Class III, IV & V Cavity Preparations for Composites PDF

Class III, IV and V Cavity Preparations for Composites Less complex while preparing the tooth. Almost universally accepted. INTRODUCTION Repairable....

Class III, IV and V Cavity Preparations for Composites Less complex while preparing the tooth. Almost universally accepted. INTRODUCTION Repairable. Insulating, having low thermal conductivity. "Composite Resin" is a three dimensional combination of Decreased micro leakage. two or more chemically different materials with a distinct Increased strength. interphase between them. Good retention. Minimal interfacial staining. Basically, composite resins consist of a resin matrix reinforced by means of fillers. In order to provide interfacial DISADVANTAGES bonding between these two chemically different materials, a silane coupling agent is present. To control the More difficult, time consuming and costly. polymerization reaction, activators, initiators and inhibitors More technique sensitive. are incorporated. May exhibit greater occlusal wear in areas of high occlusal stress. COMPOSITION: Insertion is more difficult. Establishing proximal contacts, axial contours and These are the structural components in dental resin- based embrasures is more difficult. composites: Proper technique is mandatory in the placement of etchant, primer and adhesive on the tooth structure. Matrix- A plastic resin material that forms a continuous Finishing and polishing procedures are more complex. phase and binds the filler particles. Filler - reinforcing particles and/or fibres that are dispersed CLINICAL TECHNIQUES FOR CLASS III DIRECT in the matrix. COMPOSITE RESTORATIONS Coupling agent-bonding agent that promotes adhesion Class III restorations are done on the proximal surfaces of between filler and resin matrix. anterior teeth, which do not Involve the incisal angles. Initial clinical procedures: Anaesthesia is necessary for patient comfort and helps decrease salivary flow during the procedure. Occlusal assessments must be made to determine tooth preparation design. Composite shade must be selected before the tooth dehydrates. INDICATIONS FOR COMPOSITE RESIN RESTORATIONS The area must be isolated to permit effective bonding. Most class III, IV and V cavities are 4-7/26 restored with composite resins as they restore optimal esthetics. CONTRAINDICATIONS The main contraindication for use of composite for Class III, IV and V restorations is an operating area that cannot be adequately isolated. Class V restorations also may have their durability compromised when the restoration extends onto the root surface (no marginal enamel). TOOTH PREPARATION Any extension onto the root surface requires the most meticulous efforts of the operator to best ensure a Tooth preparation for class III direct composite restoration successful, long lasting restoration. involves: ADVANTAGES 1) Obtaining access to the defect (caries, fracture). Esthetic. 2) Removing faulty structures (caries, defective dentin, Conservative in tooth structure removal. defective restoration). 3) Creating convenience form for the restoration. Conventional preparation: Lingual approach is preferred for the following reasons: -Indicated for restorations involving the root surface Facial enamel is conserved for enhanced esthetics. 1. Using a No. ½, 1, 2 round bur prepare the outline form on Unsupported facial enamel may be preserved for the root surface bonding.. Color matching is not so critical. 2. Extend the preparation into sound walls lesion is accessible from the lingual 3. Extend pulpally 0.75mm in depth 4. The gingival/cervical and incisal walls are perpendicular to the root surface (box like design) 5. A continuous groove retention can be prepared 0.25 mm (½ of diameter of bur) into dentin of the gingival and incisal walls with a % round bur. Indications for Facial Approach 6. The groove is placed at the junction of the axial and the external walls. 1. The carious lesion is positioned facially. 7. Clean preparation and inspect the final preparation 2. Teeth are irregularly aligned, making lingual access undesirable. 3. Extensive caries extent into the facial surface. 4. Faulty restoration that was originally placed at the facial surface. When restoring approximating carious lesions or faulty Beveled Conventional Class III restorations on adjacent teeth at the same appointment, if one lesion is larger, (more extended outline form), than the -Indicated for replacing an existing defective restoration in other, then the larger outline form is developed first. the crown portion of the tooth -when restoring a large carious lesion for which the need for The second preparation can be more conservative because increased retention and/or resistance form is anticipated. of the improved access provided by the larger preparation. The reverse order would be followed when the restorative Lingual Access material is inserted. 1. Use a round bur No. 1/2, 1. 