Mandibular major connectors

MANDIBULAR MAJOR CONNECTORS

1. MANDIBULAR MAJOR CONNECTORS DR EAKETHA P LOKESH 2 nd Year PG Dept : of Prosthodontics

2. CONTENTS Introduction Definitions History Ideal requirements of major connectors Special structural requirements for mandibular major connectors Lingual bar DR EAKETHA P LOKESH 2

3. Sublingual bar Linguoplate Interrupted linguoplate Cingulum bar Lingual bar with cingulum bar (Double lingual bar) Labial bar Swing –lock design Conclusion R eferences DR EAKETHA P LOKESH 3

4. No component of a removable partial denture should be added arbitrarily or conventionally. Each component should be added for a good reason and to serve a definite purpose .” - McCracken DR EAKETHA P LOKESH 4

5. 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 .” – GPT-9 DR EAKETHA P LOKESH 5

6. Each component of the prosthesis has a name that is most often descriptive of its function. A major connector, for example, does exactly what its name implies. DR EAKETHA P LOKESH 6

7. HISTORY The 1 st mention of partial denture restoration – Heister in 1711 A block of bone or ivory was carved to fit the mouth, merely by measurement and constant fitting. Girardot.R.L . History and development of partial denture design. Journal of American dental association 1941; 28(9): 1399-1408 DR EAKETHA P LOKESH 7

8. Pierre Fauchard , (father of modern dentistry) , first described this technique in 1728. He describes the construction of a partial restoration using labial and lingual connector . Having made 2 blocks of ivory to occlude with a complete upper denture, and realizing that they would not function separately, he conceived the idea of a connector. DR EAKETHA P LOKESH 8

9. Girardot.R.L . History and development of partial denture design. Journal of American dental association 1941; 28(9): 1399-1408 DR EAKETHA P LOKESH 9

10. Techniques were further developed in 1899 when Dr. William G.A. Bonwill described clasping abutments with individually contoured gold circumferential clasps that were then soldered to a main plate or major connector. Kreyer R. Digitally designed RPD framework : embracing new technologies for higher quality and better results .Inside Dental Technology 2012;3(3) DR EAKETHA P LOKESH 10

11. Ideal Requirements Of The Major Connector DR EAKETHA P LOKESH 11

12. Chief functions DR EAKETHA P LOKESH 12

13. To Function Effectively And Minimize Potentially Damaging Effects, All Major Connectors Must 1 . Be RIGID 2 . Provide VERTICAL SUPPORT and protect the soft tissues 3. Provide a means for obtaining INDIRECT RETENTION where indicated 4. Provide a means for placement of one or more denture bases 5. Promote patient comfort Stewarts clinical removable partial prosthodontics, 3 rd Edition, DR EAKETHA P LOKESH 13

14. I. RIGIDITY – 1 st requirement of all major connectors A properly designed rigid major connector helps in broad distribution of the forces to the sub-adjacent supporting area Hence, occlusal loads may be transmitted to abutment teeth, other teeth included in RPD design., associated soft tissues and underlying bone DR EAKETHA P LOKESH 14

15. Flexible major connector – may cause severe damage to the hard and soft tissues Allows forces to be concentrated on teeth & segments of the residual ridges ↓ sed support for the associated denture bases ↓ sed ridge height Tooth mobility or tooth loss Resorption of the hard & soft tissues DR EAKETHA P LOKESH 15

16. It should not impinge on free gingival margin and other soft tissues . Marginal gingivae – highly vascular Susceptible to injury from sustained pressure Hence, care should be exercised during the design and fabrication of RPD. DR EAKETHA P LOKESH 16

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20. III. Should never be considered an indirect retainer. Although a major connector may play an auxiliary role in resisting rotation of the prosthesis , it is the action of the rests and rest seats that is responsible for indirect retention . A major connector that is not properly rested will undergo rotation and may cause orthodontic movement of the associated teeth. DR EAKETHA P LOKESH 20

21. IV. The Proper Placement Of Denture Bases . Generally , the type of major connector will be dictated by the number and location of edentulous areas. Certain major connectors are indicated for anterior tooth replacement , while others are not. Some major connectors may be selected for tooth-supported removable partial dentures, but not for tooth-tissue– supported applications. In each instance, a major or connector must allow appropriate placement of the associated denture base(s ) . DR EAKETHA P LOKESH 21

