Date: 2/3/2015
FUNDAMENTALS IN TOOTH
PREPARATION
Dr. Gaurav Garg (M.D.S.)
Lecturer, College of Dentistry
Al Zulfi, M.U.
Learning objectives
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A t the end of lecture students should know:
Definition of tooth preparation
Needs for restoration
Objectives of tooth preparation
Factors affecting tooth preparation 7 conservation
of tooth structure
Tooth preparation terminologies
Tooth/Cavity Preparation
Definition: The mechanical alteration of a
defective, injured, or diseased tooth in order
to best receive a restorative material which
will re-establish a healthy state for the tooth
including esthetic corrections where indicated,
along with normal form and function.
Need of Restoration
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Caries
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Malformed, discolored or fractured teeth
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Restoration replacement
Need of Restoration
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Attrition
Abrasion
Erosion
Objectives of Tooth Preparation
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Remove all defects and give the necessary
protection to pulp.
Locate the margins as conservatively as possible.
Form the cavity so that both the restoration and
tooth can withstand the load of mastication.
Allow for the esthetic and functional placement of
a restorative material.
Factors affecting tooth preparation
1. General Factors
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Pulpal & periodontal status
Occlusal relationship
2.Dental anatomy
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Direction of enamel rods
Thickness of enamel /dentin
Size and position of pulp
Relationship of tooth to its supporting tissues
Factors affecting tooth preparation
3.Patient factors
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Age
Esthetic consideration
Economic status
Patients with high risk caries
4.Affected (hard) & infected Dentine (soft)
• Infected dentin contain bacteria- should be
removed
Factors affecting tooth preparation
5. Restorative material factors:
 An amalgam restoration requires a specific tooth
preparation form that ensures: (1) retention of the
material within the tooth and (2) strength of
material in terms of thickness and marginal form
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Composite restorations do not typically require
tooth preparations as precise as those for amalgam
CONSERVATION OF TOOTH STRUCTURE
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Every effort should be made to make restorations
as small as possible
Smaller the tooth preparation, the stronger is the
remaining unprepared tooth structure.
Keep minimal extensions of the tooth preparations,
especially faciolingually and pulpally.
TOOTH PREPARATION TERMINOLOGY
Simple, Compound, and Complex
Tooth Preparations
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A tooth preparation is termed:
Simple if only one tooth surface is
involved
Compound if two surfaces are
involved
Complex for a preparation
involving three (or more) surfaces
Cavity Structure
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Walls
Angles
Floor
Tooth Preparation Walls
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Internal Wall: An internal wall is a
prepared (cut) surface that does not
extend to the external tooth surface
Axial wall: An axial wall is an internal
wall parallel with the long axis of the
tooth
Pulpal wall: A pulpal wall is an
internal wall that is both
perpendicular to the long axis of the
tooth and occlusal of the pulp
Tooth Preparation Walls
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External Wall: An external wall is a
prepared (cut) surface that extends to
the external tooth surface, andsuch a
wall takes the name of the tooth
surface (or aspect) that the wall is
toward
Floor (or Seat): A floor (or seat) is a
prepared (cut) wall that is reasonably
flat and perpendicular to those
occlusal forces that are parallel to the
long axis of the tooth. Examples are
the pulpal and gingival walls
Tooth Preparation Walls
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Enamel Wall: The enamel wall is
that portion of a prepared
external wall consisting of
Dentinal Wall: The dentinal wall is
that portion of a prepared
external wall consisting of
dentin, in which mechanical
retention features may be
located
Tooth Preparation Angles.
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Line Angle: A line angle is the junction of two planal
surfaces of different orientation along a line
Point Angle: A point angle is the junction of three
planal surfaces of different orientation
Cavosurface Angle and Cavosurface Margin: Angle
of tooth structure formed by the junction of a
prepared (cut) wall and the external surface of the
tooth The actual Junction is referred to as the
cavosurface margin
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DENTINOENAMEL JUNCTION & CEMENTOENAMEL
JUNCTION
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Dentinoenamel Junction: The DEJ
is the junction of the enamel and
dentin
Cementoenamel Junction: The CEJ
is the junction of the enamel and
cementum. It also is referred to as
the cervical line.
INTRACORONAL AND EXTRACORONAL TOOTH
PREPARATIONS
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Intracoronal:
within the tooth crown (Box Like)
Extracoronal:
Crowns
References & Suggested reading
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Sturdevant's art & science of operative dentistry-2006Theodore M. Roberson, Harald O. Heymann, Edward J. Swift, Jr.
Principles of operative dentistry (2005)- A.J.E. Qualtrough, J.D.
Satterthwaite, L.A. Morrow and P.A. Brunton.
Fundamentals of Operative Dentistry- 2nd Edition- Summitt &
Robbins