RPD SUPPORTRPD SUPPORT SUPPORT: Means “To Bear”.SUPPORT: Means “To Bear”.RPD Support: RPD Support: Ability of RPD to:Ability of RPD to: - Bear occlusal forces / stresses.- Bear occlusal forces / stresses. - Resist tissue-ward displacement / sinking.- Resist tissue-ward displacement / sinking.Influenced by: Influenced by: - Ridge, DST & Teeth Conditions.- Ridge, DST & Teeth Conditions. - Denture Design Feature.- Denture Design Feature.

RPD SUPPORT RPD SUPPORT RPD SUPPORT: RPD SUPPORT: Mucosa Support:Mucosa Support:Mucosa & bone underneath not made to support RPD.Mucosa & bone underneath not made to support RPD.A given force displace mucosa 10-times > than the:A given force displace mucosa 10-times > than the:

- amount of tooth-intrusion into its socket.- amount of tooth-intrusion into its socket.Recovery of displaced Recovery of displaced mucosa:mucosa: visco-elasticvisco-elastic as to: as to:

- purely - purely elasticelastic recovery of recovery of PDLPDL..Upon load removal: Mucosa recovers in 72 Hours:Upon load removal: Mucosa recovers in 72 Hours:

- compared to PDL recovering instantaneously.- compared to PDL recovering instantaneously.Mucosa underneath a denture remain deformed.Mucosa underneath a denture remain deformed.Cortical bone underneath firm mucosa provide:Cortical bone underneath firm mucosa provide:

- good support & stable foundation.- good support & stable foundation.> Support> Support potential: potential: U-shaped ridge (Height & width).U-shaped ridge (Height & width).

RPD SUPPORT RPD SUPPORT RPD SUPPORT: RPD SUPPORT: Mucosa Support:Mucosa Support:Upper RPDs: Upper RPDs: Wider tissue coverage by RPD base. Wider tissue coverage by RPD base. Palatal Plate provide better support.Palatal Plate provide better support.

- - Good Areas:Good Areas: Hard palate, tuberosity. Hard palate, tuberosity.Saddles & Support & RPD Design for a:Saddles & Support & RPD Design for a: - DES & Post. Bounded Spaces in the same upper arch:- DES & Post. Bounded Spaces in the same upper arch: - Recommended design: - Recommended design: Horse-shoe design RPD.Horse-shoe design RPD.Saddles Extension on Bounded space side:Saddles Extension on Bounded space side:

--1/31/3 area b/w ridge crest & midline of palate. area b/w ridge crest & midline of palate.Saddles Extension for Free-ended space:Saddles Extension for Free-ended space:

- 2/3 –1/2- 2/3 –1/2 area b/w ridge crest & midline of palate. area b/w ridge crest & midline of palate.

Lower K-I & K-II RPDs: Lower K-I & K-II RPDs: FES / DES RPDs: FES / DES RPDs: Base extended to E.O.R / Buccal Shelf. Base extended to E.O.R / Buccal Shelf.

RPD SUPPORT RPD SUPPORT

RPD SUPPORT RPD SUPPORT RPD SUPPORT:RPD SUPPORT:Mucosa Support (Contd):Mucosa Support (Contd):

RPD SUPPORT RPD SUPPORT RPD SUPPORT: “Every” RPD (Dyer 1972):RPD SUPPORT: “Every” RPD (Dyer 1972):Utilize design principles of “Spoon denture”:Utilize design principles of “Spoon denture”:

- a space maintainer & RPD in children:- a space maintainer & RPD in children:- replacing missing upper anterior teeth.- replacing missing upper anterior teeth.

Best example of mucosa-supported RPD.Best example of mucosa-supported RPD.Design features:Design features:Denture base well-away from FGMs.Denture base well-away from FGMs.Denture base on displaceable palatal mucosa:Denture base on displaceable palatal mucosa:

- pin-damming / food-lines carved (seal).- pin-damming / food-lines carved (seal).- Base sealed on lateral NV bundles.- Base sealed on lateral NV bundles.

Posterior border extended upto “Ah” line.Posterior border extended upto “Ah” line.

RPD SUPPORT RPD SUPPORT RPD SUPPORT: RPD SUPPORT: ““Every” Design RPD (Contd):Every” Design RPD (Contd):Point contact with natural teeth:Point contact with natural teeth: - located near the occlusal surface.- located near the occlusal surface. - leaving easily self-cleaning space below:- leaving easily self-cleaning space below:

- contact points b/w natural & denture teeth.- contact points b/w natural & denture teeth.OI Free Occlusion in CR & Excursions.OI Free Occlusion in CR & Excursions.Use teeth narrow BL dimensions if multiple saddles.Use teeth narrow BL dimensions if multiple saddles.Incorporate labial flange for A-P bracing of RPD.Incorporate labial flange for A-P bracing of RPD.Incorporate metal wire or acrylic distal posts:Incorporate metal wire or acrylic distal posts:

- on last erupted teeth in arch for P-A bracing.- on last erupted teeth in arch for P-A bracing.Adams’ Clasps Adams’ Clasps OR OR No ClaspsNo Clasps . .

