social pharmacy d-pharm 1st year by Pragati K. Mahajan
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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
5. â˘Design sequence for mandibular major connector
â˘Non Rigid Connectors
â˘Review of literature
â˘Summary
â˘Conclusion
â˘References
6. âNo component of a Removable
Partial Denture should be added
arbitrarily or conventionally. Each
I
component should be added for a
NTRODUCTION
good reason and to serve a definite
purposeâ.
WL McCracken
7. Major 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)
8. Basic requirements of Mandibular
major connectors.
o Rigid & provides cross-arch stability - broad distribution of stress.
o Should not interfere with & non irritating to the tongue.
o Should not alter the contour of the lingual surface of the
mandibular alveolar ridge.
o Should not impinge on the oral tissues when the prosthesis is
inserted or rotate in function.
9. o Cover no more tissue than is absolutely necessary.
o Does not contribute to the retention or entrapment of food
particles.
o Has support from other elements of the framework to
minimize rotational tendencies during function.
o Made from an alloy compatible with the oral tissues.
10. Design 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.
1) Tooth-borne prostheses: 30 guage,0.010 inches.
2) 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:
1) 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:
1) Periodontal status of abutment teeth
2) Quality of the supporting soft tissues
3) Bone index
4) Movement of the dento-alveolar
segment
5) Lingual tori
16. Recording the Height of floor of the
mouth
o Make a custom tray 3mm short of elevated floor of the mouth.
o Then using an impression material record the area by asking the
patient to lick the upper lip.
17. Types Of Mandibular Major Connectors
LINGUAL BAR
SUBLINGUAL BAR
CINGULUM BAR (Continuous bar)
LINGUAL BAR WITH CINGULUM BAR (Continuous bar)
LINGUOPLATE
LABIAL BAR
HINGED CONTINUOUS LABIAL BAR
18. Lingual Bar
Lingual Bar Major Connector
⪠Indications:
8mm vertical space between
gingival margin and floor of the mouth.
20. Lingual Bar Major Connector
Characteristics and location
o Half-pear shaped with bulkiest portion inferiorly located.
o Superior border tapered to soft tissue.
o Superior border located at least 3mm inferior to gingival
margins.
o Inferior border located at the ascertained height of the
alveolar lingual sulcus when the patients tongue is slightly
elevated.
21. Lingual Bar
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.
.
22. ADVANTAGES
It may be flexible if poorly
constructed.
Lingual bar connector has
minimal tissue coverage and
has minimal contact with oral
tissues.
Rigidity is less compared to a well
constructed lingual plate.
It does not contact the teeth,
so decalcification of the tooth
surface is minimized.
DISADVANTAGES
23. Lingual Bar Major Connector
Block out & relief of master cast
o All tissue undercuts parallel to path of placement.
o 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.
o No relief is necessary when the lingual surface slopes
inferiorly and posteriorly.
24. Lingual Bar Major Connector
Waxing Specifications
- 6 gauge, half-pear shaped wax form reinforced by 2224 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.
25. Linguoplate
Lingual plate
Indications:
o
o
o
o
High lingual frenum , shallow vestibule.
Severe vertical resorption
Presence of lingual tori.
Stabilization of periodontally weak teeth.
Contraindications:
o In lingually inclined mandibular anterior teeth.
o Wide embrassures and diastema
26. Linguoplate
Characteristics and location
o Half-pear shaped with bulkiest portion inferiorly
located.
o Thin metal apron extending superiorly to contact
cingula of anterior teeth and height of contour of
posterior teeth; and interproximally to contact points.
o Scalloped contour of apron as dictated by
interproximal blockout.
27. Linguoplate
oThe superior border should be knife edge and contoured to
intimately contact lingual surface above the cingula.
oClose inter proximal space to level of contact points.
28. Linguoplate
ADVANTAGES
o Provides more support and stabilization when compared to other
connectors.
o Can be used in stabilizing the periodontally weakened teeth.
o When it is supported at each end by a rest it contributes to the action
of indirect retention.
o Provision to include more teeth in the design
29. Linguoplate
DISADVATAGES
o It covers the tooth structure and the gingival tissue.
o 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)
30. Linguoplate Modifications
Interrupted Lingual Plate
o 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
31. Linguoplate
BLOCKOUT & RELIEF
â˘All involved undercuts of contacted teeth parallel to the path of
placement.
â˘All involved gingival crevices.
â˘Lingual surface of alveolar ridge.
WAXING SPECIFICATIONS
â˘Inferior border 6-gauge, half pear shaped wax
form reinforced with 24-gauge sheet wax.
â˘Apron 24-gauge sheet wax.
FINISH LINE: Butt joint
32. Double Lingual Bar
Double lingual bar
⢠This type of major connector is also called âKennedy barâ 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 âcontinuous lingual claspâ major connector,
because of series of clasp arms connected on the lingual surfaces of
lower anterior teeth.
