All-in-One Procera Implant Bridge (PIB) versus ... - Nobel Biocare

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Materials and equipment Figure 2: Three implant level fits at 20 times magnification of a 14-unit seven implant PIB responsibility — just tell me what to do! I can hear the crunch of pliers, the bang of a hammer, all to deliver yet another passive substructure. After all this, Wirz et al concluded, ‘Soldered joints are described as having a clear reduction in corrosion resistance, not to mention tissue irritation.’ (And so will lead to fracture, due to elements in solders that help to reduce the temperature.) At the time, it was all we had, and it still has its place in modern dentistry today. Technicians lived, and technicians retired and died. There were those who could solder in this way and who thought it was good. There were those who were not so good at it and who looked for other ways, so that they didn’t have to do it any more. Treatment plans changed, as did techniques; and so the seed was sown. These were difficult times for those who knew not how. The birth of laser-welding Then came the birth of ‘titanium’ in everyday dentistry. Now, not only could the inattentive and under-trained not solder, but neither could the skilled! The race was on to solve the titanium soldering problem. In a flash, ‘laserwelding’ followed, healing all wounds. An intense heat source heats just the area that needs melting together to the maximum depth of 1.5mm (an average connecter on a bridge should be 3mm). Technicians were happy again because: • There were no more investment models • It was direct on the model • There was no more flux • It was quick. Although it is always unrealistic to expect perfection, I was surprised when I read a recent article on laser/phaserwelding, (Lightening in a Bottle by Joachim Mosch, Andreas Hoffman and Michael Hopp), in which they make the assertion that, ‘This development can actually be considered one of the major breakthroughs (advancements) in dental technology in the last 15 years.’ They go on to say: • ‘Proper welded joints will lead to a perfect passive fit’ • ‘Consequently, the surface condition of the components to be welded (highly polished or sandblasted) will influence the effect of the laser energy. The shinier the surface the less effective the laser will be, as more of the light energy hitting the object will be reflected away, reducing the ‘melting’ effect’ • ‘Laser-welders typically need service and maintenance once a year, and a new laser lamp, every three years’ • ‘In a laser-welder, the argon gas needs to be adjusted almost every time before welding, and the position of the nozzle is often in the technician’s way’ • ‘The energy needed to penetrate the 1.5mm would overheat the alloy’ • ‘Practically, distortion must also be considered. To avoid distortion during the welding process, place the spots carefully’ • ‘The bent bar at the top prevents distortion’. I stopped reading at this point because it seemed to me that the overwhelming evidence pointed to the fact that to produce a passive, complicated implant integral structure is but a dream. I personally saw a laserwelded implant bridge, where one of the fixtures was shy of the implant replica by 0.5mm. For me, laser-welding is not the answer. It can do things that conventional soldering sometimes cannot do, but it is still only as good as the technician who is using it. There is still a ‘melting pool’ contraction at the site of melting the metals. Depending on the user, and using conventional soldering, this can be larger than a precision-soldered join at 0.2mm. After studying articles, and trying the process myself, I find laser-welding has more applications than conventional soldering, but I do think that in conventional work, when repairing holes in castings, the time taken to re-wax and add the new unit into the Private Dentistry October 2008 105
‘I can now finalise my substructure in the lab and start to be creative with much more freedom and expression than ever before. I can fire my titanium porcelain onto some PIBs and I can use Gradia composites on others. I am making single unit substructures through to full arches, and they can be made in zirconia as well as in titanium.’ next casting ring is more accurate and less time-consuming. In bridge cases, where the metal needs actually to touch on another at the welding join, it will require a much higher level of skill than conventional soldering in order to ensure that, by adding and subtracting to the join, it touches exactly. All that sounds troublesome and time-consuming to me. But there again, laser-welding does have its place, because it is one of the only methods that work with titanium. And even now, with experience born out of 12 years of marriage, a little voice is saying in my head, ‘Be constructive; do not just criticise.’ We knew it all along So there it was all along, the answer right from the beginning. As technicians, we all do it every day and all the time, on nearly every coping we make. We mill it and trim it. No soldering or welding in any shape, way or form. No heat expansion or contraction, no gaps to fill, no flux to contaminate, no technique-sensitive preliminary procedures, no material cost. Just hours and hours of milling and cutting, until our fingers fall off and we join the exhausted heap of solderers and laser-welders of time gone by. I am sorry and afraid that my story is not over yet! I have been over-seeing this method by using cad-cam and a milling machine in the construction of passive units, using the Procera All-in- One system for the last four years. (In an attempt to save my fingers and it is so easy.) Yet, it does not seem to be part of our everyday routine in every laboratory and dental practice. It is being challenged by other less accurate products on the market. Why doesn’t anyone seem to be talking about it? So I wondered; am I missing out on the miracle of laser-welding? Might I need to buy one? I used the Noble Biocare open tray technique, in which screw-retained impression copings are connected and duralayed to one another, and a viscous, hard-bodied accurate impression material is injected into a custom-made tray. In this impression, the soft tissue solid model is poured, and on this a diagnostic try-in is created, using metal temporary cylinders that are connected together in acrylic. I then finish the framework in acrylic and Sweden does the rest. My reward is an engaging (single-units), non-engaging zirconia or titanium, allin-one milled structure that fits. And, boy does it fit! This fit (see Figure 2) is due to its unsurpassed ability to contact-measure simple, pure, implant replicas of given dimensions, and then laser-scanning the external framework, which does not need the accuracy of contact-scanning. Together this arithmetical equation is re-enacted with milling tools, transforming a solid homogeneous titanium block into dentistry at its best. I welcome this form of technology in my profession. It ensures for the patient what would be unachievable by man. I can now finalise my substructure in the lab and start to be creative with much more freedom and expression than ever before. I can fire my titanium porcelain onto some PIBs and I can use Gradia composites on others. I am making single unit substructures through to full arches, and they can be made in zirconia as well as in titanium. The only limitation with this phenomenal product is that, with screw-retained substructures, you are unable to deviate more than 20 degrees from the implant screw-hole opening. (You can also use the multi-unit abutment for Noble Biocare implants that can correct an axial alignment of the implant for the desired positioning of the screw-channel, etc — the list goes on.) We are, however, able to work around most implants’ head-placement, as implants at bone level mean that the point of rotation allows for a marked relocating potential of the access hole. This deviation, in measure, is about 7mm at 2cm from axis of rotation. The access-hole is smaller than some rivals, as the screwdriver access is the thickness of the screw-head, rather than the screwdriver used. Using a composite case, if you want the screw to be integral in the framework, the hole is much more discreet because the screwdriver shaft is only 1.5mm thick. What I like most about the PIB method is the freedom of aesthetics. It is, at last, a solution that I would use in my own mouth instead of a denture. As a technician for 20 years, I have always maintained that the aesthetics of full arch implants and their emergence profiles with long root effects do nothing for me. Some dentists say, ‘It does not matter what’s under your lip because you cannot see it.’ I suspect that many patients, given the choice, would actually have existing work redone for better tissue aesthetics. We have the materials and we have the skills. All we need to do is educate dentists, technicians and patients, and encourage them to use it. PIB benefits The advantages of PIBs are manifold. 106 Private Dentistry October 2008
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All-in-One Procera Implant Bridge (PIB) versus ... - Nobel Biocare

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