Lecture Number Five by Dr. Sohail Abbas Khan http://helpingdentists.blogspot.com

2. PREPARATION OF AN IDEAL CLASS II CAVITY
CARIOUS LESIONS ON PROXIMAL SURFACES.

3. STEPS IN CAVITY PREPARATION
FOLLOW THE PROCEDURE
FOR PREPARING CLASS I.
MARK THE OUTLINE WITH
A LEAD PENCIL AND OPEN
IT WITH ½ ROUND BUR.
BURS # 245 & 330 ARE IDEAL FOR
PRODUCING OCCLUSAL
CONVERGENCE OF THE FACIAL AND
LINGUAL WALLS.
3MM

4. ORIENTATION OF THE BUR IS THE KEY IN PREPARATION.LONG AXIS
OF THE BUR MUST BE PARALLEL TO THE CROWN OF THE TOOTH.

5. WITH A SWEEPING DRAG, MAINTAINING THE SAME DEPTH
AND BUR ORIENTATION, CUT THE TOOTH TOWARDS MESIAL
PIT. THIS WILL PRODUCE A FLAT PULPAL FLOOR. REMEMBER
NOT TO MOVE THE BUR AGAIN AND AGAIN,OTHERWISE YOU
WILL WIDEN THE ISTHMUS.

6. EXTEND THE PREPARATION DISTO
FACIALLY AND DISTO LINGUALLY TO
INCLUDE FISSURES THAT RADIATE FROM
THE PIT, WITH A SLIGHT OCCLUSAL
CONVERGENCE. REMEMBER TO MAINTAIN
THE BUR ORIENTATION AND DEPTH AND
MAKE SURE THE BUR IS NOT STOPPED
DURING THE WHOLE PROCEDURE.

7. VARIOUS STEPS IN OCCLUSAL PREPARATION.
(NOTE THE ANGULATION OF THE BUR)

8. VARIOUS STEPS IN OCCLUSAL PREPARATION.
(CONTINUED)

9. VARIOUS STEPS IN OCCLUSAL PREPARATION.
(CONTINUED)
EXTEND THE PREPARATION PROXIMALLY BUT
MUST STOP 0.8MM SHORT OF MARGINAL RIDGE.

10. WITH A LEAD PENCIL, MARK THE EXTENSION OF
THE FACIAL AND LINGUAL WALLS OF THE
PROXIMAL BOX RELATIVE TO THE CONTACT AREA.
PREPARING A PROXIMAL BOX

11. CREATE A REVERSE CURVE IN
AN OCCLUSAL OUTLINE. THIS
WILL RESULT WHEN
DEVELOPING THE MESIO FACIAL
WALL PERPENDICULAR TO THE
ENAMEL ROD DIRECTION.
HOWEVER, THE REVERSE CURVE
ON THE LINGUAL ASPECT WILL
BE MINIMAL.
ESTABLISH 0.5 MM CLEARANCE
WITH THE ADJACENT PROXIMAL
SURFACE FACIALLY, LINGUALLY
AND GINGIVALLY.CHECK
CLEARANCE WITH THE TINE OF
EXPLORER.

12. PREPARING A PROXIMAL BOX (CONTINUED)
MAKE A DITCH,VERY CLOSE TO
CONTACT, ENTERING HALF OF
THE 245 BUR (245 BUR IS 3 MM
LONG).THE REQUIRED DEPTH
OF PULPAL FLOOR IS BETWEEN
1.5 TO 2 MM. THE BUR MUST
NOT STOP ROTATING WHILE
CUTTING IN THE CAVITY.
POSITION THE BUR IN THE
PULPAL FLOOR NEXT TO
REMAINING MARGINAL
RIDGE.MOVE THE END OF THE
BUR TO CUT A DITCH
GINGIVALLY ALONG THE
EXPOSED DENTINOENAMEL
JUNCTION.THIS WILL CUT 0.5 MM
INTO DENTINE AND 0.2 TO 0.3 MM
INTO ENAMEL.

13. MOVE THE BUR FACIALLY AND LINGUALLY
ALONG THE DEJ. EXTEND THE DITCH
GINGIVALLY AND TILT THE BUR LIGHTLY
TOWARDS MESIAL.DURING PREPARATION,
KEEP CHECKING THE DEPTH WITH
PERIODONTAL PROBE.
PROXIMAL DITCH CUT MUST BE
DIVERGENT GINGIVALLY WHICH
IS ACHIEVED BY THE SHAPE OF
245 BUR.

14. FINISHING OF THE CAVITY WALLS:
REMOVE ANY IRREGULARITIES FROM THE MARGIN AND REMOVE
UNSUPPORTED ENAMEL BY USING CHIESELS, HATCHETS TO ESTABLISH FINAL
FACIAL, LINGUAL AND GINGIVAL MARGINS.
USING GMT(GINGIVAL MARGIN TRIMMER, BEVEL THE AXIOPULPAL LINE ANGLE
AND GINGIVAL MARGIN.

15. USING GMT, CREATE THE BEVELS IN
GINGIVAL AND AXIOPULPAL WALL.
MAKE BEVEL ON OCCLUSAL WALL.

16. WALLS AND FLOORS OF CAVITY PREPARATION
LINE ANGLES OF THE CAVITY PREPARATION
BUCCAL
(FACIAL)
WALL
AXIAL WALL
LINGUAL WALL
CAVOSURFACE MARGIN
PULPAL WALL
GINGIVAL WALL
AXIAL WALL
LINGUAL WALL
GINGIVO-BUCCAL
AXIO-PULPAL
AXIO-
GINGIVAL
PULPO-LINGUAL
AXIO-LINGUAL
AXIO-PULPAL
GINGIVO-LINGUAL
AXIO-GINGIVAL

17. VARIOUS WALLS CREATED DURING CLASS II PREPARATION
RIGHT ANGLE
NO BEVEL
ROUNDED
ENAMEL WALL
PARALLELS
DIRECTION OF
RODS ONLY –
NO BEVEL
ACUTE
AXIO-
GINGIVAL
ANGLE
RETENTIVE
GROOVE
AMALGAM
RIGHT ANGLE

18. MEASUREMENTS OF THE PREPARED CAVITY

19. EXAMPLES OF CLASS II CAVITY PREPARATION

20. EXAMPLES OF CLASS II CAVITY PREPARATION

21. REASONS FOR FAILURE IN CAVITY PREPARATION
EXTERNAL OUTLINE FORM INTERNAL FORM FINISH