Management of Kennedys Class III Classification

Management of Kennedys Class III Classification with all the essential designs

1. Presented by: Dr. Jehan Dordi 2 nd Yr. MDS MANAGEMENT OF KENNEDY’S CLASS III CLASSIFICATION 1

2. CONTENTS 2 Terminologies Introduction History Principles of designing Biomechanical considerations Essentials of partial denture design Designing of class III Review of literature Summary Conclusion References

3. TERMINOLOGIES 3

4. 4 RPD- A removable denture that replaces some teeth in a partially edentulous arch; the removable partial denture can be readily inserted and removed from the mouth by the patient . Biomechanics- An application of the principles of engineering design as implemented in living organisms. D irect retention- retention obtained in a removable partial denture by the use of clasps or attachments that resist removal from the abutment teeth. I ndirect retention - the effect achieved by one or more indirect retainers of a removable partial denture that reduces the tendency for a denture base to move in an occlusal direction or in a rotational path about the fulcrum line

5. 5 Clasp - the component of the clasp assembly that engages a portion of the tooth surface and either enters an undercut for retention or remains entirely above the height of contour to act as a reciprocating element; generally it is used to stabilize and retain a removable partial denture. Rest - a rigid extension of a removable partial denture that contacts the occlusal, incisal, cingulum, or lingual surface of a tooth or restoration, the surface of which is commonly prepared to receive it Major connector- the part of a removable partial denture that joins the components on one side of the arch to those on the opposite side M inor connector- the connecting link between the major connector or base of a removable partial denture and the other units of the prosthesis, such as the clasp assembly, indirect retainers , occlusal rests, or cingulum rests

6. INTRODUCTION 6

7. 7 The design process is a series of steps that leads toward a solution of the problem and includes; Identifying a need, Definition of the problem, Setting design objectives, Developing a design rationale, Devising and evaluating alternative solutions, and Providing the solution. Authorities in the field of removable partial denture design may differ on their approach in developing the design of each individual prosthesis . There is however, complete agreement that the correct design incorporates proper use and application of mechanical and biological principles.

8. HISTORY – EVOLUTION OF RPD DESIGN 8

9. 9 1711 - First description of RPD was by Heister - he carved a block of bone to fit the mouth. 1728 - Pierre fauchard father of modern dentistry described construction of lower RPD using two carved blocks of ivory joined together by metal labial and lingual connectors . 1846 - Retentive clasps were first discussed by Mouton . 1880 - First maxillary RPD using palatal connector was by balkwell . 1899 - Bonwill introduced clasping abutments with gold circumferential clasps. 1913- Roach introduced wrought wire clasp

10. 10 1914- Infra bulge clasp was first mentioned by Henrichsen 1970 - Infrabulge clasp did not gain popularity until Roach promoted this concept. Prothero coined the term “ fulcrum line ” 1970 to present – Investigative and research years

11. Biomechanical Classification Of Removable Partial Denture 11

12. 12 This is based on the nature of the supporting tissues . In tooth borne abutment teeth border edentulous space and all the forces are transmitted through the abutment teeth to the bone . Class III belongs here .

13. 13 In tooth mucosa borne functional forces are transmitted through abutment teeth and mucosa to the bone. Class 1,2,4 belong to this grp . In mucosa borne regardless of natural teeth present support is derived entirely from the muco-osseous segment . Most commonly interim or transitional prosthesis belong to this category.

14. 14 Class I, II and IV RPD are subjected to greater stresses because their support is a combination of tooth and soft tissue . Hence in order to achieve methods to control forces acting on RPD we must know development of these forces.

15. BIOMECHANICAL CONSIDERATIONS 15

16. Simple machine 16 Lever Wedge Inclined plane Screw P ulley Wheel and axle

17. Lever 17 A lever is a rigid bar supported somewhere along its length . It may rest on the support or may be supported from above. There are three types of levers

18. CLASS I 18 A class-1 lever has its fulcrum located somewhere between the effort and the resistance. In cantilever type of RPD where there is distal extension if there is bone r esorption of the residual alveolar ridge under the distal extension , it will result in an effort leading to first order lever movement along the fulcrum line

19. CLASS II 19 With a class-2 lever , the fulcrum is at one end, the effort is at the other end and the resistance is in the middle. Seen as indirect retention in removable partial denture

20. CLASS III 20 In a class-3 lever , the fulcrum is at one end and the effort is applied between the fulcrum and the resistance . Usually seen in the tooth supported RPD . Upon consuming sticky food , the food exerts pulling effort on the prosthetic teeth while the natural teeth and retainers exert counteracting forces from both sides .

