 MPLANTS
have, in the last 15 to 20 years, paved the way to restoration of the edentulous
and partially edentulous mouth. However, many patients cannot afford the
time or money required to complete this treatment successfully. Making
an Overdenture (OVD) using a simple ball-and-socket type of attachment
for extra retention is a proven and easy alternative treatment to implants.
The Flexi-Overdenture® attachment is based on
the patented split-shank Flexi-Post® for the highest retention of the
post in the root and the fewest problems. The ball-and-socket attachment
delivers high retention for full and partial dentures, providing a simple,
inexpensive overdenture at chairside. The Flexi-Overdenture supports a
nylon attachment that is incorporated into an overdenture (Figure 1).
Alternatively, and for great ease of replacement, a threaded version of
the nylon attachment can be threaded into an EZ-Change® metal receptacle
(keeper) that in turn is incorporated into the denture (Figure 2). The
post allows the dentist to utilize remaining roots to support the retention
of a denture.
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FIGURE 1
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FIGURE 2
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The
Steps for Placement of the Flexi-Overdenture
Try to retain two canine teeth in each arch for the abutments for the
OVD. If canines are not available, try to use bicuspids next. However,
any tooth—even just one tooth—will provide additional retention for the
OVD.
Determine the optimum post size by placing the plastic template over
an undistorted x-ray. There should be at least one millimeter of
lateral tooth structure at the most apical placement of the post.
After determining the correct post size, prepare the post hole, using
a sequence of Gates Glidden drills followed by the color-coded primary
reamer exactly correlated to your post size (Figures 3 and 4).
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FIGURE 3
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FIGURE 4
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After using the correct primary reamer, prepare the countersink/root
facer preparation with the countersink/rootfacer drill (Figure 5).
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FIGURE 5
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Try placing the post that corresponds to your preparation. It should
be fully seated (Figure 6).
If the post does not seat fully, shorten the apical end of the post
the appropriate amount for full seating (Figure 7).
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FIGURE 6
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FIGURE 7
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Coat the internal surface of the post hole and the shank of the post
with Flexi-Flow Auto® reinforced composite cement and place the post
into the root.
Let set for four minutes.
Place the nylon cap on the ball of the Flexi-Overdenture attachment.
Make sure that the colored rubber band is on the ball of the attachment.
The rubber band blocks out the undercut of the ball (Figure 8).
Mark the top of the nylon cap with a disclosing paste and place the
denture over the root (Figure 9).
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FIGURE 8
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FIGURE 9
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Remove the denture, noting where it has been marked with the paste (Figure
10).
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FIGURE 10
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Relieve enough acrylic from the denture to allow the denture to sit
passively over the nylon cap (Figures 11 and 12).
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FIGURE 11
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FIGURE 12
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Once you have confirmed that the denture is sitting passively supported
only by the ridges, place a doughy mix of acrylic into the relieved site,
place the nylon cap over the acrylic and keep it in position until the
acrylic hardens (Figure 13).
Remove the denture and relieve the excess underlying acrylic (Figure
14).
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FIGURE 13
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FIGURE 14
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The denture now has the added retention supplied
by the ball-and-socket attachment provided by the Flexi-Overdenture attachment.
Over time, the nylon attachment will wear, out reducing the amount of retention
it provides. The nylon attachment can be replaced by drilling out
the old attachment and cold-curing a new one in. To reduce the time
and effort necessary for replacement, Essential Dental Systems, Inc., has
developed the EZ-Change attachment for rapid replacement of the worn nylon
attachment. To incorporate it into the denture do the following:
Instead of the nylon attachment, place the EZ-Change attachment, which
consists of a metal receptacle (keeper) and a threaded nylon attachment
within it (Figure 15).
The two components of the EZ-Change attachment are incorporated into
the denture in the same manner as the original nylon cap.
When the nylon attachment now wears out, it is a simple matter to use
the EZ-Change wrench to unthread the worn-out nylon cap from the metal
insert and thread in a new one (Figure 16). No cold-curing is necessary,
the entire process taking only a few seconds.
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FIGURE 15
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FIGURE 16
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The ball-and-socket is very user-friendly for the patient.
It snaps in easily, the patient can both hear and feel when the ball is
seated, and there are no components to bend or break. This is a viable
and time-tested alternative technique for those who cannot have implants.
July-September 2005
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