Retention Methods in Maxillofacial Prosthetics

RETENTION IN
MAXILLO FACIAL
PROSTHESIS
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

INTRODUCTION

RETENTION IN MFP
Intra oral prosthesis: Anatomic retention
Mechanical retention
Extra oral prosthesis: Anatomic retention
Mechanical retention

RETENTION IN MFP
ANATOMIC MECHANICAL ADHESIVES IMPLANTS OCCLUSI
ON

ANATOMIC RETENTION
 Residual maxillary retention
Teeth
Alveolar ridge
 Within the defect retention
 Residual hard palate
 Residual soft palate

Anterior nasal aperture
Lateral scar band
Floor of the orbit
Lateral Pterygoid plate
Nasal septum

Residual maxilla retention:
Teeth:
Alveolar ridge:
• Utilization of the
physical properties
• Ridge size and shape
• The palatal contour
• premaxillary segment
or the tuberosity

Within-the-defect retention:
 Large defects contribute intrinsically to the
retention of the obturator prosthesis

 There are intrinsic areas within and around the
defect that can provide retention
The residual soft palate
The residual hard palate
The anterior nasal aperture
The lateral scar band

Residual soft palate:
Extension of the obturator prosthesis on to the
nasopharyngeal side of the soft palate will
provide retention.

Residual hard palate:
 Depending on the of the line of palatal
resection
 Undercut along this line into the nasal or
paranasal cavity.
 Engagement of the medial wall of the defect
can increase retention.

Anterior nasal aperture:
This can be entered unilaterally or bilaterally.

Lateral scar band:
The skin superior to the junction tends to stretch
creating an area above the scar band that can be
engaged by the obturator prosthesis.
This minimizes vertical displacement of the
prosthesis

Retention is like a castle held together by proper
Support and Stability.if any one fails the whole
castle comes crumbling down….

SUPPORT
It is the resistance to movement of a
prosthesis toward the tissue.
The support available from the
residual maxilla and
from within the defect

Within-the- defect support:
 Positive support within the defect to
prevent rotation of the prosthesis into it
must be considered.
This support can be achieved by contact of
the prosthesis with any anatomic structure
that provides a firm base.

the floor of the orbit,
the bony structures of the Pterygoid plate,
the anterior surface of the temporal bone
The nasal septum

STABILITY
 It is the resistance to prosthesis
displacement by functional forces.

Residual maxilla stability:
If natural teeth remain, the bracing
components of the prosthesis framework
can be used to minimize movement in all 3
directions.
In edentulous patients, maximal extension
into the mucobuccal fold

Within-the defect stability:
 Maximal extension of the prosthesis in all lateral
directions must be provided.
 Maximum contact possible with the medial line of
resection, the anterior and lateral walls of the defect,
the pterygoid plates, and the residual softpalate must be
established.

Occlusion:
 The most important aspect of stability is
occlusion.
Maximal distribution of the occlusal force in
centric and eccentric jaw positions is imperative
to minimize the movement of the prosthesis and
the resultant forces to individual structures.
The patient with an acquired maxillary defect
should not masticate over the defect.

MECHANICAL RETENTION
Under this category, the operator has a
myriad of devices and proven techniques to
consider or use as the case demands.
TEMPORARY PERMANENT

Temporary mechanical retention:

ORTHODONTIC BANDS AND
PREWELDED BRACKETS TO
RETAIN TEMPORARY
PROSTHESIS

PERMANENT MECHANICAL
RETENTION
Cast clasps:
 Most common method for retaining a
prosthesis is using a cast metal clasp which
enters a undercut.
Properly designed clasp will provide
stability, splinting, bilateral bracing, and
reciprocation, as well as retention.

CAST CIRCUMFERENTIAL
CLASP
WROUGHT-CAST COMBINATION
AKERS CLASP
CAST ROACH-AKERS
COMBINATION CLASP
MANDIBULAR MOLAR RING
CLASP

PRECISION ATTACHMENTS
These prefabricated attachments can be
placed into cast crowns for the best in
esthetic and mechanical retention.

SEMIPRECISION ATTACHMENTS,
CUSTOM MADE
This attachment is formed in the wax
pattern, using a specially shaped mandrel
mounted on the parallelometer.

SNAP-ON ATTACHMENT
It is a preformed precious- metal precision piece
designed to retain and to stabilize a
prosthesis.
A Baker bar or Anderson bar is the rod
connecting two abutment crowns, and the clip
engages this rod.

BAKER SNAP-ON
ATTACHMENTS SOLDERED
TO THE CAST FRAMEWORK
CROSS-ARCH
SPLINTING USING
11-GAUGE BAR
SNAP-ON ATTACHMENT

MAGNETS
Magnets have been
used since 1950
1970 rare earth magnets
were used clinically
for denture retention.

Magnetic systems used in dentistry

Closed Field Systems
• Soft magnetic
material is cemented
to the root and a
closed field magnet
is set into the denture
base

MAGNETS
BAR ENGAGED IMPLANT FIXTURE
TO PREVENT ROTATION OF BAR
AND LOOSENING OF SCREW
POSTERIOR SURFACE
OF NASAL PROSTHESIS.
NOTE: MAGNETIC
ATTACHMENTS

BAR ENGAGING
PROSTHESIS
PROSTHESIS IN
POSITION

Advantage of magnets
 Have no moving parts to fatigue and break
 Are self seating
 require no paralleling
 Transmit no damaging lateral forces to
compromised abutments.
Disadvantages of magnets:
Possibility of corrosion if the capsule leaks
or wears through

GATE TYPE OR SWING LOCK
DEVICE
This retentive aid
helps gain partial
retention for many
loose or
periodontally
involved teeth.

