When black or white is not the only solution Part 1

14 april 2015

telescopicimplanttreatment

■ When black or white is not the only solution

– a telescopic implant treatment: Part 1

By Ulrich Heker, DTM Educational aims, objectives and outcomes ■ Educational aim: – to illustrate via a real life case study how multiple technologies can be employed to achieve a patient’s desired result ■ CPD outcomes: – to gain an overview of the specific issues that prevented the use of a standard approach to treatment – to illustrate how a team approach to a problem can achieve an ideal solution – to gain an understanding of the practical implications and techniques used to achieve a completely detachable prosthesis based on telescopic implants

Dentists are often faced with situations where black or white, prosthesis or implant, is not the only option. This is a case study of a telescope implant treatment (Kennedy Class 1) in the upper jaw of a female patient.

Ulrich Heker (Master Dental Technician) describes the treatment of a UK patient with a completely detachable prosthesis based on telescopic implants, combining the best of both technologies to provide an optimal solution for the client at a reasonable cost.

(T = telescope with implant; x = missing)

the

technologist

Case history The patient presented a unique challenge for the dentist. The 55-year-old female had worn a classical gold/gold telescope prosthesis for many years. The original elegant work had evolved over the years through repeated extensions and relining.

Finally, with a plate completely covering the palate, it had mutated into a full denture.

The patient did not want to wear a full denture under any circumstance, so now implants appeared to be the only alternative.

However, from an oral surgical point of view, both sides were unsuitable for implants due to the lack of bone material.

The patient had also rejected the necessary but expensive augmentation of the molar areas. Individual attachments were also out of the question, as the patient wanted a palate-free prosthetic solution.

After thorough consideration, the decision fell in favour of a combination of implants with individual abutments and detachable, palatal bar-free telescope prosthesis.

This was the situation:

april 2015 15

telescopicimplanttreatment

Technique Planning

core verifiable CPD

The cost would have been exorbitant if I had followed the conventional route of using high gold/platinum content or semi-precious alloy to make all the inner and outer parts. I estimated it would need 25–30 grams of high concentration gold or gold-reduced alloy, such as Degulor® MO, to guarantee sufficient material thickness/strength.

bonded to a chrome cobalt (CrCo) tertiary structure using a two-component cement.

CrCo also allows a less bulky construction than using gold alloys, whilst also reducing the need for soldered connections. As there were to be no transversal connectors, the design of the tertiary structure was critical.

Fig. 1: RN Variobase

The alternative consisted of primary parts made from non-precious metal (NPM) alloy, capped with 0.2–0.3 mm of gold as secondary crowns. These would then be

The patient was fitted with Regular Neck (RN) implants. After a successful healingin, the RN implants were exposed and a pick-up impression taken with an individual tray over the impression posts.

The author recommends using an open special tray that is rigid, to allow access to

the retaining screws of the pick-up impression copings.

After preparation of the gum mask, measurements could be taken from the master model with laboratory implants.

The replaced impression post screws acted as axis extensions of the laboratory implants. This gave a simple and more definitive means of optimising the axis of insertion. An extra split cast meant exact repositioning was possible at any time.

The RN® burn-out copings were attached to the screwed-in bases and adjusted to length as necessary in the articulator.

materials & equipment

Fig. 2: Situation after exposure

The primary parts were milled on RN burn-out copings in wax and cast in non-

Fig. 3: Positioned and shortened RN burn-out copings within gum mask

the

technologist

16 april 2015

telescopicimplanttreatment

�

� � Fig. 4: Milling the primary parts in wax

�

Fig. 5: Finished wax milling

Fig. 6: Primary parts before casting

precious alloy. The secondary parts were smoothed and carefully attached to a Straumann RN Variobase®. The units were then screwed into the master model, precisely milled and polished.

a certain period of time. With Galvano crowns, this can quickly lead to a loss of adhesion that cannot be restored.