2 depending on the size of the Depending on the extent of the preparation to be caries to enlarge the opening sufficiently to allow for caries restored, there are three designs: removal. CONVENTIONAL: WHEN CARIES IS ENTIRELY ON 2. Extend external walls to sound tooth structure using a ROOTH SURFACE straight bur. BEVELED CONVENTIONAL: WHEN THE CAVITY IS 3. Extend the gingival and incisal walls up to extent of caries LARFE AND ENAMEL MARGINS BEVEL IS GIVEN AT AN or location of old restoration. ANGLE OF 45 DEGREES TO THE CAVOSURFACE Unless necessary, DO NOT: MODIFIED: WHEN THE CARIOUS LESION IS SMALL Include the proximal contact. extend into the facial surface.  extend subgingivally. ADVANTAGES OF ENAMEL BEVEL The ends of the rods are more effectively etched than otherwise only the sides of the enamel rods are exposed. ➤ Increase in etched surface area results in a stronger enamel to resin bond, which increases retention of the restoration and reduces marginal leakage and marginal discoloration. ➤Incorporation of cavosurface bevel may enable the restoration to blend more esthetically with the coloration of the surrounding tooth structure. 4. Create an axial wall depth of 0.2mm into the dentin/DEJ (approximately 0.75-1.25mm depth) 5. Axial wall is convex, following the external contour of the tooth. 6. Remove all remaining infected dentin, using a round bur or small spoon excavator. 7. Remove friable enamel at the margins. 8. If necessary, prepare retention [grooves or coves) prepare it along the gingivaxial line angle, and sometimes at the Modified Class III incisoaxial line angle 25 mm with a round bur. most used type of cavity preparation indicated for small and moderate lesions or faults. designed to be as conservative as possible. preparation walls have no specific shapes or forms other than an external angle of 90 or more degrees preparation design appears to be scooped or concave 1. Use a 1/2, 1, 2 round bur, point of entry is within the incisogingival dimension of the lesion, perpendicular to the enamel surface. 9. Place cavosurface bevel or flare at the enamel except at 2. Remove all remaining caries or defect. the gingival margin area. 3. No attempt is made to create a uniform axial preparation 10. Use a flame shape or round bur resulting in a 45 degrees walls rather, the objective is to selectively remove tissue as angle to the external tooth surface. conservatively as possible 11. Bevel width should be 0.5-2 mm. depending on the size of the preparation. 12. Clean the preparation of any debris and inspect final preparation.  CLASS IV TOOTH PREPARATIONS Where do we find class 4 lesions ? G.V BLACK CLASSIFICATION Class 1: Caries affecting pits and fissures on occlusal third of molars and premolars, occlusal two-thirds of molars and premolars, and lingual part of anterior teeth. Class II: Caries affecting proximal surfaces of molars and premolars. Class III: Caries affecting proximal surfaces of central incisors, lateral incisors, and cuspids without involving the incisal angles. THINGS TO CONSIDER IN PERFORMING CLASS IV TOOTH PREPARATIONS Class IV: Caries affecting proximal including incisal angles of anterior teeth. Preoperative assessment of occlusion is important in this type of tooth preparation because it may influence the tooth Class V: Caries affecting gingival one-third of facial or lingual preparation extension (placing margins in non contact surfaces of anterior or posterior teeth. areas), and retention and resistance forms features. Class VI: Caries affecting cusp tips of molars, premolars, Occlusal factors may dictate a more conventional tooth and preparation form, with more resistance form features and secondary, resistance form features. Proper shade selection may be more difficult for large Class IV restorations that don't have normal dentin color. Prewedging before tooth preparation would benefit the effort to restore the proximal contact. For large class IV lesions or fractures, a preoperative impression may be taken to be used as a template for developing the restoration contours. In addition to the etched enamel margin, retention of the composite restorative material in this type of tooth preparation may be obtained by 1. Groove or other shaped undercuts 2. Dovetail extensions TYPES: CONVENTIONAL CLASS IV BEVELED CONVENTIONAL CLASS IV MODIFIED CLASS IV 1. CONVENTIONAL CLASS IV Has few indications except for any portion of the restoration extending onto the root. 3. Threaded pins Designed with 90 - degree cavosurface margin and requires groove retention form when extended onto the root BEVELED CONVENTIONAL CLASS IV For restoring large proximal areas that also include the incisal surface of an anterior tooth. 