Our lab has used products and Equipment from Renfert for years for polishing and finishing of both single units and bridges fabricated using all-ceramic and metal.

The purchase of a Sirona CAD/CAM unit, with which we extended the range of manufactured material by lithium disilicate, zirconia and laser-sintered chrome cobalt, gave rise to the question, which processes and materials could we use to provide the perfect finish for our high-quality restorations? Would the previously tried and tested materials still meet this challenge? In the following you can read about our experiences.

Lithium disilicate

We use the following Renfert products for finishing lithium disilicate: the diamond disc ›Dynex Brillant‹ to separate the milled restoration from the block, the articulating spray ›Occlutec‹ to check the high spots and the polisher ›Polisoft A‹ to polish the restoration.

We use the following procedure:

  1. We separate the tooth from the Lithium disilicate block using the ›Dynex‹ Brillant and a moist sponge.
  2. Using a water-cooled turbine and a finecut diamond cutter we adapt the tooth to the die with the aid of the contact spray.
  3. After polishing of the larger surfaces,the occlusion is checked using the pearshaped diamond cutter for ceramic ›Italcos PD 10 E‹.
  4. The polisher ›Polisoft A‹ is extremely versatile. Trimming it to a lens shape enables precise polishing of surfaces and material-friendly creation of the macrotexture of cusps or other distinctively polished surfaces.
  5. The lithium disilicate obtains a much more homogeneous surface, the positive effect of which is even more clearly highlighted after sintering. A perfect result is achieved when stains and shades are applied, even with high demands.

 

e.max and zirconia

I would now like to digress a little and Focus on the porcelain that we use in the lab. We veneer zirconia frameworks using ›IPS e.max‹ porcelain, which is held in high regard by the dentists we work with because of the esthetic quality. This porcelain gives the restorations a natural, vital and translucent appearance similar to that of natural teeth and is an important factor in our success over the past three years.

We also like the precise, fine cut of the ›Turbo-Flex S‹ diamond disc (Fig. 2, 3) with zirconia units, which are separated from the blocks before sintering. Multi-unit bridges milled from 85/40 zirconia blocks are only separated from the block after sintering using the ›Dynex Brillant‹ diamond disc (Fig. 1). These discs are used in conjunction with the moist sponge ›wet‹ technique (Fig. 4) and their flexibility and strength make them ideal for preparing interdental spaces. The wet technique avoids overheating of the material; we guide the cutoff discs simultaneously over the Connection to be separated and over a wet sponge.

Zirconia in visible positions

When we prepare zirconia for visible Areas (occlusal or palatal surfaces, strengthening margins, connector areas) we polish the material in a few, simple steps:

  1. We finely prepare the occlusal grooves, strengthening margins and connectors using a water-cooled turbine and flameshaped diamond cutter.
  2. We smooth the extensive surfaces, such as the palatal surfaces, using a pearshaped, aluminum-oxide rotary instrument.
  3. Finally, we polish all visible areas using the ›Polisoft polisher‹. First this is trimmed to a lens shape, ›Kohinoor paste‹ is then applied to it for polishing all surfaces at a low motor speed (Fig. 5). A perfect result is created with smooth, high-luster surfaces, which provide less surfaces for plaque to attack.

 

CrCo

With laser-sintered and milled CrCo as well as bars and Toronto bridges we also obtain smooth surfaces that save time and costs by polishing the margins using ›Polisoft A‹, pre-polishing using ›Bison brushes‹ with ›Saphir‹ polishing paste and then high-luster polishing using a mounted cotton buff and ›Saphir‹.

Contact detection

In the past I have tried many articulating sprays but a direct comparison with ›Occlutec-Spray‹ shows the following Advantages:

  1. After adjustment of the restoration, the spray can be easily removed without leaving colored marks on the dental stone model (I have never liked sending finished restorations on colored models  to the dental surgery).
  2. It is very easy to use and the powder film is so thin that the dimensions of the die are not distorted.
  3. The high gas pressure in the Container enables an optimal spray technique to be used. It is not necessary to spray the die several times. This may result in an ›onion layer effect‹ which can detrimentally affect the precision and result in impairment of the fit (I don‘t want to remind you here of the importance of a passive fit of zirconia and disilicate on the die).
  4. ›Occlutec‹ is also ideal for adjusting the proximal contacts, preparing pontics with tissue-supported porcelain contact surfaces and for adaptation of the tissue section of implant-borne crowns to obtain an optimal emergence profile.

Conclusion

In conclusion, I can confirm that I will also continue to use Renfert products in future. The products are reliable and are also highly developed technically with regard to application with new materials. We used ›Polisoft A‹ in the past for ›Empress‹ and for metal and now we also use it for lithium disilicate, zirconia, milled and laser-sintered CrCo. ›Kohinoor polishing paste‹, which was ideal for polishing porcelain, is now optimal for use with zirconia. There are also new products such as ›Dynex Brillant‹, which performs optimally with the new ceramics, or the ›silicone disc ‹ Art. No. 86 0000 that can be used for zirconia as well as disilicate and ›IPS e.max‹ porcelain.

This all shows me how a modern Company can cater for the latest market demands and customer requirements. By revising existing products and through the addition of new products Renfert enables its partners to optimally process new materials, helping customers to fabricate optimal restorations.

We hope that Renfert continues along the winning path of providing customers with new, high-quality equipment and consumables as well as proven products to adapt to the materials of tomorrow.

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Guido Testa was born in the province of Varese, Italy in 1958. 1977 he graduated in Milan and 1984 he became the owner of a laboratory in Busto Arsizio. Since ...

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