class V and class VI amalgam cavity preparation (lecture purpose only )

1. Topic:- Class V And Class VI
Amalgam Cavity Preparations
Presented by
Dr Nadeem Aashiq
MDS 1st year

2. Introduction
• Class V caries
Smooth surface caries located on the gingival/cervical
third of labial/buccal or more rarely the lingual surfaces
of all teeth

3. Non carious cervical lesion
• Class V lesion resulting from factors other than
dental caries are known as non carious cervical
lesion
• Abrasion
• Abfraction
• Erosion

4. Erosion
Abfraction

5. Restorative materials for Class V
cavity
• Amalgam
• Composite
• Resin modified GIC
• Compomers

6. Indications for amalgam as
restorative material
• Non-esthetic areas
• Areas where access and visibility are limited
• Areas where moisture control is difficult
• Areas those are significantly deep gingivally

7. Contraindications for amalgam as
restorative material
• Esthetically important areas

8. Advantages of amalgam as restorative
material
• Amalgam restorations are stronger than other
direct restorations
• Easier to place
• less expensive to the patient
• Usually easier to finish and polish

9. Disadvantages of amalgam as
restorative material
• The primary disadvantage amalgam restorations
are that they are metallic and non-esthetic.
• The preparation for an amalgam restoration
typically requires 90-degree cavo-surface margins
specific and uniform axial depths, and
incorporation of secondary retentive features, all
of which results in a less conservative preparation
than that for other esthetic restorative materials.

10. Clinical technique for class V amalgam
preparation
• Isolation
• Moisture in the form of saliva, gingival sulcus fluid or gingival hemorrhage must
be excluded during caries removal, cementation, and filling procedure because:
1- It may contaminate the pulp during caries removal especially with pulp exposure.
2- Negatively affect the physical properties of the cement and filling material.
• So isolation is important during class V cavity preparation because sometimes
the caries may extend subgingivally and should extend the margin of the
restoration subgingivally, so we do isolation to protect the gingiva and provide
access while eliminating seepage of sulcular fluid into the cavity preparation or
restorative material.
• Isolation done by:
1- Cotton roll
2- Retraction cord
3- Rubber dam.

11. • Outline form :
• The shape of class V cavity is trapezoidal in shape or could be kidney
shaped to be more conservative.
• Using round bur to start entry to the cavity, the direction of the bur
should perpendicular to the buccal (or palatal) surface of the tooth ,
then using the fissure bur of suitable size, enter the carious lesion to
a limited initial axial depth of 0.5 mm inside the DEJ.

12. • This depth is usually 1 to 1.25 mm total axial depth,
depending on the incisogingival/occlusogingival location
(The enamel is considerably thicker occlusally and
incisally than cervically) However, if the preparation is on
the root surface, the axial depth is approximately 0.75
mm.)

13. • Resistance form
• Depth of the cavity is 1.5 mm : the axial wall of the cavity should not
be flat , if we do so will not have even depth of the cavity because
of convexity of tooth structure , so the axial wall should be slightly
convex.

14. • cavosurface line angle (90-110).
• Rounded internal line angles
• Removal of unsupported enamel
• Mesial and distal walls should be slightly diverge
• Occlusal and gingival walls should be perpendicular to the long
axis of the tooth and parallel to each other, any convergence of
these walls will create unsupported enamel.

15. • Retention form
I- Retention mean in class V cavity is made by making
retention grooves or retention holes. This depend
on the size of cavity , in small conservative cavity ,
retention holes is made , while in large class V cavity
, retention grooves are necessary.
II- In case of more extensive class V cavity we may
need to ( pins) as extra retention.

16. • Position of the retentive means:
• Best position is axioocclusal and axiogingival line angles.
• Method of placement :
1 Retention holes: using a small round bur (no. 1/4) and make two
holes at axioocclusal line angle and two holes at axiogingival
line angle.
2 Retention grooves: using a small round bur (no. 1/4) making two
holes at axioocclusal line angle then connecting between them
by small round bur or by small fissure bur, holding the bur in
oblique direction. Same thing is done on axiogingival line angle.