21. Inclined Plane 21 Forces against the inclined plane may result in deflection of that which is applying the force or may result in the movement of the inclined plane .Neither of these results are desirable. An angle greater than 90 degrees will not yield the desired axial loading and will produce an inclined plane effect . This inclined plane effect can produce slippage of the prosthesis away from the abutment teeth and can cause orthodontic movement of abutment teeth , with concurrent pain and bone loss .

22. Wedge 22 A wedge by definition is a solid object with a broad base and its two sides arising to intersect each other forming an acute angle opposite the base.

23. DESIGN CONSIDERATION 23

24. Principles of Design by A.H. Schmidt (1953) 24 The dentist must have a thorough knowledge of both the mechanical and biologic factors involved in removable partial denture design. The treatment plan must be based on a complete examination and diagnosis of the individual patient. The dentist must correlate the pertinent factors and determine a proper plan of treatment. A removable partial denture should restore form and function without injury to the remaining oral structure. A removable partial denture is a form of treatment and not a cure.

25. 25 Direct Retention Retentive clasp arm Element of partial denture that is responsible for transmitting most of the destructive forces to the abutment teeth . So RPD should be designed to keep clasp retention to a minimum yet provide adequate retention to prevent dislodgement of denture.

26. 26 Qualities of Clasp More flexible retentive arm of the clasp , less stress is transmitted to abutment tooth. But as flexibility of clasp increases , both lateral and vertical stresses transmitted to residual ridge increases .

27. 27 Length of clasp Flexibility can be increased by lengthening the clasp . Clasp length may be increased by using a curved rather than a straight course on an abutment tooth.

28. 28 Material used in clasp construction Chrome alloy - greater stress than gold clasp. To compensate for this property, clasp arm of chrome alloy are constructed with smaller diameter.

29. 29 Clasp Position Quadrilateral configuration- class 3 Tripod configuration- class 2 Bilateral configuration- class 1 Quadrilateral clasping requires direct retainers to be placed at both ends of the edentulous spaces in a Class III , Modification 1 , partially edentulous arch. This design provides optimal retention and stability for the removable partial denture.

30. 30 For the Class II, Modification 1 , partially edentulous arch, tripodal clasping is ideal. Direct retainers should be designed to engage abutments adjacent to both edentulous spaces. For a Class I partially edentulous arch, bilateral clasping is indicated. Although this design does not permit optimal control of harmful forces, it is the best design for existing conditions

31. 31 Frictional control A RPD should be designed so that guiding planes are present on as many teeth as possible. Guiding planes are prepared surfaces that are parallel to each other and parallel to the path the denture takes as it is inserted and withdrawn from the mouth. The frictional contact of the prosthesis against these parallel surfaces can contribute significantly to the retention of the removable partial denture.

32. 32 Indirect Retention Part of RPD that helps direct retainer prevent displacement of distal extension denture by resisting the rotational movement of the denture around the fulcrum line established by the occlusal rests . Essential in design of classes I and II partial denture .

33. 33 Rests Directs forces to long axis of the tooth . Floor of the rest seat < 90° - helps it to grasp the tooth and prevent its migration. Occlusal rest – gently rounded . Rest must be free to move within the rest seat- permits release of stresses that will be transmitted to abutment . More teeth that bear rest seat, less will be stress placed on each tooth .

34. ESSENTIALS OF PARTIAL DENTURE DESIGN. 34

35. FIRST STEP 35 Decide how the partial denture has to be supported. If Tooth supported . Evaluate : Periodontal health Crown and root morphologies Crown to root ratio. Location of tooth in arch. Length of edentulous span. Opposing dentition. It should be systemically developed and outlined on an accurate diagnostic casts .

36. 36 If tooth and tissue supported . Quality and contour of supporting bone and mucosa Extent to planned coverage of ridge. Type and accuracy of impression registration. Accuracy of denture base. Design characteristics of the component parts of framework. Anticipated occlusal load.

