Denture Neutral Zone
This article will cover two methods of the neutral zone and some techniques in full dentures and how it relates to placement of implants. The neutral zone is the area where the displacing forces of the lips, cheeks and tongue are in balance. It is in in this zone that the natural dentition lies, and where the implants should be positioned. Comfort and speech is better with neutral zone dentures compared to conventional methods since the neutral zone uses the patient's physiology rather than the natural landmarks. The first method starts with making a lower base plate, next, mix green and red compound material together. start to melt red and green compound on the base plate about 4 mm, then adapt the mixed compound to form a bite rim. It should be placed in a water bath to soften the compound, When it is ready place it in the patient's mouth. The patient is then instructed to drink warm water. When swallowing, the cheek and tongue will compress the compound to create a matrix for the neutral zone. Repeat the process to maximize the result, then trim away the excess and retry the base plate for stability. Continue to process until the compression stops. If the maxillary is not edentulous, make the bite trim short as to have no contact with the upper teeth. Place the compound base plate on the aster model. Using silicone lab putty, make a matrix of the labial and lingual aspect of the neutral zone indicated on the base plate. remove the base plate to expose the mandibular ridge. Using the labial and lingual matrices, you can fabricate a neutral zone stent to help in location and angulation of the implants in the zone. In the second method a wax rim and a special tray of acrylic are adapted to the lower ridge with spur or fins projecting upwards toward the upper arch. This helps with retention of the impression material Two occlusal pillars are built up in self cured acrylic on opposite sides of the lower arch (approximately the area of the first molars). These pillars are moulded and adjusted to the correct height so as to give the usual 3 mm freeway space. A thick mix of viscogel is then placed around the rest of the lower tray distally and mesially to the occlusal pillars. The patient is then asked to talk, swallow, and drink some water. After 5 to 10 minutes the set impression is removed from the mouth and examined. The viscogel material will have been moulded by the patient's musculature into a position of balance. Then we follow the same procedure for constructing the matrices of the labial and lingual. Next set up the bite registration using a face bow and mount. use a bar and clip system for the over denture such as the Bredent VSP snap joint, Set up the teeth using the lingual side of the silicon matrix of the neutral zone. the teeth should have a lingualised occlusion that results in a stable position of the denture at every articulating movement, protrusive and left or right lateral movements. many implant companies recommend lingualised occlusion for implant retained restorations. This approach is better than an anatomical one especially when there is little muscle control. During try in stage an impression should be taken of the external tongue with the denture implant. At this point wax can be added to the denture for stability before processing, On final insertion the patient should find the denture quite firm and stable.

Bredent has just introduced a new product that will eliminate cross contamination in the polishing process. dangerous germs multiply in the pumice slurry through relines and repairs from different patients. Furthermore in conjunction with the pumice disinfectant, the pumice power remains most for 2 -3 weeks without mixing new powder. This disinfectant contains natural scents as well as skin care additives. The pumice disinfectant increases the adhesion of the mixed powered to the brush and the denture. This way it saves polishing time since it is not required to take up pumice slurry as often. This also avoids many splashes. Call Dent-line for prices at 1-800-250-5111

Mercury Fillings Lawsuit Launched
A class action lawsuit was filed in court on May 31, 1998 on behalf of all Canadians with mercury fillings in their mouths who were never told of the potential risks. "It could be billions of dollars", said David Himelfarb, the lawyer bringing the action against the Canadian government, provincial dental association and manufacturers, Dentsply International and Johnson and Johnson. Himelfarb represents about 8,000 patients who have or once had the fillings. "Canadians for Mercury Relief" wants money to have them replaced. the group asked the court for a broad definition of eligible members. It hopes all Canadians with fillings be included in the lawsuit. Effects of mercy exposure include memory lapses, hot flashes and paralysis, a news conference announcing the suit heard. Research also indicates links to Alzheimer's, the group said. But Health Canada said the fillings are not causing illness in the general population, and a "total ban .... is not considered justified". Source: Toronto Star, April 1st, 1998.

Seminar Date
Dent-line of Canada will sponsor a presentation on various attachments and screw retained bridge work. The seminar will take place at the 25 th Anniversary of Technorama 1999 to be held Friday March 26,1999 and Saturday, March 27,1999 at The Inn On The Park, 1100 Eglinton Ave. East, Toronto, Ontario, M3C 1H8. Continuing education points would apply. Plan to attend a once a year opportunity to participate in a two day program designed just for you! For additional information call 1-800-250-5111

VKS SG Housing
The VKS-SG castable Housing is available in both 2.2 and 1.7 mm. The housing is CAD CAM designed and is manufactured from extruded plastic which burns out in the furnace. You sprue and cast in the alloy of your choice. It can be soldered onto a chrome partial or can be incorporated into acrylic since it has an extended tag for retention. This housing gives the user more control over the outcome if the chrome casting is not made in house. The housing can be utilized for new cases or old cases that may require a repair or a rebuild. For further details contact Dent-line of Canada Inc. at 1-800-250-5111

Did You Hear the One?
A gentleman was invited to give a speech at a dinner banquet. On his way out of the house, he forgot his dentures. As a result, he arrived at the function in a frazzle. One of the event organizers noticed his frustration and asked if he could help. He explained that he had forgotten his dentures and needed them to speak and eat. The organizer pulled a denture out of his pocket and handed it to him to try. It was too loose, so he gave him another, but that one was too tight. Finally, the third denture fit well enough for him to go on with the dinner and speech. He thanked the organizer profusely, where upon he asked him where his clinic was located, since he was in the market for a new clinician. The organizer said "I'm not a clinician, I'm an undertaker".

The Dent-liner; Vol. 2, No. 3
Publisher: Peter T. Pontsa RDT
Editor: A. Van Breemen BA
E-Mail: info@dent-line.com