22. V. a major connector must promote patient comfort . Consequently , the edges of a major connector should be contoured to blend with the oral tissues . Tori also should be avoided if possible DR EAKETHA P LOKESH 22

23. VI. It is good design policy to make the major connector as symmetrical as possible. In addition, the borders of a maxillary major connector should cross the palatal midline at right angles Tissues covering the maxillary midline are often thin and susceptible to irritation. By crossing the maxillary midline at right angles, the length of the crossing may be minimized and the potential for irritation reduced . DR EAKETHA P LOKESH 23

24. MANDIBULAR MAJOR CONNECTORS DR EAKETHA P LOKESH 24

25. Special Structural Requirements I. Mandibular major connectors are long and relatively narrow . Therefore, special consideration must be given to the design of such connectors . Stewarts clinical removable partial prosthodontics, 3 rd Edition, DR EAKETHA P LOKESH 25

26. 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 DR EAKETHA P LOKESH 26

27. 2 . Unlike maxillary major connectors , for which relief is infrequently required , mandibular major connectors may require relief between a mandibular removable partial denture and the underlying soft tissues . The amount of relief is dependent upon several factors. DR EAKETHA P LOKESH 27

28. For an entirely tooth-supported prosthesis, little or no relief is needed because the denture does not tend to move in function. DR EAKETHA P LOKESH 28

29. For a distal extension removable partial denture, however, a moderate amount of relief my be indicated because this type of prosthesis tends to rotate during function. Relief prevents the margins of the major connector from lacerating the sensitive lingual mucosa as a result of this movement. DR EAKETHA P LOKESH 29

30. 3. The slope of the anterior ridge also influences the amount of relief needed . If the soft tissues are vertical, or nearly so, only minimal relief is required. Tissues that slope toward the tongue require the greatest amount of relief because any movement of the connector will bring it into contact with the adjacent soft tissues. if the anterior ridge is undercut, sufficient space may be created when the technician blocks out the undercut area. DR EAKETHA P LOKESH 30

31. 4 . It is important to note that bead lines are not used in conjunction with mandibular major connectors. Contact with the friable mucosa of the mandibular arch may cause irritation, ulceration, and patient discomfort. DR EAKETHA P LOKESH 31

32. Types of mandibular major connectors DR EAKETHA P LOKESH 32

33. Lingual Bar Lingual bar is the basic form of the mandibular major connector. Most frequently used It requires minimum of 8 mm of lingual vestibular space . 33 Because of its simplicity in design and construction, a lingual bar should be used unless one of the other connectors offers a definite advantage. A lingual bar is indicated for all tooth-supported removable partial dentures unless there is insufficient space between the marginal gingivae and the floor of the mouth. DR EAKETHA P LOKESH

34. Indications: All tooth-supported removable partial dentures unless there is insufficient space between the marginal gingivae and the floor of the mouth. DR EAKETHA P LOKESH 34

35. Structural details Half pear shaped in cross section With wider part towards the lingual sulcus ( inferior border ) Thinner part towards the marginal gingival ( superior border ) Should follow the lingual contours of alveolar process but not contacting it (o.5 mm clearance), to allow movement under function. 35 DR EAKETHA P LOKESH

36. The upper border of the major connector should be around 3-4 mm away form the marginal gingival. The thickness of the lingual bar should be around 4-5 mm superior inferiorly . 36 Availability of space is a key factor in determining whether a lingual bar can be used. To accommodate a lingual bar, at least 8 mm of vertical space must be present between the gingival margins of the teeth and the floor of the mouth (Fig 2-36). 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. Failure to provide 3 mm of space may lead to irritation of the adjacent soft tissues. DR EAKETHA P LOKESH

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38. ADVANTAGES Simple design minimal contact with the remaining teeth and soft tissues. It does not contact the teeth, so decalcification of the tooth surface is minimized. DISADVANTAGES Extreme care in the design and construction of a lingual bar. Too thin/ too flexible – permits the concentration of destructive forces on individual teeth and segments of the mandibular arch. DR EAKETHA P LOKESH 38