33. Double Lingual Bar
Characteristics and location
o The lower component displays same charecteristics
as that of a lingual bar.
o The upper bar should be half oval ,2-3mm in height
and 1mm thick, presenting scallopped appearance.
o Two bars joined by minor connectors on each end
34. Double Lingual Bar
ADVANTAGES
oEffectively extends indirect retention in an anterior direction.
oContributes to horizontal stabilization.
oIt helps in minor amount of support to the prosthesis.
oThe gingival tissues and inter-proximal embrassures are not covered by
the connector, which helps in free flow of saliva.
35. Double Lingual Bar
DISADVATAGES
o Patient may feel discomfort because it alters the normal position
of the tongue.
o If connector does not maintain intimate contact with tooth surface
there will be food entrapment
British Dental Journal 189, 414 - 424 (2000)
36. Double Lingual Bar
BLOCKOUT & RELIEF
â˘Same as for lingual bar.
â˘No relief for continuous bar except blockout of interproximal
spaces
WAXING SPECIFICATIONS
â˘Same as lingual bar.
â˘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
37. Sublingual Bar
Sublingual Bar
Indications
o The height of the floor of the mouth in relation to the free
gingival margin is less than 6mm.
o 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:
o Lingually tilted remaining natural teeth.
o Inoperable lingual tori.
o High attached lingual frenum.
38. Sublingual Bar
o Accurately record the functional depth and width of the
lingual sulcus
o These sulcus dimensions are retained on the master cast
resulting in a bar whose maximum cross-sectional
dimension is oriented horizontally.
o Rigidity
Height ~ Rigidity2
Width ~ Rigidity3
o The increased width of the sublingual bar connector
therefore ensures that the important requirement of
rigidity is satisfied.
39. Cingulum Bar
Continuous bar (cingulum bar)
⢠Indication:
Improper axial alignment of the anterior teeth requiring
excessive blockout of interproximal undercuts.
⢠Contraindications:
â In lingually tilted anterior teeth.
â Wide diastema between mandibular anterior teeth.
40. Cingulum Bar
Characteristics and location
o Thin narrow metal strap located on cingula of anterior teeth,
scalloped to follow interproximal embrassures.
o Originates bilaterally from rests of the adjacent principle
abutments.
41. Cingulum Bar
BLOCKOUT & RELIEF
â˘No relief for cingulum bar except interproximal spaces.
WAXING SPECIFICATIONS
â˘A cingulum bar pattern formed by adapting two strips of 28gauge, 3mm wide over the cingula and into interproximal
embrassures.
FINISH LINE: Butt joint
42. Labial Bar
Labial Bar
Indication:
o Large inoperable lingual tori.
o Severe & abrupt lingual undercuts.
o Lingually inclined lower anterior & premolars.
43. Labial Bar
Characteristics and location
o Half-pear shaped with bulkiest portion inferiorly located on the
buccal aspect.
o Superior border tapered to soft tissue and 4mm inferior to labial
gingival margins.
o Inferior border located in the labial buccal vestibule; at the junction
of attached & mobile mucosa.
44. Labial Bar
BLOCKOUT & RELIEF
â˘All tissue undercuts parallel to path of placement and when the labial
surface is either undercut or parallel to the path of placement.
â˘No relief if labial surface of alveolar ridge slopes inferiorly.
WAXING SPECIFICATIONS
â˘6-gauge half-pear shaped wax form reinforced with 22-24 gauge
â˘Long bar more bulkier than shorter bar.
â˘Minor connector joined with occlusal or other superior components
by a labial approach.
FINISH LINE: Butt joint
46. Hinged continuous labial bar
Characteristics and location
⢠This type of major connector is the modification of linguoplate which is
incorporated in the âSwing-lockâ
⢠Design consists of labial bar i.e. connected to the major connector by
hinge on one end and latch at the other end.
47. Hinged continuous labial bar
o Support is provided by multiple rests on the remaining natural
teeth while stabilization and reciprocation is by ingual plate.
o Retention is provided by bar type retentive clasp arms projecting
from the labial bar & contacting the infrabulge areas on the labial
surfaces
49. Design 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
ď Split Bar major Connector
ď Ticonium Hidden Lock Partial
Denture
CONNECTORS
ď The 12 Gauge Chrome Wire
Stress Breaker
ď Disjunct Dentures
52. NON RIGID
CONNECTORS
Split Bar Major Connector
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.
53. NON RIGID
CONNECTORS
Ticonium Hidden Lock Partial Denture
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.
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. NON RIGID
CONNECTORS
The 12 Gauge Chrome Wire Stress Breaker
The 12 gauge chrome wire stress breaker avoids the complexities
of most stress breaker designs and yet offers many clinical
advantages.
56. 1. The 12 gauge wire is adapted to the
refractory cast. The wire is coated with
die lubricant and the wax up is
completed.
2. The wax must not go beyond the
maximum convexity of the wire.
3. The wire is removed and the casting is
completed.
57. 4. After recovering the casting the
wire is welded or soldered.
5.
Then the connection between
the denture base and the main
major connector is separated to
activate 12 gauge chrome wire.
