|
|
|
|
|
Lecture by Prof Nentwig and Dr Weighl on dental implants - Courtesy ROOTS
|
The opinions and photographs within this web page are not ours. Authors have been credited for the individual posts where they are. - www.rxroots.com |
From: Sanjay Jamdade To: ROOTS Sent: Sunday, May 24, 2009 1:45 AM Subject: Re: [roots] Dr. Nentwig and Weigl I attended Prof Nentwig & Dr Weigl's lecture. There were hundreds of facts and figures that I couldn't pen them all down. But those points which struck me were as follows:- 1) Before designing the system Prof Nentwig and 'What's his name' engineer colleague listed out what it is about dental implants that makes them less appealing to patients and dentist, what were the desirable characteristics patients and dentists both wanted. So in the 80's the duo set out to invent "the perfect implant ". That was in Frankfurt. 2) Amongst eliminating the undesirables, they decided to do away with a) the retention screw due to it's notoriety for breakages b) transverse screw retention that you see in Frialit and Xive systems c) doing away with tarnow's principle of inter implant distance d) doing away with crown root ratio e) doing away with large prosthetic inventory f) doing away with Augmentations amongst many others 3) Amongst the desirables was having a true to life emergence profile-no matter which diameter implant you used - rather emergence profiles have nothing to do with the width of the implant used. You don't need to put an implant to get an emergence profile. You can get the same in many other ways too e.g. ovate pontics 4) So they came out with progressive non cutting threads so that the bone has to be pre-tapped and reamed before rathcheting the implant in. This lets the implant get screwed in easily which on healing takes support from the cancellous bone rather than the cortical bone preventing cortical bone loss. They added a morse taper connection abutment to eliminate the securing screw. Which also led to inadvertent platform shifting as well as eliminating the microgap created by the clearance fit instead they have a cold weld which resists rotation As a result of the tapered connection-cold weld the bone does not detect the microgap between abutment and implant and the bone grows all over the shoulder. They recently added cell plus surface upto the shoulder of the implant to hasten the osseo integration. they have also added indexed abutments for the dntists who are keen on using indexing ( though both of them don't care a damn whether they are indexed or not). With bone growing on top of the shoulder/platform of the implant you have a well supported gingiva growing on top of the implant surrounding the healing collar giving excellent emergence profile as well as assuarance of logeivity of the implant due to maintainance of tissue support. The cold welding makes it, what Dr Ashok Sethi calls, the only "smell free implant abutment" They also have a "Syncone abutment" to use in an "all on 4"- Ankylos style, ofcourse with a gold plated female coping giving a snug feeling. This Syncone denture is cantillevered. 5) Dr Weigl showed plenty of slides of some very interesting situations e.g. narrow implant and a large crown with excellent soft tissue around the ceramic crown, narrow implant in the distal socket of a lower molar and a large cantilevered crown. 8 mm implants in Molars avoiding the lift, narrow implants in thin ridge avoiding lateral onlay graft most of the time. 6) immediate implantation in posteriors post atraumatic extractions, especially in multi rooted teeth. Even immediate implant and immediate loading, progressive loading. Temporization to achieve tissue contours justlike they were preoperatively. Two cantilevered molars on either side of lower and upper bridges. That too functioning for years without bone loss! 7) versatility of the reamer used for osteotomy. clockwise to condense and anti clock wise to ream. 8) immediate loading, early loading and regular loading. Did you know that early loading in 6 weeks can actually be beneficial to bone formation? He showed plenty of slides on dog and monkey studies. Prof Nentwig compared subjects with delayed loading protocol with that of early 6 weeks loading. The 6 weeks loaded implant actually collected bone around themselves! That is there is an over all time saving of about 50 %. He said that healing followed the same principles as would follow in a case of Jaw fracture. There were informative graphs on that. 9) The climax came when Dr Weigl compared the different systems which claim to have platform switching. He played the laboratory recordings of flexion and opening up of microgaps in all the claimants to platform switching. No prize for guesing that Noble Biocare fared WORST in the lab