4. Combination of these Gingival and incisal retentive undercuts may be indicated. in large class IV preparations similar to the undercuts used in the class III preparations are placed in which rounded undercuts are placed in the dentin along line angles and into point angles where ever possible. An arbitrary dovetail extension onto the lingual surface of the tooth may enhance the restoration's strength and retention, but it is less conservative and not used often Pin retention is sometimes necessary but is discouraged for some reasons: Placement of pins in anterior teeth involves the risk of perforation either into the pulp or through the external surface. Some pins may corrode because of microleakage of the restoration, resulting in significant discoloration of the tooth and restoration. *** despite these disadvantages, when a large amount of tooth structure is missing, pin retention may be necessary to retain the composite restoration. Characterized by an outline form that occurs when the preparation walls are prepared as much as possible perpendicular or parallel to the long axis of the tooth. Which results to a design that provides greater resistance to biting MODIFIED CLASS IV forces that could cause fracture of the tooth or restorative material. Done by using an appropriate size of round carbide For small or moderate Class IV lesions or traumatic bur or diamond instrument at high speed with air - water defects. coolant. Objective is to remove as little tooth structure as possible, all weakened enamel is removed and initial axial wall depth while removing the fault and providing for appropriate is established at.5mm into dentin.excavate any remaining retention and resistance forms infected dentin. If necessary, a Ca OH liner and RMGI base are applied, bevel is prepared. Placement of retention form which is primarily provided by micromechanical bonding of the composite to the tooth structures. additional retention may be obtained by increasing the width of the enamel bevels or placing retention undercuts, if this is necessary, gingival retention groove is prepared using a No. 14 round bur, prepared.2mm inside the DEJ at a depth of.25 An appropriate size mm. at an angle bisecting the junction of the axial wall and round bur or gingival wall. This groove should extend the length of the diamond instrument gingival floor and slightly up the facioaxial and linguoaxial is used to remove any existing lesion or defective restoration. line angles. No retention undercut is usually needed at the incisal area, where mostly enamel exists. Usually no or little initial tooth preparation is indicated for fractured incisal corners other than roughening the fractured tooth structure. Cavosurface margins are prepared with a beveled or flared configuration similar to that previously described. Axial depth depends on the extent of the lesion, previous restoration or fracture but initially is no deeper than.2mm inside the DEJ. Usually without groove or cove retention form, instead retention is obtained primarily from the bonding strength of the composite to the enamel and dentin. Teeth with minor traumatic fractures require less preparation and if fracture is confined to enamel, retention can be attained by simply beveling sharp cavosurface margins in the fractured area with a flamed-shaped diamond instrument followed by bonding.  Sign of neglectful oral hygiene because lesions often occur in multiples Tooth surface around the marginal gingiva becomes decalcified and rough which further accumulates food and irritates the tissue. Class 3 and class 4 restorations First attempts to treat the incipient lesion is to apply topical fluorides and to improve oral hygiene COMPOSITES CELLULOID STRIPS FINISHING STRIPS WEDGE FLOSS Due to the esthetic considerations, composite materials are the most frequently used material ei. Microfill composites because these composites can flex rather than debond when tooth flexes under heavy occlusal forces which results to: L Increased restoration smoothness. CLASS V RESTORATION Dr. Hazel P. Alipio 2. Restoration flexibility when tooth undergoes cervical flexure Located at the gingival third of the facial and lingual tooth surfaces.  maintained by keeping the instrument's long axis perpendicular to the root surface. Axial wall follows the original contour of the facial surface which is convex outward mesiodistally and sometimes occlusogingivally. Outline form extension is dictated by the extent of the caries, defect or old restoration indicated for replacement All the external preparation walls are visible when viewed from a facial position. (outwardly divergent walls). FINAL TOOTH PREPARATION TYPES OF CLASS V TOOTH PREPARATION Removal of remaining infected dentin or old restorative material (if indicated on axial wall). Application of calcium hydroxide liner and RMGI base. Sometimes, preparation of groove retention form Prepared with No. ¼ bur along the full length10-11/23 gingivoaxial and incisoaxial(occlusoaxial) he angle with.25 mm. in depth into the external walls and next to the axial wall at an angle that bisects the junction between the axial wall and gingival or incisal wall.this should leave