58. ADVANTAGES:
1. The rigidity of the 12 gauge wire avoids overloading the
mucosa.
2. The mucosa is also more evenly loaded
3. It is easy to splint teeth with this design.
4. The fabrication is relatively simple.
5. Repairs are rarely needed and are also simple.
59. NON RIGID
CONNECTORS
Disjunct Dentures (Geissler, Watt 1965 )
Principle:
o Tooth borne & mucosa-borne parts of denture are disjoined.
o Tooth borne part providing splinting of remaining teeth & only retention
for mucosa borne part.
60. Structural details:
â˘The tooth borne part is a lingual plate and thus
provides stabilization for the remaining teeth.
â˘The tissue borne part is a lingual bar which consists of
denture bases along with the teeth at its terminals.
61. Advantages:
o Independent movement between the tooth supported and
tissue supported parts decreases the forces on periodontally
weakened remaining teeth.
Disadvantages :
o It is technically difficult to fabricate
o Patient may complains of rattling of the framework during
mastication.
62. Disadvantages of non rigid major connectors:
1.
The broken stress denture is usually more difficult to fabricate
and therefore more costly.
2.
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.
3.
If relining is not done when needed, excessive resorption of
the residual ridge may result.
63.
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)*
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
* J Prosthet Dent 1985; 54(6):805-809
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. Summary
â˘For a tooth supported removable partial denture the lingual bar is the
suitable major connector.
â˘Long span edentulous ridges in which there is posterior abutment and
indirect retention is needed, the lingual plate is indicated.
â˘When anterior teeth are periodontally treated and needs support and
stabilization, the lingual plate or double lingual bar may be used.
â˘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. Conclusion
â˘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.
â˘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.
71. Refrences
â˘McCrackenâs Removable Partial Prosthodontics. A.B. Carr, G.P. McGivney, D.T.
Brown. Elsevier.11th ed.
â˘Stewartâs Clinical Removable Partial Prosthodontics. Rodney D. Phoenix, David
R. Cagna, Charles F. DeFreest. Quintessence 3rd ed.
â˘Clinical Removable Partial Prosthodontics. Stewart, Rudd, Kuebker. Ishiyaku
EuroAmerica.2nd ed.
⢠David Henderson. Major connectors for mandibular removable partial
dentures: Design & function. J Prosthet Dent.1973; 30(4): 532-548
â˘David Henderson : Major connectors for mandibular removable partial
dentures: Design and function. J Prosthet Dent 1973; 30: 530-549.
â˘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
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. A good head and a good
heart are always a
formidable combination.
Nelson Mandela
The major frame work of this tower is a Spiral y shaped design , inspired by the hymenocallis flower which helps to reduce the impact of wind .Each tier of the building steps back in a spiral pattern up the building which deflects wind and prevents formation of whirlpools in the air tht would cause tower to sway.Similarly while designing a cast partial denture , the major framework which is the major connector has to be designed to tolerate forces and in accordance with the of existing oral conditions.
The pt should be instructed to elevate and protrude the tongue so that the tip touches the vermelion border of the upper lip , this activates the floor of the mouth and raises tissues to the height thtocurs during function. As pt maintains this position a periodontal probe is gebtly positioned so tht the tip of the probe rests on the floor, and reading is taken from most apical prtion of the gingival margin, readings r thrn transferred to the cast.
According to Mccracken the former methodisfound to beless variable hence more clinically acceptable.
A lingual bar should be used unless one of the other connectors offers definitive advantage.
Inferior border at the ascertained height of the alveolar lingual sulcus when patients tongue is elevated
Step back design in presence of wide embrasure . care must be taken not to decrease the rigidity of the major connector
Indicated primarily when open embrasures exist.
Rests should be placed at each end of upper bar and lacted no further than mesialfossae of first premolar.
In this instance the lingual bar has been positioned too close to the gingival margin. The continuous clasp offers only limited tooth support for the denture.The denture has sunk into the tissues, stripping away the gingival tissues on the distal and lingual aspects
A modification of the lingual bar that has been demonstrated to be useful when the height of the floor of the mouth in relation to the free gingival margins is less than 6mm.
The basic principles of major connector design includes:
Thus the amount of tipping forces are reduced on the abutment teeth.
A design using a dual-casting technique is the Ticonium hidden-lock design. Ticonium Premium 100 is a finegrained alloy developed specifically for removable partial dentures. This results in a stronger crystalline structure and better fit than that of the more typical, coarse-grained alloys. Proof Stress: 790 MPa
DisadvantagesMore prone to collect debris and become un hygienic. And also there may be chances of tissue trap at the junction between the two parts.
When the occlusal forces are applied, most of them directed towards the tissue borne part.
8 major connector designs were evaluated during speaking, chewing and swallowing and for general comfort by
conducted a clinical trial using the experimental gingivitis model developed for periodontal clinical research
. Five lingual bar major connectors of different cross-sectional forms were cast in chrome-cobalt alloy. Vertical and horizontal forces were applied to each point while the opposite side was gripped in Instron