Extra oral defects

EXTRA ORAL DEFECTS
By Hossam Faisal

• Extra-oral Defects are the result of trauma, treatment of neoplasms, or congenital
malformations.
• They constitute both facial and other defects as limbs, digits...etc, but we will be
discussing those of the orofacial region
• In order to properly deal with Extra-oral defects, we need to further classify extra-
oral defects according to the missing structure:
• Auricular defect
• Nasal Defect
• Orbital/Hemi facial defect
• Ocular Defects

• Furthermore, construction of a properly functioning and
satisfactory prosthesis requires better understanding of
the technique and materials of fabrication of the
prosthesis, as well as the means of retention

1. AURICULAR DEFECTS
• Total Ear defects "Total auriculectomy defects" are easier than the partial defects.
• Retaining the tragus would better the mask the anterior margin of the prosthesis
• Line the defect with a split thickness skin graft, while avoid the use of flaps with hair
follicles.
• Placing osseointegrated implants would better enhance the retention of the
prosthesis through attachments
• It is tougher to take impressions for the partial defects because distortion of the
remaining tissue always remains as a problem, as well as masking the remaining
tissue could be challenging

IMPRESSIONS
• The patient should be positioned in a supine position, with his head tilted towards
the other side
• The skin of the defect is marked to assist in the carving of the prosthesis and its
alignment. alternative to that, the marks could be placed on model of the existing
ear and transferred to the defect side.
• the marks include; Junction of the lobe with the side of the face, inferior and
superior margins of the tragus. Junction of the anterior aspect of the helix with the
side of the face. A line indicating the vertical angulation of the ear.
• The skin and hair adjacent to the impression area should be lightly greased with
petroleum jelly or yellow soft paraffin

IMPRESSIONS
• The meatus is packed with gauze to prevent its blockage by the impression material
• Rubber-base impression material or slightly flow mix of alginate is used. Ensure full
coverage of the area with the remaining tissue
• When taking impression of unaffected ears, the impression material is placed first
under the helix to prevent its movement and the distortion of the impression
• Due to the convolutions of the ears, the impression should not exceed 3-4 mm in
thickness, to facilitate its removal.

1. ADHESIVES
• Medical Grade adhesive applied directly to the margins of the silicone prosthesis, to
help retain the prosthesis on the tissues of the patient
Pros:
• Solvent based adhesives Provides adequate retention

1. ADHESIVES
Cons
• Water based adhesives are inefficient
• Causes deterioration of the thin silicone margins due to repeated cleansing of the
margins by the patient
• Elderly patients may not have enough dexterity to apply the partial auricular
prosthesis as the flexible silicones may distort when it is fitted within the sulci of
remaining tissues
• Challenging to retain partial auricular prosthesis due to use of adhesive on fine
complex margins.

2. COMBINED ADHESIVE/MAGNETIC RETENTION
• Concept: an acrylic base is constructed, incorporating magna caps, which is then
placed on the tissues using a suitable adhesive. The prosthesis is then fitted
magnets to retain the prosthesis onto the acrylic base

2. COMBINED ADHESIVE/MAGNETIC RETENTION
Pros:
• Alleviates the need to use adhesives on fine silicone margins
• Great use when used with partial auricular prosthesis, which often require thin
complex and convoluted margins.
• Easier to place, requiring less dexterity from the patients, as the rigid acrylic doesn’t
distort
• Cons:
• Some distortion may still occur of the remaining tissues when placing the soft
silicone prosthesis.

3. OSSEO-INTEGRATED IMPLANTS
• Placed in the mastoid bone
• Soft tissue distortion from movements of the condylar head must be taken into
consideration to ensure implant success, which can be severely exaggerated in cases
of congenital malformations.
• In healthy bone, an adequate site for fixtures has been proposed by Tjellström on an
arc of a circle located 18 mm from the external ear canal, which is then confirmed by
radiographs
• Should not be placed in hair bearing areas as this will lead to poor hygiene of the
tissues around the implant, and subsequent inflammation of the abutment/tissue
interface.
• One stage implant placement is usually used with auricular prosthesis

CONSTRUCTION OF THE TEMPLATE
• Using a caliper, measure the distance from the end of the sideburn to the anterior border of
the tragus on the normal ear and transfer this record to the defected side.
• Measure the distance from the same landmark to the posterior border of the tragus, then
transfer it to the contralateral side. This suggested the width of the tragus
• Measure the distance from the meatus to suggested superior implant site and transfer it to
the contra lateral side.
• Measure the distance from the meatus to suggested inferior implant site and transfer it to
the contra lateral side.
• Impressions are taken as discussed before.
• Impressions are casted, and clear acrylic blank is vacuumed, and perforations are made at
the implant sites.

RETENTION WITH THE IMPLANTS
• Magnetic retention is used in patients with less dexterity as it allows the prosthesis
to be self guided.
• Bar splint and clip is preferred for younger patients, especially those who are
athletically active and require more retention and more reliable prosthesis.

