major and minor connectors Flashcards
major connector
That component of a partial denture
which joins the minor connectors and
their attached assemblies together
to form a solid unit
purposes of a major connector
• Cross-Arch Stabilization (Counterleverage)
– Bracing elements on one side of the arch providing stability to the other
requirements of major connectors
rigidity and location
functions of major connector rigidity
functions as?
stress distribution?
torque?
tissue damage?
• Functions as one unit
• Broad stress distribution
• Reduce torque
• Avoid tissue damage
flexibility of major connector may allow for?
force concentration
major connector Non-Interference with Tissues
how to avoid this?
– Should not enter undercut areas
• avoid by changing path of insertion or by using blockout
major connectors should avoid terminating on what tissues?
free gingival margin
lingual frenum
soft palate
major connectors crossing gingival margins
minimizing impingment?
cross at abruptly 90 degrees
minimized impingement with relief
Minimizing major connector Food Impaction
locate away from?
eliminate what?
• Locate margins away from the FGM
• Eliminate “traps” or large concavities where food can collect
making major connectors unobtrusive
smooth transition from the connector to the base
smooth line angles
no border interferences with speech
where to place major connector borders from the gingival margins
6mm from the margin
where to place relief on gingival. margins
only where connector crosses
anterior of max major conn borders follow what?
valleys of the rugae
how should the major connector borders cross the midline
at right angles
thickness of major connector
uniform
beading of the connector borders
Borders beaded: 1.5 mm wide & 1mm deep
– Displaces soft tissue, seals border (helps maintain tissue contact). Also, provides additional strength (for maxillary major connectors)
avoiding tissue impingement deminsions
–6mm from gingival crest (Maxillary)
–3mm from gingival crest (Mandibular)
–Cross at right angles to the gingival margins
what to avoid location wise for a major connector
• Tissue impingement
• Ending on crests of rugae
• Irritation of surface eminences during insertion / removal
• Ending on incisal 1/3 of anterior teeth
improper location of the major connector coudl cause
Food impaction
• Occlusal interferences
• Speech interference
• Gagging
• Tongue irritation
MAXILLARY MAJOR CONNECTORS types
Palatal Strap
Palatal Plate
Anterior-Posterior Strap
Horseshoe or “U”
Palatal Strap
- Indications -
• Tooth supported situations -Class III
• Small posterior edentulous areas
• Minimal tissue support required
• Patient preference
how wide must the palatal strap be for rigidity
8-10mm
Palatal Strap
- Contraindications -
• Distal extension situations –Class I or II
• Severe palatal undercuts
• Large torus
• RPD to replace anterior teeth
• When definitive support from palatal tissue is required
Palatal Strap
- Advantages -
• Excellent support and rigidity
• Distribute stress of mastication over a wider area
Palatal Strap
- Disdvantages -
discomfort and interference with phoetics
Palatal Strap
- Location -
• Anterior border follows valley between rugae at right angle to median suture
• Posterior border at right angle to median suture
• Confined to area bounded by four principle rests
palatal plate indications
• Long-span distal extension RPDs with or without anterior tooth replacement
• Flat residual ridges
• Periodontally weakened abutments
Palatal Plate
- Contraindications -
• Severely undercut
torus
Palatal Plate
- Advantages -
Optimum support and rigidity
Increase retention due to increased interfacial surface tension
Palatal Plate
- Disadvantages -
• Can not be used with torus
• Coverage of the palate may diminish taste, interfere with phonetics.
• Difficult to cas
Palatal Plate
- Location -
• Anterior border between rugae valleys and at right angle to median
suture
• Posterior border :Extends to junction of soft and hard palate
Anterior-Posterior Palatal Strap
- Indications -
• Circumvent a torus
• Strong, widely separated abutments (Distal extension RPDs; Distal extension RPDs also replacinganterior teeth)
Anterior-posterior Palatal Strap - Contraindications -
• SOME maxillary designs due to narrow bulky straps
• Patients with high narrow vaults
• Phonetic interference
Anterior-posterior Palatal Strap
- Advantages -
• Structurally, very rigid - straps in 2 planes
• Minimal tissue coverage
Anterior-posterior Palatal Strap
- Disadvantages -
• Large amount of border area to blend
Anterior-posterior Palatal Strap demensions
• Anterior/posterior straps – 6-8 mm wide
• For palatal opening to be beneficial, the space between anterior & posterior straps should be 15 mms.
