Transcript Major Connectors

Major Connectors
Rola M. Shadid, BDS, MSc
Major Connector
A major connector is the component of
the RPD 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 RPD to which all
other parts are directly or indirectly
attached.
Functions of Major Connector
 Unification
 Partial denture acts as one unit
 Connects various parts
Functions of Major Connector
 Stress Distribution
 Distributes functional loads to both
teeth & mucosa
Functions of Major Connector
 Cross-Arch Stabilization *
(Counterleverage)
 Bracing elements on one side of the
arch providing stability to the other
Requirements of Major Connector
 Rigidity *
 Functions as one unit
To Increase Rigidity
 Use a more rigid alloy
 Chrome-cobalt > gold alloys; cast > wrought
 Shape (cross-section)
 1/2 round > 1/2 pear shaped > flat bars
To Increase Rigidity
 Increase the bulk as the length increases
 Corrugate linguoplate or rugae areas
Requirements
 Non-Interference with soft tissues
 Should not enter undercut areas
 avoid by changing path of insertion
 or by using blockout
Non-Interference With Tissues
 Avoid terminating on:
 Free gingival margin
 Cross abruptly at 90o
 Relief is used to minimize
impingement
Borders of maxillary
connector should be placed
a minimum of 6 mm away
from and parallel to the
gingival margins.
Border of mandibular
connector should be located
a minimum of 4 mm below
the gingival margin
Non-Interference With Tissues
 Avoid terminating on:
 Hard structures such as the midpalatal suture or mandibular tori
 Place relief
Non-Interference With Tissues
 Avoid terminating on:
 Lingual frenum & the movable soft palate
 Soft tissue movements must also be allowed
Minimize Food Impaction
 Locate margins away from the FGM
 Eliminate "traps" or large concavities
where food can collect
Unobtrusive *
 Smooth transition from connector to
denture base - butt joint
Unobtrusive
 Line angles and edges should be smooth
and rounded
 Borders should not interfere with speech
Relief
 Mandibular major connectors should be
located and/or relieved to prevent
impingement of tissue because the distal
extension denture rotates in function.
 Except for a palatal torus or prominent
median palatal suture area, maxillary
connectors ordinarily require no relief.
Mandibular Major Connectors
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Lingual Bar
Lingual Plate
Sublingual bar
Lingual bar with cingulum bar
(continuous bar)
 Labial bar
 Swing lock design
Mandibular Major Connectors
 Lingual Bar
 Most common in mandibe
 Use whenever possible
Mandibular Major Connectors
 Lingual Bar
 Shape
 Flat on tissue side
 Convex or tear-drop on
tongue side
 (1/2 pear shape, with
thin edge toward teeth)
Lingual Bar
 Located above moving
tissue but as far below the
gingival tissue as possible
 The superior border should
be tapered toward the
gingival tissue superiorly
with its greatest bulk at the
inferior border, resulting
in a contour that is a halfpear shape.
Mandibular Major Connectors
 Lingual Bar
 Size
 Occluso-gingival width = 4 to 6 mm
 Thickness = l.5 to 2 mm
Inferior Border of Lingual Bar *
 Patient lifts tongue
 Activates floor of mouth
 Measure from tip of probe to free
gingival margin
OR
o Make impression
with lifted tongue
o Measure on cast
Inferior Border of Lingual Bar
Lingual Bar
 Position
 Superior border
 3-4 mm or more below FGM
 As far from gingival margin as
possible
Mandibular Major Connector Relief
 Eliminates impingement
 Wax spacer (relief) placed under major
connector
 One thickness of 30 gauge wax *
Lingual Bar Indication
The lingual bar should be used for
mandibular RPD where sufficient space
exists between the slightly elevated
alveolar lingual sulcus and the lingual
gingival tissue (more than 8 mm)
Contraindications for Lingual
Bar
 Remaining natural
anterior teeth severely
tilted lingually
 Interfering lingual tori
 High attachment of
lingual frenum
 Interference with
elevation of the floor of
the mouth during
functional movements (< 8
mm)
Lingual Plate (Linguoplate)
 Lingual bar with extension over cingula of
anterior teeth
 Use where a lingual bar cannot be used
Lingual Plate
Inferior border at the
ascertained height of
the alveolar lingual
sulcus when the
patient's tongue is
slightly elevated.
Lingual Plate
 Rest at each end of lingual plate
 Prevents forces being directed facially
 Easier denture tooth addition than bar *
Lingual Plate Variations
 May show through embrasures
Lingual Plate Indications
 Potential Impingement from lingual bar
 High floor of the mouth (< 8 mm)
 Prominent lingual frenum
 Lingual tori
Lingual Plate Indications
 The residual ridges in Class I arch have
undergone such vertical resorption that they
will offer only minimal resistance to horizontal
rotations of the denture through its bases.
