PRINCIPLES, CLASS I, CLASS II Flashcards
the mechanical alteration of a tooth to receive a restorative material which will return the tooth and area to proper form, function and esthetics
CAVITY PREPARATION
dependent on the materials that you are going to use
CAVITY PREPARATION
True or false
One of the OBJECTIVES OF CAVITY PREPARATION:
- Remove all defects and give the necessary protection to the pulp
True
True or false
One of the OBJECTIVES OF CAVITY PREPARATION:
Locate the margins of the restoration as conservatively from the cavity so that under the forces of mastication the tooth or the restoration will not be displaced
True
True or false
One of the OBJECTIVES OF CAVITY PREPARATION:
Allow for the esthetic and functional placement of a restorative material
True
refers to a set of terms used in communication by persons in the same profession that enables them to understand one another.
Nomenclature
O
Occlusal Tooth Preparation
MO
Occlusal and Mesial Surfaces
MOD
Mesial, Occlusal, and Distal Surfaces
prepared surface that extends to the external tooth surface
EXTERNAL WALL
such a wall takes the name of the tooth surface (or aspect) that
the wall is adjacent to
EXTERNAL WALL
ex.:
o near the buccal/facial surface is the facial and lingual wall
o near the gingiva is the gingival wall/floor and
distal/mesial wall
EXTERNAL WALL
prepared surface that does not extend to the external tooth surface
INTERNAL WALL
ex.:
o axial wall
- parallel with the long axis of the tooth
INTERNAL WALL
pulpal wall and gingival wall
- -perpendicular to the long axis of the tooth also called floors or seats
INTERNAL WALL
CAVITY PREPARATION ANGLES
LINE ANGLES
POINT ANGLES
junction of two planar surfaces of different orientation along a line
LINE ANGLES
two walls forming a line
LINE ANGLES
internal line angle if the apex points into the tooth
LINE ANGLES
external line angle if the apex points away from the tooth
LINE ANGLES
junction of three planar surfaces of different orientation forming a point
POINT ANGLES
An angle usually seen in Class II
POINT ANGLES
for the point angles, there is an additional axiolingual gingival
point angle or axiofacial gingival angle
POINT ANGLES
the angle of tooth structure formed by the junction of a prepared wall and the external surface of the tooth
CAVOSURFACE ANGLE
the actual junction
CAVOSURFACE MARGIN
90 degrees cavosurface angle
CAVOSURFACE MARGIN in Amalgam
butt joint cavosurface margin
CAVOSURFACE MARGIN in Amalgam
rationale:
o to prevent fracture at the margins since amalgam has weak edge strength
CAVOSURFACE MARGIN in Amalgam
In CAVOSURFACE MARGIN in Composite what degree angle is for Class I
90 degrees cavosurface angle
In CAVOSURFACE MARGIN in Composite what degree angle is for Class II
45 degrees cavosurface angle
true or false
In CAVOSURFACE MARGIN in Composite what degree angle is for Class III, IV & V, bevel cavosurface
margins
True
In CAVOSURFACE MARGIN in Cast Gold/Metal what degree angle?
45 degrees
True or false
The strongest enamel margin is composed of full-length enamel rods supported on the preparation side by shorter enamel rods, all of which extend to sound dentin with an angle greater than 90 degrees.