CONSTRUCTION OF THE PROSTHETIC EAR
• Impressions are taken as previously discussed for both ears
• Marks are made for the orientation of the ear; at the junction of
the anterior helix with the side of the head, as well as the junction
of the lobe with the side of the head. Horizontal and vertical lines
are made at these markers
• Wax is warmed in a water bath, placed on the model of the
defected ear, and sculptured to a mirror image of the normal ear

The main measurements to consider is:
• length from the anti tragus to the lobe.
• Length from the top of the tragus to
the top of the superior helical rim.
• The width of the inner tragus to the
concha rim
• the overall length of the ear from the
superior helical rim to the inferior
border of the lobe

• After sculpting, the margins are adapted to ensure good integrity with the skin,
either by warming the margins of the wax and placing it on the patients skin, then
slightly flexing the margins to ensure adequate fit, or through scraping the model of
the ear at the margins, then warming the wax and adapting it to the new margins.
• The second technique has an advantage over the first in that the margins are greatly
distorted to ensure good fit in the first method

• The Wax pattern is then flasked in a large dental flask or maxillofacial flask
• The mold should be a three part mold to facilitate removal of the prosthesis from
the flask without tearing
• The appropriate material selected, base shades are determined, and processing is
completed
• Extrinsic coloration is done chair-side, to color match the adjacent skin

2. NASAL PROSTHESIS
• Nasal defects are difficult to restore, as the nose is the most prominent part of the
face.
• Denture modification or construction is important before the construction of the
nasal prostheses as the denture will alter the amount of the lip support and its
contour
• Total rhinectomy if preformed is hard to be surgically reconstructed, while it is
prosthetically challenging and relies on the artistic ability of the prosthodontist due
to the absence of any anatomical landmarks

NASAL PROSTHESIS
• However, Total Rhinectomy defects will provide a better result esthetically, as partial
rhinectomy defects has residual nasal structrues that are roften displaced, making it
difficult to restore the appearance of the symmetry. As well as the inherent difficulty
of hiding the margins of the prosthesis in partial rihnectomy defects

RETENTION
• Adhesives: same as the auricular prosthesis, however, retention is
also further challenged due to the warm air always being expelled
from the nose during breathing.
• Combined Direct adhesive/ Magnetic retention

• Spectacle retention:
• The most basic method of retention for the prosthesis. Especially useful for elderly
patients with limited dexterity.
• Corrected lenses should be used if the patient suffers uses spectacles for correction
of sight.
RETENTION

ADHESIVE VS. SPECTACLE RETENTION

RETENTION
• Osseointegrated Implants :
Bar clip retention
• Two stage implant placement technique
• Placement of implants; the floor of the nose is the most favorable site. Craniofacial implants
(4-5mm) with 10-15 mm width in between, and the fabrication of retention bar, or adding an
oral implant (7-10mm) in the glabella, and splinting it with the other implant to achieve
better retention.
• Placing craniofacial implants at the glabella is not advocated and has shown lower success
rate.
• An acrylic resin substructure is the constructed, which contains the retentive elements of the
prosthesis. It must fit within the confines of the nasal prosthesis and must have sufficient
surface area so that the bond between the resin and the silicone doesn’t fail.

OSSEOINTEGRATED IMPLANTS
CRANIOFACIAL IMPLANTS (4-5MM)

SPLINTING IMPLANTS TOGETHER

CLIP ATTACHMENTS FOR IMPLANTS

RETENTION
• Osseointegrated Implants :
Magnetic retention:
• Could be placed on a single implant placed in the floor of the
nose
• Causes less stresses on the implants

• Intranasal anatomical retention
• The use of this method should be highly selective, as the tissues of the nasal
mucosa is highly sensitive, and is subjected to ulceration due to the movement of
the prosthesis that will fit into the remaining undercuts of the nasal cavity.
• Should this method be used, the prosthesis lining must be made from the softest
silicone durometer available to reduce the probability of ulceration.
RETENTION

IMPRESSION
• Challenge: avoiding distortion of the soft tissue
• Apply a layer of light bodied impression material
• Apply gauze over the impression material as it begins to polymerize
• Apply succeeding layers of quick setting plaster to the impression material to
provide support for the elastic material. The initial layer must be thinned and
partially set before adding the subsequent layers
• The master cast is made out of stone

SCULPTING THE WAX PATTERN
• The margins should be thinned, blended with the adjacent skins,
and placed in areas that could be easily hid (underneath the
margins of spectacles..etc)
• The stipples, lines and grooves must be more prominent than
those of the adjacent skins, as some of the details are lost during
flasking and application of extrinsic colorants

FLASKING
• A hole is placed through the cast & the wax pattern is luted to the cast externally,
and also from the back to insure the engagement of undercuts of the usable
undercuts and proper extension of the floor of the nose
• The nostrils are sealed
• The shade guide selected should lighter than the lightest skin tone of the patient
• Silicone is vibrated through the opening in the back of the cast, and processed

EXTRINSIC COLORATION
•Browns applied first, followed by red and blue
highlights, while darker browns and grays are
applied to the lines and grooves to simulate
shadows.