37. SECOND STEP 37 Connect the tooth and tissue support units. These connection is facilitated by designing and locating major and minor connectors in compliance with the basic principles and concepts.

38. THIRD STEP. 38 Determine how the partial denture is to be retained. Select clasp design that will: Avoid direct transmission of tipping or torqueing forces to the abutment Accommodate the basic principles of clasp design by definitive location of components parts correctly positioned on abutment tooth surfaces. Provide retention against reasonable dislodging forces. Be compatible with undercut locations , tissue contour and esthetic desires of the patient.

39. FOURTH STEP 39 Connect the retention units to the support units FIFTH STEP. Outline and join the edentulous area to the already established design components.

40. VARIOUS FACTORS INFLUENCING DESIGN 40

41. 41 Arch relationship. Occlusal relationship of remaining teeth. Orientation of occlusal plane. Space available for restoration of missing teeth. Arch integrity. Tooth morphology . Type of major connector indicated, based on existing and correctable situations.

42. 42 III. If distal extension bases are involved then. Need for indirect retention. Clasp designs that will minimize forces directed towards abutment teeth. Type of base material for later rebasing . IV. Materials to be used both for framework and for the bases . V. Type of replacement teeth to be used, influenced by the opposing dentition.

43. 43 Need for abutment restoration which may influence the type of clasp arms to be used . Patients past experience and reason for making a new denture . VIII. Response of oral structures to previous stress, the amount of abutment support remaining . IX. Method to be used for replacing single teeth or missing anterior teeth.

44. ESSENTIALS OF DESIGN IN CLASS III 44

45. 45 The design of class III RPD originates on the diagnostic cast so that all mouth preparations may be planned and performed with a specific design in mind . Direct retention Retention can be achieved with much less potential harmful effect on the abutment teeth . Prosthesis are entirely tooth borne , the transmission of harmful forces to the abutment and ridges can be minimized. The position of the retentive undercut on abutment teeth is not critical .

46. 46 Clasps Quadrilateral positioning of direct retainers is ideal. Tooth & soft tissue contours, esthetics should be considered . Type of clasp selected is not critical. Bracing arms must be rigid Reciprocal elements must be rigid . Rests Rests should be prepared next to the edentulous area. Rests should be used to support the major connector and lingual plating. Indirect retention It is usually not required.

47. 47 Major connectors The simplest connector should be selected. The major connector should be rigid. It should not impinge on gingival tissue. Support from the hard palate should be used in the design of major connector. The major connector can be extended onto the lingual surfaces of the teeth to increase rigidity, distribute lateral stresses, improve indirect retention or eliminate potential food impaction areas . Usually a palatal strap is used, if modification spaces are present anteroposterior bar can be considered .

48. 48 Minor connectors They must be rigid. They should be positioned to enhance comfort, cleanliness and the placement of artificial teeth . Occlusion Centric occlusion and centric relation should coincide A harmonious occlusion should be established with no interceptive contacts and with all eccentric movements dictated by or in harmony with the remaining natural teeth. Artificial teeth should be selected and positioned to minimize stresses produced by prosthesis.

49. 49 Smaller and/or fewer teeth and teeth that are narrower bucco-lingually may be selected. The teeth should be positioned over the crest of the ridge for mechanical advantage. Teeth should be modified to produce sharp cutting edges and ample escape ways. Denture base Functional type of impression is not required. Extent of coverage of residual ridge should be determined by appearance, comfort and the avoidance of food impaction areas .

50. SUMMARY 50

51. 51 Retention should not be the prime objective of design instead, efficiency, esthetics, comfort and preservation should be taken care. Simplest type of clasp and connector that will accomplish design objective should be employed. Tooth support should be exploited to the extent that it is available . No parts should impinge on free gingival margin . All connectors must be rigid . Principle of indirect retention should be employed when feasible. Harmonious occlusion should be developed. The base of the partial denture should be constructed from a functional impression .

52. CONCLUSION 52

53. 53 The important factor is that basic principles of designing are not violated. Retainer choice, rest placement, connector design are all critical factors. However, the fact remains that adequate time must be spent in proper diagnosis and devising a workable treatment plan in terms of patients prosthetic needs and expectations. Once this is achieved the rather mechanical tasks of RPD design can be carried out to ensure that patients receive the full benefit of our knowledge and skills.