However, in the author’s experience, the combination of materials used here avoids this issue and has the following advantages:

Fitting of the primary parts with a pick-up impression is not necessary at this stage, so modelling of the secondary crowns could be started straight after milling.

In order to avoid confusion over the abutments, a key base was made from light cured acrylic (plastic) to act as a positioning reference.

� Signs of wear in the primary parts are completely prevented owing to the hardness of the non-precious metal (NPM) alloy. � Primary parts in non-precious metal (NPM) alloy can be made much

thinner than when using precious alloy.

(The fact that the primary parts are coloured silver instead of gold should be discussed with the patient beforehand and consent given).

The consistent, highly polished finish of primary parts made from NPM, reduces the ‘scratching’ of the inner surfaces of the secondary parts. Here, the primary part works rather like a non-abrasive polisher, as seen in the broad, glossy friction surfaces.

Production of the secondary parts is less expensive.

Longer lasting friction when compared to Galvano (electroforming) high gold crowns.

Secondary parts can be reworked and re-milled safely, as they are substantially more stable than thin, pure gold Galvano crowns.

Note: The fitting of the outer parts should be carried out under the stereomicroscope, with repeated checking using a contact colour such as Tanaka Bite-X. The components were subsequently fixed to the primary parts and milled again.

The final milling creates parallel external surfaces, important for the production of the metal frame. Using parallel guides also meant there was no danger of unexpectedly perforating the secondary parts.

The coarse milling cutter used at this stage gave the desired amount of abrasion whilst also creating an ideal adhesive surface.

Careful modelling in Pattern Resin® and subsequent pre-milling of the plastic caps significantly reduced the time spent on metalwork.

If you look closely under a microscope at the friction surfaces in conventional telescopic work, you nearly always see narrow striations and traces of wear on both primary and secondary crowns after

the

technologist

Fig. 7: Individual telescope abutments

Fig. 8: Modelling of the secondary caps in Pattern Resin®

april 2015 17

telescopicimplanttreatment

core verifiable CPD

Fig. 10: Milling the Pattern Resin® caps

Fig. 11: Secondary crowns finished for final milling

Fig. 12: Parallel milling and simultaneous thinning of the secondary crowns

materials & equipment

Fig. 9: Key base to help avoid rotation errors of the primary parts in situ

Temporarily blocked in casting resin, the secondary parts could be removed for testing. It was now possible to see whether the work carried out so far was error-free.

For fitting, a 1.5 mm Erkolen® foil was thermoformed over the complete work for positioning. Following small corrections, the try-in was secured using a matrix.

Normally, milling on the master model would be frowned upon as there are certain inherent risks e.g. accidental damage. However, the removable gum mask leaves sufficient working space to allow milling without the risk of damage to the model. Open analogues should be protected by means of an impression post.

A useful tool for work with abutments is an acrylic extension attached as a handle to the lab implant.

Making the tertiary structure to the final fitting Part II of this article will appear in the next edition of The Technologist. It will take you through the final stages of making the tertiary structure and the final fitting of the telescope implant. The article will also include a list of all the materials used and the manufacturers.

Conclusion A dentist is often faced with situations where black or white, prosthesis or implant, are not the only options. Apart from the oral surgery considerations, there are also factors such as the patients’ preferences and cost. With this article, we have taken you down the road towards a solution that combines the best of both worlds in a case study of a telescope implant treatment (Kennedy Class 1) in the upper jaw of a female patient. Part II will continue with the completion of the

treatment, patient and dentist feedback and supporting practical information.

About the author Ulrich Heker is the owner-manager of Ulrich Heker Dental Laboratory founded in 1996 with the strap line TEETH ‘R’ US. As a qualified master craftsman (German 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 on the river Ruhr and is an accomplished ‘western-style’ rider in his spare time. Ulrich is fluent in English and can be contacted at: Ulrich Heker, D-45130 Essen Corneliastr. 17, T: +49 201 797 955, ulrich@teethrus.de, Video skype: TEETH ARE US, www.german-smile.info.

the

technologist