Major connector In prosthodontics

Component part major connector in RDP

1. Major Connectors Presented by Dr Mujtaba Ashraf MDS II Dept. of Prosthodontics 17/12/2016 Dr Mujtaba Ashraf 1

2. Contents Introduction to components Major Connectors Types of maxillary major connector Types of mandibular major connector Conclusion References 17/12/2016 Dr Mujtaba Ashraf 2

3. Introduction to Component Parts Each of the component parts of a removable partial denture contributes to specific functions of the prosthesis and the name is most often descriptive of its function. Components of a typical removable partial denture are: Major connectors Minor connectors Rests Direct retainer/Clasps Indirect retainers One or more denture bases in conjunction with prosthetic teeth. 17/12/2016 Dr Mujtaba Ashraf 3

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5. Major Connector Definition: The part of a partial removable dental prosthesis that joins the components on one side of the arch to those on the opposite side. GPT-8 17/12/2016 Dr Mujtaba Ashraf 5

6. A major connector is the component of the partial denture that connects the parts of the prosthesis located on one side of the arch with those on the opposite side. It is that unit of the partial denture to which all other parts are directly or indirectly attached- McCraken A major connector joins the components on one side of the arch with those on the opposite side. Therefore, all components are attached to the associated major connector either directly or indirectly. Kenneth Stewarts 17/12/2016 Dr Mujtaba Ashraf 6

7. HISTORICAL BACKGROUND Dr. Norman Nesbett of Boston in 1918 introduced a denture of the metal type to the profession. His method consisted of casting the clasps for each tooth individually and then attaching them by means of solder to a cast gold boxing which enclosed the replacement tooth or teeth. In 1925 Dr. Polk E. Akers published a paper describing the technique for casting a removable partial denture framework in one piece. Although it was not accepted first, later it became a momentous technical break -through and over the period of next few years became accepted widely. 17/12/2016 Dr Mujtaba Ashraf 7

8. The chief functions of a major connector include: - unification of the major parts of the prosthesis, distribution of the applied force throughout the arch to selected teeth and tissue, and minimization of torque to the teeth. A properly designed major connector effectively distributes forces throughout the arch and acts to reduce the load to any one area while effectively controlling prosthesis movement. 17/12/2016 Dr Mujtaba Ashraf 8

9. It is through the major connector that other components of the partial denture become unified and effective. If the major connector is flexible, the ineffectiveness of connected components jeopardizes the supporting oral structures and can be a detriment to the comfort of the patient. Failure of the major connector to provide rigidity may be manifest by traumatic damage to periodontal support of the abutment teeth, injury to residual ridges, or impingement of underlying tissue. 17/12/2016 Dr Mujtaba Ashraf 9

10. Major connectors should be designed and located with the following guidelines in mind : 1. Major connectors should be free of movable tissue. 2. Impingement of gingival tissue should be avoided. 3. Bony and soft tissue prominences should be avoided during placement and removal . 17/12/2016 Dr Mujtaba Ashraf 10

11. 4. Relief should be provided beneath a major connector to prevent its settling into areas of possible interference, such as inoperable tori or elevated median palatal sutures . 5. Major connectors should be located and/or relieved to prevent impingement of tissue that occurs because the distal extension denture rotates in function. Appropriate relief beneath the major connector avoids the need for its adjustment after tissue damage has occurred 17/12/2016 Dr Mujtaba Ashraf 11

12. Major Connecter Design Specification 17/12/2016 Dr Mujtaba Ashraf 12

13. Margins of major connectors adjacent to gingival tissue should be located far enough from the tissue to avoid any possible impingement. To accomplish this, it is recommended that the superior border of a lingual bar connector be located a minimum of 4 mm below the gingival margin(s) 17/12/2016 Dr Mujtaba Ashraf 13

14. At the inferior border of the lingual bar connector, the limiting factor is the height of the moving tissue in the floor of the mouth. Because the connector must have sufficient width and bulk to provide rigidity, a linguo-plate is commonly used when space is insufficient for a lingual bar. 17/12/2016 Dr Mujtaba Ashraf 14

15. If less than 8 mm exists between gingival margins and the movable floor of the mouth, A linguoplate, a sublingual bar, or a continuous bar is preferred as a major connector. Relief is provided for soft tissue under all portions of the mandibular major connector and at any location where the framework crosses the marginal gingiva. The inferior border of mandibular major connectors should be gently rounded after being cast to eliminate a sharp edge. 17/12/2016 Dr Mujtaba Ashraf 15