39. Linguo Plate (Lingual Plate, Lingual Strap, Lingual Apron, Lingual Shield) most commonly used in case of periodontally compromised remaining teeth. 39 DR EAKETHA P LOKESH

40. IndicationS High frenal attachment The space available for a lingual bar is limited (vestibule<8 mm). Presence of lingual tori. Kennedy’s class I - when indirect retention is needed. Stabilization of periodontally weakened teeth. Future replacement of one or more incisor teeth. 40 DR EAKETHA P LOKESH

41. Contraindications In lingually inclined mandibular anterior teeth. Wide embrasures and diastema 41 DR EAKETHA P LOKESH

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43. Structural details Half pear at the lower border with plate like extension up to the cingulum of the anterior teeth. The upper border follows the natural curvature of supra- cingulum surface, (scalloped shape) extends up to the middle t hird of the tooth and enters the interproximal surface up to contact point. 43 DR EAKETHA P LOKESH

44. S 44 Superior border of a linguoplate should display a scalloped appearance DR EAKETHA P LOKESH

45. Advantages The lingual plate provides exceptional rigidity, indirect retention. The lingual plate also provides stabilization of periodontally weak teeth. Prevents over eruption of anterior teeth. In case of future loss of any anterior teeth the lingual plate provides an opportunity to replace the missing teeth without changing the framework. 45 When posterior teeth have been lost and there is a need for additional indirect retention , the use of a lingual plate may be advantageous . While a lingual plate does not serve as an indirect retainer, it may contribute to indirect retention if it is properly rested at each end. DR EAKETHA P LOKESH

46. DISADVANTAGES By covering lingual gingival surfaces it prevents physiologic stimulation of soft tissues inflammation . Decalcification of teeth and inflammation of marginal gingival metal display in wide interproximal spaces. 46 By covering lingual gingival surfaces it prevents physiologic stimulation of soft tissues and thus may leads to inflammation . DR EAKETHA P LOKESH

47. If wide interproximal spaces are present ,then step backs can be provided for upper cingulum bar to prevent its visibility. DR EAKETHA P LOKESH 47

48. Interrupted lingual plate: It is a type of the lingual plate recommended in wide interproximal areas . Here the upper border of the lingual plate is cut longitudinally to prevent its display through the wider interproximal spaces 48 DR EAKETHA P LOKESH

49. Sublingual Bar A modification of the lingual bar Described by Brantenburg and Tryde Demonstrated to be useful when the height of the floor of the mouth does not allow placement of the superior border of the bar at least 4 mm below the free gingival margin is the sublingual bar. 49 Hansen. C.A, Campbell.D.J . Clinical comparison of two mandibular major connector designs : The sublingual bar and the lingual plate. J Prosthet Dent 1985;54 (6):805-810 DR EAKETHA P LOKESH

50. The bar shape remains essentially the same as that of a lingual bar , but placement is inferior and posterior to the usual placement of a lingual bar, lying over and parallel to the anterior floor of the mouth DR EAKETHA P LOKESH 50

51. INDICATIONS The height of the floor of the mouth in relation to the free gingival margin is less than 6mm . If it is desired to keep the free gingival margins of anterior teeth exposed and there is inadequate depth of the floor of the mouth. 51 DR EAKETHA P LOKESH

52. CONTRAINDICATIONS Inoperable/ interfering lingual tori High attachment of lingual frenum Interference with elevation of the floor of the mouth during functional movements. DR EAKETHA P LOKESH 52

53. Lingual Bar with Cingulum Bar ( Double lingual bar , Split bar, Kennedy bar , Continuous lingual clasp). 53 DR EAKETHA P LOKESH

54. Referred as “ CONTINUOUS LINGUAL CLASP ” major connector, because of series of clasp arms connected on the lingual surfaces of lower anterior teeth. DR EAKETHA P LOKESH 54

55. Indications Wide interproximal areas prevent the use of linguo -plate (in such cases it provides indirect retention) Wide diastema in lower anteriors 55 DR EAKETHA P LOKESH

56. Structural detaiLS Consists of two bars Upper bar - similar to cingulum bar Lower bar - similar to lingual bar The two bars are attached by means of a minor connector with positive vertical stops on either side to prevent settling and orthodontic movements. 56 DR EAKETHA P LOKESH

