BioMechanics/Design for Kennedy Class I and II Flashcards
_______ forces acting on teeth are thought to be biologically conducive to bone stimulation and periodontal health; these forces are distributed to the surrounding bone via Sharpey’s fibers.
Vertical
Forces ________ transmitted to teeth are destructive and apply prying or “lever-like” vectors
laterally
A distal rest, circumferential retainer and a distal extension = WHAT TYPE OF lever
Class I lever = destructive-lateral forces
***the SAGITTAL plane makes the ________ axis (aka ________ axis)
MedioLateral axis (transverse axis)
***the FRONTAL plane makes the ________ axis (aka _______ axis)
AnteriorPosterior Axis (sagital axis)
*** the HORIZONTAL plane makes the ________ axis
Vertical axis
IMPORTANT CONCEPT: The sagittal plane and its MedioLateral Axis when applying a down force are concerned with ______ of the denture (so rests and soft tissue)
SUPPORT
IMPORTANT CONCEPT: The sagittal plane and its MedioLateral Axis when applying an UP force are concerned with ______ of the denture (so rests and soft tissue)
Retention
IMPORTANT CONCEPT: What three components to an RPD are focused on retention when an upward force is applied via the Sagittal plane?
retentive arm, indirect retainer and soft tissue (some)s
IMPORTANT CONCEPT: The horizontal plane is concerned with _______ of the RPD. What are the three components that aid in this?
stability…minor connector, rest seats, soft tissue
IMPORTANT CONCEPT: the frontal plane is concerned with ________ of the RPD. What are the two components that aid in this?
stability…teeth and soft tissue
A ______ consists of a rigid bar, a fulcrum, an object to be moved, and an applied force
lever
A _____ class lever has the potential to be very efficient, and the _____ class lever the least efficient
first…third
Which three Kennedy classes function around levers?
I, II, IV
The ______ the extension base, the greater the potential for damaging loads to be generated on the opposite side of the fulcrum line
longer
WHICH FULCRUM?? Extends through two principle abutments, one on each side of the arch.
horizontal fulcrum (principle fulcrum line)
Which FULCRUM controls rotational movement of the denture in sagittal plane (denture movement toward or away from the supporting ridge)?
Horizontal Fulcrum (principle fulcrum line)
Which FULCRUM line extends through the occlusal rest on the terminal abutment and along the crest of the residual ridge, on one side of the arch.
Horizontal Fulcrum Line
Which FULCRUM line controls rotational movement of the denture in Frontal plane (a rocking movement over the crest of the ridge)
Horizontal Fulcrum line
Which FULCRUM line extends vertical just lingual to the anterior teeth and in the vicinity of the midline.
the vertical fulcrum
Which FULCRUM line controls rotational movement of the denture in horizontal plane??
the Vertical fulcrum line
Which FULCRUM line is almost entirely horizontal forces, so extremely damaging??
Vertical Fulcrum line
EVERY EFFORT should be made to keep a ________ as a vertical stop.
posterior abutment
The thickness and health of the _________ influences the loads transferred to abutment teeth
mucoperiosteum
Large, well formed _____ are capable of withstanding greater loads than are small, thin, or knife edged ridges
ridges
The more _____ the clasp the less the force to the abutment tooth but the greater the forces to the residual ridge
flexible
Which material clasp places a small percentage of the load on the abutment, and a greater percentage on the residual ridge?
Wrought Wire
Framework must be fully SEATED for the clasp to be totally ________
passive
________ clasp must contact the tooth before and while the retentive tip passes over the undercut
Reciprocal
The longer the clasp the more flexible it is (Double the length will increase flexibility ___ times)
5 times
A _______ based alloy will exert a greater load on the abutment teeth than will a gold alloy
chromium
INTERESTING!!! The surface of a ______ restoration offers MORE frictional resistance to clasp arm movement than does the _______ surface of a tooth, therefore a crowned tooth experiences (GREATER/LESSER?) stresses than one with intact enamel!!
cast gold…enamel…GREATER
REVIEW from Complete Dentures…What are the 2 primary bearing areas on the maxilla? What is the primary bearing area on the mandible?
Max: Hard Palate and ridge crests Mand: buccal shelves
WHAT TWO LANDMARKS (1 Mx, 1Md) need to be covered by acrylic for support of the RPD???
the tuberosity on the maxilla, the retro-molar pad on the mandible
What is the standard amount of undercut used for MOST clasps?? What about for the odd ball wrought wire?
0.01” for MOST…0.02” for WW
What is the gauge of Wrought Wire?
18 gauge
BOOO….Use ______ rests rather than ______ rests to reduce lever arm.
cervical RATHER THAN incisal
Place RETENTIVE and RECIPROCAL clasps near the junction of the _______ and _______ thirds of the abutment.
middle and cervical
DONE BE THAT PERSON!!!! Do not place retentive components anterior to the ________!
fulcrum line
WHY NO Retentive clasp ANTERIOR TO the FULCRUM line?Clasp components located posterior to the fulcrum line axis move _______ during occlusal loading
gingivally
WHY NO Retentive clasp ANTERIOR TO the FULCRUM line? Clasp components located anterior to the fulcrum line axis move ________ during occlusal loading
occlusally
During function: The Akers clasp arm and proximal plate move in a __________ direction disengaging from the tooth
mesiogingival
As an occlusal load is placed the I bar clasp arm and the proximal plate move in a ________ direction disengaging from the tooth
mesiogingival
IFFF Retention is to be used ANTERIOR to the fulcrum line, a _______ (______) clasp is the only acceptable retainer.
wrought wire (combination)
A retainer ANTERIOR to the fulcrum line: A wrought wire will limit the torquing action due to its _______
flexibility
WHAT ARE THE 4 components of an RPD that provide SUPPORT????
1.Rest 2.Major Connector 3.Denture base 4.Teeth through the base
These components…..Guide Plate (Proximal Plate) Lingual Plates, Rest, Rigid portions of retainers, Direct Retainers,
Major Connector, Minor connector, Denture Bases …….are all providing ________
Stability
What are the two components of an RPD providing RETENTION?
1.Direct Retainers 2.Guide plate (proximal plate)
In a Kennedy Class I or II, what are the 3 times you CANNOT use an RPI??? What would you turn to instead?
1.Frenum 2.Shallow Vestibule 3.Deep soft tissue undercut…use an RPA!
IN a Kennedy Class I or II, what are the 3 times you CANNOT use an RPA? What would you use instead?
1.Rotation 2.heavy centric contact on mesial 3.Large amalgam restoration on mesial…use a COMBINATION clasp
A distal guiding plane EXTENDS FROM the ________ to the junction of the ______ and ______ thirds of the abutment tooth. (SO it leaves a GAP on the gingiva!!)
MARGINAL RIDGE to the junction of the MIDDLE and GINGIVAL thirds
RPI: The proximal plate, in conjunction with the minor connector supporting the rest, provides the ________ and ________ aspects of the clasp assembly
STABILIZING….RECIPROCAL
RPI: The area of contact, along with the rest and proximal plate contact, provides stabilization through _________.
encirclement
I BAR: The HORIZONTAL portion of the approach arm must be located at least ___mm from the gingival margin
4mm
With the RPA clasp system the circumferential clasp is placed so that the rigid portion of the clasp arm will contact the tooth only along its _______ border at the level of the survey line.
superior