16. The borders of the major connector should run parallel to the gingival margins of the remaining teeth. Minor connectors that must cross gingival tissue should do so abruptly, joining the major connector at nearly a right angle . In this way, maximum freedom is ensured for gingival tissue. 17/12/2016 Dr Mujtaba Ashraf 16

17. Tori also should be avoided if possible. In the maxillary arch, a major connector may cover a small torus if its surgical removal is impossible and if it cannot be avoided by altering the design of the major connector. If a maxillary torus must be covered, relief should be provided. Avoiding a mandibular torus is much more complicated. Therefore, as a rule, mandibular tori should be surgically removed. 17/12/2016 Dr Mujtaba Ashraf 17

18. In the maxillary arch, because no moving tissue is present in the palate as in the floor of the mouth, the borders of the major connector may be placed well away from gingival tissue . Structurally , the tissue covering the palate is well suited for placement of the connector because of the presence of firm submucosal connective tissue and an adequate, deep blood supply. However , when soft tissue covering the midline of the palate is less displaceable than the tissue covering the residual ridge, varying amounts of relief under the connectors must be provided to avoid impingement of tissue. 17/12/2016 Dr Mujtaba Ashraf 18

19. For the gingival tissue, it is recommended that the borders of the palatal connector be placed a minimum of 6 mm away from and parallel to the gingival margins . 17/12/2016 Dr Mujtaba Ashraf 19

20. Margin should taper towards the tissues and should e nd in the valleys of rugae Except for a palatal torus or a prominent median palatal suture area, palatal connectors ordinarily require no relief. Intimate contact between the connector and the supporting tissue adds much to the support, stability, and retention of the denture. 17/12/2016 Dr Mujtaba Ashraf 20

21. Characteristics Of Major Connectors Contributing To Health And Wellbeing 1. M ade from an alloy compatible with oral tissue 2. R igid and provide cross arch stability through the principle of broad distribution of stress 3. Do not interfere with and are not irritating to the tongue 4. Do not substantially alter the natural contour of the lingual surface of the mandibular alveolar ridge or of the palatal vault 17/12/2016 Dr Mujtaba Ashraf 21

22. 5. Do not impinge on oral tis sue when the restoration is placed, is removed, or rotates in function 6. Cover no more tissue than is absolutely necessary 7. Do not contribute to retention or trapping of food particles 8. Have support from other elements of the framework to minimize rotation tendencies in function 9. Contribute to the support of the prosthesis 17/12/2016 Dr Mujtaba Ashraf 22

23. Maxillary Major Connector 17/12/2016 Dr Mujtaba Ashraf 23

24. Maxillary Major Connector 1. Palatal bar 2. Palatal strap 3. Anteroposterior palatal bar or double palatal bar 4. Horseshoe shaped or U-shaped connector 5. Anteroposterior palatal strap or closed horse 6. Complete palate 17/12/2016 Dr Mujtaba Ashraf 24

25. Palatal Bar It is a bar running across the palate which is narrow half oval in cross-section with its thickest point in the center. 17/12/2016 Dr Mujtaba Ashraf 25

26. For many years, the palatal bar was one of the most widely used maxillary major connectors. Today, palatal bar major connectors are used primarily in interim applications . Kennedy Class III limited to replacing one or two teeth on each side of arch Disadvantages Difficult for patient to get adjusted Little support from palate Should be no further anteriorly than second premolar due to tongue interference 17/12/2016 Dr Mujtaba Ashraf 26

27. Palatal Strap The palatal strap is the most versatile maxillary major connector. The palatal strap consists of a wide band of metal with a thin cross-sectional dimension 17/12/2016 Dr Mujtaba Ashraf 27

28. Because of its minimal depth, this major connector may be used to cross the palate in an unobtrusive manner. the anteroposterior dimension of a palatal strap should not be less than 8 mm. 17/12/2016 Dr Mujtaba Ashraf 28

29. Advantages of The Palatal strap Because the palatal strap is located in two or more planes, it offers great resistance to bending and twisting forces. This theory is similar to the "L-beam" principle used in building construction . Simply stated, forces transmitted on different planes are counteracted more easily . I nherently strong , it can be kept relatively thin . Since this configuration offers little interference with normal tongue action . T he increased tissue coverage helps distribute applied stresses over a larger area. 17/12/2016 Dr Mujtaba Ashraf 29

