Component parts of cast partial dentures / orthodontic courses


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Component parts of cast partial dentures / orthodontic courses

  1. 1. Role of component partsRole of component parts of cast partial denturesof cast partial dentures INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Component PartsComponent Parts 1)1) Major connectorMajor connector 2)2) Minor connectorMinor connector 3)3) Occlusal restsOcclusal rests 4)4) Direct retainerDirect retainer armarm 5)5) Stabilizing orStabilizing or reciprocalreciprocal componentcomponent 6)6) Indirect retainerIndirect retainer
  3. 3. Component partsComponent parts  Major ConnectorsMajor Connectors  Minor connectorsMinor connectors  RestsRests  Indirect retainersIndirect retainers  Denture bases & artificial teethDenture bases & artificial teeth  Direct retainersDirect retainers
  4. 4. Major ConnectorsMajor Connectors  Connects parts of theConnects parts of the Prostheses locatedProstheses located on one side of theon one side of the arch to those on thearch to those on the opposite sideopposite side  All other parts of theAll other parts of the PD are attached to itPD are attached to it either directly oreither directly or indirectly.indirectly.
  5. 5. REQUIREMENTSREQUIREMENTS All major connectors must beAll major connectors must be  be rigidbe rigid  provide vertical support and protect the softprovide vertical support and protect the soft tissuestissues  provide a means of obtaining indirectprovide a means of obtaining indirect retentionretention where indicatedwhere indicated
  6. 6.  Provide an opportunity of positioningProvide an opportunity of positioning denture bases where needed.denture bases where needed.  Maintain patient comfort.Maintain patient comfort.  Not create food entrapment areas, as farNot create food entrapment areas, as far as possible self possible self cleansing.
  7. 7.  Should not interfere with and is notShould not interfere with and is not irritating to the tongue.irritating to the tongue.  Should not impinge on oral tissues whenShould not impinge on oral tissues when the restoration is placed, removed orthe restoration is placed, removed or rotates in function.rotates in function.  Covers no more tissues than isCovers no more tissues than is absolutely necessary.absolutely necessary.
  8. 8. Maxillary Major ConnectorsMaxillary Major Connectors  Palatal BarPalatal Bar  Palatal StrapPalatal Strap  A-P Bar/strap, closed horseshoeA-P Bar/strap, closed horseshoe  Horse shoe/ U shaped connectorHorse shoe/ U shaped connector  Palatal platePalatal plate
  9. 9. Palatal BarPalatal Bar  Narrow half-oval barNarrow half-oval bar  Mainly used asMainly used as interim pd nowinterim pd now  Bulky, difficult for ptBulky, difficult for pt  Limited to replacingLimited to replacing one/two teeth onone/two teeth on either side of archeither side of arch  Not placed ant toNot placed ant to IIpmIIpm  Only in Cl.3 archOnly in Cl.3 arch
  10. 10. Palatal strapPalatal strap  Most widely usedMost widely used  Not less than 8mmNot less than 8mm widewide  Width increases withWidth increases with edentulous spanedentulous span  More rigid with lessMore rigid with less bulkbulk  Ant border- Post toAnt border- Post to rugae/valleyrugae/valley  Cl.3 arches, rarelyCl.3 arches, rarely Cl.2, never in Cl.1 &Cl.2, never in Cl.1 & 44
  11. 11. A-P Palatal BarA-P Palatal Bar  Excellent rigidity,Excellent rigidity, strong L-beam effectstrong L-beam effect  Used in Cl.2 & 4Used in Cl.2 & 4 frequently, also Cl.1 &frequently, also Cl.1 & 33  Provides less support,Provides less support, completely dependantcompletely dependant on remaining teethon remaining teeth  Used when ant & postUsed when ant & post abutments are widelyabutments are widely separatedseparated
  12. 12. A-P Palatal BarA-P Palatal Bar  Indicated in pts withIndicated in pts with large palatal toruslarge palatal torus where surgery iswhere surgery is ruled outruled out  Contraindicated inContraindicated in high narrow vault-high narrow vault- phoneticsphonetics  Not first choiceNot first choice connectorconnector
  13. 13. Closed horse-shoeClosed horse-shoe A-P Palatal StrapA-P Palatal Strap  Better support thanBetter support than A-P BarA-P Bar Indicated in Cl.1 & 2Indicated in Cl.1 & 2 arches where morearches where more teeth to be replacedteeth to be replaced ToriTori
  14. 14. Horse-shoe/ U shaped connectorHorse-shoe/ U shaped connector  Borders must be 6mmBorders must be 6mm from ging. margin/from ging. margin/ extend onto ling surfextend onto ling surf  Lateral bordersLateral borders should be at jnshould be at jn horizontal & verticalhorizontal & vertical slopesslopes  SymmetricSymmetric  Cl. 4Cl. 4  Hard palatal sutureHard palatal suture line & inoperable toriline & inoperable tori  Less rigid, not usedLess rigid, not used in Cl.1 & Cl.1 & 2.
