class V for Different Restorations.pdf

Different Designs of Class V Cavity Preparations Class V tooth preparations, by definition, are located in the gingival one third of the facial and lingual tooth surfaces. Class V Cavity Preparation for Amalgam Restoration Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr...

Different Designs of Class V Cavity Preparations Class V tooth preparations, by definition, are located in the gingival one third of the facial and lingual tooth surfaces. Class V Cavity Preparation for Amalgam Restoration Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Factors affecting Outline Form • The outline form for the Class V amalgam tooth preparation is determined primarily by: 1. Height of contour. 2. Position of the gingival margin. 3. Position of line angles. 4. Esthetics. Prof. Amal Sakr 16-12-2021 Proper outline form for Class V amalgam tooth preparations Cavo surface margins are extended to sound tooth structure A limited axial depth of 0.5 mm inside the DEJ and 0.75 mm inside cementum (when on the root surface). This depth is usually 1 to 1.25 mm total axial depth, depending on the incisogingival (i.e., occlusogingival) location . The enamel is considerably thicker occlusally and incisally than cervically. Prof. Amal Sakr 16-12-2021 Armanteriaum • A tapered fissure bur of suitable size(e.g., No. 271) is used to enter the caries lesion. • An appropriate carbide bur (usually No. 2 or No. 4) may be used for the initial tooth preparation. • Round burs are indicated in areas inaccessible to a fissure bur that is held perpendicular to the tooth surface. • If needed, smaller round burs may also be used to define the internal angles in these preparations, enhancing proper placement of the retention grooves. Prof. Amal Sakr 16-12-2021 Steps for Cavity Preparation: When the entry is made, the bur orientation is adjusted to ensure that all external walls are perpendicular to the external tooth surface and parallel to the enamel rods. Often, this requires changing the orientation of the handpiece to accommodate the cervical ,mesiodistal and incisogingival (i.e., occlusogingival) convexity of the tooth. The preparation is extended incisally, gingivally, mesially, and distally until the Cavo surface margins are positioned in sound tooth structure such that an initial axial depth of 0.5 mm inside the DEJ . Prof. Amal Sakr 16-12-2021 • Because the axial wall follows the mesiodistal and incisogingival (i.e., occlusogingival) contours of the facial surface of the tooth, it usually is convex in both directions. • In addition, the axial wall usually is slightly deeper at the incisal wall, where more enamel (i.e., approximately 1-1.25 mm in depth) is present than at the gingival wall, where little or no enamel (i.e., approximately 0.75-1 mm in depth) may be present. • A depth of 0.5 mm inside the DEJ permits placement of necessary retention grooves without undermining enamel. Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 When extending uncially (A), gingivally (B), mesially (C), and distally (D), the bur is positioned to prepare these walls perpendicular to the external tooth surface. Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Retention Form Because the mesial, distal, gingival, and incisal walls of the tooth preparation are perpendicular to the external tooth surface, they usually diverge facially. Consequently, this form provides no inherent retention, and retention form must be provided because the primary retention form for an amalgam restoration is macromechanical. A No. 1/ 4 round bur is used to prepare two retention grooves, one along the incisoaxial line angle and the other along the gingivoaxial line angle. The handpiece is positioned so that the No.1/ 4 round bur is directed generally to bisect the angle formed at the junction of the axial wall and the incisal (i.e., occlusal) wall. Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Class V Cavity Preparation for Composite Restoration Prof. Amal Sakr 16-12-2021 Prof. Amal Sakr 16-12-2021 Class V Cavity Preparation for Anterior restorations Checklist for Class V Anterior Restorations ✓Anesthesia for patient comfort & decrease salivary flow rate. ✓Shade selection before the tooth dehydrates & concomitantly lightens. ✓The area must be isolated to permit effective adhesion. Small or Moderate Lesions or Defects • The objective of the Class V tooth preparation for small or moderate lesions or defects that do not extend onto the root surface is to restore the lesion or defect as conservatively as possible. Indications • Small or moderate Class V tooth preparations are ideal for small enamel defects or small primary caries lesions. • These include decalcified and hypoplastic areas located in the cervical third of the teeth, which may be restored for esthetic reasons. Fig. 8.47 Class V tooth preparation. A, Small cavitated Class V lesion. B, Restored with composite resin. (Courtesy Vilhelm G. Ólafsson.) Prof. Amal Sakr 16-12-2021 • After the usual preliminary procedures, the initial tooth preparation is accomplished with a round diamond or carbide bur, eliminating the entire enamel lesion or defect. • The preparation is extended into dentin only when the defect warrants such extension. • No effort is made to prepare 90-degree Cavo surface margins. • If carious tissue remains in dentin, it is selectively removed with a round bur or spoon excavator. • Beveling is performed all around except gingival margin >where enamel is absent or very thin. Prof. Amal Sakr 16-12-2021 . A, Small cavitated Class V lesion B, Surrounding enamel defect is prepared with round diamond instrument. Preparation designs for Class V initial composite restorations (primary caries) No effort is made to prepare the walls as butt joints, and usually no secondary retentive features are incorporated. The lesion or defect is conservatively prepared resulting in a form that may have a divergent wall configuration and an axial surface that usually is not uniform in depth. • Small or moderate Class V tooth preparations also are used to restore noncarious cervical lesions (NCCLs). ➢NCCLs have a multifactorial etiology in which contributing factors include intrinsic and/or extrinsic erosion, abrasion, abfraction, and/or biocorrosion ➢If the causative factors are not eliminated, these lesions tend to progress and enlarge with time. Guidelines recommended by Academy Operative Dentistry for Restoration Of Non-Carious lesions • Inability to eliminate or greatly reduce the rate of lesion progression. • Esthetic unacceptability of the lesion to patient. • Significant sensitivity of exposed dentin. • Threat to strength of the tooth. Moderate Class V • Kidney bean’ concave-shaped tooth design below the height of the contour of the tooth . • Bevel placed appropriately on all walls except gingival wall. • Extended within DEJ 0.2-0.8 mm axially (not recommended to be on the same level). Fig. 8.48 A, Class V caries. B, Typical outline form . Prof. Amal Sakr 16-12-2021 larger preparation designs for Class V restorations Large Defects Class V • Indications: • This preparation design is indicated for the replacement of an existing, defective Class V restoration that initially used a conventional preparation or for a large, new caries lesion. Prof. Amal Sakr 16-12-2021 • In Class V tooth preparation for large lesions or defects that extend onto the root surface ,the gingival aspect of the preparation form is like that for a Class V amalgam restoration. Prof. Amal Sakr 16-12-2021 • The features of the preparation include a 90-degree Cavo surface margin. • Groove retention form usually is not necessary but may be used if retention of the restoration is a concern. • The enamel margins are prepared using the same design described for small or moderate Class V tooth preparations, that is, with a conservative enamel bevel. Prof. Amal Sakr 16-12-2021 Completed Class V tooth preparation extending onto the root; the incisal margin is beveled; the root portion has a retention groove for increased retention. Retention grooves on the incisal aspect are rarely required and are shown here for illustration purposes only. Class V Cavity Preparation for Glass Ionomer Restoration Prof. Amal Sakr 16-12-2021 When is glass ionomer material of choice for restoring Class V? • If the cavity is extended on the root and there is no enamel margin for etching and bonding . • If moisture control is impossible. • Why? • This is because these materials are water-based • they are self-adhesive • And release fluoride which may have a cariostatic effect. • Decreased salivary function. • Decreased patient motivation. • Patient is medically compromised. Why RMGI over GI? • Due to their improved moisture tolerance, polyacid-modified composites may be an appropriate choice for these types of cavity. Glass Ionomer &Resin Modified Glass Ionomer • No cavosurface bevels are recommended • Retention rates 93% • RMGI offers high fluoride release and excellent recharge capacity • Best served on root surfaces