54. REVIEW OF LITERATURE 54

55. Shetty PK, Shetty BY, Hegde M, Prabhu BM . Prosthesis for long span Kennedy’s Class III partially edentulous condition : A case report . Journal of Nepal Dental Association. 2013 Jan;16(1):83. 55 Shetty et al did a case report on Prosthesis for long span Kennedy’s Class III partially edentulous condition. A 29 years old female with bilateral missing of lower posterior teeth for 7 years presented for prosthodontic treatment.

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61. Zancopé K, Abrão GM, Karam FK, Neves FD. Placement of a distal implant to convert a mandibular removable Kennedy class I to an implant-supported partial removable Class III dental prosthesis: A systematic review. The Journal of prosthetic dentistry. 2018 Jun 1;113(6):528-33. 61 The purpose of this systematic review was to evaluate the current evidence about the placement of a distal implant associated with a mandibular PRDP to improve patient satisfaction and the clinical performance of the abutment tooth and distal implant . Two independent prosthetic specialist reviewers conducted this systematic review . The search was performed using selected clinical studies with PRDP associated with distal implants published in English up to May 2018 from the PubMed and Cochrane Library databases.

62. 62 A data extraction form was developed to collect general information : Authors, Title, Year of publication, Aim of study, Level of evidence, Number of participants, Number of implants used, Implant system, Implant length and diameter , Abutment type, Masticatory performance, Patient satisfaction, Implant mean bone loss, Abutment tooth mean bone loss, Prosthetic complications, Follow-up period, and Implant survival rate.

63. 63 The initial electronic search identified 231 studies, and the manual process identified 15 studies (total of 246 studies). After the title and abstract reading and the removal of duplicates, the full texts of 43 studies were obtained. The articles that did not meet the inclusion criteria were excluded (28 studies), and the data from 15 studies were extracted. Seven were retrospective studies, 1 a crossover pilot study, 2 case series, 2 paired clinical studies, and 3 case reports, demonstrating that a high number of the selected studies were of low methodological quality. Nevertheless , the high survival rates for PRDP associated with dental implants have been described .

64. 64 The following conclusions were drawn from this systematic review: The use of a partial removable dental prosthesis associated with a dental implant to convert a Kennedy class I to class III dental prosthesis increases patient satisfaction and masticatory performance and does not impair implant survival rates. Clinical studies with comparable methodology are still lacking to define protocols about the use of distal implants associated with PRDP that consider the abutment tooth survival rate. Long-term , prospective clinical trials are still needed to understand which implant abutments increase abutment tooth survival rate.

65. REFERENCES 65 Rodney D. Phoenix, David R. Cagna , Charls F. Defreest . Stewart’s Clinical Removable Partial Prosthodontics. 4 th edition. Alan b. Carr and David T. Brown. McCracken’s Removable Partial Prosthodontics. 12 th Edition . Removable partial denture design. Arthur J Krol , Theodore Jacobson, Fredreick Finzen . 5th edition Robert W. Loney , Removable Partial Denture Manual. 2008 Indirect retention in partial denture design. J Prosthet Dent 2003, 90, 1-5.  Evolution of removable partial denture design. Journal Of Prosthodontics 1994, 3,158.  Mendonca DB, Prado MM, Mendes FA, Borges T de F, Mendonca G, do Prado CJ, et al. Comparison of masticatory function between subjects with three types of dentition. Int J Prosthodont 2009;22:399-404 .

66. 66 Chronopoulos V, Sarafianou A, Kourtis S. The use of dental implants in combination with removable partial dentures: a case report. J Esthet Restor Dent 2008;20:355-64 . Praveen M, Chandra Sekar A, Saxena A, Gautam Kumar A. A new approach for management of Kennedy’s class I condition using dental implants: a case report . J Indian Prosthodont Soc 2012;12:256-9 . Bortolini S, Natali A, Franchi M, Coggiola A, Consolo U. Implant-retained removable partial dentures: an 8-year retrospective study. J Prosthodont 2011;20:168-72. Grossmann Y, Levin L, Sadan A. A retrospective case series of implants used to restore partially edentulous patients with implant-supported removable partial dentures: 31-month mean follow-up results. Quintessence Int 2008;39:665-71 .

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