  15. 15. PALATAL PLATE TYPEPALATAL PLATE TYPE CONNECTORCONNECTOR INDICATIONSINDICATIONS  In most situations inIn most situations in which only some or allwhich only some or all anterior teeth remainanterior teeth remain  Class II arch with a largeClass II arch with a large posterior modificationposterior modification space and some missingspace and some missing anterior teethanterior teeth
  16. 16. Palatal platePalatal plate  Ultimate rigidity & support, coveringUltimate rigidity & support, covering half/more of hard palatehalf/more of hard palate  Post border – jn of hard & soft palatePost border – jn of hard & soft palate  Ant border – 6mm from marginal gingiva/Ant border – 6mm from marginal gingiva/ cover cingulacover cingula  Cl.1 & Cl.2 with modificationsCl.1 & Cl.2 with modifications  Heavy occl forces , flat/flabby ridges,Heavy occl forces , flat/flabby ridges, shallow vault, transition to CD, cleft ptsshallow vault, transition to CD, cleft pts  Disadv- Extensive coverage-soft tissueDisadv- Extensive coverage-soft tissue reaction-inadequate oral hygienereaction-inadequate oral hygiene
  17. 17.
  18. 18. BeadingBeading Denotes scribing of aDenotes scribing of a shallow groove on theshallow groove on the maxillary master castmaxillary master cast outlining the palataloutlining the palatal major connectormajor connector exclusive of rugaeexclusive of rugae areas.areas. Depth & width of 0.5 toDepth & width of 0.5 to 1mm1mm Fades out 6mm fromFades out 6mm from Gingival marginGingival margin
  19. 19. Purpose of beadingPurpose of beading 1) To transfer the major1) To transfer the major connector design toconnector design to the investment castthe investment cast
  20. 20. 2) To provide a visible2) To provide a visible finish line for thefinish line for the castingcasting 3) To ensure intimate3) To ensure intimate tissue contact of thetissue contact of the major connector withmajor connector with selected palatalselected palatal tissuetissue 4) Prevents food debris4) Prevents food debris under the connectorunder the connector 5) Enhances retention5) Enhances retention & stability& stability
  21. 21.
  22. 22. Summary of IndicationsSummary of Indications  Perio support of remaining teeth weak –Perio support of remaining teeth weak – PalatalPalatal plateplate  Good perio support –Good perio support – Palatal strap/A-P barPalatal strap/A-P bar  Long distal extn bases –Long distal extn bases – Complete palatalComplete palatal plate/ closed horseshoeplate/ closed horseshoe  Cl. 4 –Cl. 4 – Horseshoe, Closed horseshoe, completeHorseshoe, Closed horseshoe, complete palatepalate depending on no. & location of postdepending on no. & location of post missing teeth, support of rem. Teeth, andmissing teeth, support of rem. Teeth, and opposing occlusionopposing occlusion  Inoperable torus –Inoperable torus – Horseshoe, closed, A-P BarHorseshoe, closed, A-P Bar  Single palatal bar rarely indicated.Single palatal bar rarely indicated.
  23. 23. MandibularMandibular  Lingual barLingual bar  Lingual plateLingual plate  Double lingual bar/ Kennedy barDouble lingual bar/ Kennedy bar  Labial barLabial bar
  24. 24. STRUCTURALSTRUCTURAL REQUIREMENTSREQUIREMENTS 1.1. Long and relatively narrow because of spaceLong and relatively narrow because of space limitationslimitations 2.2. Rigidity without addition of bulkRigidity without addition of bulk 3.3. Relief should be provided . Amount of reliefRelief should be provided . Amount of relief depends on type of connector.depends on type of connector. 4.4. Beading is never indicated.Beading is never indicated.
  25. 25. Lingual barLingual bar  Most frequently used, half pear shapedMost frequently used, half pear shaped  Atleast 8mm space requiredAtleast 8mm space required
  26. 26. Lingual BarLingual Bar  Half pear shaped with bulkiest portionHalf pear shaped with bulkiest portion inferiorly located.inferiorly located.  Superior border tapered to soft tissue,Superior border tapered to soft tissue, located 4 mm inferior to gingivallocated 4 mm inferior to gingival margins.margins.  Inferior border located at the asertainedInferior border located at the asertained height of the alveolar lingual sulcusheight of the alveolar lingual sulcus when the patients tongue is elevated .when the patients tongue is elevated .
