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Download RESTS AND REST SEATS Denture Base Artificial Teeth Supporting Rests Retainers Direct retainers Indirect Retainers Connectors : Major Connectors Minor

Post on 28-Mar-2015




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Slide 2 Slide 3 RESTS AND REST SEATS Slide 4 Denture Base Artificial Teeth Supporting Rests Retainers Direct retainers Indirect Retainers Connectors : Major Connectors Minor Connectors The Component Parts of Removable Partial Dentures Slide 5 Slide 6 Slide 7 Clasp assembly Slide 8 REST Slide 9 Rests: - Are rigid extensions of a Partial Denture, Placed in Rest Seats, Which are prepared on either the Occlusal, Lingual surfaces or Incisal edges of the teeth, providing Support to the Partial Denture Slide 10 Slide 11 The Quality of the Prosthesis to Resist Displacement Towards Denture Supporting Structures Support Slide 12 Functions Of The RestsFunctions Of The Rests 1. Support 2. Transmitting vertical stress along the long axis of the tooth 3. Secure the clasp in its proper position 4. Distributing the Occlusal Load 5. It May Act As Indirect Retention. Slide 13 1-Support SUPPORT & FORCE TRANSMISSION Slide 14 Transmitting Vertical Stress Along The Long Axis Of The Tooth Slide 15 3-Secure the clasp arms in their proper position Slide 16 Secure the Clasp in Its Proper Position Slide 17 4-Distributing the Occlusal Load Slide 18 5-May Act As Indirect Retention Slide 19 Slide 20 6-Restore occlusion of the abutment that show tilting or infra-occlusion (overlay rest) Slide 21 Tipped molar (Mesially inclined mandibular molar) Slide 22 Onlay (reduce cusp angle) Slide 23 7-Direct food away from tooth contact and embrasure area Slide 24 Embrasure Rest A Gap Between Two Molars Slide 25 Slide 26 Slide 27 8-Resistance to Lateral Displacement of the Prosthesis but applying damaging horizontal forces on abutment teeth Slide 28 Assembly ( A- Rests are either a part of a Clasp Assembly (primary rest) Or Auxiliary Rest An Auxiliary Rest Types of rests:- Slide 29 Clasp assembly Slide 30 Auxiliary rest Slide 31 B-According to the relations to edentulous span: - B-According to the relations to edentulous span: - 1. Adjacent to the saddle 2. Away from the saddle Slide 32 C- According to positions: - C- According to positions: - 1. Occlusal rest{ molars- premolar} 2. Lingual rests{ cingulam of canines-or casted lingual restorations} 3. Incisal rests {canines- incisors} Slide 33 A Rigid Extension of a RPD That Contacts the Occlusal Surface of a Posterior Tooth or Restoration, on a Rest Seat Specially Prepared to Receive it. I- Occlusal Rest Slide 34 Forms and Requirements of Rest Seat Preparation 1- Should Be Rounded Triangular in Shape the Base of the Triangle at the Marginal Ridge About 2.5 mm in Width, and Its Rounded Apex Is Directed Towards the Center of the Tooth 2.5m.m. Slide 35 Rest Seat 2 -The Marginal Ridge Is Lowered Approximately 1 to 1.5 Mm of Teeth in Relation to a Vertical Line (permit sufficient bulk ) 1mm1mm Slide 36 3- The floor of the rest seat should be spoon shaped Slide 37 Forms and Requirements of Rest Seat Preparation Prevent Slippage of the Prosthesis Creating an Orthodontic Like Force 4- 4- The angle between the minor connector and the rest should be less than 90 To Direct the Forces Along the Long Axis of the Tooth Slide 38 Rest Seat 4- Spoon Shaped Inclined Apically As It Approaches the Center of the Tooth 1mm1mm Slide 39 Slide 40 Forms And Requirements Of Rest Seat Preparation 5- 5-Rest seats are prepared in sound enamel, existing restorations or in crowns and inlays 6-If an amalgam restoration is present, it could be replaced by a cast restoration (Occlusal rests can be prepared in an old amalgam restoration 7-Preparations for the occlusal rest must precede making master cast and follow proximal preparation (guiding planes and elimination of undesirable undercuts) Slide 41 GUIDING PLANES Slide 42 Slide 43 Requirements of the Occlusal Rest I- I-O.R. must fit the tooth ( minimize food collection and preserve their location in relation to the tooth 2- It must be strong enough to withstand the loads without deform 3- 3-It must not raise the vertical dimension of occlusion Slide 44 Slide 45 Slide 46 Not Raise the Vertical Dimension Slide 47 Slide 48 Employed Only on a Perfectly Periodontally Healthy Tooth Special Considerations Helps in Preventing Lateral Movement of the Denture 1- Boxed shaped occlusal rest Slide 49 Slide 50 II- Lingual Rests I- Occlusal Rest III. Incisal Rest Rests Slide 51 II-Lingual Rests C. Canine Ledge A- Cingulum Rest (inverted V Rest) B. Ball Rest Slide 52 II-Lingual Rests C. Canine Ledge A- Cingulum Rest ( V Rest ) B. Ball Rest Slide 53 Lab Ling M D 2 mm A 1- 1.5 mm Half -Moon Shaped V- Shaped Slide 54 Slide 55 Slide 56 Adequate Tooth Preparation Directs Forces Down the Long Axis of Tooth Slide 57 Slide 58 III- Incisal Rest seat 1.5mm 2mm Slide 59 1.5mm Slide 60 III- Incisal Rest Used Predominantly As Auxiliary Rests or As Indirect Retainers Rigid Extension More Applicable on Mandibular Teeth 2.5 mm Wide and 1.5 mm Deep Slide 61 Slide 62 The Lingual Rest Is Preferable to an Incisal Rest Less Bothersome to a Curious Tongue More Esthetic Placed Closer to the Center of Rotation of the Abutment Tooth Slide 63 Lingual Rest Will Exert Less Leverage and Reducing Its Tendency to Tipping Slide 64 Post Is More Readily Removed by Application of Force Near Its Top Than by Applying Same Force Nearer Ground Level Slide 65 IV- Embrasure Hooks Placed in Embrasures Between Teeth Extending Over the Buccal or Labial Surface but Never Extend Below Survey Line. Slide 66 IV- Embrasure Hooks Act As Indirect Retainer Resistance to Lateral and Anteroposterior Movement Slide 67 IV- Embrasure Hooks Poor Esthetics and Wedging Action on Teeth Slide 68 THANK YOU