opd new class 1 and 2

1. Outline form

2. Resistance form

3. Retention form

4. Convenience form

5. Removal of remaining decay

6. Finishing of enamel margins and walls

7. Cleansing of the cavity

7 steps in cavity preparations

outline form

• refers on the extent of the preparation on the surface of the tooth

• carrying it will occupy in the finished restoration

1. Pits and fissures

2. Proximal surfaces

3. Gingival third of the facial and lingual surfaces

caries susceptible areas

1. The proximal line angles

2. All smooth surfaces, above (incisal or occlusal to) the height of contour. Caries immunity occurs beneath the free gingival area.

cleansing area (by saliva, food, lips, tongue)

resistance form

refers to the internal form of the cavity which enables the tooth and restoration to best resist or withstand the forces of mastication

1. adequate depth = .5 - 1 mm into sound dentin

2. must have smooth and usually flat pulpal and axial walls which meet the remaining walls at a definite but rounded angles

3. surrounding walls are parallel to the line of force ; floors are perpendicular to the line of force

4. proper width of the cavity

how to achieve resistance form

retention form

refers to the internal form of a cavity which enables the restoration to resist displacement through tipping or lifting

1. parallel or nearly parallel lateral dentin walls

2. presence of dovetail

3. undercuts (occluso-buccal and occluso-lingual walls) and/ or converging walls

4. retention grooves (proximo-buccal and proximo-lingual walls)

5. pins/ pinholes/ postholes

how to achieve retention form

convenience form

refers to the extension of the preparation so that it may be most conveniently seen, approached and restored

convenience form

is a term meaning “ to gain access”

width of the isthmus should be 1/3 to 1⁄4 of the intercuspal distance

convenience form

will help prevent restoration movement

resistance form = FLAT FLOOR

may allow an amalgam restoration a rocking action = wedging force (shearing of tooth)

resistance form = ROUNDED PULPAL FLOOR

• use of spoon excavator

• slowly rotating round burs

removal of remaining decay may be done by?

finishing of enamel margins and walls

• removal of unsupported enamel rods (shaping of the enamel walls in line with direction of enamel rods)

• enamel walls - planed to smoothness

1. Remove debris with air or water syringe

2. .Dry and isolate the cavity

3. Medicate. Place the necessary pulp protection.

4. Dry again

5. Place the necessary restorative material (permanent or temporary)

toilet or cleansing of cavity procedure:

enameloplasty

eliminating the developmental faults by removing it with the side of a flame-shaped diamond stone, leaving a smooth surface

enameloplasty

Using ____ on the terminal ends of shallow fissures to conserve tooth structure

1. ease of use

2. long term clinical research

   results

3. Excellent wear resistance

4. Lower cost than for composite

amalgam advantages

1. Nonesthetic

2. Less conservative

3. Weakens tooth structure

amalgam disadvantages