  27. 27.
  28. 28.
  29. 29.
  30. 30.
  31. 31. Sublingual barSublingual bar Used when the height of floor of the mouth inUsed when the height of floor of the mouth in relation to the free gingival margins is lessrelation to the free gingival margins is less than 6mm.than 6mm.  Inferior border at height of lingual sulcus.Inferior border at height of lingual sulcus.
  32. 32. LinguoplateLinguoplate Pear shaped lingual bar with metal extending onto lingual tooth surface
  33. 33. LingouplateLingouplate  Adequate blockout &Adequate blockout & relief under MCrelief under MC  Superior borderSuperior border placed above cingulaplaced above cingula to close space uptoto close space upto contact pointscontact points  Always supported byAlways supported by a rest located noa rest located no further than mesialfurther than mesial fossa of 1fossa of 1stst premolarpremolar
  34. 34. Lingouplate - IndicationsLingouplate - Indications When lingual frenum is high / space available for lingual bar is limited (Min 8mm)
  35. 35.  In Cl. 1, where residual ridges haveIn Cl. 1, where residual ridges have undergone excessive vertical resorptionundergone excessive vertical resorption  Stabilizing periodontally weakened teethStabilizing periodontally weakened teeth  Mandibular toriMandibular tori  Lingoplate mod with incisal rests toLingoplate mod with incisal rests to prevent mand. ant teeth fromprevent mand. ant teeth from supraeruption in retrognathia & deep bitesupraeruption in retrognathia & deep bite  Future replacement of one/more anteriorFuture replacement of one/more anterior teeth will be facilitated by addition onteeth will be facilitated by addition on retention loopsretention loops
  36. 36. DisadvantagesDisadvantages  Extensive coverage may lead toExtensive coverage may lead to decalcification of enamel surfaces ordecalcification of enamel surfaces or irritation of soft tissue with poor oralirritation of soft tissue with poor oral hygienehygiene
  37. 37. Double lingual/ Kennedy BarDouble lingual/ Kennedy Bar  Lingual bar withLingual bar with continuous barcontinuous bar retainerretainer  Axial alignment of antAxial alignment of ant teeth such thatteeth such that excessive blockout ofexcessive blockout of interproximalinterproximal undercuts ifundercuts if liguoplate is usedliguoplate is used  More tongueMore tongue annoyanceannoyance
  38. 38. Labial barLabial bar  Lingually inclined teethLingually inclined teeth  Mandibular toriMandibular tori  Difficult for patient to adjustDifficult for patient to adjust
  39. 39. Swing lockSwing lock Has a hinge device at one end & locking device in the other. This allows it to be positioned more intimately agnst Gingival tissue.
  40. 40. Dental barDental bar  When clinical crowns are long, andWhen clinical crowns are long, and lingual bar is contraindicated.lingual bar is contraindicated.
  41. 41. SpacingSpacing  Lingual barLingual bar  Notched linguoplate,Notched linguoplate, Double lingual barDouble lingual bar
  42. 42.
