Most casts submitted to dental labs for fabrication of removable partial dentures lack designs or design prescriptions. An approach to partial denture design is presented and a RPD design sequence is proposed.  Issues related to position of rests, selection and design of major connectors, minor connectors, denture base connectors, and retainers are discussed.



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Designing Removable Partial Dentures – Planning Sequence for RPD Patients — Course Transcript

  • 1. Designing RPD’s Planning sequence for RPD patients Ting Ling Chang DDSDivision of Advanced Prosthodontics, Biomaterials and Hospital Dentistry UCLA School of DentistryThis program of instruction is protected by copyright ©. No portion ofthis program of instruction may be reproduced, recorded or transferredby any means electronic, digital, photographic, mechanical etc., or byany information storage or retrieval system, without prior permission.
  • 2. Designing RPD’s Planning sequence for RPD patientsv  Diagnostic assessment and preliminary impressionsv  Diagnostic casts mounted in centric relationv  Draw the ideal RPD design (on paper)v Survey the study casts and determine the most advantageous position (MAP) of the designed RPD path of insertion and withdrawalv  Revise and finalize the RPD design
  • 3. Designing RPD’s Planning sequence for RPD patientsv  Diagnostic casts mounted in centric relation
  • 4. Designing RPD Frameworks Draw the ideal RPD design (on paper)v There are no classic designs.v Any design is a product of diagnosis, treatment planningv Abutment, arch and occlusal criteriav The application of design principles and philosophyv A knowledge and appreciation of RPD biomechanics
  • 5. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers
  • 6. Mandibular Design Issues of concernv  Proximal Plates – include 2.0 mm of mucosal coverage. Reduce if visible and non-esthetic.v  Minor Connectors to Rests – The vertical components to the rests should be at least 5.0 mm apart to reduce food entrapment. Consider lingual plate if closer.v  Denture Base Connectors – v  Retention of the resin saddle. v  Must be short of movable tissues. v  Should have relief. v  Allow spot metal seating check on master cast. Connectors are placed toward the lingual to prevent impingement
  • 7. Mandibular RPD Design Issues of concernv  The major connectors may not impinge upon movable soft tissues such as frenum, or vestibular areas.v  Superior horizontal components must be clear of marginal gingival tissue edge by 3.0 mm or consider lingual plate.v  The lingual borders of the plate or bar may need to be physiologically molded for the final impression/master cast.v  Finishing lines between the metal and resin must be marked.v  Relief is commonly utilized under the major connectors.
  • 8. Maxillary RPD Design Issues of concernv  Relief is not commonly used under maxillary major connectors.v  Design components should not impinge on soft tissues (soft palate, vibrating line areas).v  Beadings or pressure seals are used on major connectorsv  Proximal plates – guide planes designed to include 2.0 mm of mucosal tissue coverage. Reduce if esthetic areas involved.v  Denture base connectors – short of movable tissues. Should have relief (22 gauge). Allow for spot metal seating contact for fit verification.
  • 9. Mandibular RPD Design Optionsv  Occlusal rests v  Mesial or Distal v  Trans-occlusal v  Cingulum rest v  Incisal rest (direct support or indirect retainer)v  Major connectors v  Lingual bar v  Lingual platev  Retainers v  “I” bar v  Cast circumferential clasps v  Wrought wire clasps
  • 10. Maxillary Design OptionsOcclusal Rests v  Mesial or Distal v  Trans-occlusal v  Cingulum v  Circular concaveMajor Connectors v  Full Palatal Coverage v  Anterior-posterior (A-P) Strap v  Anterior Palatal Strap v  Tran-palatal or Posterior Palatal Strap v  Other
  • 11. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers
  • 12. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers Issues of ImportanceRests v Center of the tooth for molars-tooth- borne v Open for cingulum v Easy to check proper seating v Easy to clean v Short of transverse ridge for premolars v Incisal rest should extend onto the labial surface v Ball and socket type to allow pure rotation
  • 13. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers OptionsMajor connectors-Mandible v Lingual bar v Lingual plateMajor Connectors-Maxilla v Full Palatal Coverage v Anterior-posterior (A-P) Strap v Anterior Palatal Strap v Tran-palatal or Posterior Palatal Strap
  • 14. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers Issues of ImportanceMajor Connectors-Maxilla v Must be rigid v Beadings or pressure seals are used on major connectors v Must be short of the vibrating line v Must extend to the lingual side of the hamular notch
  • 15. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers Issues of ImportanceMajor connectors-Mandible v The major connector must not impinge upon movable soft tissues such as frenum, or vestibular areas. v Must be of sufficient bulk to ensure rigidity v Relief is commonly utilized under the major connectors. v On the tooth borne side of the mandible the major connector forms the inferior border of the prosthesis
