Dental Stuff
CLASS 1 AMALGAM RESTORATION
INITIAL TOOTH PREPARATION
Outline Form:
It is the perimeter of tooth preparation in width, length and depth dimensions.
Location:
i. Occlusal surface of posterior teeth ii. Occlusal 2/3rd of Facial & Lingual surfaces of posterior teeth iii. Lingual surfaces of anterior teeth
Shape:
i. Mortise Shape
Inverted Cone Shape Mortise
Box Shape Mortise
Mortise shape defines that each wall and floor is in form of a flat plane, meeting each other at definite line and point angles.
It is the most accessible type of shape.
Boundaries:
Facial Groove
Lingual Groove
Mesial Marginal Ridge*
Distal Marginal Ridge*
*Step short of Marginal Ridge Crest
Eliminate all defective tooth structures
Eliminate unsupported Enamel
Width of any portion of cavity (mesiodistally/buccolingually) should be at least 1.5mm
All line and point angles should be rounded but definite
Resistance Form:
It is the shape & placement of preparation walls that best enable both the restoration & tooth to withstand, without fracture, masticatory forces delivered principally in long axis of tooth.
Box shape
Smooth & Flat Pulpal floor
Parallel Walls
Mesial/Distal walls should be divergent: 2 to 5 degrees
Diverge slightly pulpo-occlusally in buccal & lingual groove extensions
Rounded internal angles
Depth= 0.5mm into dentine (DEJ 0.5mm)
Cavosurface angle: The angle formed by the junction of the wall of a prepared tooth cavity with the external surface of the tooth.
It should be from 90⁰ to 110⁰
Retention Form:
Enamel margins should be prepared at a right obtuse angle
Buccal/Lingual walls should be convergent: 2 to 5 degrees
Converge slightly pulpo-occlusally in areas of triangular ridge
Convenience Form:
It facilitates & provides sufficient visibility, accessibility & ease of instrumentation in preparing and restoring the teeth.
Proper refinement of the line and point angles is sufficient to produce the necessary convenience form
INITIAL TOOTH PREPARATION
Outline Form:
It is the perimeter of tooth preparation in width, length and depth dimensions.
Location:
i. Occlusal surface of posterior teeth ii. Occlusal 2/3rd of Facial & Lingual surfaces of posterior teeth iii. Lingual surfaces of anterior teeth
Shape:
i. Mortise Shape
Inverted Cone Shape Mortise
Box Shape Mortise
Mortise shape defines that each wall and floor is in form of a flat plane, meeting each other at definite line and point angles.
It is the most accessible type of shape.
Boundaries:
Facial Groove
Lingual Groove
Mesial Marginal Ridge*
Distal Marginal Ridge*
*Step short of Marginal Ridge Crest
Eliminate all defective tooth structures
Eliminate unsupported Enamel
Width of any portion of cavity (mesiodistally/buccolingually) should be at least 1.5mm
All line and point angles should be rounded but definite
Resistance Form:
It is the shape & placement of preparation walls that best enable both the restoration & tooth to withstand, without fracture, masticatory forces delivered principally in long axis of tooth.
Box shape
Smooth & Flat Pulpal floor
Parallel Walls
Mesial/Distal walls should be divergent: 2 to 5 degrees
Diverge slightly pulpo-occlusally in buccal & lingual groove extensions
Rounded internal angles
Depth= 0.5mm into dentine (DEJ 0.5mm)
Cavosurface angle: The angle formed by the junction of the wall of a prepared tooth cavity with the external surface of the tooth.
It should be from 90⁰ to 110⁰
Retention Form:
Enamel margins should be prepared at a right obtuse angle
Buccal/Lingual walls should be convergent: 2 to 5 degrees
Converge slightly pulpo-occlusally in areas of triangular ridge
Convenience Form:
It facilitates & provides sufficient visibility, accessibility & ease of instrumentation in preparing and restoring the teeth.
Proper refinement of the line and point angles is sufficient to produce the necessary convenience form
References: -Art & Science of Operative Dentistry 5th edition -Operative Dentistry by Marzouk