  43. 43. Component partsComponent parts  Major ConnectorsMajor Connectors  Minor connectorsMinor connectors  RestsRests  Indirect retainersIndirect retainers  Denture bases & artificial teethDenture bases & artificial teeth  Direct retainersDirect retainers
  44. 44. Minor ConnectorsMinor Connectors  Joins all the otherJoins all the other component parts tocomponent parts to the Majorthe Major ConnectorConnector  Distributes stressesDistributes stresses that occur againstthat occur against certain componentscertain components to otherto other componentscomponents  RigidRigid
  45. 45. Join clasp assembly to MCJoin clasp assembly to MC  Broad BL, thin MD,Broad BL, thin MD,
  46. 46. Join IR, Auxillary rest to MCJoin IR, Auxillary rest to MC  Form rt. angle, jnForm rt. angle, jn should be curvedshould be curved  Placed inPlaced in embrasureembrasure  Relief given forRelief given for marginal gingivamarginal gingiva
  47. 47. Join Denture base to MCJoin Denture base to MC  Latticework constructionLatticework construction  Mesh ConstructionMesh Construction  Bead, Wire, or Nail-headBead, Wire, or Nail-head minor connectorsminor connectors
  48. 48. RequirementsRequirements  Strong enough to anchor denture baseStrong enough to anchor denture base  Rigid enough to resist breakage/flexingRigid enough to resist breakage/flexing  Not interfere with artificial teethNot interfere with artificial teeth arrangementarrangement
  49. 49. LatticeworkLatticework  2 struts of metal ext along edent ridge, smaller2 struts of metal ext along edent ridge, smaller struts connect the 2 strutsstruts connect the 2 struts  Longitudinal strut on crest avoidedLongitudinal strut on crest avoided  Provides strongest attachment to DBProvides strongest attachment to DB  Easiest to relineEasiest to reline
  50. 50. MeshworkMeshwork  Thin sheet of metal with multiple holesThin sheet of metal with multiple holes over crest of ridgeover crest of ridge  More difficult to pack acrylicMore difficult to pack acrylic  Not strong attachmentNot strong attachment
  51. 51. Bead, Wire or Nail-headBead, Wire or Nail-head  Casting fits directly onCasting fits directly on ridge, no reliefridge, no relief  HygienicHygienic  Difficult to adjust base,Difficult to adjust base, cannot be relinedcannot be relined  Weakest of 3 typesWeakest of 3 types  Used on tooth supported,Used on tooth supported, well healed ridges whenwell healed ridges when interarch space is limitedinterarch space is limited and acrylic by itself wouldand acrylic by itself would not have sufficientnot have sufficient strengthstrength
  52. 52. Approach arm for bar claspApproach arm for bar clasp  Only minor connector not rigidOnly minor connector not rigid  Should have smooth even taperShould have smooth even taper
  53. 53. Finish linesFinish lines  To prevent acrylicTo prevent acrylic from being thinnedfrom being thinned excessively in orderexcessively in order to produce a smoothto produce a smooth joint, the junction ofjoint, the junction of tha major & minortha major & minor connectors mustconnectors must provide space for aprovide space for a butt joint .butt joint . Internal finish lines formed by relief wax before duplication
  54. 54. Component partsComponent parts  Major ConnectorsMajor Connectors  Minor connectorsMinor connectors  RestsRests  Indirect retainersIndirect retainers  Denture bases & artificial teethDenture bases & artificial teeth  Direct retainersDirect retainers
  55. 55. RestsRests Component that serves primarily to transfer forces along long axis of abutments – Rests , support Prepared surface of a tooth/fixed restoration – rest seat
  56. 56. Auxillary functions of restsAuxillary functions of rests  Distribution of horizontal forceDistribution of horizontal force  Maintaining components in their correctMaintaining components in their correct positionposition  Protecting the denture-abutment tooth jnProtecting the denture-abutment tooth jn  Indirect retentionIndirect retention  ReciprocationReciprocation  Preventing supraeruptionPreventing supraeruption  Improving occlusal contactImproving occlusal contact
  57. 57. TypesTypes OcclusalOcclusal CingulumCingulum IncisalIncisal
  58. 58. Component partsComponent parts  Major ConnectorsMajor Connectors  Minor connectorsMinor connectors  RestsRests  Indirect retainersIndirect retainers  Denture bases & artificial teethDenture bases & artificial teeth  Direct retainersDirect retainers
  59. 59. Indirect retentionIndirect retention  Indirect retainer.Indirect retainer.  The component of removableThe component of removable partial denturepartial denture that assists thethat assists the direct retainer in preventingdirect retainer in preventing displacement of the distaldisplacement of the distal extension denture baseextension denture base byby functioning through lever actionfunctioning through lever action on the opposite side of theon the opposite side of the fulcrum linefulcrum line when the denturewhen the denture base moves away from thebase moves away from the tissues in pure rotation aroundtissues in pure rotation around the fulcrum line.the fulcrum line. (GPT-7)(GPT-7)  Indirect retainer also contributes to aIndirect retainer also contributes to a lesser degree, to the support andlesser degree, to the support and stability of the denture.stability of the
  60. 60. Indirect retainerIndirect retainer
  61. 61. Factors determining effectivenessFactors determining effectiveness  Placed in definite rest seatsPlaced in definite rest seats  Greater the distance between the fulcrumGreater the distance between the fulcrum & IR, more effective& IR, more effective  Direct retainer must be effectiveDirect retainer must be effective  Must be rigidMust be rigid  Linguoplate & Complete palate plateLinguoplate & Complete palate plate
  62. 62. Component partsComponent parts  Major ConnectorsMajor Connectors  Minor connectorsMinor connectors  RestsRests  Indirect retainersIndirect retainers  Denture bases & artificial teethDenture bases & artificial teeth  Direct retainersDirect retainers
  63. 63. Denture BasesDenture Bases  Rests on the foundation tissue and toRests on the foundation tissue and to which teeth are attachedwhich teeth are attached  Effects transfer of occlusal forces toEffects transfer of occlusal forces to supporting oral structuressupporting oral structures  May also add to estheticsMay also add to esthetics  Stimulation of underlying tissues ofStimulation of underlying tissues of residual ridgeresidual ridge  Acrylic & MetalAcrylic & Metal
  64. 64.
