Dental Tribune Asia Pacific Edition No.12, 2017

12 SCIENCE & PRACTICE Dental Tribune Asia Paciﬁc Edition | 12/2017 A fracture load study on implant- supported crown restorations An interview with Dr Nadja Rohr, Switzerland 1 2 Fig. 1: Dr Nadja Rohr.—Fig. 2: fhe crowns were loaded until fracturing occurred.—Fig. 3: Measurement results for the fracture load of the crowns (ten test samples for each restoration and luting material) made of hybrid ceramic and feldspathic ceramic, which were attached with different luting composites.—Fig. 4: Correlation between the fracture load of the crowns and the pressure resistance of the luting composites.—Fig. 5: Attaching the crowns to the zirconium dioxide implants. By DTI Owing to the rigid ankylotic anchor- ing of the implant in the bone, high forces act on the superstructure, and this can lead to chipping and fractures in the case of restorations made from conventional, brittle ce- ramics. Owing to its dual ceramic– polymer network structure, the VITA ENAMIC hybrid ceramic (VITA Zahnfabrik) has a comparatively high, dentine-like elasticity. This elasticity allows the material to ab- sorb masticatory forces. In this in- terview, Dr Nadja Rohr from the University of Basel’s centre for den- tal medicine in Basel in Switzerland reports on her findings in fracture load tests of implant-supported crowns. In an in vitro study, you examined the fracture load of crowns made of hybrid ceramic and conventional ceramic seated on one-piece ce- ramic implants. What process did you follow? Standardised molar crowns made of hybrid ceramics and feld- spathic ceramics were attached to zirconium dioxide implants (ce- ramic.implant, ø 4.0 mm, VITA Zahnfabrik) using four different attachment composites. After being stored in water for 24 hours at 37 °C, the crowns reached their breaking point. The luting materi- als used were also characterised ac- cording to their flexural strength, elastic modulus, tensile strength and pressure resistance. What were the differences between restorations made of VITA ENAMIC hybrid ceramic and conventional ceramic in the fracture load tests? With the use of hybrid ceram- ics, significantly higher fracture load values were achieved com- pared with feldspathic ceramics. In your test series, the crowns were bonded with self-adhesive and con- ventional composites. Did that af- fect the fracture load values deter- mined? High fracture load values for hybrid ceramics and feldspathic ceramics were achieved with lut- ing composites that had high pres- sure resistance. How relevant is the pressure resist- ance of a luting composite in daily clinical practice? High pressure resistance luting composites can increase the stabil- ity of the overall system. In the molar area, there are maximum masticatory forces of up to about 1,000 N. Choosing the right luting composite can have a positive ef- fect on the clinical success of hy- brid and feldspathic ceramic resto- rations. What should be considered when choosing the luting composite, and what should be taken into account during the integration process? Dentists should choose a luting composite that meets the specific clinical requirements of the case. For attaching hybrid ceramic crowns to zirconium dioxide im- plants, this would be an adhesive luting composite with high pres- sure resistance. Furthermore, it is important for the conditioning to be performed according to the manufacturer’s instructions. Editorial note: This interview wms first published in Dentml Bmrometer, Issue 7/2017. 3 4 without cement Harvard Implant Panavia SA Maxcem Elite Multilink Automix Maxcem Elite Multilink Automix Panavia SA Harvard Implant semi-permanent without cement 5

Dental Tribune Asia Pacific Edition No.12, 2017

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