Cavity prep for final yr

Dr. Fazal ur Rehman
Qazi
BDS,FCPS
FCPS training Incharge
MDS Supervisor
Asst. Prof DIKIOHS, Dept of Op
Dentistry
Dow University
Consultant Restorative Dentist,
FAZAL DENTAL PRACTICE
Khans Dental Clinic and KIHDE

Definition of Operative DentistryDefinition of Operative Dentistry
Operative dentistry is
the ART and SCIENCE of the
diagnosis, treatment, prognosis
of defects of teeth which do not
require full coverage restorations
for correction.

Indication of Operative DentistryIndication of Operative Dentistry
 Caries;
 Malformed, discolored,
or fractured teeth;
 Restoration replacement.

Program of Operative TreatmentProgram of Operative Treatment
 Patient assessment
 Examination and diagnosis
 Treatment planning
 Pain control: local anesthetic
 Isolation of the operating field

 Cavity preparation
 Matrix application
 Preparation of materials
 Insertion and carving of materials
 Finishing and Polishing
Program of Operative TreatmentProgram of Operative Treatment

Cavity PreparationCavity Preparation
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.

Cavity StructureCavity Structure
 walls
 angles
 cavity

Classification of cavityClassification of cavity
 Class I
 Class II
 Class III
 Class IV
 Class V
 Class VI
—G.V.Black in 1908

CavityCavity
 Simple cavity: only one tooth
surface is involved.
 Compound cavity: two surfaces
are involved.
 Complex cavity: three or more
surfaces are involved.

Class 1
Class 2
Class 1
Class 2
Class 3
Class 4
Class 5
Class 6

Stages and Steps
in Cavity Preparation
Initial cavity preparation stage
Final cavity preparation stage

Initial cavity preparation stage
Step 1 Outline form and initial depth
Step 2 Primary resistance form
Step 3 Primary retention form
Step 4 Convenience form

Step 5 Removal of any remaining infected
dentin if indicated
Step 6 Pulp protection
Step 7 Secondary resistance & retention form
Step 8 Procedure for finishing external walls
Step 9 Final procedures

Outline Form and Initial Depth Ⅰ
Definition:
placing the cavity margins in the
positions they will occupy in the final
preparation;
preparing an initial depth of 0.2~0.8 mm
pulpally of the dentinoenamel junction
position

Maxillary Class Ⅰ outline form

Mandibular Class Ⅰ outline form

Maxillary Class Ⅱ outline form

Mandibular Class Ⅱ outline form

Outline Form and Initial Depth Ⅱ
Principles: without any exception
all friable and/or weakened enamel
should be removed
all faults should be included
all margins should be placed in a
position to afford good finishing of
the margins of the restoration.

Outline Form and Initial Depth Ⅲ
Features:
preserving cuspal strength
preserving marginal ridge strength
minimizing facio-lingual extension
using enameloplasty
connecting two close faults or cavities
restricting the depth of the preparation
into dentin.

Primary Resistance Form ⅠPrimary Resistance Form Ⅰ
Definition:
The shape and placement of the cavity
walls that best enable both the
restoration and the tooth to withstand,
without fracture, masticatory forces
delivered principally in the long axis of
the the tooth.

Primary Resistance Form ⅡPrimary Resistance Form Ⅱ
Principles:
To utilize the box shape with a relatively
flat floor to resist occlusal loading by
virtue of being at right angles to
mastication force;
To restrict the extension of the external
walls (keep as small as possible) to
allow strong cusp and ridge areas to
remain with sufficient dentin support;

Primary Resistance Form ⅢPrimary Resistance Form Ⅲ
Principles:
To have a slight rounding of internal
line angles to reduce stress
concentration in tooth structure;
To provide enough thickness of
restorative material to prevent its
fracture under load.

Primary Resistance Form ⅣPrimary Resistance Form Ⅳ
Feature:
Box shape
Relatively flat floors
Inclusion of weakened tooth structure
Preservation of cusps and marginal ridges
Rounded internal line angles
Adequate thickness of restorative materials
Reduction of cusps for capping if indicated

Primary Retention Form ⅠPrimary Retention Form Ⅰ
Definition:
The shape or form of the prepared
cavity that resists displacement or
removal of the restoration from
tipping or lifting forces.
In many respects retention and resistance form
are accomplished in the same cutting procedure.

