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Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
Indirect retention /orthodontic nursing course
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Indirect retention /orthodontic nursing course

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Indian Dental Academy: will be one of the most relevant and exciting training

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professionals who wish to advance in their dental practice,Offers certified

courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry,

Prosthetic Dentistry, Periodontics and General Dentistry.

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  • 1. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com
  • 3. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 4. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 5. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 6. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 7. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 8. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 9. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 10. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 11. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 12. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 13. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 14. IIndirect retentionndirect retention is required on allis required on all extension-extension- base partial denturesbase partial dentures retained byretained by clasps.clasps. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 15. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 16. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 17. It is required also when the tooth atIt is required also when the tooth at one endone end of a denture base is clasped for retention butof a denture base is clasped for retention but the tooth at the other end isthe tooth at the other end is not suitablenot suitable forfor retention.retention. Extension-base partial dentures areExtension-base partial dentures are needed more often than any other type ofneeded more often than any other type of removable partial denture.removable partial denture. If theseIf these statements are true, then we need to considerstatements are true, then we need to consider indirect retention carefully.indirect retention carefully. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 18. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 19. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 20. KennedyKennedy wrote thatwrote that CummerCummer advanced the ideaadvanced the idea ofof indirect retentionindirect retention and had revolutionizedand had revolutionized partial denture designingpartial denture designing.. CummerCummer reasonedreasoned that the rationale of indirect retention was athat the rationale of indirect retention was a modification of a C 1 levermodification of a C 1 lever. Indirect retention. Indirect retention was a valuable contribution to partial denturewas a valuable contribution to partial denture design. However, it is a much better example ofdesign. However, it is a much better example of aa Class 2 leverClass 2 lever than, athan, a Class 1 lever.Class 1 lever. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 21. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 22. Levers are classified according to theLevers are classified according to the location of thelocation of the fulcrum,fulcrum, thethe powerpower,, and theand the resistanceresistance in respect to each other. Therein respect to each other. There areare threethree classes.classes. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 23. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 24. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 25. In Class 1, the fulcrum is between the power and theIn Class 1, the fulcrum is between the power and the resistance. The resulting mechanical advantageresistance. The resulting mechanical advantage cancan be greater or less than onebe greater or less than one depending upon thedepending upon the locationlocation of the fulcrum along the lever.of the fulcrum along the lever. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 26. The Class 2 lever has theThe Class 2 lever has the resistanceresistance betweenbetween thethe fulcrumfulcrum and theand the powerpower, and has a mechanical, and has a mechanical advantage that isadvantage that is always greater than one.always greater than one. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 27. In Class 3, theIn Class 3, the powerpower is appliedis applied betweenbetween thethe fulcrumfulcrum and theand the resistanceresistance. Its mechanical. Its mechanical advantage isadvantage is always less than one.always less than one. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 28. TheThe mechanical advantagemechanical advantage of a lever is expressed asof a lever is expressed as thethe quotient of the power arm length divided by thequotient of the power arm length divided by the resistance arm length.resistance arm length. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 29. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 30. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 31. Indirect retention is an application of a Class 2 leverIndirect retention is an application of a Class 2 lever www.indiandentalacademy.comwww.indiandentalacademy.com
  • 32. The tooth surface on which the indirectThe tooth surface on which the indirect retention rests is theretention rests is the fulcrumfulcrum. The retentive. The retentive part of the direct retainer clasp becomes thepart of the direct retainer clasp becomes the resistanceresistance, and the, and the powerpower is represented byis represented by any force that tends to move the dentureany force that tends to move the denture base away from the underlying tissue.base away from the underlying tissue. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 33. TheThe resistance arm lengthresistance arm length, then, is the, then, is the distance between the retentive part of thedistance between the retentive part of the direct retainer clasp and the pivotal edge ofdirect retainer clasp and the pivotal edge of the indirect retention. The potential length ofthe indirect retention. The potential length of thethe power armpower arm is the distance between theis the distance between the free end of the denture base and the pivotalfree end of the denture base and the pivotal edge of the indirect retention.edge of the indirect retention. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 34. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 35. InIn all probabilityall probability, the power arm, the power arm never functionsnever functions at itsat its full potential lengthfull potential length because forces that tend to unseatbecause forces that tend to unseat the base act most often on thethe base act most often on the teeth on the baseteeth on the base.. InIn function,function, therefore, thetherefore, the length of the power armlength of the power arm isis shortershorter than its potential length.than its potential length. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 36. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 37. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 38. A list of factors thatA list of factors that influence the effectiveness ofinfluence the effectiveness of indirect retentionindirect retention must include the following:must include the following: www.indiandentalacademy.comwww.indiandentalacademy.com
  • 39. 1.1. The effectiveness of the direct retention (The effectiveness of the direct retention (thethe resistanceresistance)-)-Indirect retention cannot be moreIndirect retention cannot be more effective than the direct retention of the clasps.effective than the direct retention of the clasps. Actually, indirect retention does not begin toActually, indirect retention does not begin to function until the physiologic retentionfunction until the physiologic retention contributed by the extension base is overcomecontributed by the extension base is overcome and, simultaneously, the resistance offered byand, simultaneously, the resistance offered by the direct retention is challenged. Therefore,the direct retention is challenged. Therefore, thethe direct retention must be adequate.direct retention must be adequate. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 40. 2.2. The effectiveness of the tooth ant its rest seatThe effectiveness of the tooth ant its rest seat ((the fulcrumthe fulcrum) on which the indirect retention) on which the indirect retention rests or pivotsrests or pivots.- A fulcrum must offer positive.- A fulcrum must offer positive support for a lever to function most effectively.support for a lever to function most effectively. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 41. Its efficiency may be reduced if indirect retention isIts efficiency may be reduced if indirect retention is placed on inclined surfaces of teeth. It should beplaced on inclined surfaces of teeth. It should be placed inplaced in rest seatsrest seats on teeth capable of supporting itson teeth capable of supporting its function. The capability of any tooth to support thefunction. The capability of any tooth to support the function of a rest can be enhanced by preparing thefunction of a rest can be enhanced by preparing the rest seat so thatrest seat so that forcesforces are directedare directed parallelparallel to theto the long axislong axis of the tooth.of the tooth. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 42. 3.3. The rigidity of the major and the minorThe rigidity of the major and the minor connectors (connectors (the leverthe lever).-).-A lever must be rigid toA lever must be rigid to effect a positive action. This means that theeffect a positive action. This means that the connectorsconnectors must bemust be rigidrigid.. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 43. 4.4. The mechanical advantage of the lever-The mechanical advantage of the lever- TheThe lower the mechanical advantage, the more liftinglower the mechanical advantage, the more lifting force is necessary on the extension base toforce is necessary on the extension base to overcome the resistance of the direct retentionovercome the resistance of the direct retention and move the base off its seat - in other words,and move the base off its seat - in other words, decreasedecrease the mechanical advantage of the leverthe mechanical advantage of the lever andand increaseincrease the effectiveness of the indirectthe effectiveness of the indirect retentionretention. This is the. This is the key factorkey factor in indirectin indirect retention.retention. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 44. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 45. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 46. Basically, there areBasically, there are two waystwo ways to reduce theto reduce the mechanical advantage of a Class 2 lever.mechanical advantage of a Class 2 lever. OneOne is tois to shorten the power arm at the power endshorten the power arm at the power end of the leverof the lever. If the power arm is shortened at the. If the power arm is shortened at the fulcrum end, the mechanical advantage will befulcrum end, the mechanical advantage will be increased because the resistance arm is shortenedincreased because the resistance arm is shortened the same amount but proportionately more.the same amount but proportionately more. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 47. Since forces that tend to unseat extension bases actSince forces that tend to unseat extension bases act most often on the teeth on the bases, themost often on the teeth on the bases, the mesiodistal span of these teeth should be kept to amesiodistal span of these teeth should be kept to a minimum to keep theminimum to keep the effective length of the powereffective length of the power arm to a minimumarm to a minimum. Where possible,. Where possible, smaller teethsmaller teeth should be used to reduce the span rather thanshould be used to reduce the span rather than reduce the number of larger teeth. The smallerreduce the number of larger teeth. The smaller teeth not onlyteeth not only reduce the mesiodistal spanreduce the mesiodistal span but alsobut also thethe buccolingual widthbuccolingual width, thus presenting a, thus presenting a smallersmaller area for application of force.area for application of force. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 48. The denture bases should not be shortened toThe denture bases should not be shortened to decrease the potential length of the power armdecrease the potential length of the power arm because thebecause the base itself contributes physiologicbase itself contributes physiologic retentionretention through its intimate relationship with thethrough its intimate relationship with the underlying tissue. Moreover, the retention isunderlying tissue. Moreover, the retention is proportionateproportionate to the area covered by the dentureto the area covered by the denture base.base. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 49. TheThe other wayother way to reduce the mechanical advantageto reduce the mechanical advantage of a Class 2 lever is to lengthen the resistance armof a Class 2 lever is to lengthen the resistance arm at either of its ends. The optimum length of theat either of its ends. The optimum length of the resistance arm can be attained on extension-baseresistance arm can be attained on extension-base partial dentures by placing the indirect retention aspartial dentures by placing the indirect retention as far from the denture base as feasible and byfar from the denture base as feasible and by placing the retentive clasp tips of the directplacing the retentive clasp tips of the direct retainer as near to the denture base as possible.retainer as near to the denture base as possible. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 50. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 51. TheThe objectiveobjective is tois to increase the distance between theincrease the distance between the direct and indirect retention as much as feasible.direct and indirect retention as much as feasible. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 52. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 53. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 54. MMajor connectorajor connector stabilizers transmit forces fromstabilizers transmit forces from the major connector to the teeth and other tissues,the major connector to the teeth and other tissues, and vice versa. They serve many functions. Itand vice versa. They serve many functions. It helpshelps toto stabilizestabilize the major connector against vertical andthe major connector against vertical and lateral forces, andlateral forces, and decreasesdecreases stresses on thestresses on the principal abutment teeth by transmitting forces toprincipal abutment teeth by transmitting forces to other teeth in the arch.other teeth in the arch. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 55. Thus, the so-called indirect retainerThus, the so-called indirect retainer servesserves many functionsmany functions and is really a majorand is really a major connector stabilizer that offers indirectconnector stabilizer that offers indirect retention as its primary function.retention as its primary function. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 56. Any minor connector plus its rest (s) -incisal,Any minor connector plus its rest (s) -incisal, cingulum, ledge, or occlusal-on tooth surface (s) is acingulum, ledge, or occlusal-on tooth surface (s) is a major connector stabilizermajor connector stabilizer. Clasps for stabilization. Clasps for stabilization and retention may be included. At least three types ofand retention may be included. At least three types of major connector stabilizers employing the minormajor connector stabilizers employing the minor connector are possible.connector are possible. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 57. OneOne is the minor connector plus its rest (s) withoutis the minor connector plus its rest (s) without clasps.clasps. AnotherAnother is the minor connector plus its rest (s)is the minor connector plus its rest (s) with clasps for stabilization only. Awith clasps for stabilization only. A thirdthird is the minoris the minor connector plus its rest (s) with clasps for bothconnector plus its rest (s) with clasps for both stabilization and retention.stabilization and retention. Any of the 3 may serve as indirect retention, but theAny of the 3 may serve as indirect retention, but the first is used most oftenfirst is used most often for that purpose.for that purpose. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 58. Other partial denture units that serve to someOther partial denture units that serve to some extent as major connector stabilizers are theextent as major connector stabilizers are the secondary lingual barsecondary lingual bar, the, the lingual platelingual plate andand thethe extension baseextension base. Any of these can. Any of these can function as indirect retention.function as indirect retention. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 59. Their efficiency however may be reducedTheir efficiency however may be reduced since the secondary lingual bar and the lingualsince the secondary lingual bar and the lingual plateplate rest on inclined tooth surfacesrest on inclined tooth surfaces, and the, and the denture base rests on soft tissue. Thedenture base rests on soft tissue. The rugaerugae areaarea of the palate is covered sometimes forof the palate is covered sometimes for indirect retentionindirect retention, but rests on the teeth are, but rests on the teeth are much more effective.much more effective. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 60. A secondary lingual bar and a lingual plateA secondary lingual bar and a lingual plate alsoalso tend to stabilizetend to stabilize the teeth that theythe teeth that they contact. That is, theycontact. That is, they preventprevent lingual tippinglingual tipping of the lower anterior teeth by theof the lower anterior teeth by the occludingoccluding forcesforces of the upper anterior teeth and theof the upper anterior teeth and the muscle actionmuscle action of the lower lip.of the lower lip. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 61. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 62. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 63. On extension-base partial dentures with basesOn extension-base partial dentures with bases extending distally, the fulcrum line is usuallyextending distally, the fulcrum line is usually defined as andefined as an imaginary line passing through theimaginary line passing through the rest seat in the most posterior abutment tooth onrest seat in the most posterior abutment tooth on each side of the archeach side of the arch. Then the fulcrum line passes. Then the fulcrum line passes through the rest area of the most anterior abutmentthrough the rest area of the most anterior abutment tooth on each side of the arch when the denturetooth on each side of the arch when the denture base extends mesially.base extends mesially. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 64. For these definitions to be valid, theFor these definitions to be valid, the principal abutment teeth must have rests onprincipal abutment teeth must have rests on themthem. This is not always true, since some. This is not always true, since some partial dentures do not have a rest on thepartial dentures do not have a rest on the principal abutment tooth but on the nextprincipal abutment tooth but on the next tooth in the arch.tooth in the arch. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 65. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 66. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 67. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 68. Moreover, aMoreover, a second fulcrum linesecond fulcrum line may bemay be established when indirect retention is present.established when indirect retention is present. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 69. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 70. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 71. Therefore, “Therefore, “the fulcrum linethe fulcrum line” should be redefined” should be redefined and referred to as the “and referred to as the “primary fulcrum lineprimary fulcrum line” to” to distinguish it from the secondary fulcrum line. Thedistinguish it from the secondary fulcrum line. The fulcrum line on distal extension partial dentures,fulcrum line on distal extension partial dentures, then, isthen, is an imaginary line passing through the mostan imaginary line passing through the most distal rest seat (of a tooth) on each side of the arch.distal rest seat (of a tooth) on each side of the arch. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 72. If the denture base extends mesially, theIf the denture base extends mesially, the primary fulcrum line passes through theprimary fulcrum line passes through the most mesial rest seat on each side of themost mesial rest seat on each side of the arch.arch. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 73. When a second fulcrum line is produced by indirect retention, www.indiandentalacademy.comwww.indiandentalacademy.com
  • 74. the prosthesis rotates about the primary fulcrum line if the denture base is forced tissueward, www.indiandentalacademy.comwww.indiandentalacademy.com
  • 75. and about the secondary fulcrum line if the dentureand about the secondary fulcrum line if the denture base is lifted off the tissue.base is lifted off the tissue. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 76. However, if a second fulcrum line is notHowever, if a second fulcrum line is not produced by indirect retention,produced by indirect retention, www.indiandentalacademy.comwww.indiandentalacademy.com
  • 77. the prosthesis rotates about the primary fulcrum linethe prosthesis rotates about the primary fulcrum line whether forces move the denture base toward orwhether forces move the denture base toward or away from the tissue. Theseaway from the tissue. These fulcrum linesfulcrum lines are notare not only the fulcra produced by vertical stops on theonly the fulcra produced by vertical stops on the teeth, but the others are irrelevant to this discussionteeth, but the others are irrelevant to this discussion since they are not concerned with indirect retention.since they are not concerned with indirect retention. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 78. These designs emphasize the fact that indirect retention is located in relation to the retentive part of the direct retainer clasps, not to the primary fulcrum line. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 79. As a matter of fact,As a matter of fact, indirect retention does oneindirect retention does one thingthing: it prevents the retentive part of the direct: it prevents the retentive part of the direct retainer clasps from becoming a fulcrum or point ofretainer clasps from becoming a fulcrum or point of rotation about which the prosthesis could rotaterotation about which the prosthesis could rotate when forces move the denture base(s) away fromwhen forces move the denture base(s) away from the underlying tissue.the underlying tissue. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 80. When rotation about the clasp tips is prevented byWhen rotation about the clasp tips is prevented by any unit(s) of the partial denture, the dentureany unit(s) of the partial denture, the denture base(s) cannot move away from the tissue until thebase(s) cannot move away from the tissue until the resistance to deformation of the retentive clasps isresistance to deformation of the retentive clasps is overcome.overcome. IndirectlyIndirectly then, partial denture unitsthen, partial denture units preventing this rotationpreventing this rotation retainretain the denture bases inthe denture bases in contact with the underlying tissue, hence the namecontact with the underlying tissue, hence the name indirect retentionindirect retention.. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 81. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 82. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 83. The principle of indirect retention is shown to beThe principle of indirect retention is shown to be an application of aan application of a Class 2 leverClass 2 lever. The so-called. The so-called indirect retainer is aindirect retainer is a major connector stabilizermajor connector stabilizer. A. A secondary fulcrum linesecondary fulcrum line is usually established whenis usually established when partial design includes indirect retention. Indirectpartial design includes indirect retention. Indirect retentionretention preventsprevents the retentive clasp tips fromthe retentive clasp tips from becoming a fulcrum about which the prosthesisbecoming a fulcrum about which the prosthesis could rotate when forces move the denture basecould rotate when forces move the denture base away from the tissue.away from the tissue. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 84. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 85. 1.1. Kennedy E.Kennedy E. : Partial denture construction.: Partial denture construction. 2.2. Cummer WECummer WE. : Partial denture service.. : Partial denture service. 3.3. McCrackenMcCracken WEWE. : Partial denture construction. : Partial denture construction 4.4. Steffel V LSteffel V L. Planning removable partial dentures.. Planning removable partial dentures. J Prosthet DentJ Prosthet Dent 19621962;; 22:: 3535.. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 86. For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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