41994_Australasian_Dentist_100_EMAG

CATEGORY LINICAL

here is identical to the previous Tetric Evo ow Bulk-Fill, but is now approved for light curing in 3 seconds with the Bluephase PowerCure curing light. As before, this bulk ow can also be polymerised with less powerful curing light, the recommended polymerisation time is then 10 seconds, as before. is was followed by the layer-by layer construction of the occlusal surface with the Tetric Prime, which was already presented in the 1st case (Figs. 14 to 17). Tetric Prime is not a bulk- ll material and must therefore be applied in thinner layers. In return, it o ers the complete colour spectrum and ideal translucency for harmonious integration in the posterior region. In the present case, it can be discussed whether the colour integration on a molar is really so relevant or whether the occlusal surface could not have been built up with a modelable bulk- ll material. In the case of a class I and II restoration, I would use a bulk ll as standard, and in the case of cusp replacement, especially the buccal cusps, I take the aesthetic needs of my patients into account in my decision. Patient case 3: Adjacent cavities with Tetric PowerFill e initial situation is a D3 caries at 34 distal and 35 mesial (Fig. 18). In the case of adjacent cavities, both matrices are always inserted into the proximal space and wedged after preparation (Fig. 19). A one-step procedure (insertion of only 1 die, restoration of the tooth in question and then change to the other tooth) usually leads to the partial die bulging into the cavity of the adjacent tooth after application of the separating ring, thus

overcontouring the lling. is must then be painstakingly corrected before the adjacent tooth is restored. e application of both submatrices ensures that the proximal contact is correctly located in the middle of the proximal space and that overcontouring is avoided. However, this doubles the amount by which the teeth would have to be separated, as each die has a thickness of about 30μm. In order to avoid insu cient proximal contact, the procedure is modi ed. First of all, the steps of the adhesive technique are carried out (Fig. 20). When using a modern universal adhesive, a so-called “selective etch”, i.e. the selective etching of the enamel with phosphoric acid before the application of the adhesive, should be carried out whenever possible 1,2 . e subsequent application of the universal adhesive to the enamel and dentin should always be active, i.e. the adhesive is kept in motion on the surface with the microbrush for at least 20 seconds. After that, it is blown dry well so that the solvent (usually a water/ alcohol mixture in the case of universal adhesives) evaporates.

Fig. 21: Condition after filling the cavity on tooth 34 (yellow arrow) with a layer of Tetric PowerFill and light curing for 3 seconds with the PowerCure light. Then the separation ring is removed (red arrows).

All photos © Dr. M. Lenhard

really close to the lling surface. If in doubt, I recommend triggering the 3s mode a 2nd time, i.e. polymerising for 6 seconds. e curing light allows an immediate 2nd release, but after that the function is locked for 30 seconds to prevent rapid multiple exposure and thus the risk of overheating of the pulp. In practice, this lock is not an obstacle. If another increment composite is needed, it will takemore than 30 seconds for the composite to be applied and adapted. Anyone who delegates polymerisation to the assistant is advised to activate the exposure assistant installed in the latest generation of Ivoclar Vivadent curing lights (Bluephase G4 and PowerCure), at least initially. is measures the light re ected back from the tooth surface into the light guide. If this falls below a limit value, the curing light assumes that the distance to the lling surface is too large for correct polymerisation and switches o again within 100 milliseconds. e user is warned acoustically to repeat the polymerisation correctly. ese aids make perfect sense, because all relevant parameters (abrasion, fracture resistance, colour stability and edge quality) depend directly on adequate curing 11 . In general, too little attention is still paid to the topic of polymerisation, considering that 11% of the curing lights used in German practices do not meet the minimum performance requirement and only half of the practices regularly check the performance of the curing lights 12 . After lling the 1st cavity, the separating ring is now removed and the die of the restored cavity is loosened slightly and pulled out to the side. e pull is always in the direction of the tip of the separating wedge (Fig. 22). is guarantees that the die of the adjacent cavity remains in place. Subsequently, the separating ring is reinserted (Fig. 23). With this approach, a tight contact point of the adjacent restorations is achieved exactly in the middle of the interdental space. Figure 24 shows the condition of the lled cavities immediately after the die is removed. When working out and polishing,

All photos © Dr. M. Lenhard

Fig. 20

With the Adhese Universal used here, in combination with the 3s program (3050 mW/cm2) of the Bluephase Power-Cure curing light, curing can be carried out in 3 seconds. With conventional polymerisation lights in the power range from 500 to 1400 mW/cm2, the polymerisation time remains at 10 seconds as before. After the adhesive technique, the cavities are restored with Tetric Power-Fill. e material can be applied and hardened as a bulk- ll composite in 4mm thick layers. If the cavities are not deeper than 4mm, the lling is carried out using a 1-layer technique. If you are unsure about the cavity depth, you can simply check the depth using a periodontal probe. Figure 21 shows the situation after lling the cavity 34 using a layer of Tetric PowerFill and a polymerisation of 3 seconds. is short curing time is only allowed in combination with the PowerCure curing light in 3s mode. If another light is used, the recommended curing time is 10 seconds. A prerequisite for adequate polymerisation in 3 seconds is that the light can be brought

Fig. 18: Initial situation: Proximal caries at 34 and 35.

Fig. 19: In order to achieve a correct proximal contour and correct position of the proximal contact, both matrices are always inserted and wedged in adjacent cavities.

All photos © Dr. M. Lenhard

84 AUSTRALASIAN DENTIST