Retention in maxillo facial prosthesis./cosmetic dentistry course

transcript

RETENTION IN MAXILLO FACIAL

PROSTHESIS

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

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 OCCLUSION

ANATOMIC RETENTION

Residual maxillary retention

Alveolar ridge Within the defect retention Residual hard palate Residual soft palate

Anterior nasal apertureLateral scar bandFloor of the orbitLateral Pterygoid plateNasal 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.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

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.www.indiandentalacademy.com

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 in maxillo facial prosthesis./cosmetic dentistry course

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