished and polished.

Fig. 10: The patient was discharged after finishing, polishing and functional testing of the restorations on teeth 26 and 27.

Fig. 09: The matrix could be removed from the proximal space only with a pull-off resistance. This is an indication of a sufficient contact point.

the tension rings of the already available sectional matrix system “Palodent System” (Dentsply Sirona) were used (Fig. 8). Depending on the situation, various rings of the Palodent V3 (Dentsply Sirona) and Composi-Tight 3D System (Garrison Dental Solutions) systems are also used. From a biomechanical point of view, it is important that the time at which the respective tension ring should be inserted is crucial. In the case of deep defects and only little remaining tooth substance, the undercuts should rst be lled out with high-viscosity composite so to stabilize the cusps (Denner, 2016). e tension ring may be inserted only after this step. It is worth mentioning, at this point, that a tension ring with high recovery force can lead to fractures of fragile walls as well of entire cusps. On the other hand, the tension ring should be set as soon as possible independently of the size of the cavity. is should be done at the latest before the hardening of the bonding in narrow cavities or before the application of composite into

the proximal contact point area in larger cavities. e reason for this is that when a tension ring is t, the matrix in the contact point area could shift or, in the worst case, the previously set contact point gets lost. In the patient described here, cusps were still adequately supported by healthy dentin and therefore they did not need to be further stabilised. at is why the tension ring was t immediately and before the bonding agent and the rst ow increment were used (not shown in the images). Discussion Meaningful use of the incremental layering technique e incremental technique is carried out layer by layer after conditioning the cavity with a bonding agent. e surface is then always coated with a owable material according to the same principle: Each increment is applied with maximum free surface area and polymerised separately (here: Nano-hybrid ORMOCER composite “Admira Fusion Flow”, VOCO). is way,

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