30. Disadvantages of the palatal strap In some instances, a patient may complain of excessive palatal coverage . The increased soft tissue coverage associated with papillary hyperplasia . 17/12/2016 Dr Mujtaba Ashraf 30

31. Anteroposterior Palatal bar/ Double Palatal bar Displays characteristics of palatal bar and palatal strap major connectors. 17/12/2016 Dr Mujtaba Ashraf 31

32. The anterior bar is relatively flat . Its cross-sectional shape is similar to that of a palatal strap. Borders of the anterior bar are positioned on the appropriate slopes of prominent rugae, thereby allowing it to blend with the contours of the anterior palate Posterior bar is half oval. The strap and the bar are connected by two longitudinal elements along the lateral slopes of palate giving a circular configuration which provides rigidity . 17/12/2016 Dr Mujtaba Ashraf 32

33. Indications : when anterior and posterior abutment teeth are widely separated. cases with large inoperable palatal tori. patient who wants to avoid complete palatal coverage. Class II and Class IV conditions. 17/12/2016 Dr Mujtaba Ashraf 33

34. Advantages : R igid S trong L-beam effect contributes to good resistance L imited soft tissue coverage . Disadvantages : Less palatal support Not indicated with high narrow palatal vault U ncomfortable with multiple borders , provides interference to the tongue 17/12/2016 Dr Mujtaba Ashraf 34

35. Horseshoe connector/ U-shaped connector The horseshoe connector consists of a thin band of metal running along the lingual surfaces of the remaining teeth and extending on to the palatal tissues for 6 to 8 mm. 17/12/2016 Dr Mujtaba Ashraf 35

36. The medial borders of this connector should be placed at the junction of the horizontal and vertical slopes of the palate. Rigidity can be increased by extending the borders slightly onto the horizontal surfaces of the hard palate. 17/12/2016 Dr Mujtaba Ashraf 36

37. Indications Anterior teeth replacement In patients with tori and prominent mid palatine suture. Need to stabilize anterior teeth 17/12/2016 Dr Mujtaba Ashraf 37

38. Advantages of the horseshoe connector Reasonably strong Derives some vertical support and indirect retention from palate Disadvantages of the horseshoe connector Less resistance to flexing and movement at open end- hence cannot be used in distal extension Greater bulk in anterior part is required avoid flexing-interference in phonetics and patient comfort 17/12/2016 Dr Mujtaba Ashraf 38

39. Closed horse/ anteroposterior palatal strap The anteroposterior palatal strap is a structurally rigid major connector that may be used in most maxillary partial denture applications Two palatal straps- one anterior and other posterior, connected by flat longitudinal elements on each side of lateral slope palate. 17/12/2016 Dr Mujtaba Ashraf 39

40. This major connector is particularly indicated when numerous teeth are to be replaced, or when a palatine torus is present . Advantages: Rigid with less thickness Good palatal support Strong, L-beam effect Disadvantages: Interference with phonetics and patient comfort in some case. 17/12/2016 Dr Mujtaba Ashraf 40

41. Complete Palate The complete palate provides the ultimate rigidity and support. It also provides the greatest amount of tissue coverage. 17/12/2016 Dr Mujtaba Ashraf 41

42. The anterior border of a complete palate must be kept 6 mm from the marginal gingivae, or it must cover the cingula of the anterior teeth. The posterior border should extend to the junction of the hard and soft palates . 17/12/2016 Dr Mujtaba Ashraf 42

43. Indications : Kennedy’s class I condition where length of span is long with anterior modification. In cases with flat, flabby ridges and shallow palatal vaults where high stability is required. F or patients with well developed muscles of mastication or presence of all mandibular teeth. I n cleft palate cases with a narrow steep palatal vault . 17/12/2016 Dr Mujtaba Ashraf 43

44. Review of Indications for Maxillary Major Connectors If the periodontal support of the remaining teeth is weak , more of the palate should be covered; thus a wide palatal strap or a complete palate is indicated . If the remaining teeth have adequate periodontal support and little additional support is needed, a palatal strap or double palatal bar can be used . For long-span distal extension bases where rigidity is critical, a closed horseshoe or complete palate is indicated . 17/12/2016 Dr Mujtaba Ashraf 44

