Mandibular Major Connectors

1. Good morning In the sweetness of friendship let there be laughter, and sharing of pleasures. For in the dew of little things the heart finds its morning and is refreshed. Khalil Gibran

2. BURJ KHALIFA

3. M andibular M ajor C onnectors a bhishek K avlekar

4. C ontents Introduction Definition Basic Requirements of mandibular major connectors Recording Lingual Sulcus Types of mandibular major connectors

5. Design sequence for mandibular major connector Non Rigid Connectors Review of literature Summary Conclusion References

6. I NTRODUCTION “ 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”. -WL McCracken

7. M ajor Connector 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 ) G losasary of prosthodontic terms

8. B asic requirements of Mandibular major connectors. Rigid & provides cross- arch stability - broad distribution of stress. Should not interfere with & non irritating to the tongue . Should not alter the contour of the lingual surface of the mandibular alveolar ridge . Should not impinge on the oral tissues when the prosthesis is inserted or rotate in function .

9. Cover no more tissue than is absolutely necessary . Does not contribute to the retention or entrapment of food particles . Has support from other elements of the framework to minimize rotational tendencies during function . Made from an alloy compatible with the oral tissues.

10. D esign Specifications Placement of borders : The superior borders are placed atleast 3 mm from the gingival margins . Relief: To prevent tissue impingement at rest & during function . Tooth -borne prostheses : 30 guage ,0.010 inches . Tooth /tissue-borne prostheses : More relief is required .

11. Relief required for tooth /tissue-borne prostheses depends upon : a) Relationship of fulcrum line to major connector : When the fulcrum line is posterior to the major connector , less relief is required (28 guage ,0.013 inches to 26 guage , 0.016 inches )

12. 2) When the fulcrum line is anterior to the major connector , more relief is required (26 guage ,0.016 inches to 24 guage ,0.020 inches )

13. 3) Shape of adjacent alveolar ridge : The lingual slope of the alveolar ridge influences the amount of relief required , due to the rotation of the prosthesis tissue- wards .

14. Quality of supporting structures: Periodontal status of abutment teeth Quality of the supporting soft tissues Bone index Movement of the dento - alveolar segment Lingual tori

15. R ecording the Height of floor of the mouth U sing a P eriodontal probe

16. R ecording the Height of floor of the mouth Make a custom tray 3mm short of elevated floor of the mouth . Then using an impression material record the area by asking the patient to lick the upper lip .

17. T ypes Of Mandibular Major Connectors

18. L ingual Bar Major Connector Indications: 8mm vertical space between gingival margin and floor of the mouth. Lingual Bar

19. Contraindications : Inoperable lingual tori . High lingual frenum attachment. Interferences during functional movements of the floor of the mouth . Lingual Bar

20. Characteristics and location Half-pear shaped with bulkiest portion inferiorly located. Superior border tapered to soft tissue. Superior border located at least 3 mm inferior to gingival margins. Inferior border located at the ascertained height of the alveolar lingual sulcus when the patients tongue is slightly elevated. Lingual Bar Major Connector

21. At least 8mm of vertical space between the active tissues of the floor of the mouth and the gingival margins of the teeth is required. . Lingual Bar

22. ADVANTAGES DISADVANTAGES It may be flexible if poorly constructed. Rigidity is less compared to a well constructed lingual plate. Lingual bar connector has minimal tissue coverage and has minimal contact with oral tissues. It does not contact the teeth, so decalcification of the tooth surface is minimized.

23. Block out & relief of master cast All tissue undercuts parallel to path of placement. An additional thickness of 32-gauge wax when the lingual surface of the alveolar ridge is either undercut or parallel to the path of placement. No relief is necessary when the lingual surface slopes inferiorly and posteriorly . Lingual Bar Major Connector

24. Waxing Specifications - 6 gauge , half-pear shaped wax form reinforced by 22-24 gauge sheet wax adapted to the design width. Long bar require more bulk than short bar. Finish lines Butt joints with minor connectors for retention of denture bases. Lingual Bar Major Connector

25. Lingual plate Indications: High lingual frenum , shallow vestibule. Severe vertical resorption Presence of lingual tori . Stabilization of periodontally weak teeth. Contraindications : In lingually inclined mandibular anterior teeth. Wide embrassures and diastema Linguoplate

