Transcript Class III Cavity Preparation

Class IV Cavity Preparation
Alaa Sabrah, BDS, MSD, PhD
18 Dec, 2014
Goals and Objectives
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2.
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5.
What is the definition of Class IV cavity?
Identify the different types of Class IV cavity
Preparation?
Compare and contrast different approaches to caries
for Class IV ?
Compare the design and retention form for the
different types of Class IV cavity Preparation?
Describe the clinical technique for
treating Class IV carious lesion?
Sturdevant's Art and Science of Operative
Dentistry (5th Edition)
Definition
 Class IV- Involves incisal edge of anterior tooth.
 Similar to class III but also involve the incisal edge.
Clinical Technique
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2.
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7.
Anesthesia (Pt comfort,
decrease salivary flow).
Occlusal assessment: more
important for class IV.
(determine design, adjust
the restoration function).
Shade selection (more
difficult for large
cavities).
Isolation (visibility,
effective bonding).
Tooth preparation.
Pulp Protection.
Restoration.
Laurie St-Pierre, 2014
Tooth Preparation
Class IV
Conventional
Beveled
Conventional
Modified
Conventional
Tooth Preparation
 Minimum clinical application.
 Indication: Restoring the portion
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


Axial wall

External wall
Root surface

of a cavity that extend to root
surface.
Why? More retention and
resistance needed.
Design: Butt Joint margins.
Walls = walls for amalgam
F and L Cavosurface margin=90˚
Gingival floor ┴ long axis of the
tooth.
Uniform depth.
Tooth Preparation
Class IV
Conventional
Beveled
Conventional
Modified
Conventional
Tooth Preparation
 Indication: restoration of large carious
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


lesion or replacing defective
restoration in the crown.
Why? More retention/resistance are
needed
Design: some beveled enamel margins
with conventional wall design.
Cavosurface margin=45˚ on beveled,
90˚ on non beveled margins.
External walls ┴ enamel surface
Tooth Preparation
Retention:
 Enamel bevel or flare:
Deep bevel for more
retention (0.25-2mm).
 Retention groves.
 Undercuts.
 Dovetail
 Pins
W Amin, A Kassab, N Salim. The Internet Journal of Dental
Science. 2007 Volume 6 Number 1.
Tooth Preparation
Class IV
Conventional
Beveled
Conventional
Modified
Conventional
Tooth Preparation
 Indications: small and
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



moderate lesions or faults
designed to be as conservative
as possible in the crown.
Why? All enamel margins
Design: No specific shape
Cavosurface margin ≥ 90˚
External walls = no shape.
Only include caries or defective
restoration.
Pulp Protection
 Place calcium hydroxide in
deep caries on the axial wall.
 Add RMGIC linear to protect
the calcium hydroxide from
being dissolved by Acid etch
application.
Class IV Resin Restoration
ESTHETIC DENTISTRY USING
COMPOSITE RESINS
 Class IV Fracture Repair: Direct Technique
 Conservative treatment versus crown
 Restores incisal edge
 Class IV fracture
 Extension of
Class III lesion
 Defect
Class IV Resin Restoration
 Use clear Mylar strip to provide “proximal wall” to
restore against
 Place wedge between the teeth gingivally to seal the
cervical margin, and protect the adjacent teeth.
Class IV Fracture Repair
 Place adequate bevel
 Larger the cavity: need bigger or wider bevel
 Bevel may be 0.25-2 mm wide
 use 7901/ 7802 finishing burs, round or flame shaped burs to
place bevel.
Class IV Resin Restoration
 Etching:
 Manufacture instruction.
 Placed 0.5mm beyond
the prepared margins.
 15-30 s.
 Wash and dry.
 Dentin should remain
moist (NO over drying
or polling of excess
water I allowed).
Class IV Resin Restoration
 Place bonding agent according to manufacturer
instructions.
 Air dry to remove any solvent.
 Light cure for 10-20 s.
Class IV Fracture Repair
 Restore
 incremental build-up, cure from various directions
 restore cervical area first
Class IV Fracture Repair
 Restore
 Custom lingual matrix: Larger restoration.
Class IV Fracture Repair
 Restore
 Custom lingual matrix: Larger restoration.
Laurie St-Pierre, 2014
Class IV Fracture RepairFinishing
 Finishing the Class IV: Use finishing burs, stones,
hand instruments, discs, and/ or scalpel to finish.
Class IV Fracture Repair
 Assessment:
1.
the incisal edge length and thickness.
The occlusion with opposing
teeth.
2.
Laurie St-Pierre, 2014