Anterior-posterior Palatal Strap - Location -Posterior strap
– distal extension to vibrating line and extended through hamular notches
– tooth supported not more posterior than distal abutment
Horseshoe or U-shaped
- Indications -
• **In very high vault palate **
• Large inoperable torus
• Anterior tooth replacement
• Patient is intolerant of palatal coverage
Horseshoe or U-shaped
- Contraindications -
• The Least Rigid maxillary connector, therefore ANYTIME another connector may be used
Horseshoe or U-shaped
- Advantages -
• Can be designed to replace missing anteriors
• Conforms to patient’s previous experience
Horseshoe or U-shaped
- Disadvantages -
• Requires additional bulk for rigidity
• Can interfere with patient’s tongue/speech
• Even with rest, may lack support causing possible tissue impingement
Horseshoe or U-shaped
- Location -
• Anterior border:
– terminates in valley of rugae at right angle to suture, or;
– on the cingula of teeth extending contact point to contact point
• Posterior border located at the turning point of the palate
BEADING OF THE MAXILLARY CAST
A prepared groove on the master cast along the designated borders of maxillary major connector
This produces a positive bead on the major connector of the RPD
BEADING OF THE
MAXILLARY CAST
- functions -
• Increased rigidity
• Guide for finishing
• Compensates for casting inaccuracies
• Displaces soft tissue, preventing food/fluid collection
BEADING OF THE
MAXILLARY CAST
- form -
• 1/2 round
• 1 mm deep and 1.5 mm wide
• Feathers out to nothing 6 mm from free gingival margin
• Shallower over mid-palatal suture
MANDIBULAR MAJOR CONNECTORS types
Lingual bar
Lingual plate
Labial bar
Lingual bar
- Indications -
required measurement?
• Whenever possible, if no contraindications are evident
• A depth of at least 7 mm measured from the lowest point of the gingival margins to the floor of the mouth is required
Lingual bar
- Contraindications -
• Shallow floor of mouth and prominent frenum
• Inoperable tori
• Teeth in linguoversion
• Teeth require stabilization
• RPD requires additional stabilization
• RPD requires benefit of additional indirect retention
• Contingency planning
Lingual bar
- Advantages -
• Covers the minimum of the tissues
Lingual bar
- Disadvantages -
• It may be flexible if poorly
constructed
Lingual bar
- Location -
• Superior border 3-4 mm inferior to free gingival margin
• Inferior border at height of lingual sulcus with tongue slightly elevated
• Bar height is 4-5 mm
measuring Inferior Border Mandible
• Patient lifts tongue
–Activates floor of mouth
• Measure from tip of probe to free gingival margin
Lingual plate- Indications -
anticipated replacement of?
retention?
ridge shape?
tori?
pt?
Insufficient lingual vestibular space for lingual bar (less than 7 mm from gingival margins to the floor of the mouth)
• Anticipated future replacement of anterior teeth
• Indirect retention
• Bilateral distal extension with flat residual ridges (Provide resistance against horizontal movements)
• Presence of mandibular tori
• Patient preference
Lingual plate
- Contraindications
• Adequate depth to floor of the mouth for a bar
• Prominent diastemas (large interdental spaces)
• Severely anterior crowding
• No additional requirement for indirect retention
• Patient preference
• Teeth in linguoversion
Lingual plate
- Advantages -
• More rigid than lingual bar
Lingual plate
- Disadvantages -
• Covers teeth and tissue
• Compromised oral hygiene “possible increase enamel decalcification”
• More metal to fit, more difficult to fit the framework
• Esthetic with diastemas (however, can modify plate to overcome)
Lingual plate- Location -
what is required at ends?
• Superior border contacts cingula of anterior teeth extending from contact
point to contact point
• Inferior border at height of alveolar lingual sulcus with tongue elevated
• Must be supported by rests at terminal ends
Labial bar
- Indications -
• Lingually inclined anterior or posterior teeth
• Prominent, superiorly located inoperable tori
labial bar - Contraindications -
Where tooth positioning will
permit another connector
labial bar advantages
Permits an RPD to be fabricated
labial bar disadvantages
Difficult to fabricate
Must be bulky to be rigid
Not esthetic
Traps food in vestibular area
Labial bar
- Location -
• Superior border is at least 4 mm from buccal and labial free gingival margin
• Inferior border is located at the junction of the attached and unattached mucosa
MINOR CONNECTOR
That component of a
partial denture which
joins the major
connector with other
parts of the framework
minor connector joins what to the major connector
– the clasp assembly
– indirect retainers or auxiliary rests
– the denture base
minor connector role in bar type clasps
Serves as an approach arm for a vertical projection or bar type clasp
MINOR CONNECTOR Functions
transfers functional stresses to?
Transfers effect of retainers, rests and stabilizing components to?
unites what components?
resists what type of movement?
• Transfers functional stress to abutments
• Transfers effect of retainers, rests and stabilizing components to the rest of the denture (abutment to prosthesis)
• Unites retainers, rests and denture base to the major connector
• Helps to resist lateral movement
MINOR CONNECTOR REQUIREMENTS
rigid/bulk?
shape?
thickest toward?
angle to join major?
tapers to?
smooth?
minimum between vertical components?
• Rigid with minimal bulk
• Located in embrasure
• Triangular in shape
• Thickest toward lingual
• Joins major connector at right angle
• Tapers to contact point
• Smooth and rounded
• Minimum of 5mm between vertical connectors
MINOR CONNECTOR
REQUIREMENTS
• Cover minimal?
• Cross gingiva at?
• Must not impinge on?
• Contact?
• Minimal interference with?
• Cover minimal gingival tissue
• Cross gingiva at right angle
• Must not impinge on tissue
• Contact guiding plane surfaces
• Minimal interference with denture tooth placement
