Major and Minor Connectors Flashcards
what is the major connector
joins the minor connectors anf their attached assemblies together to form a unit
what does the major connector do
- counter leverage
- cross arch stabilization
- unification of components
what does cross arch stabilization (counterleverage) do
- bracing elements on one side of the arch providing stability to the other
what are the requirements of major connectors
- rigidity
- location
what does rigidity do
- functions as one unit
- broad stress distribution
- reduce torque
- avoid tissue damage
flexibility =?
force concentration
what should you avoid terminating on
free gingival margin
- lingual frenum and the movable soft palate
- soft tissue movement must be allowed
how should you minimize food impaction
- locate margins away from teh FGM
- eliminate traps or large concavities where food can collect
what does unobtrusive need to be
-smooth transition from connector to denture base- butt joint
- smooth line angles and edges
- borders should not interfere with speech
what are the considerations for maxillary major connectors
- borders are placed parallel to and a minimum of 6 mm from gingival margins
- no relief required ecept where crossed gingival margin
- anterior borders follow valleys between rugae
- anterior and posterior borders cross midline at right angle
- uniform thickness of metal
- borders beaded: 0.75-1mm wide and deep
why does the border need to be beaded
- displaces soft tissue, seals border to maintain tissue contact, provides additional strength
what tissue impingmeents should be avoided
- 6mm from gingival crest- maxillary
- 3mm from gingival crest - mandibular
- cross at right angles to the gingival margins
what locations should be avoided
- tissue impingement
- ending on crests of rugae
- irritation of surface eminences during insertion and removeal
- ending on incisal 1/3 of anterior teeht
what should be considered in maxillary major connector selection
- palatal tori
- anterior teeth replacement
- anterior teeth stabilization
- indirect retention
- phonetics
- patient attitudes
- support
- retention
- stability
- contigency planning
- occlusion
what are the types of maxillary major connectors
- palatal strap
- palatal plate
- anterior posterior strap
- horseshoe or “U”
what are the indications for palatal strap
- tooth supported situations- class III
- small posterior edentulous areas
- minimal tissue support required
- patient preference
how thick should the palatal strap be
8-10 mm
when is the palatal strap contraindicated
- distal extension situations- class I or II
- severe palatal undercuts
- large tori
- RPD to replace anterior teeth
- when support from palate in required
what are the advantages to palatal strap
- excellent support and rigidity
- distribute stress of mastication over wide area
what are the disadvantages of palatal strap
coverage of palate may cause discomfort and interference with phoentics
where is the palatal strap located
- 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 4 rests
when is the palatal plate used
- long span distal extension RPDs with or without anterior tooth replacement
- flat residual ridges
- periodontally weakened abutments
when is palatal plate contraindicated
severely undercut torus
what are the advantages to palatal plate
- optimum support and ridigity
- increase retention due to increased interfacial surface tension
what are the disadvantages to the palatal plate
- can not be used with torus
- coverage of the palate may diminish taste, interfere with phonetics, difficult to cast
what is the location of the palatal plate
- anterior border between rugae valleys and at right angle to median suture
- posterior border: extends to junction of soft and hard paalte
when is anterior posterior palatal strap indicated
- circumvent torus
- strong widely separated abutments
when is anterior posterior palatal strap contraindicated
- some maxillary designs due to narrow bulky straps
- patients with high narrow vaults
- phoenetic interference
what are the advantages and disadvantages of anterior posterior palatal strap
- advantages: structurally, very rigid straps in 2 plans, minimal tissue coverage
- disadvantages: large amount of border area to blend
where is the anterior posterior palatal strap located
- anterior posterior straps - 6-8mm
- for palatal opening to be beneficial the space between anterior and posterior straps should be 15mm
- posterior strap: distal extension to vibrating line and extended through hamular notches
- tooth supported not more posterior than distal abutment
when are horseshoe or U shaped indicated
- in very high vault palate