between the groove and the margin, sufficient remaining wall dimension of.25 mm to prevent fracture. While preparing the grooves it should be I. CONVENTIONAL observed that the remaining wall dimension is equal to the half diameter of the bur head, 0.5 mm. the preparation is For portion of carious lesion or defect entirely or partially on then cleaned, if indicated and inspected for approval. the facial or lingual root surface of a tooth. A tapered fissure carbide (700, 701 or 271) or similarly shaped diamond is used at high speed with air water spray. If access interproximally or gingivally is limited, a no. 1 or 2 round bur or diamond may be used to prepare the tooth. With tapered fissure bur, entry is made at 45- degree angle to the tooth surface by tilting the handpiece distally. As cutting progresses distally, one maneuvers the handpiece in such a manner that the bur's long axis is perpendicular to the external surface of the tooth during preparation of the outline form which should result in 90 - degree cavosurface margins. II. BEVELED CONVENTIONAL Initial preparation should have axial depth of.75mm. any Has beveled enamel margins and indicated for replacement infected dentin retained in the initial axial wall is removed of an existing, defective class V restoration that initially used during the final stage of the tooth preparation. a conventional preparation or for a large new carious lesion. A.75 mm. axial wall depth provides adequate external wall Exhibits a 90 degree cavosurface margin (that are width for: subsequently beveled) and an axial wall that is uniform in depth. 1. Strength of the preparation wall Axial depth into the dentin is.2mm groove retention is 2. Strength of the composite unnecessary and.5mm when a retention groove is planned and margin is still in the enamel. 3. Placement of retention groove if necessary Larger preparations are combination of beveled enamel Distal, mesial and incisal (occlusally and gingivally for margins and 90-degree root and are combined beveled indicated extensions) and the proper initial depth is conventional and conventional preparations  No effort to prepare the walls are butt joints and usually no ADVANTAGES OF BEVELED CONVENTIONAL OVER groove retention is incorporated. CONVENTIONAL TOOTH PREPARATION Lesion or defect is "scooped " out a preparation form that 1. Increased retention owing to the greater surface area of has divergent wall configuration and axial surface is not etched enamel afforded by the bevel uniform in depth. 2. Decreased microleakage owing to the enhanced bond Ideal for small enamel defects or small but cavitated lesions between the composite and the tooth. that are largely or entirely in the enamel these include decalcification and hypoplastic areas located in the cervical 3. Decreased need for retention form and consequently less third of the teeth. removal of tooth structures. Initial preparation is made with a round or elliptical diamond -initial axial wall depth is.2mm into the dentin when groove or bur with initial stage with no deeper than 2mm into the retention is unnecessary. dentin Infected dentin is removed with round bur or spoon excavator. COMPLETION OF THE TOOTH PREPARATION IS ACHIEVED BY: CLASS V TOOTH PREPARATION FOR ABRASION AND Removal of any remaining infected dentin and if indicated, EROSION LESIONS of old restorative material. Abrasion Application of Ca OH liner or RMGI base if necessary. Loss or wearing away of tooth structure resulting from mechanical forces. eg. strenuous toothbrushing with hard Preparation of gingival retention groove if either the gingival bristled toothbrush or abrasive toothpaste. margin is located on root surface or the preparation is large In the form of a notch or v shape. enough to warrant groove retention form. Placement of bevel on the enamel margins with a flame-shaped or round diamond instrument resulting in an angle approximately 45 degrees to the external tooth surface and prepared to a width of.52mm. When large Class V has to be prepared with carious lesion or faulty restoration extending into the root surface, gingival wall is prepared as conventional Class V (with retention Erosion groove ) with a depth of.75 mm and only the enamel Saucer shaped notch resulting from chemical dissolution. cavosurface margins are beveled. Eg. sustained exposure to citric acid or vomitus III. MODIFIED For small and moderate Class V lesions or defects. Bean shaped To restore lesion or defect as conservative as possible. Idiopathic erosion or abfraction Results from flexure of tooth's cervical area due to heavy occlusal stress beginning with microfracture of the thin enamel tooth structure occlusal of the CEJ which when combined with abrasive toothbrushing could produce a "notch defect. Progressive, enlarging with time if causative factor is not eliminated. CONSIDERATIONS IN CLASS V RESTORATIONS Caries Gingival health Esthetics Sensitivity Pulp protection Tooth strength