26. Characteristics and location Half-pear shaped with bulkiest portion inferiorly located. Thin metal apron extending superiorly to contact cingula of anterior teeth and height of contour of posterior teeth; and interproximally to contact points. Scalloped contour of apron as dictated by interproximal blockout . Linguoplate

27. The superior border should be knife edge and contoured to intimately contact lingual surface above the cingula . Close inter proximal space to level of contact points. Linguoplate

28. ADVANTAGES Provides more support and stabilization when compared to other connectors. Can be used in stabilizing the periodontally weakened teeth. When it is supported at each end by a rest it contributes to the action of indirect retention . Provision to include more teeth in the design Linguoplate

29. DISADVATAGES It covers the tooth structure and the gingival tissue. The metal coverage of the free gingival tissue prevents physiological stimulation and self-cleansing of these areas by saliva. British Dental Journal   189 , 414 - 424 (2000) Linguoplate

30. 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 Linguoplate Modifications

31. BLOCKOUT & RELIEF All involved undercuts of contacted teeth parallel to the path of placement. All involved gingival crevices. Lingual surface of alveolar ridge. WAXING SPECIFICATIONS Inferior border 6-gauge , half pear shaped wax form reinforced with 24-gauge sheet wax. Apron 24-gauge sheet wax. FINISH LINE : Butt joint Linguoplate

32. Double lingual bar This type of major connector is also called “ Kennedy bar ” it distribute stresses to all of the teeth with which it comes in contact there by reducing the stresses to the underlying tissues. It is also referred as “ continuous lingual clasp ” major connector, because of series of clasp arms connected on the lingual surfaces of lower anterior teeth. Double Lingual Bar

33. Characteristics and location The lower component displays same charecteristics as that of a lingual bar. The upper bar should be half oval ,2-3mm in height and 1mm thick, presenting scallopped appearance. Two bars joined by minor connectors on each end Double Lingual Bar

34. ADVANTAGES E ffectively extends indirect retention in an anterior direction. C ontributes to horizontal stabilization . It helps in minor amount of support to the prosthesis . The gingival tissues and inter-proximal embrassures are not covered by the connector, which helps in free flow of saliva. Double Lingual Bar

35. 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 British Dental Journal   189 , 414 - 424 (2000) Double Lingual Bar

36. BLOCKOUT & RELIEF Same as for lingual bar. No relief for continuous bar except blockout of interproximal spaces WAXING SPECIFICATIONS Same as lingual bar. Continuous bar pattern found by adapting two strips (3 mm wide) of 28-gauge sheet wax over the cingula and into interproximal embrassures . FINISH LINE : Butt joint Double Lingual Bar

37. Sublingual Bar 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. Contraindications : Lingually tilted remaining natural teeth. Inoperable lingual tori . High attached lingual frenum . Sublingual Bar

38. Accurately record the functional depth and width of the lingual sulcus These sulcus dimensions are retained on the master cast resulting in a bar whose maximum cross-sectional dimension is oriented horizontally. Rigidity Height ~ Rigidity 2 Width ~ Rigidity 3 The increased width of the sublingual bar connector therefore ensures that the important requirement of rigidity is satisfied. Sublingual Bar

39. C ontinuous bar ( cingulum bar) Indication : Improper axial alignment of the anterior teeth requiring excessive blockout of interproximal undercuts. Contraindications: In lingually tilted anterior teeth. Wide diastema between mandibular anterior teeth. Cingulum Bar

40. Characteristics and location Thin narrow metal strap located on cingula of anterior teeth, scalloped to follow interproximal embrassures . Originates bilaterally from rests of the adjacent principle abutments. Cingulum Bar

41. BLOCKOUT & RELIEF No relief for cingulum bar except interproximal spaces. WAXING SPECIFICATIONS A cingulum bar pattern formed by adapting two strips of 28-gauge, 3mm wide over the cingula and into interproximal embrassures . FINISH LINE : Butt joint Cingulum Bar

42. Labial Bar Indication: L arge inoperable lingual tori . S evere & abrupt lingual undercuts. L ingually inclined lower anterior & premolars. Labial Bar

43. Characteristics and location Half-pear shaped with bulkiest portion inferiorly located on the buccal aspect. Superior border tapered to soft tissue and 4mm inferior to labial gingival margins. Inferior border located in the labial buccal vestibule; at the junction of attached & mobile mucosa. Labial Bar