45. When anterior teeth must be replaced , a horse-shoe, closed horseshoe, or complete palate may be used. The final selection must be based on modifying factors such as number and location of posterior teeth missing, support of remaining teeth, and type of opposing occlusion . If a torus is present and is not to be removed, a horseshoe, closed horseshoe, or antero -posterior palatal bar may be used: which one to use depends on other factors . A single palatal bar is rarely indicated 17/12/2016 Dr Mujtaba Ashraf 45

46. Mandibular Major Connectors 17/12/2016 Dr Mujtaba Ashraf 46

47. In general, mandibular major connectors are long and relatively narrow. Therefore, special consideration must be given to the design of such connectors. Mandibular connectors must be rigid without being so bulky that they compromise patient comfort. Furthermore, mandibular major connectors must not impinge upon the movable floor of the mouth, the associated frena , or mandibular tori. 17/12/2016 Dr Mujtaba Ashraf 47

48. 4 types of Mandibular Major Connectors Lingual bar Lingual plate Double lingual bar Labial bar 17/12/2016 Dr Mujtaba Ashraf 48

49. Lingual bar The lingual bar is perhaps the most frequently used mandibular major connector. 17/12/2016 Dr Mujtaba Ashraf 49

50. The basic form of a mandibular major connector is a half pear shape, located above moving tissue but as far below the gingival tissue as possible. It is usually made of reinforced, 6 gauge , half pear shaped wax or a similar plastic pattern . Placement of a lingual bar requires at least 8 mm of space between the gingival margins and the floor of the mouth. This permits the major connector to have a minimum height of 5 mm and allows 3 mm of space between the gingival margins and the superior border of the bar. 17/12/2016 Dr Mujtaba Ashraf 50

51. A periodontal probe may be used to measure from the gingival margins to the floor of the mouth . The patient should be instructed to elevate and protrude the tongue so that its tip touches the vermilion border of the upper lip. Intraoral measurements may be transferred to the corresponding dental cast . 17/12/2016 Dr Mujtaba Ashraf 51

52. The presence of mandibular tori complicates the design , fabrication, and placement of lingual bar major connectors. Surgical removal of mandibular tori usually is required for successful removable partial denture therapy . Indicated in Kennedy’s Class III situation and its modifications. 17/12/2016 Dr Mujtaba Ashraf 52

53. Advantages: Simple, easy to design and fabricate Has no minimal contact with oral tissue No contact with teeth, so no decalcification of teeth. Disadvantages: I f extreme care is not taken in the design and construction of a lingual bar, the resultant framework may not be rigid . Cause food entrapment and patient discomfort if it is placed over undercut Difficult to used when tori are present 17/12/2016 Dr Mujtaba Ashraf 53

54. Lingual Plate/ Linguoplate The structure of a lingual plate is basically that of a half-pear-shaped lingual bar with a thin, solid piece of metal extending from its superior border. . 17/12/2016 Dr Mujtaba Ashraf 54

55. The inferior border of a lingual plate should be positioned as low in the floor of the mouth as possible, but should not interfere with the functional movements of the tongue and soft tissues. A linguoplate should be made as thin as is technically feasible and should be contoured to follow the contours of the teeth and the embrasures 17/12/2016 Dr Mujtaba Ashraf 55

56. This thin projection of metal is carried on to the lingual surfaces of the teeth and presents a scalloped appearance A lingual plate may include "step backs" to minimize or eliminate the appearance of metal. A lingual plate must be supported by rests (arrows) located no farther posterior than the mesial surface of the first premolars. 17/12/2016 Dr Mujtaba Ashraf 56

57. Indications: When lingual frenum is high or space available for lingual bar is insufficient Kennedy Class I where residual ridges have undergone excessive vertical resorption. For stabilizing periodontally weak teeth. When future replacement of one or more anterior teeth is predicted. Presence of inoperable mandibular tori. 17/12/2016 Dr Mujtaba Ashraf 57

58. Advantages: Most rigid and provides good support and stabilization. Provides indirect retention with rest on premolars. Disadvantages: Extensive coverage of teeth may cause decalcification. Soft tissue irritation 17/12/2016 Dr Mujtaba Ashraf 58