RPD SUPPORTRPD SUPPORT RPD SUPPORT: RPD SUPPORT: Lower FES RPDs: Lower FES RPDs: Differential support problem.Differential support problem.Mesially teeth provide support for DEB of RPD.Mesially teeth provide support for DEB of RPD.Distally DEB of RPD supported on mucosa.Distally DEB of RPD supported on mucosa.Mucosa more displaceable than PDL of teeth.Mucosa more displaceable than PDL of teeth.Such RPD if made on cast made of impression:Such RPD if made on cast made of impression: - recorded in muco-static imp. material will:- recorded in muco-static imp. material will: - be unstable during function b/c of mucosa:- be unstable during function b/c of mucosa: - yielding under load & causing sinking of RPD.- yielding under load & causing sinking of RPD.Tilting forces & torque on premolar abutments.Tilting forces & torque on premolar abutments.Damage their PDL and lead to their loss.Damage their PDL and lead to their loss.

RPD SUPPORTRPD SUPPORT RPD SUPPORT: RPD SUPPORT: Lower FES RPDs:Lower FES RPDs:3-ways to solve problem of differential support:3-ways to solve problem of differential support:1. Chair-side / Intra-oral Reline of RPD: 1. Chair-side / Intra-oral Reline of RPD:

- Done at the RPD insertion stage using:- Done at the RPD insertion stage using: - close mouth impression technique - close mouth impression technique

&:&:- Hi Mol. Wt intraoral self-cure - Hi Mol. Wt intraoral self-cure

resin.resin.2.2. Flexible / Stress-breaker connection in RPD: Flexible / Stress-breaker connection in RPD:

- allows independent movements of:- allows independent movements of:- tooth-borne & tissue-borne parts of - tooth-borne & tissue-borne parts of

RPD.RPD.Technically difficult approach.Technically difficult approach.Skills not available universally.Skills not available universally.RPD distortion RPD distortion && Tissue impingement. Tissue impingement.

RPD SUPPORTRPD SUPPORT RPD SUPPORT: RPD SUPPORT: Lower FES RPDs:Lower FES RPDs:Solving problem of differential support (Contd):Solving problem of differential support (Contd):3. Recording Controlled displaced state of tissues by:3. Recording Controlled displaced state of tissues by:

- “Altered Cast Impression Procedure - “Altered Cast Impression Procedure (ACIP) (ACIP) to:to: - fabricate a Stable, Well-fit & Rigid RPD.- fabricate a Stable, Well-fit & Rigid RPD.

ACIP (Applegate 1959): 2-Step Procedure:ACIP (Applegate 1959): 2-Step Procedure:1.1. Impression Step: Impression Step: Fabricate metal FWK & Try in mouth.Fabricate metal FWK & Try in mouth. Add temporary acrylic bases with its fitting surface:Add temporary acrylic bases with its fitting surface:

- relieved from ridges by 0.25mm relief spacer.- relieved from ridges by 0.25mm relief spacer. Controlled displaced state of mucosa obtained by:Controlled displaced state of mucosa obtained by:

- painting molten wax (Kerr. Correcta wax No.4):- painting molten wax (Kerr. Correcta wax No.4):- using a camel hair brush.- using a camel hair brush. (Contd)(Contd)

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RPD SUPPORTRPD SUPPORT RPD SUPPORT: Lower FES RPDs (Contd):RPD SUPPORT: Lower FES RPDs (Contd):Solving problem of differential support (Contd):Solving problem of differential support (Contd):Upon each layer of wax, FWK is inserted in mouth.Upon each layer of wax, FWK is inserted in mouth.FWK held stationary & pressed in place by;FWK held stationary & pressed in place by;

- firmly holding it thru lingual major connector.- firmly holding it thru lingual major connector.No pressure on temporary bases.No pressure on temporary bases.Continue painting molten fluid wax on fit surface until:Continue painting molten fluid wax on fit surface until:

- even, smooth & glossy fitting surface obtained.- even, smooth & glossy fitting surface obtained.2.2. Cast-altering step: Cast-altering step:Done on master cast on which FWK was tried / fitted.Done on master cast on which FWK was tried / fitted.FES areas of cast cut with FES areas of cast cut with frit-sawfrit-saw (wire saw). (wire saw).Fit Trayed FWK to altered cast (No FES parts).Fit Trayed FWK to altered cast (No FES parts).Add new FES areas to cast by pouring stone mix.Add new FES areas to cast by pouring stone mix.

RPD SUPPORTRPD SUPPORT RPD SUPPORT: Lower FES RPDs (Contd):RPD SUPPORT: Lower FES RPDs (Contd):Solving problem of differential support (Contd):Solving problem of differential support (Contd):When set, remove temporary bases from cast.When set, remove temporary bases from cast.Add wax bases & occlusal rims to FWK.Add wax bases & occlusal rims to FWK.Register MMR & face-bow transfer records.Register MMR & face-bow transfer records.Establish occlusion on articulator.Establish occlusion on articulator.Prepare waxed-up RPD for trial.Prepare waxed-up RPD for trial.On Trial, accomplish final wax-up & seal RPD on:On Trial, accomplish final wax-up & seal RPD on:

- new altered cast.- new altered cast.Invest, de-wax, pack mould and process / finish RPD.Invest, de-wax, pack mould and process / finish RPD.Fit RPD in mouth.Fit RPD in mouth.Review & Recall visits.Review & Recall visits.