Resto II cast metal restoration onlay inlay converted PDF

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Lecture notes on Cast Metal Restorations: Indications, Contraindications, Advantages, and Disadvantages...

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RESTOII: CAST METAL RESTORATION INLAY/ONLAY

SB Cast Metal Restorations -may be completed in 2 appointments 1. Prepare the tooth and take an impression 2. Delivering the restoration to the patient Materials qualities -have high compressive strength and tensile strength 1. Traditional high-gold alloys 2. Low-gold alloys 3. Palladium-silver alloys 4. Base metal alloys Indications: 1. Large restoration 2. Endodontically treated teeth 3. Teeth at risk of fracture 4. Dental rehabilitation with cast metal alloy 5. Diastema closure and occlusal plane correction 6. Removable prosthodontics abutment Advantages: 1. The superior physical properties of the cast metal alloy to withstand better the forces imparted by the partial denture 2. The rest seats, guiding planes and other aspects of contour relating to the patient denture are better controlled when the indirect technique is used Contraindications: 1. High caries rate- less chance of recurrent caries 2. Young patient- large pulp chambers 3. Esthetics 4. Small restorations Advantages: 1. Strength 2. Biocompatibility 3. Low wear 4. Control of contour and contacts Disadvantages: 1. Number of appointment and higher chair time 2. Temporary restoration 3. Technique sensitive 4. Cost 5. Splitting force- onlay do not have this disadvantage RESTORATIVE TECHNIQUE FOR CAST METAL RESTORATION 1. Interocclusal records • Very important to evaluate occlusion • An evaluation should include: ➢ The occlusal contacts in maximum intercuspation ➢ The occlusal contacts that occur during mandibular movements 2. Temporary Restoration • Mock preparations before placement of the temporary crown (indirect method) • Making an impression followed by the direct placement of a temporary crown (direct method) • This impression should be: ➢ Non-irritating and protects the prepared tooth from injury ➢ Protect and maintain the state of health of the periodontium ➢ Maintain the position of the prepared, adjacent, and opposing teeth ➢ Provide the aesthetic, phonetic, and masticatory function as indicated ➢ Have adequate strength and retention to withstand the forces of which it will be subjected 3. Tooth preparation 4. Final Impression 5. Working Cast and Dies • Working cast ➢ An accurate replica of the prepared and adjacent unprepared teeth that allows the metal restoration to be lubricated in the laboratory • Die ➢ The replicas of the prepared and the adjacent unprepared that is individually removable 6. Wax pattern 7. Spruing, Investing, and Casting 8. Seating, Adjusting, and Polishing

Similarities of Class II Inlay and Class II Amalgam Preparations: • The occlusal outlines pits and fissures and other enamel defects • There is a smooth, flowing outline with no sharp irregularities • The proximal wall is parallel to the proximal external surface (occlusal view) • Proximal walls are diverging • Pulpal floor is parallel to the occlusal table • Axiopulpal line angle is bevelled Differences between Class II inlays and Amalgam Preparation: AMALGAM INLAY

THIN SECTIONS

cannot support occlusal surfaces

can support occlusal surfaces

ISTHMUS WIDTH

¼ of intercuspal distance

1/3 of the intercuspal distance (wider)

BUCCAL AND LINGUAL WALLS

converging

diverging

S- CURVE

Present

Not present, but w/ primary and secondary flares (outward)

PROXIMAL CAVOSURFACE WALLS

0.5mm out of contact

1mm out of contact

AXIAL WALL

Parallel to the long axis

Diverges cervicoocclusally

CAVOSURFACE MARGINS

90butt joing (enamel margin) 2mm Corrosion products seals the gap between the restoration and the tooth

150-140 enamel margin 30-40 metal margin 1mm The luting cement seals the gap between the restoration and the tooth

GROOVES

None

Slight proximal walls

GINGIVAL BEVEL

None

MIN. THICKNESS OF THE CUSPAL AREA

0.5mm & 30 wide - This is performed to remove weak enamel resulting into a restoration that is burnishable. - This is also provides for a proper fir of the restoration by creating a lanting portion (lab sliding fit) in the gingival area

