1. Class IV Cavity Preparation
بسم الله الرحمن الرحيم
Class IV Cavity Preparation
Alaa Sabrah, BDS, MSD, PhD
18 Dec, 2014

2. Goals and Objectives 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)

3. Definition Class IV- Involves incisal edge of anterior tooth.
Similar to class III but also involve the incisal edge.

4. Clinical Technique 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.
2. occlusal factors may dictate a more conventional tooth preparation form, with more resistance form features (boxlike, flat
floors, and walls and floors parallel to the long axis and perpendicular to the occlusal forces) and secondary retention form
features (grooves and wider bevels).
3. shades selection may be more difficult for large Class IV restorations that do not have normal dentin colorations (translucent incisal edge).
the use of a microfill composite as a veneer over a hybrid composite core may provide improved esthetic results.
Laurie St-Pierre, 2014

5. Modified Conventional
Tooth Preparation
Class IV
Conventional
Beveled Conventional
Modified Conventional

6. Tooth Preparation Minimum clinical application.
Indication: Restoring the portion 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.
Root surface
Axial wall
External wall
F and L Cavosurface margin=90˚ and Gingival floor ┴ long axis of the tooth. (Resistance form).
boxlike form may provide greater resistance to fracture of the restoration and tooth form masticatory forces.

7. Modified Conventional
Tooth Preparation
Class IV
Conventional
Beveled Conventional
Modified Conventional

8. Class III Tooth Preparation
Indication: restoration of large carious 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
Class III

9. 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 Volume 6 Number 1.
In addition to the etched enamel margin, retention of the composite restorative material in beveled conventional Class IV
tooth preparation may be obtained by groove or other shades undercuts, dovetail extensions, threaded pin, or a combination of these.

10. Modified Conventional
Tooth Preparation
Class IV
Conventional
Beveled Conventional
Modified Conventional

11. Class III Tooth Preparation
Indications: small and 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.
Class III

12. Place calcium hydroxide in deep caries on the axial wall.
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.

13. Class IV Resin Restoration

14. 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
The Class IV composite restoration has provided the profession with a conservative treatment to restore fractured defective, or cariously involved anterior teeth when, previously, a porcelain crown may have been the treatment of choice.

15. 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.

16. Class IV Fracture Repair
Place adequate bevel
Larger the cavity: need bigger or wider bevel
Bevel may be mm wide
use 7901/ 7802 finishing burs, round or flame shaped burs to place bevel.

17. 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).

18. Class IV Resin Restoration
Place bonding agent according to manufacturer instructions.
Air dry to remove any solvent.
Light cure for s.

19. Class IV Fracture Repair
Restore
incremental build-up, cure from various directions
restore cervical area first
After the bonding adhesive has been applied and cured, insert the composite and cure in increments to ensure complete polymerization and to possibly reduce the effect of polymerization shrinkage.

20. Class IV Fracture Repair
Restore
Custom lingual matrix: Larger restoration.

21. Class IV Fracture Repair
Restore
Custom lingual matrix: Larger restoration.
Laurie St-Pierre, 2014

22. Class IV Fracture Repair- Finishing
Finishing the Class IV: Use finishing burs, stones,
hand instruments, discs, and/ or scalpel to finish.

23. Class IV Fracture Repair
Assessment:
the incisal edge length and thickness.
The occlusion with opposing
teeth.
Laurie St-Pierre, 2014

24. تم بحمد الله