Dental Tribune United Kingdom

About the author Ulrich Heker is the Owner-Manager of Ulrich Heker Dental Labora- tory, founded 1996 with the strap line “TEEH ‘R’ US”. As a qualified Master craftsman (Ger- man Master Dental Technician) since 1991, he has over 26 years experience both at the bench and in running a successful business. Ulrich lives in Mülheim at the river Ruhr and is an accomplished “Western Style” rider in his spare time. Ulrich is fluent in Eng- lish and can easily be contacted at: Ulrich Heker D-45130 Essen Corneliastr. 17, T: +49 201 797955, www.german-smile.info, ulrich@teethrus.de August 1-7, 201128 Clinical United Kingdom Edition snugly into this milled groove and rests on the ledge. The grooves and ledges are already incorporated dur- ing wax modelling and are pre-milled with special wax mills. The cast crowns then pro- ceed to the first fitting and the coping impression in the den- tal practice. The crowns are re- turned to the lab with the over- impression from which the master model is created. The abutment crowns are shaded with ceramics. Due to the ex- pected oxidation during the fir- ing of the ceramics, it is only possible to mill and polish the surfaces afterwards. It is a great help at this juncture if the dental position- ing has been established previ- ously. After firing, the crowns carrying the attachments are transferred with a key to the milling plate (made out of plas- ter of Paris or an appropriate holder). The milling plate now de- termines the position of the at- tachment. All the milling sur- faces previously cast in wax are then milled and polished. All milled planes are now abso- lutely parallel. The Teflon female compo- nent for each tooth is short- ened, as required, to fit the attachment’s length and is ap- plied to the male component. Undercuts are filled with wax. Here the female attach- ment cap also acts as a spacer – so do not interchange! Further casting proceeds as usual and the work is ready for the production of the model cast. The casting of the grooves, ledges and attachment compo- nents must be bubble-free. As with the production of telescopes, the handling of the model and the casting materi- als require considerable expe- rience in order to get a really good fit of the stress breakers and the base of the cast. The insertion of the female components (usual colour yel- low) into the cast is facilitated by a special tool which is in- cluded in each package. Inser- tion of the female component into the model cast should be possible using light pres- sure. If it is too loose, then it will fall out later: if too tight, then the whole model could be lifted or the patient cannot remove the prosthesis. The walls of the female part should be parallel, sitting completely within the model. Otherwise the model casting needs to be reworked. The conversion of the wax model into methacrylate does not require any special effort; however, one should not forget to protect the attachment from unwanted intrusion of the resin by blocking with wax. The housings for the female components are coated with composite, rendering the at- tachment invisible. It is advisable to have a notch close to the attachment, in the resin of the prosthesis, where the patient can find a hold with a fingernail for easier re- moval of the prosthesis. Small beads of clear plastic applied to the prosthesis can fulfil the same objective. Generally, rod attachments and similarly constructed at- tachments require a bordering gap in order to incorporate an extracoronal attachment. If the construction requires an attachment point in a still- complete dental row, then a groove-shoulder attachment can be used. These are intracoronal horseshoe-shaped elements that are attached to the oral side of the crown (hiding them from view) to which the match- ing interlocking denture with mirrored elements can attach (see article 1 in this series). The secondary construction, as well as a stress breaker, is made of high-quality gold alloy that is soldered with the mod- el cast to guarantee a perfect and tension-free fitting (Note: you cannot exchange the male component within RSS). Conclusion Ninety-five per cent of all at- tachment work can be com- pleted with the two attachment types described here. Attachments are par- ticularly applicable when it proves impossible to pro- duce parallel abutment teeth. The attachment is used to create a bridge be- tween misaligned abut- ment teeth such that a secure insertion of a prosthesis becomes possible. They can be a cost-effective alternativeto double crowns. They are aes- thetically attractive and user- friendly solutions for the pa- tient. DT “Excellence is the result of al- ways striving to do better” -Pat Riley page 27DTß Close up of Rod Attachments male Part - Typical individual attachment Collage of a so called RSS Attachment Collage of separating attachment in case of diverging abutment teeth A precision milling mashine Close up of Rod Attachments female Part ‘As with the production of telescopes, the handling of the model and the casting ma- terials require considerable experience in order to get a really good fit of the stress breakers and the base of the cast’