44. BLOCKOUT & RELIEF All tissue undercuts parallel to path of placement and when the labial surface is either undercut or parallel to the path of placement. No relief if labial surface of alveolar ridge slopes inferiorly. WAXING SPECIFICATIONS 6-gauge half-pear shaped wax form reinforced with 22-24 gauge Long bar more bulkier than shorter bar. Minor connector joined with occlusal or other superior components by a labial approach. FINISH LINE : Butt joint Labial Bar

45. Hinged continuous labial bar Indications: Missing key abutments. Unfavorable tooth contour. Unfavorable soft tissue contours. Teeth with questionable prognosis. Contraindications: Poor oral hygiene. Shallow buccal labial vestibule. High frenal attachment. Hinged continuous labial bar

46. Characteristics and location This type of major connector is the modification of linguoplate which is incorporated in the “ Swing-lock ” Design consists of labial bar i.e. connected to the major connector by hinge on one end and latch at the other end. Hinged continuous labial bar

47. Support is provided by multiple rests on the remaining natural teeth while stabilization and reciprocation is by ingual plate. Retention is provided by bar type retentive clasp arms projecting from the labial bar & contacting the infrabulge areas on the labial surfaces Hinged continuous labial bar

48. Sequence of design considerations

49. D esign of Mandibular Major Connectors Step I -Outline the basal seat areas on the diagnostic cast. Step II -Outline the inferior border of the major connector.

50. Step III -Outline the superior border of the major connector . Step-IV -Connect the basal seat area to the inferior and superior borders of the major connector and add minor connectors to retain the acrylic resin base.

51. NON RIGID CONNECTORS Split Bar major Connector Ticonium Hidden Lock Partial Denture The 12 Gauge Chrome Wire Stress Breaker Disjunct Dentures

52. Split is provided between the denture base area and the major connector . When occlusal forces are applied they are transferred more towards the tissue supported base and then they are transmitted to the abutment teeth. Split Bar Major Connector NON RIGID CONNECTORS

53. This is a two piece casting, the top half, which is the major connector supporting the direct retainers and other rigid components, is cast first. The bottom half, which is the connector between the denture bases, is cast to the major connector next. Ticonium Hidden Lock Partial Denture NON RIGID CONNECTORS

54. The hidden lock is created by mechanical means, and the split between the two connectors is made possible by the thin oxide shell that forms during the making of the two sections. What appears to be a conventional lingual bar or linguoplate actually is two bars connected by a movable joint at the midline

55. The 12 gauge chrome wire stress breaker avoids the complexities of most stress breaker designs and yet offers many clinical advantages. The 12 Gauge Chrome Wire Stress Breaker NON RIGID CONNECTORS

56. The 12 gauge wire is adapted to the refractory cast. The wire is coated with die lubricant and the wax up is completed. The wax must not go beyond the maximum convexity of the wire . The wire is removed and the casting is completed .

57. After recovering the casting the wire is welded or soldered . Then the connection between the denture base and the main major connector is separated to activate 12 gauge chrome wire.

58. ADVANTAGES : The rigidity of the 12 gauge wire avoids overloading the mucosa. The mucosa is also more evenly loaded It is easy to splint teeth with this design. The fabrication is relatively simple. Repairs are rarely needed and are also simple.

59. Disjunct Dentures ( Geissler , Watt 1965 ) Principle: Tooth borne & mucosa-borne parts of denture ar e disjoined. Tooth borne part providing splinting of remaining teeth & only retention for mucosa borne part. NON RIGID CONNECTORS

60. Structural details: The tooth borne part is a lingual plate and thus provides stabilization for the remaining teeth. The tissue borne part is a lingual bar which consists of denture bases along with the teeth at its terminals.

61. Advantages: Independent movement between the tooth supported and tissue supported parts decreases the forces on periodontally weakened remaining teeth. Disadvantages : It is technically difficult to fabricate Patient may complains of rattling of the framework during mastication .

62. Disadvantages of non rigid major connectors: The broken stress denture is usually more difficult to fabricate and therefore more costly. Vertical and horizontal forces are concentrated on the residual ridge, resulting in increased ridge resorption . Many stress breakers designs are not well stabilized against horizontal forces. If relining is not done when needed, excessive resorption of the residual ridge may result.

