Fixed lecture 1 Flashcards
Considerations Affecting Future Dental Health
Axial reduction
Margins
Occlusal considerations
Preventing tooth fractures
Biologic considerations,
which affect the health of the oral tissues.
Mechanical considerations,
which affect the integrity and durability of the restoration.
Esthetic considerations,
which affect the appearance of the patient
luting agent
Cement to maintain
CVC
complete veneer crown
MCC
metal ceramic crown
ACC
all ceramic crown
Zirconia
metal, looks nice.
CVC indications
- Extensive coronal destruction.
- Short clinical crowns 3.Endodontically treated teeth.
- Maximum retention and resistance are needed.
- Correction of axial contours
CVC CONTRAINDICATIONS
1.Wherever an intact buccal or
lingual wall exists.
2. If less than maximum retention and resistance are needed.
3.If objectives can be met with a more conservative restoration.
PROS CVC
Because all axial surfaces of the tooth are included in the preparation, the complete cast crown has
greater retention than a more conservative restoration. Has greater resistance form than a partial coverage
restoration on the same tooth.
A complete cast crown allows the operator to
modify axial tooth contour as well as occlusal modification
CONS
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 perform electric vitality testing of an abutment tooth.
Patients may object to the display of metal associated with complete cast crowns.
chamfer
a finish line design for tooth preparation in which the
gingival aspect meets the external axial surface at an obtuse angle.
finish line
the terminal portion of the prepared tooth.
axial inclination
the alignment of the long axis of a tooth to a selected plane, often the horizontal plane.
convergence angle
the taper of a crown preparation, the angle, measured in degrees, formed between opposing axial walls.
Convergence angle
The angle or taper formed by opposing axial walls
Recommended range 2°–10° Ideal 6 ° to optimize retention
path of placement or POW
the specific direction in which a prosthesis is placed on the abutment tooth or remove from it.
Should be nearly coincident with the tooth’s long axis
undercut
any irregularity in the wall of a prepared tooth that prevents the seating or removal of a casting - pretty much a wax casting gets deformed when removing it.
Opposing axial walls which do not converge occlusally
Sequence CVC
occlusal guide grooves occlusal reduction axial guide grooves axial reduction( Buccal and Lingual) axial reduction (Interproximal) finishing and evaluation
CVC Dimensions
Central groove = 1 mm
Functional cusp = 1.5 mm
Non-functional cusp = 1 mm
Chamfer width = 0.5 mm
Occlusal Guide Grooves
242.6M diamond bur in high speed handpiece
depth grooves are placed 0.2mm shallower than the intended tooth reduction to allow for smoothing
FUNCTIONAL cusp
buccal cusp in mandibular arch
lingual cusp in the maxillary arch
242.6M and 747 diamonds 169L carbide
when moved parallel to the long axis of the tooth will create a tapered surface converging 3–4° from the cervical toward the occlusal
Axial guide grooves
place three shallow grooves in the buccal axial wall and three in the lingual axial wall with a 242.6M diamond
one groove in the center and one at each mesial and distal line angle
grooves determine the path of withdrawal of the restoration and should be in the long axis of the tooth
DISADVANTAGE chamfer
Care needed to avoid unsupported lip of enamel
ADVANTAGE chamfer
Distinct margin, adequate bulk, easier to control
Line angles
should be rounded
axial wall line angle
occlusoaxial line angle cavo-surface line angle
Excess reduction will occur if:
xcessive convergence angle
preparation does not follow
tooth anatomy
POW diverges from long axis of the tooth
excessively wide chamfer (>0.5mm)
excessive gingival extension of preparation
Finishing***
a polished surface is unacceptable
Evaluation:
functional cusp: 1.5mm central groove: 1.0mm non-functional cusp: 1.0mm path of withdrawal: ±5° convergence: 6° chamfer width: 0.5mm interproximal chamfer placement: 0.5mm interproximal clearance
linguo-occlusal line angle reduction: 0.8mm
margin smoothness
rounding of line angles
overall smoothness
margin placement: 0.5mm above plastic gingiva or 1.0mm coronal to CEJ (whichever is more coronal)
Adaptation
Degree of fit between prosthesis and supporting structures.
Axial inclination
long axis to plane (usually horizontal plane).
Axis of prep
Planned line or path of placement and removal for a dental restoration.
Bevel
slanting edge, slanting finish line and curve of tooth prep
butt
to bring any two flat-ended surfaces into contact without overlapping as in butt joint.
chamfer
finish line design for tooth preparation in which the gingival aspect meets the external axial surface at an obtuse angle.
chamfer angle
angle between chamfered surface and one of the original surfaces from which the chamfer was cut.
complete crown
restoration that covers all the coronal tooth surfaces.
convergence angle
taper of a crown prep - angle formed between opposing axial walls.
divergence angle
the sum of the angles of taper of opposing walls of a tooth preparation that diverge away from each other.
Draw
the taper or convergence of walls of a prep for a restoration.
extracoronal retainer
part of fixed prosthesis uniting the abutment to the other elements of the prosthesis that surrounds all or part of the prepared crown.
interocclusal clearance
the arrangement in which the opposing occlusal surfaces may pass one another without any contact. Amount of reduction achieved during tooth preparation to provide for an adequate thickness of restorative material.
lingual inclination
deviation of the coronal portion of a tooth from the vertical plane toward the tongue.
margin
outer edge of a crown, inlay, onlay or other restoration.
path of placement
the specific direction in which a prosthesis is placed.
retention arm
an extension that is part of a removable dental prosthesis and is used to aid in the fixation of the prosthesis.
shoulder finish line
finish line design for tooth preparation in which the gingival floor meets the external axial surfaces at approximately a right angle.
undercut
below HOC
veneer
thin sheet of material usually used as a finish.
Sextant 1
9-12 o clock - maxillary right molars and premolars
Sextent 2
9-11 o clock incisors and canines maxillary
Sxtent 3
10-12 o clock left maxillary molars and premolars
Sextant 4
9-11 o clock left mandibular molars and premolars
Sextant 5
10-12 o clock mandibular incisors and canines
Sextant 6
9-11 o clock right mand molars and premolars
242.6M bur
0.8mm to 1.3 mm
747 bur
0.5,6-1
169 l bur
Head Diameter:
0.9
Tip Diameter:
0.5