to fabricate mouthguards and vacuum-formed
templates. Many of the steps involved in fabricating
these devices are similar and fairly simple to learn.
Mouthguards are constructed of acrylic resin or
vinyl-like material that covers and protects all of the
teeth in the arch. The purpose of a mouthguard is to
reduce the potential for injury to the teeth and
surrounding tissues. Although a mouthguard does not
prevent the teeth from fracturing, it does keep the
fragments from lacerating or embedding in the oral
tissue. The mouthguard also reduces the risk of
concussion by acting as a shock absorber. If the head is
impacted, the guard cancels part of the force, reducing
the risk of concussion.
Preparing the Cast
The first step in fabricating a mouthguard is to
draw the outline of the mouthguard on the cast with a
soft lead pencil. Design the mouthguard by drawing or
scribing a line around the maxillary arch in the buccal
flange area to the highest point to which you want the
material to extend. Normally, the mouthguard extends
to the point where the soft tissue meets the attached
gingiva. Next, trim the working cast as close to the
outline as possible as seen in figure 8-36(A). The
thickness of the cast base should not exceed 6 mm. The
reason for trimming the cast as specified is to facilitate
the cacuum formation and to minimize stretching and
thinning of the vinyl plastic during the molding. For
the same reason, drill a hole in the palate with a large
pear-shaped bur. Soak the cast in water for a couple of
seconds to prevent the hot thermoplastic material from
adhering to the cast. Remove excess water from the
cast. Place the wet cast on the perforated plate of a
Vacuum-Forming the Mouthguard
Several different types of vacuum-forming
machines can be used to adapt thermoplastic material.
Most machines consist of a perforated plate connected
to a source vacuum, an electrical heating element, and
a metal frame in which the vinyl plastic blank can be
clamped. Regardless of the machine's manufacturer,
the procedures used to adapt the material are basically
the same. The construction procedures, in general,
consist of the following steps:
1. Clamp a vinyl plastic blank in the frame, and
place it in position to be heated. The molding
temperature usually is estimated by the amount the
sheet of vinyl plastic material "sags" as it softens (fig.
8-36(B)). Excessive heating of the material will cause
the mouth protector to stretch and thin out. Sharp
reproductions of the surface detail are not necessary.
2. When the material is ready, turn the vacuum on
and move the frame to the molding position (fig.
8-36(C)). Hold it in this position until the vinyl plastic is
completely adapted to the contours of the cast.
3. Turn off the vacuum. Release the clamp on the
frame and set the cast with the mouth protector aside
until it cools completely.
Completing the Mouthguard
Trim excess material away with scissors as shown
in figure 8-36(D). Heat a Bard-Parker blade and trim
the outline of the mouthguard. Remove the
mouthguard and reduce the borders to approximately
5-7mm. A large bur, arbor band, or finishing stone
may be used to reduce the border thickness. Polish the
edges with pumice, or lightly flame the mouthguard
with an alcohol torch. Flaming has the benefit of
clearing any cloudy areas in the material. Wash and
disinfect the mouthguard, then place it in a prosthetic
denture bag for delivery to the patient.
The completed mouthguard should conform to the
general outline presented in figure 8-36(E). Notice
that the posterior border of the maxillary mouthguard
ends on the hard palate, and that the facial flanges do
not restrict the movement of any frena. The posterior
border may end in the rugae area to increase the
patient's speech and comfort.
Provisional fixed restorations (temporaries) are
usually made using some type of matrix or template.
Two methods more commonly used for providing
these templates are the impression method and the
vacuum-forming method. Basically, the template or
impression is a shell that will be filled later with
tooth colored resin and seated on the prepared teeth,
forming the provisional restoration. For this purpose,
we will only discuss making a template using the
vacuum-forming method since you are already
familiar with how to make an impression.