Jost Prestin
Master Dental Technician
Germany
Everyone is familiar with the problem. Many different diamond polishing pastes are tested but none produces the required result, namely an effective and mainly quick polish of the respective material. As a result, there are four or five polish packs in the laboratory that have been started and no one uses them. This is also a cost factor, as diamond polishing pastes are not exactly inexpensive.
I contacted Renfert with this problem. The majority of diamond polishing pastes available on the market are simply not abrasive enough, smear excessively or too much time is required to achieve the necessary degree of polish. Following the development of a new formula and many hours of testing and changing the ingredients, the Renfert Polish all-in-one was available. The formula was then further adapted to suit zirconium oxide and lithium disilicate, as higher abrasion is required, particularly for zirconium oxide. The result is three highluster polishing pastes for ceramics: Renfert Polish all-in-one, Renfert Polish ZrO2 and Renfert Polish LiSi2.
Preparation and use on Zirconium oxide – Renfert Polish ZrO2
Zirconium oxide should be prepolished using a coarse, diamond-coated silicone polisher. It is particularly important to use a low motor speed (approx. 8 000–10 000 rpm) and apply minimal pressure when polishing. Zirconium oxide can discolor if there is excessive heat build-up. This then produces purple-grey shading. After elimination of the milling and grinding grooves, the Framework is then polished to a high luster using Renfert Polish ZrO2 and a Bison brush (at approx. 12 000–15 000 rpm). A brilliant, shiny high luster is achieved very quickly due to the extra-coarse diamond grit size of Renfert Polish ZrO2. Polishing is particularly important in the occlusal region. If the occlusal surface is not polished perfectly, a monolithic zirconia crown or bridge produces extremely heavy abrasion on the opposing teeth.
Prepolishing of zirconium oxide using a coarse, diamond-coated silicone polisher
High-luster polish of zirconium oxide using Renfert Polish ZrO2 and the Bison brush
Preparation and use on Lithium disilicate – Renfert Polish LiSi2
The Renfert silicone polisher is used for prepolishing lithium disilicate (10 000–15 000 rpm). Overheating should also be avoided in this case, as cracks may occur with this material due to extreme heat fluctuations. Renfert Polish LiSi2 and a Bison brush are then used for polishing to a high luster (10 000–12 000 rpm). With Lithium disilicate the polish of the occlusal surfaces is just as important as with zirconium oxide, and also after the occlusion has been adjusted intraorally.
Prepolishing lithium disilicate using the Renfert silicone polisher
High-luster polish of lithium disilicate using the Renfert Polish LiSi2 and the Bison brush
Preparation and use on veneering porcelain, hybrid porcelain or high-performance resin – Renfert Polish all-in-one
There is always the question with veneering porcelain of what level of glaze is required. This should be oriented to the residual teeth, particularly in the anterior region. However, all areas of a crown or bridge that are in contact with the gingiva should be polished to a high luster. With veneering porcelain a glaze firing at 10–15 degrees lower temperature than that given by the manufacturer is advisable (this maintains the surface texture) to close small porosities in the porcelain. The porcelain is then polished using a Bison brush at 5 000–10 000 rpm and applying minimal pressure. Hybrid ceramics are polished using the same procedure.
High-luster polishing of veneering porcelains
Tip for the anterior region: tooth surfaces almost never have a shiny, high-luster surface but more of a satin finish glaze. The high-luster effect is only created by the film of saliva on the tooth. After the glaze firing and polishing using the Renfert Polish all-in-one, simply restore the matt finish of the buccal surfaces using a diamond-coated Renfert silicone polisher manually. Following prepolishing using a silicone polisher, high-performance resins such as PEEK are first polished using a bison brush and Renfert Polish all-in-one (5 000–10 000rpm) and then a shiny high-luster polish is produced using a wool mop and a small amount of polishing paste (5 000–10 000rpm).