Class II Amalgam Preparation

#29 DO

Overview

  • Outline Form
    Outline Form

    extent of preparation on tooth surface

    *amalgam preparations are typically larger than comparable composite preparations due to material requirements

  • Retention Form
    retention form

     form, shape, and configuration of the tooth preparation that resists the displacement or removal of restoration from the preparation under lifting and tipping masticatory forces

  • Resistance Form
    resistance form

    internal form of tooth preparation that allows restoration to resist forces of mastication

  • Convenience Form
    convenience form

    form of tooth preparation that allows for physical and visual accessibility to preparation 

Armamentarium

Instruments and Materials

Video Demonstration

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Procedures

A
  • Clinical note: The final preparation dimensions are determined by the extent of the carious lesion or existing, faulty restoration
B
C
D
  • Optional: Place a matrix band or metallic fender wedge interproximally to protect the adjacent tooth from iatrogenic damage
E
  • Bur options: pear shaped carbide bur (330)
F
G

Clinical note: The final preparation depth is determined by the extent of the carious lesion or existing, faulty restoration

H
  • Always keep the bur perpendicular to the long axis of the tooth
  • Follow the anatomical grooves of the tooth
  • ​Leave a small “enamel shell” interproximally to protect the adjacent tooth from iatrogenic damage
I
  • BL width of occlusal outline: at least 1mm
  • BL width of isthmus: 1-1.5mm
  • ​BL dimension must accommodate the smallest condenser
J
  • Follow the anatomy of the grooves

Bur options: pear shaped carbide burs (330, 245)

K
L

Bur options: pear shaped carbide burs (330, 245)

M
  • The gingival contact is broken <0.5mm
  • When the gingival contact is broken, the tip of the explorer will pass through the broken contact

Drop the box = creating the proximal box!

N
O
  • Position the flat side of the instrument against the enamel shell and push the instrument outward toward the adjacent tooth

Hand instrument option: enamel hatchet

P

Bur options: pear shaped carbide burs (330, 245) <br>

Hand instrument options: enamel hatchet

Q
  • The exit angles are 90º degrees to the tooth surface, following the direction of the enamel rods
  • The buccal and lingual walls are occlusally convergent
  • The axial wall is occlusally divergent
R
  • The tip of the explorer should pass through buccal, lingual, gingival contacts
S

Bur options: pear shaped carbide burs (330, 245)

T
U

Bur options: round carbide burs (4, 6)​

V
  • Remove unsupported enamel
  • Remove steps/ledges ​
  • Bevel the axiopulpal line angle
W

Hand instrument options:  enamel hatchet, enamel hoe, gingival margin trimmer

X
Y
  • Use the explorer to check for smoothness
  • Use the probe to check for appropriate depth and width
  • Clinical note: The final dimensions of the preparation are determined by the extent of the carious lesion or existing, faulty restoration

Checklist


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Common Mistakes

References

Hilton, T. J., Ferracane, J. L., &amp; Broome, J. C. (2013). Summitt’s fundamentals of operative dentistry a contemporary approach. Quintessence Publishing Co. Inc. 
Ritter, A. V., Boushell, L. W., Walter, R., &amp; Sturdevant, C. M. (2019). Sturdevant’s art and Science of Operative Dentistry. Elsevier. 

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