63. R eview of Literature

64. Larry D. Campbell (1977)* Aim: To evaluate the multiple removable partial denture designs by test patients. Conclusions: Mandibular lingual bar was chosen over the lingual plate by a 3:1 ratio. Metal borders parallel to tongue movement were better tolerated than those lying transverse. In general, patients adapted best to major connectors that covered the least amount of soft tissues * J Prosthet Dent 1977;37(5): 507-516

65. Hansen & Campbell (1985)* * J Prosthet Dent 1985; 54(6):805-809 Aim : To evaluate patient acceptance of the sublingual bar when compared to the linguoplate connector and to determine the preferred design. They were judged on the parameters of speech, chewing & resting comfort. Conclusion : The sublingual bar compared favorably with the lingual plate in patient acceptance and it should be considered as a viable design alternative when a lingual plate was not used

66. McHenry,Johansson (1992) Aim : To evaluate the effect of removable partial denture mandibular major connector design on surrounding gingival tissues Results showed a greater increase in mean gingival inflammation with the control than with the test suggesting that cingulum bar has fewer detrimental effects on gingival tissues than linguoplate . * J Prosthet Dent 1992;68(5):799-803

67. Ben-Ur, Mijiritsky , Gorfil , and Brosh (1999)* Aim : To investigate the design and cross-sectional shape of major connectors most favorably influencing rigidity and flexibility. Conclusion : They concluded that the cross-sectional shape was the most important factor in achieving rigidity and that the half-pear shaped cross-section proved to be the most rigid major connector. * J Prosthet Dent 1999:81(5):526-32

68. Pienkos , Morris, Cameron and Looney(2007) Conducted a study to determine the minimum major connector diameter that would provide adequate functional strength; in order to enhance patient comfort & tissue health. It was concluded that it was safe to reduce the lingual bar to a width of either 3 or 2.5 mm * J Prosthet Dent 2007;97:299-304

69. S ummary For a tooth supported removable partial denture the lingual bar is the suitable major connector. Long span edentulous ridges in which there is posterior abutment and indirect retention is needed, the lingual plate is indicated. When anterior teeth are periodontally treated and needs support and stabilization, the lingual plate or double lingual bar may be used. When the tissue of the floor of the mouth are active and <8mm space available between tissue and marginal gingiva , a lingual plate is preferred.

70. Major connectors by uniting the other components of a removable partial dentures acts like a foundation bringing about bilateral distribution of forces which depends on the rigidity of the connector. Although there are many variations in major connector, a thorough comprehension of all factors influencing their design will lead to the best design for each patient. C onclusion

71. McCracken’s Removable Partial Prosthodontics. A.B. Carr, G.P. McGivney, D.T. Brown. Elsevier.11 th ed. Stewart’s Clinical Removable Partial Prosthodontics. Rodney D. Phoenix, David R. Cagna , Charles F. DeFreest . Quintessence 3 rd ed. Clinical Removable Partial Prosthodontics. Stewart, Rudd, Kuebker . Ishiyaku EuroAmerica.2 nd ed. David Henderson. Major connectors for mandibular removable partial dentures: Design & function. J Prosthet Dent.1973; 30(4): 532-548 David Henderson : Major connectors for mandibular removable partial dentures: Design and function. J Prosthet Dent 1973; 30: 530-549. Carl A. Hansen, Donald J. Campbell : Clinical comparison of two- mandibular major connector designs: The sublingual bar and the lingual plate. J Prosthet Dent 1985; 54: 805-808 R efrences

72. Z . Ben-Ur, S. Matalon , I. Aviv : Rigidity of major connectors when subjected to bending and torsion forces. J Prosthet Dent 1989; 62: 557-562 . Mansuang Arksornnukit,Hisashi Taniguchi and Takashi Ohyama.Rigidity of three different types of mandibular major connectors through vibratory observation. Int J Prosthodont 2001;14: 510-516 Todd Pienkos , Jack Morris, Peter Gronet , Stephan Cameron and Stephen Looney: The stength of multiple major connector designs under simulated loading.J Prosthet Dent 2007;97:299-304 Robert Walter, James Brudvik , Ariel Raigrodski , Lloyd Mancl , Kwok-Hung Chung: A comparision of the rigidity of five mandibular major connectors for partial removable dental prostheses via load deflection.J Prosthet Dent 2010;104:182-190

73. THANK YOU ! A good head and a good heart are always a formidable combination. Nelson Mandela

74. M andibular M ajor C onnectors a bhishek K avlekar