Operative Final Exam - Lectures: Rubber Dams and Class II Tooth Preps Flashcards
What are the goals of a rubber dam?
- moisture control
- retraction and access
- patient safety
- increase operator efficiency
What are the advantages of rubber dam isolation?
- dry, clean operating field
- improved access and visibility
- patient protection
- increased operating efficiency
- improved properties of dental materials
What are the disadvantages of rubber dam isolation?
- time consuming
- patient objection
- interferes with access
What are the two types of rubber dam retainers/clamps?
- winged clamp
- anterior clamp
What are the 4 parts of a rubber dam retainer/clamp?
- bow
- hole
- jaw
- prong
True or false: Rubber dam should be passed between interproximal contacts.
true
True or false: The rubber dam should not go into the gingival sulcus on the facial and lingual surface of teeth.
FALSE. The rubber dam should be inverted into the gingival sulcus around the teeth.
Describe the steps of the removal of a rubber dam.
- cut the septa
- remove the retainer/clamp
- remove the rubber dam/frame
- examine the rubber dam for any missing pieces
- remove any torn pieces from the patient’s mouth
True or false: Sharp angles should be made in occlusal outline of a Class II tooth prep.
FALSE. Sharp angles should be avoided in the occlusal outline.
Why is it bad to have a wide isthmus?
the triangular ridges of the cusps would be removed and the cusps would be weaker
How deep should the occlusal prep of a Class II tooth prep be?
1.5-2.0 mm
The occlusal prep of a Class II tooth prep should be perpendicular to the long axis of the tooth in every mandibular posterior tooth except which tooth?
mandibular 1st premolar (because the non-functional cusp makes the crown tilt severely to the lingual)
How wide should the isthmus of an occlusal prep be?
1.0 mm
What should the bur orientation be parallel to? What should it be perpendicular to?
- parallel to the long axis of the tooth
- perpendicular to the occlusal table
What does the location of the proximal box depend on?
the location of the interproximal contacts
How deep should the proximal box extend?
2.5-3.0 mm
How high should the axial wall be?
1.0 mm
What instrument should remove “crab claws” from a proximal box so as not to damage the adjacent tooth?
large spoon
What instruments are used to refine proximal box walls?
- 10-7-14 (#8-9 hatchet)
- #169 bur
What is used to bevel the enamel portion of the gingival wall?
enamel margin trimmer
What is used to bevel the axiopulpal line angle?
gingival margin trimmer
How much space should be between the buccal and lingual edges of the proximal box and the adjacent tooth?
0.2-0.3 mm
How much space should be between the gingival edge of the proximal box and the adjacent tooth?
0.5 mm
Does the proximal box converge or diverge occlusally?
converges occlusally as a retentive feature
What two burs are used to place retention grooves?
- # 169 bur
- 1/4 round bur
When prepping an occlusal outline, should it be done meisal to distal or distal to mesial?
distal to mesial
With what bur is the occlusal outline usually prepped?
330 bur
With what bur is the proximal box usually formed?
245 bur
With what bur is the proximal box usually refined?
169 bur
True or false: The final clearance of the proximal box should be checked with the wedge in place.
FALSE. The wedge should be removed prior to checking the final clearance.
With what burs is a slow-speed used to refine the occlusal outline?
256 or #245 bur
List the 9 steps of tooth preparation.
- outline form and initial depth
- primary resistance form
- primary retention form
- convenience form
- remove any remaining defective tooth or materials
- pulp protection
- secondary resistance and retention form
- finish external walls
- cleaning and sealing the preparation
Explain what is done during the 1st step in tooth preparation: outline form and initial depth.
- margins are placed where they will be in the final prep (preop visualization)
- ideal placement
- extend for decay
In order to gauge buccal and lingual clearance of the proximal box, what 4 instruments may be used? Which is closest to the correct measurement of 0.5 mm?
- perioprobe = 0.5 mm
- shepard hook explorer = 0.76 mm
- # 8/9 hatchet = 0.6 mm
- pig tail explorer = 0.5 mm
Explain the purpose of the primary resistance form (step 2 of tooth preparation). How is this achieved in tooth preparation?
a shape that enables tooth and restorative materials to resist vertical forces in long axis of tooth
- flat floor
- flat walls
- rounded internal line angles
- thickness of material
- cap weak cusps
Explain the purpose of primary retention form (step 3 of tooth preparation). How is this achieved?
resistance to tipping or lifting forces
- converging walls of box and isthmus
Explain the purpose of convenience form (step 4 of tooth preparation). How is this achieved?
shape or form that provides for adequate observation and accessibility
- proximal extensions or clearance
At what angle should the cavosurface margin be with the external walls of the prep at the edge of the box? In the occlusal outline? At the gingival edge of the proximal box?
- 90 degrees at the edges of the box (no “crab claws”)
- 100 degrees or greater at the occlusal margins
- sloped gingival margin
Describe the shape of the occlusal outline form of a maxillary molar when performing a DO or MO tooth prep. Does the occlusal prep go through the oblique ridge?
the prep only extends up until the oblique ridge (it does NOT cross the oblique ridge!)
Describe the shape of the occlusal outline form of a maxillary molar when performing a MOD tooth prep. Does the occlusal prep go through the oblique ridge?
the prep only extends up until the oblique ridge on either side so it preserves the oblique ridge
Describe the shape of the occlusal outline form of a maxillary molar when performing a OL extension tooth prep.
the extension into the lingual groove leaves the distolingual cusp weak so the cusp is usually taken out too and capped, hooded, overlayed, or onlayed with restorative material
