Topics of the day:
1. Cementing Stainless steel crown Herbsts
Roy King asked a question about cementing ss crowned Herbst back about a month ago. I'm sorry I didn't respond in a timely manner. When I looked at the responses I felt that I should chime in too.
I use a lot of cantileverd ss crown Herbsts and we have a technique that works very well. I virtually never have loose crowns and my chair time at removal is 4 minutes. No sweat on my part and no red knuckles for the patient.
One key to bond success with crowns is to not cut down their occlusal-gingival length. You need this length for retention - crown length is nearly as important as the cement.
To cement the crown we use GC Fuji ortho LC mixed on a cold slab. We mix for two crowns per mix since the cement sets rather quickly. After isolating the molar we do a critical step at the cementation for ease of removal: We place a piece of sheet casting wax intimately on the occlusal surface. The wax is: Sybron Kerr casting wax sheets - gauge #26 green. It comes in a box of 32. Wax on the occlusal is light years ahead of Vasoline as a barrier and does not make for loose crowns.
When making the Hebst, we adapt the wax to the occlusal of the molar on the patient's study cast to get the correct size and shape. At cementation I dry off the tooth and push the wax tightly onto the occlusal surface of the tooth. The wax sticks very well when all is dry and provides a total barrier for the cement to not bond to the occlusal surface. Once the wax is in place we push the crown down with finger pressure and the cement oozes out around the crown. We quickly use high volume suction and the air/water syringe to wash off all the extra cement. After most of the cement is rinsed off, we have the patient bite down on the plastic side of a band seating instrument to fully seat the crown. A little more cement oozes out and we proceed to fully rinse off all the extra cement before proceeding to the next crown. My doctor time to do four crowns is 4 minutes - but when I am finished there is no additional clean up.
At removal I use the high speed hand piece with a cross-cut fluted carbide bur and score a cut from the gingival border (almost) of the crown at the mesiobuccal line angle. The cut extends across the occlusal to the distal of the tooth. I cut all four crowns first. Next I use a bond removing plier (Orthopli 098-A) to remove the crown. I warn the patient that I will pull somewhat hard on their tooth so they know what to expect. Usually little tugging is necessary. I use the plier to grab onto the crown at the gingival aspect and at my bur cut and squeeze, twist, and peel to remove the crown. They come off with little effort. If their is resistance it is usually due to the bur cut not extending gingival enough at the mesial buccal line angle.Simply cut the crown a little more with the handpiece.
When the crown is removed there is absolutely no cement on the occlusal surface. I frequently take a scaler and simply flick off the wax if it doesn't come off on its own as the crown is removed. We rinse off the tooth as I am flicking off the wax. There will be some cement on the buccal and lingual which comes off easily with a Rocky Mtn band remover and gentle pressure. A scaler is helpful too. The work in removing a crown is cleaning the occlusal which we never need to do. The buccal, lingual and even the mesial and distal clean up easily and quickly without a handpiece or ultrasonic scaler. This procedure can be delegated in some locales.
I have used this approach for years. It is consistent and reliable. I learned the approach in bits and pieces. I have never seen it presented this way at a meeting.
Their is a steep learning curve to nearly every nuance about the Herbst. However,every little thing makes all the difference.
Critical error on my Herbst bonding message. I improperly listed Fuji LC as the cement I use for Herbst cementation. Sorry I was looking a bottle we use for occasional bracket placement. I picked up the wrong bottle to get the label information. The Herbst cement we use is: /GC Fuji I Glass Ionomer Luting Cement.
We have a patient diagnosed as Marfan's syndrome seeking Orthodontic treatment. The patient demonstrates many features of marfan's syndrome, (Cardiac abnormalities, hyperextension of joints, dispropertionate limbs etc. However, no webbed fingers) Is it a contraindication for orthodontic treatment considering the collagen status of such a person? Any information about managaement (including references)would be greatly appreciated.
Dr Ganesh Somayaji
Any suggestions regarding digital study models? What are the options out there now, how do they stand up legally and what happens to the models if that company goes belly-up or is bought out at some stage in the future. Is there any option out there to scan models in an industry standard, platform-independent format which can then be read and measured in a standard CAD application, in the same way as a 2-D image can be captured in JPEG, TIFF or .pdf formats and opened in any of many applications. Any help very much appreciated.
Does anyone know of a source or pricing of x-ray scanners for dental impressions? Has anyone on ESCO tried this? A private email is fine if this needs to be kept classified <g>.
11TH INTERNATIONAL SYMPOSIUM ON DENTOFACIAL DEVELOPMENT AND FUNCTION
June 18 - 22, 2006 Sheraton Chicago Hotel and Towers, Chicago, IL USA
The 11th International Symposium on Dentofacial Development and Function, one of the most important events in the fields of craniofacial biology, orthodontics, and dentofacial orthopedics, to be held in Chicago at the Sheraton Chicago Hotel and Towers from June 18-22, 2006. We are requesting your sponsorship, participation, and friendship.
The meeting presents an opportunity for clinicians and researchers to meet dentofacial specialists from all over the world and gain exposure to the latest advances in research, techniques, and products through educational courses and a trade exhibition. An exciting interactive program has been assembled based around the following themes: Craniofacial Genetics, Bioengineering and Technology, Tooth Agenesis and Craniofacial Anomalies, Management of Functional and Behavioral Problems, Clinical Orthodontics, and Clinical Pediatric Dentistry. In addition to an exciting scientific and clinical program on the Chicago lakefront, an outstanding social program is planned to promote greater audience participation and communication with the speakers and exhibitors. Don't miss this opportunity to join your peers in one of the most exciting cities in North America-- Chicago . Network with dentofacial specialists from all over the world while gaining exposure to the latest advances in research and techniques through an extensive educational course and trade exhibit.
Welcome to visit the Symposium website at http://www.uic.edu/depts/dort/symposium.html for detailed information on our speakers, programs, registration, and abstract submission.
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