  • 16. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers Issues of Importancev Proximal plate must extend 2 mm onto the tissuesv Minor connectors must cross the ginigival margins at a 90 degree anglev Space between the vertical portions of minor connectors should be 4-5 mm.v Space between the horizontal portions ofmajor connectors and ginvival margin should b 3-4 mm
  • 17. RPD Design Sequence v  Rests v  Major Connectors v  Minor Connectors v  Denture Base Connectors v  Retainers Issues of Importancev Should not impair the placement of denture teethv In the maxilla should not cover the tuberosityv Should be positioned on the crest of the ridge and on the lingual sidev Should enhance the rigidity of the RPD framework
  • 18. RPD Design Sequencev  Restsv  Major Connectorsv  Minor Connectorsv  Denture Base Connectorsv  Retainers Issues of Importancev The horizontal extension of the “I” bar retainer should be at least 2-3 mm from the gingival marginv The vertical portion of the “I” bar retainer must cross the gingival margin at a 90 degree anglev The “I” bar retainer must engage the abutment tooth at the greatest point of mesial distal curvature
  • 19. RPD Design Sequencev  Completed preliminary design
  • 20. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design sequence v  Rests v  Major connector v  Minor connectors v  Denture base retainers v  Retainers
  • 21. The Basic Requirements of a Direct Retainer A properly designed direct retainer (clasp) assembly should provide:v  Supportv  Stabilizationv  Reciprocationv  Encirclementv  Passivityv  Retention
  • 22. The Basic Requirements of a Direct Retainer A properly designed direct retainer (clasp) assembly should provide:v  Supportv  Stabilizationv  Reciprocationv  Encirclementv  Passivityv  Retention
  • 23. The Basic Requirements of a Direct Retainer A properly designed direct retainer (clasp) assembly should provide:v  Supportv  Stabilizationv  Reciprocationv  Encirclementv  Passivityv  Retention
  • 24. The Basic Requirements of a Direct Retainer A properly designed direct retainer (clasp) assembly should provide:v  Supportv  Stabilizationv  Reciprocationv  Encirclementv  Passivityv  Retention
  • 25. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design Issues Why did we use a lingual plate in this case?v  Status of potential abutments v  Endodontic status v  Periodontal statusv  Rests v  Cingulum v  Circular concavev  Palatal connector v  Presence of large torus v  Periodontal statusv  Retainers v  Size of teeth v  Angulation of teeth
  • 26. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design Issues v Why no lingual plate in this patient?v  Status of potential abutments v When an anterior palatal strap is used what design factors need to be kept in mind? v  Endodontic status v  Periodontal statusv  Rests v  Cingulum v  Circular concavev  Palatal connector v  Presence of large torus v  Periodontal statusv  Retainers v  Size of teeth v  Angulation of teeth
  • 27. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics. v What would you do if the premolarsDesign Issues presented with a 60:40 crown root ratio? v How would your design change if the 2ndv  Status of potential abutments premolars had been endodontically treated? v  Endodontic status v  Periodontal statusv  Rests v  Cingulum v  Circular concavev  Palatal connector v  Presence of large torus v  Periodontal statusv  Retainers v  Size of teeth v  Angulation of teeth
  • 28. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design Issues v Why did we use a circumferentialv  Status of potential abutments clasp on the molar v  Endodontic status v  Periodontal statusv  Rests v  Cingulum v  Circular concavev  Palatal connector v  Presence of large torus v  Periodontal statusv  Retainers v  Size of teeth v  Angulation of teeth
  • 29. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics. v What are the special needs of thisDesign Issues patient? Retention, stability or support?v  Status of potential abutments v What if the left cuspid was an v  Endodontic status overdenture abutment? How would this v  Periodontal status change your design?v  Rests v  Cingulum v  Circular concavev  Major connectorv  Retainers v  Size of teeth v  Angulation of teeth
  • 30. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics. v Why the circumferential clasp onDesign Issues the premolar rather than an “I” bar?v  Status of potential abutments v Why incisal rests rather than v  Endodontic status cingulum rests? v  Periodontal status v Why lingual plate rather thanv  Rests lingual bar? v  Cingulum v  Circular concavev  Major connectorv  Retainers v  Size of teeth v  Angulation of teeth
  • 31. Important Points for Unilateral Extensions:Proximal Plates (Guide Planes) and Minor Connectors are PARALLEL. What role is played by the rest on the premolar?“Options on Tooth-borne Side: v  Molars are better abutments than premolars. v  May need C-clasp (tilted tooth, etc.) v  Buccal Reciprocation is Crucial.
