Intro to Fixed Pros and Full Coverage Preps Flashcards
What is centric relation?
TMJ Dependent position (Independent of tooth position)
What is MIP (Maximum Intercuspation)?
Tooth Dependent position (Independent of Condyle position)
When should you consider fixed pros/full coverage preparation?
- **where there is extensive coronal destruction (caries, trauma, previous restorations, endo)
- where maximum retention and resistance form is needed
- where axial and occlusal contours require substantial correction
When should you not consider fixed pros/full coverage preparation?
- when a more conservative restoration can function (partial veneer crown, etc.)
- esthetics
What is the sequence of a complete metal crown preparation?
- occlusal reduction/functional cusp bevel
- axial reduction
- proximal reduction
- secondary retentive features (if required)
- margination
What is the process/tool used for occlusal reduction?
- depth-orientation grooves
- round-end taper diamond (5856L-016)
What are the measurements of the functional cusp bevel?
1.5 mm tapers to 1.0 mm
(round-end taper diamond…5856L-016)
What is the chamfer margin? What depth are you looking for?
–Margination: Where the crown meets the tooth
–0.5 mm clearance
–half diameter of small chamfer diamond…smooth, continuous, and well-defined
from internet….chamfer margin is a type of tooth preparation where the edge of the tooth is cut at a slight angle, creating a smooth, rounded bevel
What is considered the adequate dimension of axial reduction (in mm)?
–for both facial and lingual
0.5-1.0 mm
What bur is used for the retention groove? (include measurements)..When would you use this?
full depth of 170L bur….used when don’t have a lot of resistance
(0.5mm or 1.5???)
from internet: when a tooth preparation has limited natural retention features, such as on a short clinical crown or a tooth with significant tooth structure loss, as the groove provides extra surface area for the cement to adhere to, significantly increasing the crown’s stability and resistance to dislodgement
What side of the tooth should the retention groove be placed?
Usually placed on the functional cusp of the tooth
buccal (functional cusp..depends on max and mand?)
Mandibular=Buccal
Maxillary=Lingual
What are the morphologic occlusal reduction measurements for functional cusp, central fossa, and non-functional cusp?
functional cusp - 1.5 mm clearance
central groove (fossa?) - 1.5 mm
non-functional cusp - 1.0 mm
What does beveling the functional cusp do?
Describe the clearance indicated.
- realigns the functional cusps with the opposing central groove
- completes occlusal clearance
- provides uniform 1.5 mm occlusal clearance
What are the steps for the facial and lingual axial reduction?
(using round-end taper diamond and small chamfer tapered diamond)
–Describe the desired reduction and inclination?
–adequate reducton: 0.5-1mm
–Parallelism–orientation of draw:
(Faciolingually, Mesiodistally)
- determine the path of draw before starting axial wall prep**
- consider the ideal orientation for each axial wall
- 6-10 degrees of taper TOC (total occlusal covergence) of opposing walls (ideal)
If you skip the facial and lingual axial reduction step what will happen to the crown?
over contoured
from internet: An overcontoured crown refers to a dental crown that has excessive bulk or convexity, particularly in its buccal, lingual, or proximal surfaces. This means the crown extends beyond the natural contour of the tooth, creating an unnatural shape.
What bur should you use for the proximal axial reduction?
- needle chamfer diamond
or - small chamfer diamond
Explain Path of draw
how the crown is seated…tapered walls (walls have angle)
What bur is used for Margination–finish line?
–What is desired?
small chamfer tapered diamond
–smooth, no sharp angles (makes harder to seat crown)
internet: Margination in crown preparation refers to the process of shaping and refining the finish line (or margin) of the prepared tooth to ensure a proper fit and seal of the final crown
describe ways to verify path of draw
direct: hand piece…….measure axial line angles
indirect: mouth mirror……appearance (smooth, rounded…no steps, scratched?)
Describe the process of creating Depth cuts during occlusal reduction… what are you looking for? depth of clearance, angles, etc.
–typically follow the inclines of the tooth
–consider the planned restoration
–complete the metal crown
–1.5mm clearance on functional cusp and central groove
–1mm reduction on non-functional cusp
What are 2 ways to verify occlusal clearance after crown insertion?
1) using flex tabs..each with different measurement
2) Regisil
What are you looking for when verifying morphologic reduction?
?Round Occlusal - Axial Line Angles