analysis. There was double opening of gaps for NBC one at the implant abutment interface the other below the collar ( I wonder how that is possible, is the collar seperately stuck on the implant in NBC implants?) So much for Noble Biocare claim of platform switching! He said that it isn't sufficient to have platform switcing you need a tapered abutment and subcrestal placement of implants for it to acheive any control on bone loss. Dr Nene and Prof Dr Turner from India gave interesting presentations on their experiences with Ankylos. I found their presentations very open minded, though they had little time for questions and answers. They had a flight to catch. The prosthetic restoration is what is going to be the biggest challenge for the Indian dentist with only a couple of technicians tuned in to the prosthetic rehabilitation nuances of this great implant. That is after they have over come the initial difficulty of arranging for the finances for the system as well as overcome Friadent's sluggish international service. In addition in case they have overcome the obstacle of patient's limited finances and overall lack of enthusiasm. If the Indian doctor can overcome these hurdles Ankylos will beat the competition black and blue. But knowing India and knowing Dentsply that numero uno position may take decades to reach. A fantastic but out of reach system for most Indian dentists. The Rolls Royce of Implants, too bad we can't afford:( - Dr Sanjay Jamdade Thank you, Sanjay! Kendo, thanks for doing what you are doing, Kendo, to help many of us around the globe, tirelessly and continuously, we do appreciate it tremendously. Can I also ask a few questions too, please tell me what you can about them. Others on the list can also chip in and enlighten us. "doing away with tarnow's principle of inter implant distance" what do you mean here? how near can the ankylos be put in - next to teeth, and next to another implant? am attaching a small pdf showing what tarnow has stated earlier - exciting to see if these principles can be narrowed even further. what about the blood supply to the neighbouring tooth then? and also to osseointegration of 2 nieghbouring implants also? "They added a morse taper connection abutment to eliminate the securing screw." the screw is still very much there, isn't it? Are they saying that immediate loading of narrow implants in extracted molar sockets is fine and works well all the time? Kendo, do you use Ankylos as immediate loading, or do you bury them every time? - viji "doing away with tarnow's principle of inter implant distance" Well Dr Weigl showed a slide why Tarnow put that principle of inter implant distance. It seems that when the eventual bone loss to the first thread does take place, the bone loss associated along with it would not be just vertical bone loss but also some horizontal bone loss. It is estimated to ne 1.5mm on each implant totaling to 3mm between two implants. That's where tarnow's rule of Minimum 3 Mm interimplant distance came from. And when that occurs the papilla just flattens out due to loss of support from bone below. You than cannot have papilla. With the Ankylos they claim that since there is no bone loss your implants can be closer. There were pictures of very closly kissing implants. I can't comment on the tooth-implant distance, cause don't remember any such discussion (hey occasionally I dozed off, but no one noticed and I was clever enough to take a back seat well in advance, these Professors can get monotonous after some time!) "They added a Morse taper connection abutment to eliminate the securing screw." Yeah the screw is very much there. But there is a difference according to the duo. The screw is used to help tighten the tapered connection. That's where it's role is over. It doesn't matter what happenes to the screw after the cold weld has occured. The screw does not secure or support the abutment it's the tapered connection that does. All the masticatory load and other loads are borne by the Tapered connection. The screws in other hexed abutments take a considerable load and are hence subject to occlusal loads and subject to screw loosening, metal fatigue and fractures. The Ankylos screw is plainly incidental. About the immediate loading of immediate narrow implants in Molars I have to admit that the luncheon at le Meridien was good and led me to feast on the lunch. I had my shut eye. Even the coffee wouldn't help me. (We have Prof Nentwig on record reccomending it for early loading patients!) So I can't confirm or deny that. But It was Prof Turner who showed immediate loading in premolars. (Actually by that time I was awake!). By the way to summarize the duo it could be said that they said "Size does not matter!" - Dr Sanjay Jamdade
