Retake C3

Clinical-Lab stages of MRPD

Clinical stages

1. Examination, anamnesis, treatment plsm & anatomical/preliminary impression. Alginte in stock tray.

2. Treatment plan. Adjustments on survey.

• Guiding planes 2-4mm.

• Occlusal rest 1-1.5mm.

• Bite registration

• Funcitonal impression.

3. Try in metal framework. Occlusion. Occlusal rest & Stability check.

4. Try in MRPD, wax rims & adjust. Bite registration. Determine shape & shade of artificial teeth-

5. Try in freamework w/ teeth. Occlusion, shade & shape check + patient agreement.

6. Final try-in. Stability, retention, occlusion, shade & shape check. PT nstruction for MRPD care & wear. Follow up 1 week + 1 year.

Lab Stages

1. Make dg cast, survey & custom tray.

2. Master cast, second survet. Fireproof model copy. Metal framework from wax (channels + funnel). Cast metal framework. Adjust + polish.

3. Wax rims placement on metal framework.

4. Artificial teeth in wax placement.

5. Add wire clasp & replace wax w/ acrylic + finish.

Minor connectors

Def: Unit of RPD connecting other components to major connector,

Functions: Unification & rigidity. Stress distribution. Bracing element via contact w/ guiding planes. Maintain insertion path via contact with gp.

Types: Minor connectors placed into embrasure b/w 2 teeth. Gridwork minor connectors connecing denture base + teeth to major connector. E.g. → Mesh gridwork & Lattice gridwork.

Retention

Resists loads that move denture in vertical direction. Withstands the vertical forces.

Support

Resists occlusal forces.

Stability

Resists horizontal forces & forces against rotation of dentures.

Clasp Types, placement options & clasp retention.

Clasp types:

• CC → Calcium-Carbonate

• Cr/Co, gold alloy & stainless steel.

• Variations: l-bas clasp, L- or T-shaped gingivally.

Placement options:

• To engage undercuts on tooth surface for retention.

• Successfull placement: Force need to displace is greater than force of withdrawal. Detentive force dedicated design including depth & steepness of undercut.

Clasp retention

1. Clasp engages undercuts.

2. Harnesing PT’s muscular controll.

3. Using physical forces: E.g. vacuum retention from covering mucosa by denture.

MRPD /upper/ jaw connectors

• Palatal saddle: Civers most of palate. Rigid. Distributes forces effectively. Can alter post dam/be bulky.

• Palatal strap: Thin, versatile & covers minimal tissue. Hygienic & increased bending resistance. Not for high suited cases.

• Ring connector: For mulitple widely spreaded/prominent tori. Miantains rigidity with minimal bulk. Interferes w/ tongue functuion.

• Horseshoe: Class IV arches/tori. Not first choice. Minimal tissue coverage. Poor rigidity & prone to deformation.

• Anterior-posterior palatal strap: Common, combines anterior & posterior straps. Rigid, minimal tissue coverage. Can cause discomfort due to bulk.

MRPD /lower/ jaw connectors

• Lingual bar: 1st choice. Floor-Mouth depth >7-8mm. Good periodontal support. Is simple, hygienic & has minimal tissue coverage. Not possible if lingual sulcus is shallow.

• Sublingual bar: Used if there’s inadequate sulcus depth for lingual bar. Periodontal compromise. Stabilizes weak anterior teeth.

• Labial Bar: Used if lingual bar does not fit. Indications of use rare, swing lock design is a variation of design.

• Kennedy bar: Lingual bar + secondary bar resting above cingula of anterior teeth. Acts as indirect retainer & has a role in horizonal stabilization. Can create food trap b/w the 2 bars. Not recommended.

Design determining factors of RPD’s

Function: Attach prosthetic teeth to RPD

• Transfer occlusal forces to abutment teeth & tooth tissue RPD to denture foundation area.

• Replace missing alveolar tissue.

• Bracing & Retention (direct-indirect retention).

Design determining factors:

• Retention: Withstand vertical forces.

• Support: Resist occlusal forces.

• Aesthetics: Smile line, canine line, midline, facial contour & color.

• Anatomy: Ridge shape, undercuts & anatomical obstructions.

• Type: Tooth supported base = smaller. Tooth-tissue supported base = broader.

• Material: Acrylic & metal

• Maintanace: Reepair & Reline (esp. absorbed ridges).

• Extention: Coverage & anatomical landmarks.

Clinical-Lab stages of PRPD

Clincal

1. Examination, anamnesis, treatment plan & anatmical impression.

2. Border molding & funcitonal impression w/ custom tray.

3. Try in wax rims + adjustment, bite registration, teeth positioning, shape & shade.

4. Try in wax rim w/ teeth. Occlusion & articulation check, shape & shade. → Last call for adjustments.

5. Occlusion of RPD w/ articulation paper, clasp adjustment, phonetics check. Inform patient of instructions, control 1week (final fitting) + 1 yr.
   

Lab Stages

1. Make dg cast, survey & custom tray.

2. Master cast, acrylic base w/wax rim. Final survey & design.

3. Articulate cast & artificial teeth placement.

4. Corrections → Back to clinic 4 scheduling. Change wax to acrylic & wire clasp placement.

TP - Retention, Support, Stability

• Retention: Withstands vertical forces. Form alveolar arch, shape of alveolar ridges, u-shaped & firm is the best, saliva quality + quantity, labial/buccal vestibules, lingual frenum.

• Support: Resists occlusal forces. Key areas are retromolar pads (Mand), buccal shelf, posterior border (maxillary reaching vibrating line).

• Stability: Resists horizontal forces. Contributing structures → buccinator, orbicularis oris, tongue muscles, modiolus & transverse + longitudinal muscles.