Used in place of diatorics or bonding liquid on heavily adjusted teeth

1. LMT • August 2015 • www.LMTmag.com 34
How to Use Perma-Ret
to Improve Denture Retention
T
oday’s nano-composite, highly cross-
linked and hybrid denture teeth con-
tinually pose a retention problem in
cases with limited space once the
bondable lingual layer of PMMA has been
removed. Implant treatment modalities with
their rigid foundation and opposition exacer-
bate these compromised bonds.
To solve the problem, technicians often use
bonding primers, diatoric retention or slot the
lingual but I’ve discovered a better solution:
Perma-Ret, a pin retention system from Preat
Corp. The kit includes twist drills, a drill and
wire holder, collets and 80mm-long threaded
silver wire (see Figure 1). Similar to the way
metal pins are used to retain porcelain den-
ture teeth, the Perma-Ret wire is threaded
into a drilled hole in the denture teeth; the
wire is small and unobtrusive and provides
mechanical retention between the teeth and
the acrylic base. The placement technique is
easy to master and the kit pays for itself by
preventing repairs on warrantied dentures.
Here’s my technique; this is done during
setup:
1. Adjust the teeth to fit into the allowable
space.
2. Using the twist drill, drill a hole into
each tooth at a suitable angle and position as
dictated by the remaining acrylic and the hori-
zontal space before intrusion or perforation.
When I first started learning to use Perma-
Ret, I marked the drill bit with a magic marker
to indicate the depth of the hole and continue
to use this mark as a reference (see Figure
2). Preat recommends a 3mm depth but I’ve
drilled to only 1mm depth without any failure
in retention.
Using the mark on the drill bit, mark the
coinciding depth on the wire and place it into
the wire holder; expose only a short length of
wire so you don’t bend it. Thread the wire into
the hole in the tooth; you’ll feel a fair amount
of resistance while threading and your mark
ensures the wire hasn’t “bottomed out” which
can damage the tooth or wire (see Figure 3).
3. Snip the wire to 1.5-2mm (the porcelain
tooth pin length) and bend it to an angle if
needed. Don’t re-bend the wire as this will
fatigue and weaken it.
4. If needed in very tight situations, use a
rubber wheel to conform the tip of the wire to
meet the space requirements (see Figure 4).
5. Continue placing the teeth in the setup
(see Figure 5).
Figure 1 The
Perma-Ret Kit from
Preat Corp. contains
three twist drills; a
drill and wire hold-
er; two collets; and
13 pieces of 80mm-
long threaded silver
wire, which should
be enough to retain
at least 100 teeth.
Figure 2 When placing the hole and wire, remember that
retention is most effective when they are most perpendicular to
the dislodging force which, in most cases, places them parallel
to the facial. Position C in the center image would be the best
choice as it offers space and is the most perpendicular position-
ing which provides undercut. Marking the drill bit and wire with
a black marker helps to control depth of placement when you’re
learning to use Perma-Ret.
Preventing and Repairing
Midline Fractures
Before you put your Perma-Ret Kit away, I’d
like to share another application: preventing
and repairing midline fractures. When a case
comes into my lab for a midline repair, I reline
it with heat-cured GC Nature-Cryl®
because
it’s strong and prevents subsequent fractures.
Additionally, for habitually fracturing dentures,
I like to eliminate any occlusal wedging that
may propagate the fracturing and use Preat’s
eFiber reinforcement as well as Perma-Ret in
the reline/repair.
When using eFiber, place it as close as pos-
sible to the stress/fracturing point which, in the
majority of cases, coincides with the bottom of
the notch used to relieve the frenum. I place
Perma-Ret pins in the anterior teeth (see Figure
6) and use them as posts to support the eFiber
across the bottom of the notch. This allows me
to ideally position the eFiber and provide stable
placement of the teeth during acrylic packing
or injecting during relining (see Figures 7 and
8). If I know a patient habitually fractures his
denture, I’ll pin and place Perma-Ret and eFiber
when I’m processing a new one for him.
Thomas Zaleske explains how to use Preat Corp.’s Perma-Ret to provide mechanical
retention between the teeth and the acrylic base and prevent midline fractures.

2. LMT • August 2015 • www.LMTmag.com 35
Figure 8 Here’s
the denture rein-
serted into the flask
and packed as a
routine reline us-
ing the flask reline
technique. The void
is finger packed and
trial packed to en-
sure secure place-
ment. To prevent
fractures in a new
denture, perform the pin bridging, packing and curing.
Figure 6 When
relining a midline
fracture, I use the
closed flask reline
technique using
PVS putty that al-
lows me to remove
the denture from
the flask, remove
the tissue-bearing
areas and address
the fractured area.
Figure 7 I“pin
bridge”across the
midline by placing
a strip of eFiber
across the bot-
tom of the frenum
cut out (A) and
then wrap e-Fiber
around the Perma-
Ret pins (B) to form
a locked bridge. At
this point, I rein-
sert the denture
into the flask and
proceed with the
closed flask reline.
Figure 3 To gain
control and prevent
bending or tweak-
ing the Perma-Ret
wire out of shape
while threading it,
expose only a short
length of wire from
the holder.
Figure 4 Examples of various placements of Perma-Ret to ac-
commodate available space (from l. to r.): single pinned, dou-
bled pinned, tucked close and rubber wheeled.
Figure 5 Perma-
Ret can be used to
prevent breakage
or for repairs and is
an ideal way to re-
tain denture teeth
once the bondable
PMMA has been re-
moved from teeth.
Wire placement is
done at setup so
the wire angle can
be modified for
available space.
THOMAS ZALESKE has been a technician
specializing in removable prosthetics for 29
years. He’s worked as an in-house technician,
laboratory owner, author, technical colum-
nist, product developer, product manager,
technical support consultant and lecturer.
For more information about Perma-Ret,
contact Preat Corp. at 800-232-7732, 805-202-3070,
info@preat.com or www.preat.com