 For using periodontally weakened
teeth to furnish support to prosthesis and to
help resist horizontal rotation of the distal
extension type of denture. (act as periodontal
splint)
Mandibular Lingual Bar with Continuous
Bar (Cingulum Bar)
(Kennedy Bar, Double Lingual Bar)
 Lingual bar with secondary bar on
cingula of anterior teeth *
Mandibulat Lingual Bar with
Continuous Bar Indications
When a linguoplate is otherwise
indicated but the axial
alignment of anterior teeth
is such that excessive
blockout of interproximal
undercuts would be
required.
When wide diastema exists
between mandibular
anterior teeth and a
linguoplate would
objectionably display metal
in a frontal view.
Mandibulat Lingual Bar with
Continuous Bar
 Potential food trap between two bars
 Normally avoid
Maxillary Major Connectors
1.
2.
3.
4.
Anterior-Posterior Palatal Strap
Palatal plate-type connector
Single palatal strap
U-shaped palatal connector (Anterior
Palatal Strap)
5. Single palatal bar
6. Anterior-posterior palatal bar
Maxillary Major Connectors
Whenever it is
necessary for the
palatal connector to
make contact with
the teeth for support,
definite tooth
support by definite
rest seats should be
provided *
Maxillary Major Connectors
 Terminate 6.0 mm or more from free
gingival margin when possible
Anterior-Posterior Palatal Strap*
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Maximum rigidity
Minimum bulk
Use in most cases
Especially torus palatinus
Anterior-Posterior Palatal Strap
Indications
 Class I and II arches in which excellent
abutment and residual ridge support
exists, and direct retention can be made
adequate without the need for indirect
retention.
 Long edentulous spans in Class II,
modification 1 arches.
 Class IV arches
Anterior-Posterior Palatal Strap
Indications
 Inoperable palatal tori that do not
extend posteriorly to the junction of the
hard and soft palates.
 The only condition preventing its use is
when there is an inoperable maxillary
torus that extends posteriorly to the soft
palate.
Anterior-Posterior Palatal Bar
 A narrow (A-P) variation of anteriorposterior palatal strap
 Double palatal bar connector
 Requires greater bulk for rigidity
Anterior-Posterior Palatal Bar
 More objectionable to the patient
 Strap connectors provide greater
distribution of stresses
Palatal Plate-Type Connector
 Covers one half or more of the hard
palate
 Maximum tissue support
 Connector of choice in long distal
extension cases
Palatal Plate-Type Connector
 Greater stability and stress distribution
 Not used with torus
 Increases retention
Palatal Plate-Type Connector
 Connector should:
 be fabricated of uniformly thin metal *
 have accurate anatomic reproduction
of the rugae
 improves strength and rigidity
Palatal Plate-Type Connector
 Connector should:
 Cover same area as complete denture
posteriorly
 Have large surface area of mucosal contact
 improves potential for retention
Palatal Plate-Type Connector
Forms
1. A cast plate between
two or more edentulous
areas
2. A complete or partial
cast plate that extends
posteriorly to the
junction of the hard and
soft palate
Palatal Plate-Type Connector
Forms
3. An anterior palatal
connector with a
provision for extending
an acrylic resin denture
base posteriorly
Palatal Plate-Type Connector
Indications
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Abutments are periodontally involved
Maximum stress distribution is needed*
Flabby tissue
Shallow palatal vault
Single Palatal Strap
 Usually use for Class III & IV cases *
Single Palatal Strap
Strap should be 8mm
wide or approximately
as wide as the
combined width of a
maxillary premolar
and first molar.
Confined within an area
bounded by the four
principal rests
Single Palatal Strap
 Never use in cases involving distal extensions
since it must be made bulky for rigidity
 Relief may be required over bony midline
 Not used with torus
Palatal Bar
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Don’t use
Narrow anterio-posteriorly
Thick occluso-gingivally
Palatal bar objectionable due to bulk
U-Shaped or "Horse-Shoe" Palatal
Connector
 Poor connector
 Never use unless
absolutely necessary
 Requires bulk in the
rugae area (where
the tongue requires
freedom) for rigidity
U-Shaped or "Horse-Shoe"
Palatal Connector
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Too flexible
Allows movement at the posterior
Traumatic to the residual ridge
Use only where torus prohibits other
connector & extends to the posterior limit
of the hard palate
Flexes, impinging on soft tissue
References
 Chapter 5 Major and Minor Connectors,
McCracken's Removable Partial
Prosthodontics, 11th edition