57. ADVANTAGES Effectively extends indirect retention in an anterior direction. Contributes to horizontal stabilization . It helps in minor amount of support to the prosthesis. The gingival tissues and inter-proximal embrasures are not covered by the connector, which helps in free flow of saliva . 57 DR EAKETHA P LOKESH

58. DISADVATAGES Patient may feel discomfort because it alters the normal position of the tongue. If connector does not maintain intimate contact with tooth surface there will be food entrapment 58 DR EAKETHA P LOKESH

59. Cingulum Bar (Continuous Bar, Dental Bar) It is a type of major connector which rests on the cingulum of the anterior teeth. Described by Owell and Taylor (1989) Modification of the double lingual bar 59 When a linguoplate is the major connector of choice, but the axial alignment of the anterior teeth is such that excessive blockout of interproximal undercuts must be made, a cingulum bar may be considered. A cingulum bar located on or slightly above the cingula of the anterior teeth may be added to the lingual bar or can be used independently (Figure 5-14). Additionally, when wide diastemata exist between the lower anterior teeth, a continuous bar retainer may be more esthetically acceptable than a linguoplate . Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2):221-23 DR EAKETHA P LOKESH

60. INDICATION When a linguoplate is the major connector of choice , but the axial alignment of the anterior teeth is such that excessive blockout of interproximal undercuts must be made CONTRAINDICATION Lingually tilted anterior teeth DR EAKETHA P LOKESH 60

61. Although this design may reduce the possibility of food entrapment , it may not provide adequate rigidity. 61 DR EAKETHA P LOKESH

62. Structural details Follows the contours of the lingual surface of the anterior teeth above the cingulum and thus has the scalloping shape. Superio -inferiorly it is 3 mm and 1 mm thick. The cingulum bar enters the non-undercut interdental space. 62 DR EAKETHA P LOKESH

63. LABORATORY REQUIREMENTS 1. For sufficient rigidity, a minimum height of 4 mm and a thickness of 2.5 mm is necessary. These dimensions should be increased when the cingulum bar traverses more natural teeth . Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2):221-23 DR EAKETHA P LOKESH 63

64. 2. No notches in the metal to simulate tooth contour should be made because it weakens the bar . In the presence of reduced height, the bar is placed more gingivally and made thicker to provide rigidity. Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2):221-23 LABORATORY REQUIREMENTS DR EAKETHA P LOKESH 64

65. 3. The junction of the bar to the denture base must be sufficiently strong. When premolars are present, the bar can cover the lingual surfaces of these teeth. The contour of the teeth should be modified to adapt them to the path of insertion of the RPD. Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2):221-23 LABORATORY REQUIREMENTS DR EAKETHA P LOKESH 65

66. advantages Space problems for bar placement seldom exist except where anterior teeth have been worn down by attrition. No pressure is exerted on the gingival tissues when movement of the RPD occurs Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2):221-23 DR EAKETHA P LOKESH 66

67. The major connector forms one unit with the anterior teeth, which contributes to the comfort of the RPD Indirect retention is provided Repair of the RPD is simple when natural anterior teeth are lost ADVANTAGES Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2):221-23 DR EAKETHA P LOKESH 67

68. DISADVANTAGES A relative bulky metal bar is situated on the lingual surfaces of the anterior teeth especially where crowding is present Esthetics are compromised when spacing exists Marked lingual inclination of the anterior teeth precludes the use of the bar. Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2):221-23 DR EAKETHA P LOKESH 68

69. Labial bar It is a type of the major connector which is placed labial or buccal to the alveolar ridge and teeth. DR EAKETHA P LOKESH 69

70. Indications Lingually tilted anterior and posterior teeth (non correctable). Presence of large lingual tori. Severe or abrupt lingual tissue undercuts 70 DR EAKETHA P LOKESH

71. Structural details Half pear shaped with thickest part towards the labial or buccal surface and thinnest part towards the marginal gingival Usually bulkier than that of lingual bar because of its longer dimensions. The superior border : 3-4 mm away form the marginal gingiva. 71 DR EAKETHA P LOKESH

72. The inferior border should be in the labial vestibule at the junction of attached and unattached mucosa. Minor connector joined with occlusal or other superior components by a labial approach. 72 DR EAKETHA P LOKESH

