Asalaam Alekum
Dr. Gaurav garg ( M.D.S.)
Lecturer, College of Dentistry
Al Zulfi, M.U.
Date: 20/10/2015
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Outline form
Retention form
Secondary retention
Resistance form
Reverse curve
References
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Occlusaly similar to
that for the Class I
tooth preparation
Proximally there is a
box shape extension
( Occlusal Step)
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No. 245 or no. 330 bur
can be used for
preparation
Enter tooth with punch cut
and extend distally along
central fissure at uniform
depth of 1.5 mm ( 0.5 mm
inside DEJ)
Bur position for entryslight lingual tilt
1
2
4
3
5
B
Wedging.
A, Round toothpick wedge placed in gingival embrasure
protects gingiva and rubber dam during preparation of proximal box. B,
Triangular wedge is indicated when deep gingival extension of proximal box is
anticipated, because wedge's greatest cross-sectional dimension is at its base.
Consequently, it will more readily engage the remaining clinical tooth surface
DEJ
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Proximal box:
Buccolingual extension:
there should be 0.20.3mm clearance from
adjacent tooth buccaly
& lingually
Gingivally there should
be a clearance of 0.5
mm from adjacent tooth
Axial wall should follow
the external tooth
contour
Removeremaining undermined proximal enamel with enamel hatchet
on facial proximal wall (A), lingual proximal wall (B), and gingival wall
(C).
Beveling axiopulpal line angle
A, Bevel of enamel portion of gingival wall is established with
gingival margin trimmer to ensure full-length enamel rods
forming gingival margin.
B and C, Sharp angles at linguogingival and faciogingival
corners are rounded by rotational sweep with gingival
marginal trimmer ( GMT).
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Occlusal convergence of
buccal & lingual walls
Proximal Dovetail
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Retention Locks
( No. 169L or ¼
round bur can
be used)
169L
¼ round
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Minimal extension, Ideal Isthmus
width- 1/4th of Intercuspal
distance
Smooth outline and smooth walls
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90 degree cavosurface angle
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Flat pulpal & gingival floor
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Gingival floor should be bevelled
( 15-20 degree), to remove
unsupported enamel rods
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Rounded all internal line angle
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Bevelled axiopulpal line angle
¼ th of ICD
Palatal/ Lingual wall
Pulpal floor
Buccal wall
Axiopulpal line angle
Axio-lingual line angle
Axial wall
Axio- buccal line angle
Axiogingival line angle
Gingival floor
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In case of maxillary teeth, mostly the
molars, the contact area is more buccally,
i.e.; the lingual embrasures are more than
the buccal embrasures
In such cases, extending the buccoproximal wall into the embrasure lead to
excessive cutting of the buccal cusps
To avoid this, a reverse curve ( S- shaped) is
made in the buccal proximal wall so as to
have sufficient amount of dentin in that area
& also to achieve butt joint with the
cavosurface margins
Such a curve, though mostly given in
maxillary molars, can be given in any tooth
where the contact area is deviated or more
pronounced on one side.
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Conservation of tooth structure ( preserve
cuspal inclines)
Creation of 90 degree cavosurface angle
Less display of restorative material ( enhance
esthetics)
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Sturdevant's art & science of operative dentistry-2006Theodore M. Roberson, Harald O. Heymann, Edward J. Swift, Jr.
Principles of operative dentistry (2005)- A.J.E. Qualtrough, J.D.
Satterthwaite, L.A. Morrow and P.A. Brunton.
Fundamentals of Operative Dentistry- 2nd Edition- Summitt &
Robbins