59. Double Lingual Bar/ Kennedy bar A double lingual bar displays characteristics of both lingual bar and lingual plate major connectors 17/12/2016 Dr Mujtaba Ashraf 59

60. It differs from lingual plate in the middle portion is removed and the remaining is superior and inferior bar. The lower bar is similar to a lingual bar, pear-shaped in cross-section, 2-3mm high and 1mm thick 17/12/2016 Dr Mujtaba Ashraf 60

61. Just like the lingual plate upper bar should dip into the embrasures and if diastema is present, a step-back design is used. Indications When a lingual plate in otherwise indicated but axial alignment of anterior teeth entails excessive block out, eg crowding Periodontal disease resulting in large interproximal embrasures Wide diastema in lower anteriors 17/12/2016 Dr Mujtaba Ashraf 61

62. Advantages: Provides good indirect retention Horizontal stabilization As gingival tissues are not covered, marginal gingival receives natural stimulation Disadvantages: More annoyance to tongue than lingual plate Food entrapment and debris 17/12/2016 Dr Mujtaba Ashraf 62

63. Labial Bar A labial bar runs across the mucosa on the facial surface of the mandibular arch 17/12/2016 Dr Mujtaba Ashraf 63

64. Like other mandibular major connectors, a labial bar displays a half-pear shape when viewed in cross section. But , because of its placement on the external curvature of the mandible, a labial bar is longer than other mandibular major connector. 17/12/2016 Dr Mujtaba Ashraf 64

65. The only justification for using a labial bar is the presence of a gross uncorrectable interference that makes the placement of a lingual major connector impossible. Interferences that commonly lead to the selection of a labial bar are (1 ) malposition or lingually inclined teeth and (2 ) large mandibular tori that preclude the use of a lingual bar or lingual plate. 17/12/2016 Dr Mujtaba Ashraf 65

66. Advantages When the remaining mandibular teeth are tipped so far lingually that a more conventional major connector cannot be used, a labial bar may be considered. Disadvantages Unaesthetic Fullness in lower lips Patient discomfort 17/12/2016 Dr Mujtaba Ashraf 66

67. A modification of the labial bar is the hinged continuous labial bar . This concept is incorporated in the Swing Lock* design, which consists of a labial or buccal bar that is connected to the major connector by a hinge at one end and a latch at the other end. 17/12/2016 Dr Mujtaba Ashraf 67

68. In this application, the labial component does not serve as a major connector. Instead, the modified labial bar has a hinge at one end and a locking device at the opposite end. This permits an opening and closing action similar to a gate. 17/12/2016 Dr Mujtaba Ashraf 68

69. Review of indications for mandibular major connectors 1. For a tooth-supported removable partial denture, the lingual bar normally is the mandibular major connector of choice. 2. When there is insufficient room between the floor of the mouth and the gingival margins (< 8 mm), a lingual plate should be used. This major connector also is indicated for patients with large inoperable tori and patients with high lingual frenum attachments. 17/12/2016 Dr Mujtaba Ashraf 69

70. 3. When the anterior teeth have reduced periodontal support and require stabilization, a lingual plate is recommended. 4. When the anterior teeth exhibit reduced periodontal support and large interproximal spaces, a modified lingual plate (step-back design) or double lingual bar should be used . 5. When a removable partial denture will replace all mandibular posterior teeth, a lingual plate should be used . 6. A labial bar is rarely indicated. 17/12/2016 Dr Mujtaba Ashraf 70

71. Various major connector designs that can be useful in the successful construction of a removable partial denture, has been discussed. Major connectors by uniting the other components of a removable partial denture acts like a foundation bringing about bilateral distribution of forces is mainly dependent on the rigidity of the major connector used in a particular situation. Utmost care must be taken to prevent the Major connector from interfering with the normal functions, as well as bringing about damaging effects to the remaining oral structure . Conclusion 17/12/2016 Dr Mujtaba Ashraf 71

72. References McCracken’s removable partial prosthodontics – 12 th edition Stewarts removable partial prosthodontics – 4 th edition Connectors -J. C. Davenport, R.M.Basker, J. R. Heath, J. P. Ralph, PO. Glantz, and P. Hammond (BDJ) Campbell L D. Subjective reactions to major connector designs for removable partial dentures . J Prosthet Dent 1977. 17/12/2016 Dr Mujtaba Ashraf 72

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