Cavity prep for final yr
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Transcript of Cavity prep for final yr
Dr. Fazal ur Rehman QaziBDS,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.
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.
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
Final cavity preparation stage
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
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
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
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.
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
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
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
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 materialsComposite restoration:
a mechanical bond between the material
and conditioned, prepared tooth structure.
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
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 removalAllow access for restoration placementAllow access to margins for finishing,
evaluation and cleaning
Final cavity preparation stage
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
Removal of any remaining infected Removal 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.
Final cavity preparation stage
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
Pulp protectionPulp protection
Using liners or bases
to protect the pulp or
to aid pulpal recovery or both.
Final cavity preparation stage
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
Secondary resistance and retention Secondary 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 retention Secondary resistance and retention forms Ⅱforms Ⅱ
Mechanical forms
Cavity wall conditioning form
Final cavity preparation stage
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 marginwhich is composed of full-length enamel rodsthat are supported on the cavity side by shorterenamel 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 cavity preparation stage
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
Cavity preparation Matrix application Preparation of materials Insertion and carving of materials Finishing and Polishing
Program of Operative TreatmentProgram of Operative Treatment
Cavity preparation Matrix application Preparation of materials Insertion and carving of materials Finishing and Polishing
Program of Operative TreatmentProgram of Operative Treatment
Cavity preparation Matrix application Preparation of materials Insertion and carving of materials Finishing and Polishing
Program of Operative TreatmentProgram of Operative Treatment
Cavity preparation Matrix application Preparation of materials Insertion and carving of materials Finishing and Polishing
Program of Operative TreatmentProgram of Operative Treatment
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