Dent-Line of Canada Inc. Toll Free 1-800-896-6544 (for Canada only) 416-858-9865 or Fax No. 416-858-9899

Spring 2001


Inside This Issue
1. Post & Care Analysis
2. BF1 Milling Machine
3. Today’s Product: Tricutter Bur
4. German Dental Practice Insights
5. Trade News – Technical Wax & Milling Course
6. DNA Test on 600 year old teeth

Post & Core Analysis

Post and core analysis is comprised of both structural and retentive strength collectively. In over denture construction, the post and core is integrated into the natural root. It becomes evident that the construction of retentive ball/post core combinations is the foundation upon which the restoration relies. It is with this in mind that we will review published reports on post & core analysis. The first study examines the structural analysis of metals used in the construction of post & cores. It was carried out by L.Hassler, R.Milde, K.Krowsznsky and G.Gehre; this report was prompted by the results of their earlier investigations. They combined Pd. Co.and Ni. based alloys with prefabricated posts made of Pd/Ir and Fe/Cr/Ni as well as customized posts cast from the above mentioned base alloys. With the aid of physical and metallo- graphic analysis, the micro hardness, the particle size of the structure, the width of the gap between root post & core and the precentage distribution of shrinkage voids (porosity) in the cast post & cores systems were assessed. Based on the results of these analyses and considering their earlier studies of the corrosion resistance of these similar systems, they recommended in order of preference the combi- nation of copper free Pd/Ag, alloy with a prefabricated Pd/Ir post & core and as a second preference, a one piece cast post & core system using Pd/Ag , Co/Cr, Ni/Cr alloys. It should be noted here that Bredent recommends a least a 270 HV on cast balls and post to prevent premature wear on the supportive retention balls in the VKS attachment system. Another critical aspect of post & core for over denture is the retentive strength of root posts. This study carried out by I.Nergiz, R.Schnage and U.Platzer was to measure the retentive strength of a tapered root post with smooth or grooved surfaces. After insertion with phosphate cement, and to determine whether retention can be improved, they sandblasted the post and increased the surface roughness of the root canal. What was obsevered was that the posts with the sandblasted surfaces was 2.4 times more retentive than that of posts with smooth surfaces (218 Newton’s). The use of a standardized diamond coated rotary tool to prepare the root canal (clinical) prior to cementation of the sand blasted post resulted in an increase of retention of 4 times (836 Newton’s) as opposed to posts with a smooth surface. More over in all types of posts, grooves additionally improved retention by 38%. In the final study the aim of A. Shulz and T. Morneburg was to prevent the extrusion of cement beyond the apex during cementation. What they found was that the post with three vertical grooves the length of the post showed a significant reduction of extrusion of cement. What this study and the one before it shows isthat proper seating and increased retention occur when grooves are placed on posts prior to cementation. Accuracy should also improve when an over denture case follows the post attachment ball placement. The choice of base alloy for post & core construction is also important to the final outcome. Source: Peter T. Pontsa RDT

BF1 Milling Machine

The Bredent BF1Milling Machine is designed to be simple and precise for milling, surveying and drilling. The upper unit can be locked in any position or used as a free floating milling arm. The unit is made of rigid construction containing aluminum and stainless chromium steel weighing 18 kg (40 lb.). The micro motor is made by Schick and runs very smoothly and vibration free with a quick change chuck system for rapid bur exchanges. The motor unit has an on/off switch or optional foot control with forward and reverse rotation and variable speed 0 to 30,000 RPM. The high speed ensures safe and precise drilling even in hard Co/Cr alloys. There is an ergonomic adjustable table with an eye level working position. The functional locking lever for the model holder allows you to lock in a horizontal position with a turning range of 90 degrees. This allows vertical drilling while utilizing the built in micrometer that acts as a depth stop for holes or grooves. Also at the heavy duty base there is a plastic removable tray that collects scraps and ensures a clean working area. With all these features the BF1 milling unit provides an excellent price to performance ratio. For further information call 1-800-859-7589 or 905-775-9654 or email us at [email protected].

Today’s Product: Tricutter Bur

The bredent Tricutter is the easy cut bur for removal of your Thermoformed sheets effortlessly. The three sided bur will not jam in the material because of the advanced blade concept. It will cut and separate impression trays, occulsal splints, bite templates, bleaching trays, fluoridation trays and bruxisum splints. For more information call 1-800-859-7589.

German Dental Practice Insights

The number of dentists is expected to increase by an average of 2.1 % over the next few years. Due mainly to the fact more young dentists are pushing into the market than older ones retiring. Experts predict that a price war is inevitable. This has led dentists to introduce special offers and services, mainly aimed at wealthier clients. A notable trend from practice consultants has resulted in increased profit pressures. The dentist patient relationship is characterized by direct quality and cost control resulting in more clarity of treat- ment and prices. So dentists who previously focused on restorative treatment have seen a drop and have had to resort to preventative treatment. New and increasingly complex technologies and treatment methods force dentists to specialize, thus, the trend to practice networks, capable of offering the whole spectrum of services continues. In the eastern German states, 10% of dentists have formed cooperative networks and 15% of western German dentists cooperate in networks, which has doubled over the past ten years. Even though costs for dental lab services have risen disproportionately within the last few years, dental technicians increasingly face the down loading effect of price pressures burdening the dentists. Source: Infodent No. 23/2001

Trade News – Technical Wax & Milling Course: Invitation to Canadians

The technical waxing and milling course to be held in Germany in July has a few more vacancies. Although there is a cost for hotel, lunches and lab materials the experience of working with master technicians in a high tech lab under optimal conditions is exciting and rewarding and should not be missed. For details contact Peter T. Pontsa, RDT at 1-800-859-7589

Tid Bits: DNA test conducted on 600-year-old teeth are confirming that the rat-borne bacterium Yersinia pestis was indeed the cause of the medieval Black Death. Source: Infodent No. 23/2001