FIGURE 2: Prepare the initial
post hole with Gates Glidden reamers.
FIGURE 4: Use the countersink/root
facer to form the final post-hole shape.
FIGURE 6: Shorten the post
apically enough to allow for full insertion plus an additional 1 mm.
MANY RESTORATIONS in dentistry, what fits so well initially may, depending
on a patientís occlusion, deteriorate over time. The weak point
in all overdenture systems is the connection between the denture
and the post. It wears out and must be replaced.
The Flexi-Overdenture® System from Essential Dental Systems
is no different. However, an addition to the system, the EZ-Change®
Keeper and Cap Insert (Figure 1), allows for replacement in less than one
Following is the placement procedure for the post, keeper, and
Prepare the initial post hole with Gates Glidden reamers (Figure 2).
Size the post hole with the primary reamer of choice. Note that you
can eyeball the choice by placing either a post or a template over an undistorted
X-ray. The minimum requirement for placement is 1 mm of lateral tooth
structure at the most apical placement of the post within the root (Figure
After you have created the primary post hole, use the countersink/root
facer to form the final post-hole shape (Figure 4). Because the countersink/root
facer is not self-limiting, you can drill the dual preparation (preparation
for the flange and second tier of the Flexi-Overdenture post) fairly deeply
into the root. Drilling deeply has the major advantage of shortening
the lever arm of the attachment to a bare minimum. The shorter the
lever arm, the less the forces of occlusion are magnified. Having
a short lever arm may become particularly important if the abutment root
is periodontally compromised.
Assuming that the primary reamer went the full length, make a trial seating
of the post to its full depth (Figure 5).
If the post hole is prepared short of its full length, the post will not
completely seat. To ensure seating of the postís flange, shorten
the post apically enough to allow for full insertion plus an additional
1 mm to make sure that the blunt apical end of the post does not impinge
on the tapered end of the post-hole preparation (Figure 6).
Before cementing the post, place an assembled EZ-Change keeper and cap
insert onto the ball of the attachment (Figure 7). Place marking
paste onto the keeper and place the denture over it. Remove the denture
and see where the marks are impinging the denture (Figure 8). If
the keeper impinges to the point where the denture must be perforated for
the keeperís clearance or the keeper impinges in an aesthetically compromising
fashion, you may deepen the preparation into the root with the countersink/root
facer to gain an extra millimeter or two.
After you have established clearance, place Flexi-Flow Cement with Titanium
into the canal with a lentulo spiral reamer. Place about three increments
of cement with an up-and-down motion; this technique will ensure complete
coating of the canal walls. In addition, coat the shank of the post.
The cement acts as a lubricant, further easing the insertion of the post
Before cold-curing the keeper into the denture, make sure that the rubber
band covering the undercut of the ball attachment is in place. Place
pink acrylic into the denture and seat the denture for about five minutes
or until the acrylic sets.
Remove the denture and relieve the excess acrylic around the keeper (Figure
10). You can now safely remove the denture from the undercut of the
ball attachment. With this system you may never need to cold-cure
any worn-out attachments again.
Place the denture in the patientís mouth. The relationship should
be the same as before cold curing the keeper into the denture.
If at some point the cap insert wears out, take the two-pronged wrench
provided in the kit and place it in the holes inside the cap insert and
rotate out the old cap with a counterclockwise motion (Figure 11).
At times the cap insert may wear out in such a way that the internal prong
holes wear away. If this is the case, heat the wrench in a flame
until the prongs are red and then insert the wrench anywhere into the nylon
cap insert. Wait several seconds while the melted nylon solidifies
around the prongs and again rotate counterclockwise for removal.
To place a cap insert (figure 12) , place the prongs of the wrench into
the holes inside the insert, line up the thread of the insert with that
of the keeper and rotate in with a clockwise motion. You will feel
a tactile click when the cap is fully inserted. Replacement is complete
within about 30 seconds chair time and there is no need for cold curing.
Reseat the denture. It should fit as before without any change in alignment.
FIGURE 1: The EZ-Change Keeper
and Cap Insert.
FIGURE 3: Size the post hole
with the primary reamer of choice.
FIGURE 5: Make a trial seating
of the post to its full depth.