73. Disadvantages The labial/ buccal vestibule is shallow and the major connector may leads to discomfort to the patient. It is also bulkier than the lingual bar. 73 DR EAKETHA P LOKESH

74. Swing lock denture (By Simmon 1960) Consists of lingual bar/plate and labial bar. The lingual bar provides the rigidity to the framework labial bar provides the extra retention and stability. 74 Stewarts clinical removable partial prosthodontics, 3 rd Edition DR EAKETHA P LOKESH

75. Structure details The lingual bar or plate is similar to the conventional designs The labial bar is connected to lingual major connector by a hinge joint at one end and a snap joint/latch at the other end. 75 DR EAKETHA P LOKESH

76. The support is obtained by using multiple rests , which are connected to the lingual bar/plate . The stabilization and reciprocation is also provided by lingo plate. STRUCTURE DETAILS DR EAKETHA P LOKESH 76

77. The labial bar helps in retention by bar clasps. The flexibility and retentive quality of the labial bar depends upon number of teeth remaining and periodontal condition of the teeth. 77 STRUCTURE DETAILS DR EAKETHA P LOKESH

78. The FLEXIBILITY OF THE LABIAL BAR can be increased by increasing the length of the labial b ar i.e. locating the hinge joint and latch joint one tooth away from the existing natural teeth . The FLEXIBILITY OF THE RETENTIVE FINGERS ( 1-bar) can be increased by increasing the length and providing the S-shaped design. STRUCTURE DETAILS DR EAKETHA P LOKESH 78

79. Indications Missing key abutments , i.e. if premolars and canines are missing then the retention is obtained by engaging the lingual as well as labial surfaces of remaining anterior teeth. Unfavorable tooth or soft tissue contours , i.e. if liberally tilted teeth or deep lingual undercut. Teeth with questionable prognosis . Maxillofacial prosthesis (in cases of hemi- maxilectomy ). 79 DR EAKETHA P LOKESH

80. Contraindications Poor oral hygiene (since the design of the framework is complex more chance for food/debris accumulation) Shallow buccal vestibule Poor patient co-operation. DR EAKETHA P LOKESH 80

81. ADVANTAGES This design utilizes all remaining teeth and thus provides adequate retention and stability . DISADVANTAGES Poor esthetics because of metal visibility. Chances of unwanted, orthodontic forces to the teeth. 81 DR EAKETHA P LOKESH

82. Summary 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. It may be compared to the frame of an automobile or with the foundation of a building. 82 DR EAKETHA P LOKESH

83. In addition to unification, it contributes substantially to the support of the prosthesis ,in case of a maxillary major connector. The mandibular major connector contributes to indirect retention. The dentist is fully and totally responsible for the design and specifications of all components of a removable partial denture. 83 DR EAKETHA P LOKESH

84. References 84 DR EAKETHA P LOKESH

85. Textbook references Rodney D Phoenix, David R Cagna , Charles F DeFreest . Stewarts clinical removable partial prosthodontics, 3 rd Edition, Quintessence books. Alan B Carr, David T Brown. Mc Crackens removable partial prosthodontics, 12 th Edition, 2012, Elsevier Mosby. Alan B Carr, David T Brown. Mc Crackens removable partial prosthodontics, 1 st South Asia Edition, 2012, Elsevier Mosby . Oliver C Applegate “ Essentials of removable partial denture prosthesis” Kothari Book Depot. 85 DR EAKETHA P LOKESH

86. Journal references Hansen CA, Campbell DJ. Clinical comparison of two mandibular major connector designs: the sublingual bar and the lingual plate. J Prosthet Dent 1985;54(6): 804-9 . Meeuwissen.R , Keltjens.H.M et al. Cingulum bar as a major connector for mandibular removable partial dentures. J Prosthet Dent 1991 ;66(2): 221-23 Kreyer R. Digitally designed RPD framework : embracing new technologies for higher quality and better results .Inside Dental Technology 2012;3(3 ) Girardot.R.L . History and development of partial denture design. Journal of American dental association 1941; 28(9): 1399-1408 Glossary of prosthodontic terminology -9 86 DR EAKETHA P LOKESH

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