Principlals of CVC preps part 1 Flashcards
What does Fixed Prosthodntic Treatment involve
Replacement and restoration of teeth by artifical substitutes that are not readily removable from the mouth
What is Included in Patiente Selection
Chief Complaint Communication Dental history Med History Palpation Percussion Periodontal exam Systemic conditions TMJ TMJ dysfunction
Why the patient is here
CHief complaint
what is communication
being able to exlain what can be done and affordably
What does Dental history include
Fear of the dentist
Past work
What must all be considered in tooth preps
Biologic
Mechanical
Esthetic
what does Biologic considersations consider
The health of the oral tissue
What does Mechanical considerations consider
Affect the integrity and durability of the resotration
What does Esthetic considerations consider
The appearance of the patient
What are the parts of the Biological considerations of tooth preps
Prevention of damage during tooth preps (soft tissues, pulp, adjacent tooth)
Considerations affecting future dental health ( axial reduction, margins, occlusal considerations, preventing fracture)
Conserving tooth structure
parts of mechanical considerations
Resistance form
Retention form
Preventing deformational of the restoration
what is considered for resistance form
Magnitude and direction of dislodging forces
GEometry of the tooth prep
Physical properties of the luting agent
What is considered for Retntion
Manitude of Dislodging forces Geometry of the tooth prep Roughness of the fitting surface Materials being cemented Film thickness of the luting agent
What must be considered to prevent deformation of the restoration
Alloy selection
Adequate tooth reduction
Margin design
Types of Corwns
CVC- complete veneer crown
MCC- metal ceramic crown
ACC- all ceramic crown
Zirconia
a Cast-gold extracoronal restoration which covers the clinical crown
Complete veneer crown (CVC)
The final Shape of the tooth produced by instrumentation to receive a restoration
Tooth preparation
What is a complete veneer crown preparation
Extracoronal preparation involving the entire clinical crown
The removalable part removed from the main cast to wax up a crown
die
How to protect the preped tooth and gingiva while a crown is being
A provisional
What does a provisional do to help with neighboring teeth and crown placement
Provides contour that keeps nearby teeth from tipping and crowding and hurting crown placement
Indication for a single corwn
Extensive coronal destrucution from caries or trauma
Short Clinical crowns
Endodontically treated teeth
Maximum retention and resistance is needed
Correction of axial contour, correction of occlusal plane
Provide Contours to receive a removable partial denture
Contraindication for a single crown
If there is an intact buccal or lingual wall
If less than maximum retention and resistance are needed
If objectives are met with a more conservative restoration
Advance of a single corwn
Because all axial surface of tooth are included in the preparation, the complete cast crown has greater retention than a more conservative restoration
Greater resistance form than a partial coverage restoration on the same tooth
allows operator to modify axial tooth contour as well as occlusal modification
Advantages of A gold crown
High strength
Good retentive qualities
Disadvantages of a crowns ( gold specifically)
Removal of tooth structure is extensive and can have adverse effects on the pulp and periodontium
–Because of the proximity of the margin to the gingiva, it is not uncommon to see inflammation of gingival tissues
After cementation, it is no longer feasible to perform electric vitality testing of abutment tooth
Patients may object to the display of metal associated with complete cast corwns
The terminal portion of the perpared tooth ( tooth margin)
Finish line
Where the prepared tooth meets the unprepared tooth
Finish line
A Finish line designed for tooth preparation in which the gingival aspect meets the external axial surface at an obtuse angle
Chamfer
The alignment of the long axis of a tooth to a selected plane, often the horizontal plane
Axial inclination
Long axis
When preparing a Chamfer, what must be sure to be taken care of
Don’t leave and unsupported enamel
How is the long axis of the tooth determined clinically
Bisected the angle formed by opposing axial surfaces in the gingival 3rd of the tooth
The specific direction in which a prosthesis is placed on the obutment tooth or remove from it
Path of placement of POW
What should the POW coincide with
The long axis
The imaginary line along which a casting is moved when it is separated from its prepared tooth
POW
The Convergence of two opposing external walls of a tooth preparation as viewed in a given plane
Taper
The angle formed by the taper
Convergence angle
The taper formed by opposing axial walls
Convergence angle
Ideal convergence angle
6 degrees
recommended convergence angles
2-10 degrees
More taper means what
Less retention
any irregularity in the wall of a preped tooth that prevents the seating or removal of a casting
Undercut
when would a crown preparation be considered to be undercut
If a wax pattern cannot be withdrawn from its die without distortion
What are som examples of undercuts
Depression in the axial walls
Opposing axial walls which do not converge occlusally
Sequence steps of doing a CVC
Occlusal guide grooves Occlusal reduction Axial guide grooves Axial reduction (buccal and Lingual) Axial reduction (interproximal) Finishing and evaluation
Dimentions of the 242 bur
.8 tip
1.2-1.3 proximal
Dimentions of the 747 bur
.6 tip
1- 1.1 Proximal
Recommended CVC dimentions
Central goove- 1.0mm
Functional Cusp- 1.5mm
Non-functional cusp - 1.0mm
Chamfer width- 0.5mm
How deep should depth orientation grooves be
.2mm shallower than intended for smoothing later
Where is a potential site of fialure
The junction of the tooth and restoration at the gingival margin due to cement dissolution or roughness
How should the surface look
Exhibit overal smoothness with light striations created by the diamond bur (NOT POLISHED)
Also all rounded sharp line angles
Interproximal clearance
.5mm
How high should the chamfer be
.5mm above plastic gingiva
1.0mm coronal to CEJ
Whatever is more coronal
What should the final preparation provide
Maximum conservation of tooth structure
Ideal resistance form
Ideal retention form
Structural durability
Why would excess reduction occur
Excessive convergence angle Prep does not follow tooth anatomy Pow Diverges from long axis of the tooth Excessively wide margin Excessive gingival extension of prep
What form resists the removal of the restoration along its pow
Retention form
What forms resist dislodgement by forces oblique or apical
Resistance form
what form is occlusogingival length a factor of
Retention and resistance
Greater the surface area of a prep leads to better of what form
Retention and resistance
How can one increase the surface area of a prep
adding boxes and grooves
What would you do if the prep is short
As little taper as possible to increase resistance and retention
Long parallel axial walls and grooves leads to
Good retention and resistance
Short, overtapered preparation leads to
Restoration easy to remove and there’s less retention and resistance
Inadequate retention and resistance can lead to
Displacement of the restoration during function
Causes of inadequate retention and resistace
Excessive convergence angle (greater than 10 degrees)
Inadequate hight of axial walls
Insufficient axial surface area to resist tipping
What is importanat to resist distortion and allow for wear duringservice
Sufficient bulk
How to confirm walls angulation
View with one eye at the center of the occlussal surface (NO binocular vision)
hold mirror in an angle 1/2 inch from the preparation and view with 1 eye
how wide should the functional cusp bevel be
2-3mm wide (not less than 1/4 the axial wall length
what is the angle of the functioncusp bevel
45 degree angle to the POW