True
Arrange:
Initial Tooth Preparation Stage
Convenience Form
Primary Retention Form
Outline Form and Initial Depth Primary Resistance Form
Outline Form and Initial Depth Primary Resistance Form Primary Retention Form Convenience Form
Arrange:
Final Tooth Preparation Stage
- Removal of Any Remaining Enamel Pit and Fissure and/or Infected Dentin and/or Old Restorative Material
Pulp Protection - Final Procedures (Cleaning, Inspecting, Varnishing and Conditioning)
- Procedures for Finishing External Walls
- Secondary Resistance and Retention Forms
- Pulp Protection
1, 5, 4, 3, 2
shape of the area of the tooth surface included within the cavosurface margins of the prepared cavity
STEP 1: OUTLINE FORM
to establish the initial depth for tooth preparation until the junction between enamel and supporting dentin is uncompromised
STEP 1: OUTLINE FORM
the peripheral walls determine the overall outline of the preparation
STEP 1: OUTLINE FORM
True or false
All friable enamel or weakened enamel should be removed
True
True or false
All faults should be excluded
False
All faults should be included
True or false
All margins should be placed in a position that would allow
good finishing of the margin of the restoration
True
move around the cusp
- rationale: so as not to put the margins in areas of stress concentration
SPECIFIC FEATURES in the OUTLINE FORM
1⁄4 of the intercuspal distance; 1 mm
Isthmus
1⁄3 of the intercuspal distance; 2 mm
Dovetail
In the outline form, what is the Preserving marginal ridge strength
1.6 - 2.0 mm marginal ridge
In the outline form what is the Depth of preparation into dentin for:
pit and fissure caries
for axial wall
pit and fissure caries-0.2
for axial wall- 0.2 - 0.8
In outline form Connecting two close faults is less than ______mm apart
0.5 mm
This step is the shape and placement of the preparation walls done to withstand masticatory forces to prevent fracture of the restoration and tooth during function
STEP 2: PRIMARY RESISTANCE FORM
the relatively horizontal pulpal and gingival floors prepared perpendicular to the tooth’s long axis help resist forces in the long axis of the tooth and prevent tooth fracture from wedging effects caused by opposing cusps
STEP 2: PRIMARY RESISTANCE FORM
SPECIFIC FEATURES of:
Minimizing faciolingual extension
OUTLINE FORM
SPECIFIC FEATURES of :
Enameloplasty
OUTLINE FORM
(1) Relatively flat pulpal floor
(2) Box shape
(3) Inclusions of weakened tooth structure
(4) Preservation of cusp and marginal ridge
(5) Rounded internal line angles
(6) Adequate pulpal floor depth
(7) Adequate thickness of restorative material
(8) Seats on sound dentin peripheral to excavations of infected dentin
(9) Reduction of cusp for capping when indicated
RESISTANCE FORM FEATURES
to distribute occlusal stress over the entire pulpal
floor
Relatively flat pulpal floor
accomplished by using a flat-ended bur such as
inverted cone or 345
Relatively flat pulpal floor
in deep cavity preparations, GIC is placed for
pulp protection and for a flat floor
Relatively flat pulpal floor
exception: in mandibular first premolars the pulpal
floor is parallel to the line drawn from the buccal cusp tip to the lingual cusp tip
Relatively flat pulpal floor
helps the tooth resists occlusal loading by virtue of
being at right angles to the forces of mastication that are directed in the long axis of the tooth
Box shape
extending beyond required isthmus when there is a
lot of infected dentin under enamel to prevent
fracturing
Inclusions of weakened tooth structure
resistance includes achieving a shape that would
not lead to future fracture of the tooth
Inclusions of weakened tooth structure
- minimum of 1.6 mm and maximum of 2.0 mm for marginal ridges
- go around cusp to preserve it
Preservation of cusp and marginal ridge
to eliminate sharp line angles that are areas of
stress concentration that may fracture the cavity walls
Rounded internal line angles
What is the Adequate pulpal floor depth of:
__________mm from cavosurface
____________from DEJ
Adequate pulpal floor depth
- 1.5 - 2.0 mm from cavosurface
- 0.2 - 0.5 from DEJ