Primary Retention Form ⅡPrimary Retention Form Ⅱ
Principles: depending on the materials
Amalgam restoration:
developing external cavity walls that
converge occlusally and dovetail design

The devotail design provides retention form
to the occlusal portion of the cavity.
The occlusal convergence of the walls offers
retention in the proximal portion of the cavity
against displacement occlusally.

Primary Retention Form ⅢPrimary Retention Form Ⅲ
Principles: depending on the materials
Composite restoration:
a mechanical bond between the material
and conditioned, prepared tooth structure.

Convenience Form ⅠConvenience Form Ⅰ
Conception:
The shape or form of the cavity that
provides for adequate observation,
accessibility, and ease of operation
in preparing and restoring the cavity.

Convenience Form ⅡConvenience Form Ⅱ
Principles:
Allow access for caries removal
Allow access for restoration placement
Allow access to margins for finishing,
evaluation and cleaning

Removal of any remaining infectedRemoval of any remaining infected
dentin if indicateddentin if indicated
Definition:
The elimination of any infected carious
tooth structure or faulty restorative
material left in the tooth after initial
cavity preparation.

Removal of dentinal caries using round burs and spoon excavators

Pulp protectionPulp protection
Using liners or bases
to protect the pulp or
to aid pulpal recovery or both.

Secondary resistance and retentionSecondary resistance and retention
forms Ⅰforms Ⅰ
Most compound and complex cavity
preparations require additional
resistance and retention form.
The exception being those preparations
that are very conservative.

Secondary resistance and retentionSecondary resistance and retention
forms Ⅱforms Ⅱ
Mechanical forms
Cavity wall conditioning form

Mechnical form:
 Proximal locks
 Proximal slots

Step 5 Removal of any remaining infected
dentin if indicated
Step 6 Pulp protection
Step 7 Secondary resistance & retention form
Step 8 Finishing external walls
Step 9 Final procedures

Finishing the external walls ⅠFinishing the external walls Ⅰ
Definition:
is the further development of a
specific cavosurface design and
degree of smoothness that produces
the maximum effectiveness of the
restorative material being used.

Finishing the external walls ⅡFinishing the external walls Ⅱ
Objectives:
 To create the best marginal seal possible
between the restorative material and tooth
structure;
 To afford a smooth marginal junction;
 To provide maximum strength of both the
tooth and the restorative material at and
near the margin.

The strongest enamel margin is that margin
which is composed of full-length enamel rods
that are supported on the cavity side by shorter
enamel rods, all of which extend to sound dentin.

Finishing the external walls ⅢFinishing the external walls Ⅲ
The design of the cavosurface angle
The degree of smoothness of the wall

The design of the cavosurface angle:
depending on the material
 amalgam: 90°
 composite: beveling 30°~ 40°

Final proceduresFinal procedures
 cleaning
 inspecting
 varnishing
 conditioning

Matrix Application
Tofflemire Matrix System
Ivory Matrix System

Contour Matrix
Rounded instrument
such as a spoon
excavator

Armamentarium
 Amalgam Capsule
 Amalgamator
 Squeeze Cloth
 Amalgam carrier

Insertion and carving
Class Ⅰ
Class Ⅱ

Armamentarium
 Amalgam Condensers
 Anatomic Burnishers
 Carves
— Cleoid or Discoid

Start with the smallest condenser

Check with interproximal carve

Evaluate the restoration Class I
 Verify that cavosurface margin can be seen
— Flash
— Underfilled
— Voids
 Check the overall shape of the anatomy
— Look for bulky ridges that might be high
in occlusion

Evaluate the restoration Class II
Check proximal contact
Check flash and overhangs proximally
Check underfill proximally
Check outline form

Check Occlusion
Evaluate carefully with marking paper
or ribbon in Miller forceps
 Check gently in centric occlusion
 Check all excursive movement

Cavity prep for final yr

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