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

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)

Definition Class IV- Involves incisal edge of anterior tooth. Similar to class III but also involve the incisal edge. http://www.dentalaegis.com

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

Modified Conventional Tooth Preparation Class IV Conventional Beveled Conventional Modified Conventional

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.

Modified Conventional Tooth Preparation Class IV Conventional Beveled Conventional Modified Conventional

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

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. 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.

Modified Conventional Tooth Preparation Class IV Conventional Beveled Conventional Modified Conventional

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

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.

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 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.

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 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.

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

Class IV Fracture Repair Restore Custom lingual matrix: Larger restoration. http://www.oralhealthgroup.com/news/direct-class-iv-composite-restorations-from-treatment-planning-to-successful-results/1002942148/?&er=NA Laurie St-Pierre, 2014

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

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

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