  65. 65. Tooth replacementsTooth replacements  Anterior – Acrylic, Porcelain, Facings,Anterior – Acrylic, Porcelain, Facings, Tube teeth, Reinforced acrylic ponticsTube teeth, Reinforced acrylic pontics  Posterior – Acrylic, Porcelain, MetalPosterior – Acrylic, Porcelain, Metal Pontics, Metal pontics with acrylicPontics, Metal pontics with acrylic window, Tube teethwindow, Tube teeth
  66. 66. Stress breakersStress breakers  Relieves specific dental structures of aRelieves specific dental structures of a part or all of the occlusal forces andpart or all of the occlusal forces and directs those forces to other bearingdirects those forces to other bearing structures or regionsstructures or regions  Also termed – Stress equalizer, StressAlso termed – Stress equalizer, Stress director, Articulated prosthesesdirector, Articulated prostheses
  67. 67. Stress EqualizationStress Equalization  Resiliency of the tooth securedResiliency of the tooth secured by the periodontal ligament in anby the periodontal ligament in an apical direction is notapical direction is not comparable to the greatercomparable to the greater resiliency and displaceability ofresiliency and displaceability of the mucosa covering thethe mucosa covering the edentulous ridge.edentulous ridge.
  68. 68.  Therefore , it isTherefore , it is believed that a typebelieved that a type of stress equalizer isof stress equalizer is needed to replace theneeded to replace the rigid connectionrigid connection between denturebetween denture base and directbase and direct retainer.retainer.
  69. 69.  Most commonMost common type is a hingetype is a hinge device whichdevice which permits verticalpermits vertical movement of themovement of the denture base. itdenture base. it can be adjusted tocan be adjusted to control thecontrol the amount of verticalamount of vertical movement.movement.
  70. 70. Advantages.Advantages. 1.1. Minimal direct retention is required- asMinimal direct retention is required- as denture base acts more independently.denture base acts more independently. 2.2. Theoretically minimize tipping tippingTheoretically minimize tipping tipping forces on abutments .forces on abutments .
  71. 71. Disadvantages.Disadvantages. 1.1. Construction of stress director isConstruction of stress director is complex and costly.complex and costly. 2.2. Constant maintenance required.Constant maintenance required. 3.3. Difficult or impossible to repair.Difficult or impossible to repair. 4.4. Lateral movements of base can lead toLateral movements of base can lead to rapid resorption of the ridges.rapid resorption of the ridges.
  72. 72.
  73. 73.
  74. 74.
  75. 75. Major connectorsMajor connectors Mandibular arch.Mandibular arch.  Lingual plate major connector can aidLingual plate major connector can aid in distribution of functional stress -in distribution of functional stress - anterior teeth are periodontallyanterior teeth are periodontally weakened.weakened.  Also indicted in class 1 arches whenAlso indicted in class 1 arches when the need for additional resistance tothe need for additional resistance to horizontal rotation of the denture ishorizontal rotation of the denture is required because of excessivelyrequired because of excessively resorbed residual ridges.resorbed residual ridges.  Another indication is in shallow floor ofAnother indication is in shallow floor of mouth.mouth.
  76. 76.  Added rigidity provided by lingualAdded rigidity provided by lingual plate also helps in distributing stressplate also helps in distributing stress created on one side of the arch to thecreated on one side of the arch to the other side (CROSS ARCHother side (CROSS ARCH STABILIZATION).STABILIZATION).  A lingual bar should be taperedA lingual bar should be tapered superiorly with a half pear shape insuperiorly with a half pear shape in cross section and should be relivedcross section and should be relived sufficiently.sufficiently.
  77. 77. Maxillary arch.Maxillary arch.  Broad palatal major connector thatBroad palatal major connector that connects several of the remainingconnects several of the remaining natural teeth through lingual plating cannatural teeth through lingual plating can distribute stress over a large area.distribute stress over a large area.  Major connector covering hard palateMajor connector covering hard palate contributes to support, stability, andcontributes to support, stability, and retention of the prosthesis.and reducesretention of the prosthesis.and reduces the stress that is transmitted to thethe stress that is transmitted to the abutment teeth.abutment teeth.
  78. 78. Thank you For more details please visit