2. Flashcards
Describe the difference in impression techniques between tooth supported and tooth tissue supported dentures
Tooth= Regular impression
Tooth tissue= selective pressure impression
T/F All the support for a kennedy class III and IV denture comes from the teeth
t
where does support for the denture come from
the rests
Most ideal places for rest seats are
- Occlusal
- Cingulum
- Incisal
What criteria are evaluated when determining the amount of support that can be provided by an abutment tooth
- Perio health
- Crown:root
- Crow to root morphologies
- Bone index area (how tooth has responded to previous stress)
- Location of the tooth in the arch
- Relationship of the tooth to other support units (length of edentulous span
- Opposing dentition
What criteria are evaluated when determining the amount of support that can be provided by the ridge for a tooth tissue supported partial
- quality of ridge
- Extent of ridge coverage
- type and accuracy of impression
- accuracy of denture base
- design of partial components
- occlusal load
Functions of minor connectors
- Join RPD parts
- Transfer stress from one abutment across the entire arch
- Transfer the effects of retainers, rests and stabilizing components throughout the prosthesis
T/F Latticework is a minor connector
t
Latticework extends _ up the length of an edentulous ridge
2/3
Keys to successful clasp design
- Avoid direct transmission of tipping or torquing forces on abutment
- Definitive locate component parts correctly on abutment tooth
- Provide retention against dislodging forces
- Compatible with undercut location, tissue contour and esthetic contour and desires
what is the most important single factor is clasp selection
location of undercut
Difference between internal and external finish lines
external <90 degrees and internal is 90
The junction of the major and minor connectors at the palatal finishline should be located where
2 mm medial to a line that connects the lingual surfaces (cusps) of the missing posterior teeth
What are the six different mandibular major connectors
- Lingual bar*
- Lingual plate*
- Sublingual bar
- Lingual bar with cingulum bar
- Labial bar
- Cingulum bar
Indications for lingual bar
-Need 8 mm between gingival margin and alveolar lingual sulcus depth
The inferior border of the lingual bar should be located where
at the height of the alveolar lingual sulcus
Shape of lingual bar is
half pear
superior boarder of lingual bar is located where
4 mm from gingival margin
Lingual plate indications for use
-Not enough space for a lingual bar
-Class I with excessive vertical resorption
-Periodontally weak teeth
Future replacement of teeth
Lingual plate may lead to what adverse effects
- decalcification of enamel
- irritaiton of soft tissues with poor OH
Superior boarder of the lingual plate is from
cingulum up to the interproximal contacts
Which is better for evasion of lingual tori lingual (bar/plate)
plate
What are the stress releasing clasps
- All infrabuldge clasps (T bar, 1/2 T and I-bar)
- Combination clasp
Advantages of RPI
- Esthetic
- Decreased torquing of abutment tooth
- Less chance of accidental distortion resulting from proximity to denture border
Contraindications of RPI
- Soft tissue undercuts
- Shallow vestibule (need 3 mm from gingival margin)
- Severe lingual tilt (no buccal undercut)
- Undercut on DB (use T bar)
Advantages and disadvantages of 1/2 t bar
Advantages
- Esthetic
- Less coverage of abutment
Disadvantage
-Less bracing/stability
Combination clasp includes
- distal rest
- reciprocating arm
- wrought wire clasp
- proximal plate
Advantages of WW clasp
- Round (flex in all directions)
- Minimal surface contact
- can use in larger undercut (0.02 inch)
- Stress releasing
6 major types of maxillary major connectors
- Palatal strap
- Anterior and posterior palatal strap *
- Palatal plate *
- U-shaped (horseshow)
- Palatal bar
- Anterior-posterior palatal bars
Palatal plate covers how much of the hard palate
1/2 or more
Indications for complete palatal plate
- Only some anteriors remain
- Class II with large posterior mod space or missing anteriors
- Class I Poor abutment support
- extreme vertical ridge resorption
- Absence of torus
Complete Palatal plate contacts what teeth
all natural teeth in remaining arch
Posterior border ends where
junction of hard and soft palate into the hamular notch
Relation of the palatal plate termination point and the medial suture
perpendicular to one another
Indications for palatal plate
- Class I with little vertical resorption
- V or U shaped palatal vault
- Strong abutments
- More than 6 remaining anteriors in arch
- Direct retention not a problem
- No tori
Indications for anterior-posterior palatal strap
- Class I and II with excellent abutments and ridge support
- Class IV arch
- Inoperable torus that don’t extend posterior to the junction of the hard and soft palate
How broad are the anterior and posterior palatal straps
8-10 mm
How broad at the lateral palatal straps
7-9 mm
What is the anterior extent of the AP strap
the most anterior rests
Circumferential claps are commonly used on (tooth/tooth tissue) supported partials
tooth
Circumferential clasps are most commonly used where in the arch
where there is no edentulous space (aka embrassure clasp)
Palatal strap should be a t least _mm wide
8
Palatal stap commonly used for what kennedy class arches
II and III
Disadvantage of a palatal bar
bulky
Little vertical support from palate
Where can’t a palatal bar be placed
anterior to the 2nd PMs (interferes with tongue function when more anterior)
Indication for palatal bar
-1-2 teeth missing on each side (posterior to PMs )
What is the least favorable maxillary major connector and why
horseshoe … lacks rigidity
Horseshoe indicated for
prominent median palatine suture or inoperable torus
Horseshoe connector contraindicated in
Class I and II arch
Factors influencing design
- Preservation of teeth and perio
- Minimal tooth and gingival coverage
- Nature of support, tooth borne or tooth mucosa borne
- Anatomic limits (torus)
- Tooth inclination, position and contour
- Contingency planning
- Potential magnitude of applied forces
- Ease of placement and removal
- Esthetics