17. Final Tooth Preparation
• Final tooth preparation involves removal of any
remaining infected dentin, pulp protection,
retention form, finishing external walls, and final
procedures of cleaning, inspecting, and
desensitizing.
• Remove any remaining infected axial wall dentin
with a No. 2 or No. 4 bur.
• As the mesial, distal, gingival, and incisal walls of
the tooth preparation are perpendicular to the
external tooth surface, they usually diverge facially.

18. • Consequently, this form provides no inherent
retention, and retention form must be provided .
• Use a No.1/4 bur to prepare two retention grooves,
one along the incisoaxial line angle and the other
along the gingivoaxial line angle.
• The depth of the grooves should be approximately
0.25 mm, which is half the diameter of the bur.
• Finally, clean the preparation using air-water spray
and evacuation.

19. • use the air syringe to remove
visible moisture
(do not desiccate tooth
structure), and inspect the
preparation for completeness.
• If the preparation is complete,
either apply :
• desensitizer (for a non-bonded
restoration)
or
• begin the bonding procedures
(for a bonded restoration).

20. Condensation and Carving
• Using the amalgam carrier, insert the mixed
amalgam into the preparation in small
increments and condense it into the retention
areas first with an appropriately sized condenser.
• Next, condense the amalgam against the mesial
and distal walls of the preparation
• Finally, provide sufficient bulk in the central
portion to allow for carving the correct contour .

22. • Carving may begin immediately after insertion
of the amalgam

23. • the side of the carving instrument should
always rest on unprepared tooth surface
adjacent to the prepared cavosurface margin.
This prevents overcarving.
• Begin the carving procedure by removing
excess amalgam to expose the incisal (or
occlusal) margin.
• Continue removing excess to expose the mesial
and distal margins.

24. • Finally, carve away excess at the gingival
margin

25. Finishing and Polishing
• If carving procedures were performed
correctly, no finishing of the restoration
should be required.
• However ,additional finishing and polishing of
amalgam restorations may be necessary to
correct a marginal discrepancy or improve the
contour.

26. • Care is required when using stones or any
rotating cutting instruments on margins
positioned below the cementoenamel
junction (CEJ).
• This is because of the possibility of removing
cementum or notching the tooth structure
gingival to the margin or both

27. Class VI Amalgam Restorations
• The class VI tooth preparation is used to
restore the incisal edge of anterior teeth
or the cusp tip regions of the posterior
teeth.
• Indicated where attrition has removed the
enamel to expose the underlying dentin.
• When the softer dentin is exposed it
wears fasters than the surrounding
enamel, resulting in “cupped out” areas.
• As the dentin support is lost, the enamel
begins to fracture away, exposing more
dentin and often causing sensitivity.

29. • Sensitivity to hot and cold is a frequent complaint with class VI lesion,
and some patients are bothered by food impaction in the deeper
depressions.
• Enamel edges may become jagged and sharp to the tongue, lips, or
cheek. Lip, tongue, or cheek biting is occasionally a complaint.
• Rounding and smoothing such incisoaxial( or occlusoaxial) edges is an
excellent service to the patient.
• The class VI tooth preparation also is indicated to restore the
hypoplastic pit occasionally found on cusp tips.
• Amalgam may be selected for posterior class VI preparations because
of its wear resistance and longevity.

30. • For class VI amalgam preparations, the dentists enters the area
with a small tapered fissure bur (e.g., No 169L) and extends to a
sufficient size to place the cavosurface margin on enamel that has
sound dentin support.
• The preparation walls may need to diverge occlusally to ensure a
90 degree cavosurface margin.
• A depth of 1.5mm is sufficient to provide bulk of material for
strength.
• Retention of the restoration is ensured by the creation of small
undercuts along the internal line angles.
• One should be careful not to remove dentin that is supporting the
enamel.

31. • Conservative tooth preparations is particularly important with
class VI preparations because it is easy to undermine enamel
on incisal edge and cusp tips.

32. Thank you