1. Prosthodontic splints and stents are used during radiation therapy to position and shield tissues, simplify dosimetry calculations, and position radioactive sources. 2. Positioning stents are used to control tongue depression and open the bite, shielding normal tissues from radiation. 3. Shielding is used with electron beams to reduce dose to normal tissues and flatten irregular surfaces. 4. Tissue bolus devices fill irregular spaces with wax, saline, or acrylic resin to create a more homogeneous radiation dose distribution.

1. 2. Use of Prosthodontic Splints
and Stents during Therapy
Harold Gulbransen, DDS
John Beumer III, DDS, MS
Division of Advanced Prosthodontics,
Biomaterials and Hospital Dentistry
UCLA School of Dentistry
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2. Use of Prosthodontic Splints and Stents
During Radiation Therapy
Table of Contents
v Positioning stents
v Shielding
v Recontouring tissues to simplify dosimetry
v Positioning radioactive sources
v Tissue bolus devices

3. Positioning Stents
Combination bite opening and tongue
positioning stents
Controlled depression of the tongue allows the radiation
to better focus on the clinical tumor volume thereby
reducing the dose delivered to adjacent normal tissues
Master casts are made and are
mounted on an articulator with a
record made with the mandible
separated from the maxilla by
about 25 mm.
Begin fabrication by
blocking out undercuts

4. Positioning Stents
Combination bite opening and tongue
positioning stents
Extension used to
depress the tongue
For ease of insertion
opening should not
exceed 25 mm
Tip of the tongue
fits in this hole
25 mm

5. Combination bite opening and
tongue positioning stents
v This patient was treated with CRT. The
tongue is limited superiorly to the level of the
occlusal plane.
v The radiation field can be lowered sparing
significant parotid tissue and the palatal
glands. If IMRT is used the radiations can be
better confined to the clinical tumor volume
Result: More saliva
Tip of the tongue placed here output postradiation.

6. Direct technique
These positioners can be fabricated using a direct
technique. Softened baseplate wax is used and the
resultant wax pattern is invested and processed into
acrylic resin.

7. Lingual stents
Useful in patients with carcinomas of
the oral tongue that do not extend into
the floor of the mouth where the dose is
boosted locally with interstitial
brachytherapy.
The lingual stent displaces the
tongue away from the
radioactive sources imbedded in
the tongue, significantly reducing
the dose to the lingual surface of One cm thickness of acrylic
the mandible. resin reduces the dose by 50%.

8. Shielding
v Only useful when electron beam is used
v Primarily used when treating tumors of the buccal
mucosa, lip and skin.
Purpose:
a) Reduce radiation dose to normal tissues medial to the tumor
b) Simplify the dosimetry by flattening out the cheek

9. Shielding
A shield for a patient presenting
with a squamous carcinoma of the
buccal mucosa. Note that the
shield separates the mandible
from the maxilla. This serves to
flatten the buccal mucosa and
simplify the dosimetric calculation.

10. Shielding
v Only useful when electron beam is used
v Primarily used when treating tumors of the buccal
mucosa, lip and skin.
Combination bite opener shield for squamous ca of lower lip
Purpose:
a) Reduce radiation dose to normal tissues medial to the tumor
b) Simplify the dosimetry by flattening out the cheek

11. Shielding
Another shield for a patient being treated for a
lymphoma of the mandibular gingiva
Cast of overextended Shield
impression
Shield in mouth
Shield on
cast with
cerrobend
alloy

12. Positioning a Radioactive Source
This patient developed a recurrence of a
previously irradiated squamous carcinoma.
The patient was not a candidate for surgery.
After the stent is positioned
the iridium seeds which are
Master cast with acrylic resin stent. incorporated within a smaller
diameter polyethylene tubing is
The tubing is then incorporated loaded.
within the stent and a cerrobend
shield is added.
Stent with polyethylene tubing

13. Positioning a Radioactive Source
This patient presented with a superficial squamous
carcinoma of the right alveolar ridge extending into the
floor of the mouth. The position of the radioactive
sources are outlined on the cast.
The stent is fabricated with
polyethylene tubing imbedded at the
prescribed distances from the mucosal
surfaces.
The stent is
loaded with
radioactive
sources after it
has been
positioned.

14. Positioning a Radioactive Source
Following radical maxillectomy, the
patient developed a recurrence on the
posterior wall of the defect. She had
previously received 5000 cGy
postoperatively.
An impression was
made and a cast
fabricated.
Occlusal ramps were added, the
radium needles loaded and the
patient wore the appliance until
another 3500 cGy had been
An acrylic resin administered.
stent was made
and channels
were developed
to receive
radium needles.

15. Positioning a radioactive source
Patient presented with severe trismus, so the radiation
carrier was made of a flexible silicone material
The radioactive
sources are inserted
after the patient inserts
the carrier.

16. Positioning a radioactive source
v This
patient
presented with a new
superficial lesion
(squamous
carcinoma) on the
posterior lateral
surface of a
maxillectomy defect.
She had previously
received Note the implants in the
postoperative residual premaxilla. They had
radiation following a been placed following her
radical maxillectomy. initial radiation therapy.

17. Positioning a radioactive source
Tubing is imbedded within the device at prescribed
intervals which will later receive the iridium seeds.
The radioactive sources are inserted
after the carrier is positioned introrally.

18. Positioning a radioactive source
The radiation carrier is placed introrally and
loaded with the radioactive iridium.
The device was retained with the implant retained tissue
bar connected to the osseointegrated implants. Occlusal
stops are incorporated within the device to help maintain
consist positioning of the stent.

19. Tissue bolus devices
v Problem – Irrregular tissue contours create
uneven radiation dose distributions
v Bolus – a tissue equivalent material placed
directly onto or into irregular tissue contours
v Result – More homogenous dose distribution
Materials used:
v Wax
v Saline
v Acrylic resin

20. Tissue bolus devices
In this patient a saline
filled bladder was
used to fill a radical
maxillectomy defect
with a tissue
equivalent material.

21. Tissue Bolus Devices
Irregular tissue contours of external structures
This patient presented with a squamous
carcinoma of the tip of the nose. Overlaying
the nose and cheek with a tissue equivalent
material will result in more homogenous
dosimetry.
A cerrobend nasal stent was
designed and fabricated to
shield the nasal mucosa.
The surface bolus of acrylic
resin and the cerrobend nasal
stent in position.

22. Tissue Bolus
This tissue bolus is made of dental
compound. Patient is to be irradiated for a
squamous carcinoma of the nasal vestibule.

23. Tissue Bolus
This tissue bolus is made of acrylic resin. Patient is 3 weeks
S/P partial palatectomy and is to receive postoperative radiation
therapy.
The appliance fills the defect with acrylic resin
and is made of two pieces to allow for easy
insertion and removal.
The device also separates the mandible from the maxilla
and keeps the tongue below primary treatment volume.

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