Adequate thickness of restorative material
- depth depends on the restorative material that
will be used in:
Amalgam
Composite
Cast Metal
Porcelain
Amalgam
1.5 - 2. 0 mm
Composite
1.0 - 2.0 mm
Cast Metal
1.0 - 2.0 mm
Porcelain
2.0 mm
removal of soft dentin that is below the already flat pulpal floor and filling with glass ionomer cement to conserve tooth structure
Seats on sound dentin peripheral to excavations of infected dentin
cutting of cusp when enamel is already too thin
and will fracture in the future
Reduction of cusp for capping when indicated
shape or form of the prepared cavity that resist displacement or removal of the restoration from tipping or lifting forces
STEP 3: RETENTION FORM
resistance prevents fracture and retention prevents displacement
STEP 3: RETENTION FORM
resistance and retention are accomplished at the same time
STEP 3: RETENTION FORM
True or false
In the FEATURES of RETENTION FORM it will depend on the restorative material used
True
True or false
In RETENTION FORM the Convergence of B-L walls is
3 to 5 degrees and
should not be parallel but slightly converging and not too much converging
True
True or false
In RETENTION FORM the Dovetails
- should be 1 mm
- in instances where the cusp in the distal side is smaller, it is 2 mm
False
Dovetails
- should be 2 mm
- in instances where the cusp in the distal side is smaller, it is 1 mm
True or false
In RETENTION FORM the Grooves
- doesn’t help to retain the restoration
False
Grooves
- help to retain the restoration
- Convergence of B-L walls
- Dovetails
- Grooves
(4) Undercut
(5) Pins
(6) Mechanical bond composite and the conditioned tooth
structures
(7) Parallel longitudinal walls in intracoronal restorations
FEATURES in RETENTION FORM
shape that will allow vision, accessibility, and ease of instrumentation in preparing for restoring the tooth
STEP 4: CONVENIENCE FORM
provides for adequate observation, accessibility and ease of operation in preparing and restoring the tooth
STEP 4: CONVENIENCE FORM
→ extension for convenience
→ extending proximal preparations beyond proximal contact
CONVENIENCE FORM
deepening the cavity preparation to access caries for a Class II
cavity preparation
CONVENIENCE FORM
True or false
o spoon excavators
o round steel burs at low speed
Are used for REMOVAL OF THE REMAINING CARIOUS DENTIN
True
True or false
round carbide burs at high speed are used for REMOVAL OF THE REMAINING CARIOUS DENTIN
True
STEP for PULP PROTECTION IN CAVITY PREPARATION
STEP 6
for very large preparations, convergence and dovetails may not be enough
STEP 7: SECONDARY RESISTANCE AND RETENTION FORMS
use of:
o pins
o locks
o coves
o slots
STEP 7: SECONDARY RESISTANCE AND RETENTION FORMS
→ design of the cavosurface margin
→ refining of certain areas of the cavity walls to produce a
degree of smoothness
STEP 8: PROCEDURES FOR FINISHING THE EXTERNAL WALLS OF THE CAVITY PREPARATION
goal:
o produce the maximum effectiveness of the restorative material being used
STEP 8: PROCEDURES FOR FINISHING THE EXTERNAL WALLS OF THE CAVITY PREPARATION
objectives:
o to create the best marginal seal between the restorative
material and the tooth
o afford smooth marginal junction
o provide maximal strength for the tooth and material at or
near the margin
smooth the walls to allow better adaptation of the restorative material
STEP 8: PROCEDURES FOR FINISHING THE EXTERNAL WALLS OF THE CAVITY PREPARATION
cleaning, inspecting and sealing
STEP 9: FINAL PROCEDURES
→ removing all chips and loose debris that have accumulated
(wash the prep)
→ drying the cavity preparation but not dessicate as dentin is very
sensitive
STEP 9: FINAL PROCEDURES
making a final complete inspection of the preparation for any
remaining infected dentin, unsound enamel margins or any condition that renders the preparation unacceptable to receive the restorative material
STEP 9: FINAL PROCEDURES
procedure:
o use of warm water from the syringe to remove visible
debris
o use of few light surges of air from the water syringe to
remove the visible moisture
o do not dehydrate the tooth
STEP 9: FINAL PROCEDURES