  • 32. Lab Prescriptions Good Design Prescriptions will have -v  Sharp, smooth outlines in identical colorv  Design outlines proportionately drawnv  Bead seals clearly markedv  Retention areas indicatedv  Guide plane tissue contacts markedv  Resin – metal finish lines clearly marked
  • 33. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design sequence v  Rests v  Major connector v  Minor connectors v  Denture base retainers v  Retainers
  • 34. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design sequence v  Rests v  Major connector v  Minor connectors v  Denture base retainers v  Retainers
  • 35. The Basic Requirements of a Direct Retainer A properly designed direct retainer (clasp) assembly should provide:v  Supportv  Stabilizationv  Reciprocationv  Encirclementv  Passivityv  Retention
  • 36. Lab Prescriptions Good Design Prescriptions will havev  Sharp, smooth outlines in identical colorv  Design outlines proportionately drawnv  Bead seals clearly markedv  Retention areas indicatedv  Guide plane tissue contacts markedv  Resin – metal finish lines clearly marked
  • 37. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design sequence v  Rests v  Major connector v  Minor connectors v  Denture base retainers v  Retainers
  • 38. Designing RPD FrameworksDraw the ideal RPD design (on paper)v  There are no classic designs. Any design is a product of diagnosis, treatment planning, abutment, arch and occlusal criteria, with the application of design principles and philosophy and an appreciation of RPD biomechanics.Design sequence v  Rests v  Major connector v  Minor connectors v  Denture base retainers v  Retainers
  • 39. RPD Design Exercise Clean, smooth and legibleDesigns must: v  Specify retention v  Bead seals clear marked v  Resin–metal finish lines clearly marked v  Sharp, smooth outlines in identical color v  Design outlines proportionately drawn v  Guide plane tissue contact area clearly marked
  • 40. Laboratory Prescriptionv  Rx must be clearly definedv  Clearances and anatomic concerns markedv  Specify retentionv  Specify materials to be usedv  Special Requests v Evaluation of Wax-up on Refractory v Inclusion of PFM restoration on Master Cast
  • 41. Clean and legible Good Design Prescriptions will have:v  Sharp, smooth outlines in identical colorv  Design outlines proportionately drawnv  Lightly shade relief areas in light redv  Retention areas marked in heavy redv  Guide plane tissue contacts markedv  Resin – metal finish lines clearly marked
  • 42. Ability of Major Connectors to Provide Rigidity and SupportMajor Connector Support RigidityPalatal strap good to excellent good to excellentAnterior-posterior strap good excellentComplete palatal plate excellent excellentAnterior-posterior palatal bar poor goodPalatal bar poor poorHorseshoe (anterior strap) poor poorLingual bar poor goodLingual plate poor good to excellent
  • 43. Design PrinciplesList Major Connector Criteria: 1.  Rigidity 2.  Functional 3.  Anatomic 4.  Physiologic
  • 44. Anterior Edentulous Spacev  Consider Esthetic Area of Visibility.v  Consider Rotational Path Design Option.v  Consider Fixed Prosthodontic Optionv  Consider implant option.
  • 45. v  Visitffofr.org for hundreds of additional lectures on Complete Dentures, Implant Dentistry, Removable Partial Dentures, Esthetic Dentistry and Maxillofacial Prosthetics.v  The lectures are free.v  Our objective is to create the best and most comprehensive online programs of instruction in Prosthodontics