- large inoperable torus
- anterior tooth replacement
- patient is intolerance of palatal coverage
what are the advantages and disadvantages of horseshoe or U shaped
- advantages: can be designed to replace missing anteriors, confroms to patients previous experience
- disadvtanges: requires bulk for rigidity, can interfere with patients speech and tonuge, may lack support causing tissue impingement
what is the location of horseshoe or U shaped
- anterior border: terminates in the 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
what is beading of the maxillary cast
a prepared groove on the master cast along the designated borders of maxillary major connectors
what are the functions of beading on the maxillary cast
- increased rigidity
- guide for finishing
- compensates for casting inaccuracies
- displaces soft tissue, preventing food.fluid collection
describe the form of beading of max cast
- 1/2 round bur
-1 mm deep and 1.5 mm wide - feathers out to nothing 6mm from FGM
- shallower over mid palatal suture
how should you select for mandibular major connectors
- mandibular tori
- anterior tooth replacement
- indirect retention
- patient preference
- lingual frenum and floor of mouth position
-open embrasure between teeth - overlapping of anteriors
- contingency planning
what are the types of mandibular major connectors
- lingual bar
- lingual plate
- labial bar
when is the lingal bar indicated
whenever possible
- a depth of at least 7 mm measured from the lowest point of the gingival margin to the floor of the mouth is required
when is lingual bar contraindicated
- shallow floor of mouth and prominent frenum
- inoperable tori
- teeth in linguoversion
- teeth require stabilization
- RPD requires additional stabilization
- RPD required benefit of additional indirect retention
- contigency planning
what are the advantages of lingual bar
covers the minimum of the tissues
what are disadvantages of lingual bar
may be flexible if poorly constructed
what is the location of the lingual bar
- superior border 3-4mm inferior to FGM
- inferior border at heigth of lingual sulcus with tongue slightly elevated
- bar height is 4-5 mm
when is lingual plate indicatde
- insuficcient lingual vestibular space for lingual bar (less than 7mm)
- anticipated future replacement of anterior teeth
- bilateral distal extension eith flat residual ridges
- presnece of mandibular tori
- pt preference
when is lingual plate contraindicated
- adequate depth
- prominent diastemas
- severe anterior crowding
- no additional requirement for indirect retenetion
- pt preference
- teeth in linguoversion
are are advantages to lingual plate
more rigid than lingal bar
what are disadvantages to lingual plate
- covers teeth and tissue
- compromised oral hygiene
- more metal to fit, more difficult to fit the framework
- esthetic with diastemas
what is the location of lingual plate
- superior border contacts cinugla of anterior teeth extending from contact point to contact point
- inferior border at height of alveolar lingual sulucs with tongue elevated
- must be supported by rests at terminal ends
when is labial bar indicated
- lingual inclined anterior or posterior teeth
- prominent tori
when is labial bar contraindicated
if tooth positioning will permit another connector
what are advantages of labial bar
permits an RPD to be fabricated
what are disadvantages of labial bar
- hard to make
- bulky to be rigid
- not esthetic
- traps food in vestibular area
what is the labial bar location
- superior border is at least 4 mm from buccal and labial FGM
- inferior border is located at the junction of the attached and unattached mucosa
what does the minor connector join to the major connector
- the clasp assembly
- indirect retainers or auxillary rests
- the denture base
what are the functions of the minor connector
- transfers functional stress to abutments
- transfers effect of retainers, rests and stabilizing components to the rest of the denture
- unites retainers, rests and denture base to the major connector
- helps to resist lateral movement
what are the minor connector requirements
- rigid with minimal bulk
- located in embrasure
- triangular in shape
- thickest towards lingual
- joins at major connector at right angle
- taper to contact point
- smooth and rounded
-minimum of 5 mm between vertical connectors - cover minimal gingival tissue
- cross gingiva at right angle
- must not impinge on tissue
- contact guiding plane surfaces
- minimal interference with denture tooth placement
what is the proximal plate
the portion of the frameowrk that contacts the proximal side of the tooth
- also considered a minor connector
