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Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
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RETENTION IN MAXILLO FACIAL
PROSTHESIS
INDIAN DENTAL ACADEMY
Leader in continuing dental education www.indiandentalacademy.com
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INTRODUCTION
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RETENTION IN MFP
Intra oral prosthesis: Anatomic retention
Mechanical retention
Extra oral prosthesis: Anatomic retention
Mechanical retention
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RETENTION IN MFP
ANATOMIC MECHANICAL ADHESIVES IMPLANTS OCCLUSION
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ANATOMIC RETENTION
Residual maxillary retention
Teeth
Alveolar ridge Within the defect retention Residual hard palate Residual soft palate
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Anterior nasal apertureLateral scar bandFloor of the orbitLateral Pterygoid plateNasal septum
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Residual maxilla retention:
Teeth:
Alveolar ridge:• Utilization of the
physical properties
• Ridge size and shape
• The palatal contour
• premaxillary segment or the tuberosity
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Within-the-defect retention:
Large defects contribute intrinsically to the
retention of the obturator prosthesis
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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
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Residual soft palate:
Extension of the obturator prosthesis on to the
nasopharyngeal side of the soft palate will
provide retention.
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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.
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Anterior nasal aperture:
This can be entered unilaterally or bilaterally.
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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
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Retention is like a castle held together by proper Support and Stability.if any one fails the whole castle comes crumbling down….
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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
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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.
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the floor of the orbit,
the bony structures of the Pterygoid plate,
the anterior surface of the temporal bone
The nasal septum
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STABILITY
It is the resistance to prosthesis displacement by functional forces.
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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
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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.
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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.www.indiandentalacademy.com
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
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Temporary mechanical retention:
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ORTHODONTIC BANDS AND PREWELDED BRACKETS TO
RETAIN TEMPORARY PROSTHESIS
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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.www.indiandentalacademy.com
CAST CIRCUMFERENTIAL CLASP
WROUGHT-CAST COMBINATION AKERS CLASP
CAST ROACH-AKERS COMBINATION CLASP
MANDIBULAR MOLAR RING CLASP
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PRECISION ATTACHMENTS
These prefabricated attachments can be placed into cast crowns for the best in esthetic and mechanical retention.
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SEMIPRECISION ATTACHMENTS, CUSTOM MADE
This attachment is formed in the wax pattern, using a specially shaped mandrel mounted on the parallelometer.
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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.
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BAKER SNAP-ON ATTACHMENTS SOLDERED TO THE CAST FRAMEWORK
CROSS-ARCH SPLINTING USING
11-GAUGE BAR
SNAP-ON ATTACHMENT
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MAGNETS
Magnets have been
used since 1950
1970 rare earth magnets
were used clinically
for denture retention.
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Magnetic systems used in dentistry
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Closed Field Systems
• Soft magnetic material is cemented to the root and a closed field magnet is set into the denture base
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MAGNETS
BAR ENGAGED IMPLANT FIXTURE TO PREVENT ROTATION OF BAR
AND LOOSENING OF SCREW
POSTERIOR SURFACE OF NASAL PROSTHESIS.
NOTE: MAGNETIC ATTACHMENTS
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BAR ENGAGING PROSTHESIS
PROSTHESIS IN POSITION
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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
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GATE TYPE OR SWING LOCK DEVICE
This retentive aid helps gain partial retention for many loose or periodontally involved teeth.
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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.
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Spectacle retained
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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.
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Pastes
Liquid emulsions
Spray on
Double sided tape
Adhesive used is a medical grade
Disadvantage: frequent reapplication is necessary
ADHESIVES-Extra oral
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PROSTHESIS RETAINED WITH SKIN ADHESIVE
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TISSUE CONDITIONERS
They can increase retention of the prosthesis by engaging undercuts, which normally are difficult to cover.
Relining is necessary
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IMPLANTS
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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.
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CT SCAN USED TO LOCATE POSSIBLE
IMPLANT SITES
STEREOLITHOGRAPHICALLY FABRICATED 3-D MODEL
USED TO ASSESS IMPLANT SITES
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• 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.
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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.
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AURICULAR DEFECT
WAX SCULPTING FITTED TO IDENTIFY
PROPER IMPLANT PLACEMENT
SURGICAL TEMPLATE
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FLAP REFLECTED
TEMPLATE USED TO LOCATE PROPER IMPLANT POSITIONS
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MASTOID EXPOSED AND SITES
PREPARED FOR 3 IMPLANTS
IMPLANT FIXTURES PLACED
INTO PREPARED SITES
WOUND CLOSED I N 3 LAYERS
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Second surgical stage
• Second surgical stage is performed 3 to 4
months after the first stage.
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IMPLANTS BEING EXPOSED
TISSUES FLAP IS THINNED AND
PERFORATED OVER IMPLANT SITES
ABUTMENT CYLINDERS ATTACHED
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HEALING CAPS SECURED
PRESSURE DRESSING APPLIED
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ONE WEEK LATER, PRESSURE DRESSING
REMOVED
SITES HEALED 4 WEEK FOLLOWING EXPOSURE
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SILICONE TEMPLATE FABRICATED AS AN AID TO FABRICATE RETENTION BAR
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FIT OF BAR IS VERIFIED ON PATIENT
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ACRYLIC RESIN SUBSTRUCTURE TO BE
EMBEDDED WITHIN SILICONE PROSTHESIS
PLASTIC SUBSTRUCTURE CONTAINS RETENTIVE
ELEMENTS
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OSSEOINTEGRATED IMPLANTS WERE REQUIRED TO RETAIN THIS LARGE ORBITAL PROSTHESIS
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THESE IMPLANTS EXIT THROUGH MOBILE LIP TISSUES,
INCREASING RISK OF PERIIMPLANTITIS
THESE IMPLANTS ARE POSITIONED TOO FAR
POSTERIORLY, MAKING ACCESS FOR HYGIENE
DIFFICULT
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BAR-CLIP DESIGN
BARS WITH VERTICAL AND HORIZONTAL COMPONENTS
POSTERIOR SURFACE OF NASAL PROSTHESIS. CLIPS
ARE EMBEDDED IN ACRYLIC RESIN
SUBSTRUCTURE WITHIN PROSTHESIS
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BAR ENGAGING PROSTHESIS
COMPLETED PROSTHESIS IN POSITION
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Conclusion….
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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
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• 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
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Acknowledgement
• Dr.K.R.Kashinath (Prof and Head)
• Dr.Vibha Shetty (Prof)
• Dr.Harish P.V (Associate Professor)
• Dr.Vahini Reddy (Associate Professor)
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