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6. Residual maxilla retention:
Teeth:
Alveolar ridge:
• Utilization of the
physical properties
• Ridge size and shape
• The palatal contour
• premaxillary segment
or the tuberosity
8. 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
9. Residual soft palate:
Extension of the obturator prosthesis on to the
nasopharyngeal side of the soft palate will
provide retention.
10. 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.
12. 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
13. Retention is like a castle held together by proper
Support and Stability.if any one fails the whole
castle comes crumbling down….
14. 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
15.
16. 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.
17. the floor of the orbit,
the bony structures of the Pterygoid plate,
the anterior surface of the temporal bone
The nasal septum
18. STABILITY
It is the resistance to prosthesis
displacement by functional forces.
19. 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
20. 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.
21. 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.
22. 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
25. 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.
29. 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.
33. Closed Field Systems
• Soft magnetic
material is cemented
to the root and a
closed field magnet
is set into the denture
base
34. MAGNETS
BAR ENGAGED IMPLANT FIXTURE
TO PREVENT ROTATION OF BAR
AND LOOSENING OF SCREW
POSTERIOR SURFACE
OF NASAL PROSTHESIS.
NOTE: MAGNETIC
ATTACHMENTS
36. 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
37. GATE TYPE OR SWING LOCK
DEVICE
This retentive aid
helps gain partial
retention for many
loose or
periodontally
involved teeth.
41. 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.
42. Pastes
Liquid emulsions
Spray on
Double sided tape
Adhesive used is a
medical grade
Disadvantage: frequent
reapplication is necessary
ADHESIVES-Extra oral
44. TISSUE CONDITIONERS
They can increase retention of the prosthesis
by engaging undercuts, which normally are
difficult to cover.
Relining is necessary
46. 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.
47. CT SCAN USED TO
LOCATE POSSIBLE
IMPLANT SITES
STEREOLITHOGRAPHICALLY
FABRICATED 3-D MODEL
USED TO ASSESS IMPLANT
SITES
48. • 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.
49. 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.
61. THESE IMPLANTS EXIT
THROUGH MOBILE LIP TISSUES,
INCREASING RISK OF
PERIIMPLANTITIS
THESE IMPLANTS ARE
POSITIONED TOO FAR
POSTERIORLY, MAKING
ACCESS FOR HYGIENE
DIFFICULT
62. BAR-CLIP DESIGN
BARS WITH VERTICAL AND HORIZONTAL
COMPONENTS
POSTERIOR SURFACE OF
NASAL PROSTHESIS. CLIPS
ARE EMBEDDED IN
ACRYLIC RESIN
SUBSTRUCTURE WITHIN
PROSTHESIS
65. 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
66. • 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