ORBITAL PROSTHESIS
• Orbital prosthesis may be considered to be amongst the
most difficult of all facial prosthesis to construct, due to
the reconstruction of a moving organ with a prosthesis
that is static, so it becomes apparent upon movement of
the contra-lateral eye.

RETENTION
•Spectacle retention (useful in elderly patients)
•Direct adhesive retention

RETENTION
• Osseointegrated implant retention:
• Ideally, the implants should be placed in the supra orbital bone,
and should span the defect. Inferior retention should be achieved
from the zygomatic buttress or the floor of the maxilla. A
minimum of two implants is indicated for small defects, however,
larger defects require superior and inferior retention.

IMPRESSIONS
• Drape the patient. Apply a thin layer of Vaseline to hair bearing areas.
• Apply a thin layer of polysulfide to the surface of the skin.
• Apply an unfolded gauze to the surface of the polysulfide before it polymerizes.
• Coast the impression and gauze with a thin layer of polysulfide adhesive
• Apply several layers of quick set plaster to the impression. The first layer should be
very thin and applied with a brush.

SCULPTING
• Select a Globe that matches the opposite eye

SCULPTING
• Apply wax to the defect, then add the globe within the wax bolus,
position the globe correctly in relation to the atnro-posterior
planes, as well as the vertical, and the medio-lateral planes

SCULPTING
• Develop the lid contours, refine the surface texture, and add
synthetic eye lashes

FLASKING
• Wax pattern sealed to master cast.
• Wax flowed into desired undercuts and support areas through a hole made in back
of model. Stone will be poured into this opening during first stage of flasking.
• Globe is the secured
• Silicone mixed to match base shade selected and injected into mold and allowed to
polymerize

DELIVERY
• Eyelashes are tucked under the lid
• Retention and stability are achieved by engaging undercuts in the defect and
with skin adhesives

4. OCULAR PROSTHESIS
• Glass eyes have been used to treat ocular defects prior to World War II
• Due to demand of the eye during and after WWII, and the fragility of glass eyes,
acrylic prosthesis were developed.
• Loss of eyes could be the result trauma, tumors or congenital defects, with trauma
having the highest percentage (41%)
• The purpose is to restore the appearance of the lost eye

SURGICAL CONSIDERATIONS OF ENUCLEATION
• Proper Surgical result forms the basis for optimal cosmesis
• Surgical enucleation of the eye content allows the placement of ocular implants
• The implants restores the orbital volume, and are placed and wrapped with the
donor sclera (sphere shaped)
• Dermal fat grafts are used as an alternatice for volume augmentation

FABRICATION OF OCULAR PROSTHESIS

IMPRESSION
• Ocular Impression trays of suitable size is selected
• Irreversible hydrocolloid or silicone elastomer is used
• Oversized trays can cause distortion of the fatty tissues of the eye
• The trays have hollowed handle through which the impression
material is injected until it flows out of the retention holes of the
tray

FABRICATION OF THE CAST
• The impression is poured in two sections using a 30-ml medicine cup filled halfway
with dental stone
• Dental stone is poured to the posterior surface of the impression nad then placed in
medicine cup up to the anterior posterior edge
• Funnel shaped groves are made in the first part of the stone “indexing”
• Separating medium is added, them the rest of the impression is covered with
additional dental stone to the level of the interior surface of the impression tray.
• The space left by the handle of the tray will be used as a pathway for pouring of the
molten wax of the wax pattern

FABRICATION OF THE WAX TRY-IN
• Wax is poured in the previously made cast
• The wax try in is inserted in the socket and tried several times, and alterations are
made as required
• Pressure points or areas of discomfort should be noted and relieved
• In ideal conditions, the contours and palpebral fissure should resemble those of the
patient’s natural eye
• The size and location of the iris is determined while the patient is looking straight
ahead to a distant point, and marked with an indelible pen, and must match the
contra-lateral eye.

FABRICATION OF THE WAX TRY-IN
• Acrylic paints are commonly used to paint the corneal buttons to simulate the color
of the natural eye
• Ocular discs are painted, and then corneal buttons are placed on top of the ocular
discs to give the iris the its contour
• Painting of the sclera is done by embedding fibers of red cotton in the wax pattern
• It is then secured by adding a layer of clear acrylic

FINAL PROCESSING
• A mold is made in a flask. The eye is placed in the tissue side of the mold, with the
anterior curvature facing up
• White, heat-cured acrylic resin is mixed in the usual manner
• The flask is packed and processed
• The prosthesis is retrieved, flashes are removed and the surface is smoothed

Extra oral defects

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