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Proud members of D.I.A.C. since
1992
Dental
Industry Association of Canada
Association
Canadienne de l'Industrie Dentaire
dent-line of canada inc.,
1170 Concession Road 4, Loretto,
Ontario, Canada, L0G 1L0
Customer Service:
1-800-250-5111 for Canada
Tel. 519-942-9315
Fax. 519-942-8150
Exclusive
Distributors of Bredent Products in Canada since 1991
Proud Distributors for Renfert USA since 1991
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The Dent-Liner
Volume 5 Issue 2
Spring 2001
A BULLETIN DEALING WITH ISSUES FOR DENTAL HEALTH
PROFESSIONALS
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
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- Simple and precise for milling,
surveying and drilling.
- RPM 0 to 30,0000
- Right or left hand rotation
- Rapid exhange of burs.
- Runs smoothly and vibration free.
- Ergonomic adjustable table.
- Functional locking lever
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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 1-800-250-5111 or 905-775-4446 or email us
at info@dent-line.com.
Today's
Product: Tricutter Bur
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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
1-800-250-5111. |
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
1-800-250-5111
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
The Dent-liner; Vol. 5, No. 2
Publisher: Peter T. Pontsa RDT
Editor: A. Van Breemen BA
E-Mail: info@dent-line.com
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