AUXILIARY RETENTIVE
DEVICES
Buccal-lingual continuous clasp,
Guide planes,
Screws: they are specially made custom parts.
Suction cups: Inflatable balloon suction cups are
used for maxillary retention.

Spectacle retained

ADHESIVES-Intra oral
They enhance retention through optimizing interfacial
force by
(1) Increasing adhesive and cohesive properties and
viscocity of the medium lying between the denture and
its basal seal.
(2) Eliminating void between the tissue surface of the
prosthesis and the area on which it rests.

 Pastes
 Liquid emulsions
 Spray on
 Double sided tape
Adhesive used is a
medical grade
Disadvantage: frequent
reapplication is necessary
ADHESIVES-Extra oral

PROSTHESIS RETAINED
WITH SKIN ADHESIVE

TISSUE CONDITIONERS
They can increase retention of the prosthesis
by engaging undercuts, which normally are
difficult to cover.
Relining is necessary

IMPLANTS

The retention provided by the implants makes it
possible to fabricate large prosthesis that rests
on movable tissues.
Patient acceptance is significantly enhanced
Help to fabricate thin margins in silicone which
blend and move more effectively with the
mobile peripheral tissues.

CT SCAN USED TO
LOCATE POSSIBLE
IMPLANT SITES
STEREOLITHOGRAPHICALLY
FABRICATED 3-D MODEL
USED TO ASSESS IMPLANT
SITES

• Skin and soft tissues overlying the proposed
implant sites require careful examination.
• The health of the soft tissues circumscribing
the implants are easier to maintain if these
tissues are thin (less than 5mm) and
attached to the underlying periosteum.

SURGICAL PLACEMENT
• Craniofacial implant fixtures are fabricated from
pure titanium.
• Available in 3 or 5mm lengths and
5mm diameter flange.
• 2- stage surgical procedure, is employed.

AURICULAR
DEFECT
WAX SCULPTING
FITTED TO IDENTIFY
PROPER IMPLANT
PLACEMENT
SURGICAL
TEMPLATE

FLAP
REFLECTED
TEMPLATE USED TO LOCATE
PROPER IMPLANT POSITIONS

MASTOID EXPOSED
AND SITES
PREPARED FOR 3
IMPLANTS
IMPLANT
FIXTURES PLACED
INTO PREPARED
SITES
WOUND CLOSED I
N 3 LAYERS

Second surgical stage
• Second surgical stage is performed 3 to 4
months after the first stage.

IMPLANTS BEING
EXPOSED
TISSUES FLAP IS
THINNED AND
PERFORATED OVER
IMPLANT SITES
ABUTMENT
CYLINDERS
ATTACHED

HEALING CAPS
SECURED
PRESSURE DRESSING
APPLIED

ONE WEEK LATER,
PRESSURE DRESSING
REMOVED
SITES HEALED 4 WEEK
FOLLOWING
EXPOSURE

SILICONE TEMPLATE FABRICATED AS AN AID TO
FABRICATE RETENTION BAR

FIT OF BAR IS VERIFIED ON PATIENT

ACRYLIC RESIN
SUBSTRUCTURE TO BE
EMBEDDED WITHIN SILICONE
PROSTHESIS
PLASTIC SUBSTRUCTURE
CONTAINS RETENTIVE
ELEMENTS

OSSEOINTEGRATED IMPLANTS WERE REQUIRED
TO RETAIN THIS LARGE ORBITAL PROSTHESIS

THESE IMPLANTS EXIT
THROUGH MOBILE LIP TISSUES,
INCREASING RISK OF
PERIIMPLANTITIS
THESE IMPLANTS ARE
POSITIONED TOO FAR
POSTERIORLY, MAKING
ACCESS FOR HYGIENE
DIFFICULT

BAR-CLIP DESIGN
BARS WITH VERTICAL AND HORIZONTAL
COMPONENTS
POSTERIOR SURFACE OF
NASAL PROSTHESIS. CLIPS
ARE EMBEDDED IN
ACRYLIC RESIN
SUBSTRUCTURE WITHIN
PROSTHESIS

BAR ENGAGING
PROSTHESIS
COMPLETED PROSTHESIS IN
POSITION

Conclusion….

References
1 1.Sudarat kiat-annuay,Lawrence Gettlemanet et al.
Effect of adhesive retention of maxillofacial
prostheses.J Prosthet Dent 2001;85:438-41
2. Mark A.Pigno and Jeff J.Funk. Augmentation
of obturator retention by extention into the nasal
aperture.J Prosthet Dent 2001;85;349-51
3. James C.Lemon,Jack W.Martin. Technique for
magnet replacement in silicone facial prostheses.J
Prosthet Dent 1995;73:166-8

• 4. Ikuya watanabe,yasuhiroTanaka et al.
Application of cast magnetic attachments to
sectional complete dentures for patient with
microstomia. J Prosthet Dent2002;88:573-77
• 5. Jafferey E.Rubenstein. Attachments used for
implant supported facial prostheses. J Prosthet
Dent 1995;73:262-6
• 6. Yuki Kokubo and Shunji Fukushima.
Magnetic attachments for esthetic management of
an overdenture. J Prosthet Dent 2002;88:354-5

Acknowledgement
• Dr.K.R.Kashinath (Prof and Head)
• Dr.Vibha Shetty (Prof)
• Dr.Harish P.V (Associate Professor)
• Dr.Vahini Reddy (Associate Professor)

Retention Methods in Maxillofacial Prosthetics

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