People who contributed to the dental society: 1. D. Philbrook (1897): introduced the casting technique 2. William taggart: perfected the casting technique, no undercuts in the inlay and onlay  CAST METAL INLAYS

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INITIAL PREPARATION: • Carbide bur: 271L or 169L • Marginal bevels: slender, fine-grit, flame-shaped diamond instrument (no. 8862) • Gingival to occlusal divergence: 2-5 at the vertical walls are short, a maximum of 2 wall surface OCCLUSAL STAGE • Carbide bur 271: held parallel to the long axis of the tooth crown • Depth: 1.5mm, • Dovetail: 169L PROXIMAL BOX: • Carbide bur: 271 • One should guard against overcutting the facial, lingual, and gingival walls which could result in: 1. Overextension of the margins in the completed preparation

9. 10.

Try-ins of the casting Cementation

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2. Weakened tooth 3. Possible injury to the soft tissues Any carious dentin on the axial wall should not be removed at his stage A shallow (0.3mm) retention groove may be cut in the facioaxial and linguoaxial line angles with the 169L

RESTOII: CAST METAL RESTORATION INLAY/ONLAY

SB D.

FINAL PREPARATIONS: • Removal of the infected carious dentin and pulp protection by using a slowly revolving round bur (#2 or #4) or a spoon excavator ➢

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Indications for direct pulp capping: 1. Small exposures (less than 0.5mm in diameter) 2. Tooth in asymptomatic, no signs of pulpitis 3. Any haemorrhage from the exposure site is easily controlled 4. Invasion of the pulp chamber was relatively atraumatic with little physical irrigation of the pulp Indications for removal of the remaining old restorative material on the internal walls: 1. The old material is judged to be thin, non-retentive or both 2. There is radiographic evidence of caries beneath the old material 3. The pulp was symptomatic preoperatively 4. The periphery of the remaining restorative material is not intact Preparation of the bevels and flares: 1. Use a slender, flame shaped, fine grit diamond instrument 2. 30-40 marginal metal should remain for the inlay 3. 140-150 enamel margin angle should be present a. If more than 150 the marginal case metal alloy will become thin and weak b. If less than 140 the metal will be bulky and be difficult to burnish Purpose of gingival bevel 1. To remove weak enamel 2. The bevel will result into a 30 metal which is burnishable 3. A lap-sliding fit will be introduced to the gingival area to improve the fit for the metal casting Occlusal bevels 1. Use a flame-shaped, fine-grit diamond instrument 2. 40 marginal metal and 140 marginal enamel - Increased the strength of the marginal enamel, helps seal & protect the margins Secondary flare 1. The secondary flaring of the proximal walls extends the margins into the embrasures making them more selfcleansing and more accessible to finishing procedures during the inlay insertion, appointment and does so with the conservation of dentin 2. The direction of the flare result in a 40 meteal margin which produces a blunted, stronger enamel margin

MODIFICATION IN INLAY TOOTH PREPARATIONS ➢

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Mesio-occlusodistal preparation • If a marginal ridge is severely weakened because of excessive extension, the preparation outline surface should be altered to include the proximal surface Modifications of Class II preparation for esthetics • Minimal flare is desired for the mesiofacial proximal wall in the maxillary premolars and first molars • The secondary flare is omitted Facial or lingual surface groove extension • maybe indicated to provide sufficient retention Class II preparation for abutment teeth and extension subgingivally to include roof- surface lesions • Extending the facial, lingual, and gingival margins maybe indicated on the proximal surfaces of abutments for RPDs to increase the surface area for the developmental of guiding planes • The gingival extension should be accomplished primarily by lengthening the gingival bevel The maxillary first molar with an unaffected strong oblique ridge: • Retention form is attained by: 1. Creating a 2nd occlusal divergence of the vertical walls 2. Accentuating some line angles 3. Extending the lingual surface groove to an axial wall height in this extension of at least 2.5mm occlusogingivally • Resistance form dictates: 1. Routine capping of the distolingual cusp 2. Maintaining sound tooth structure between the lingual surface groove extension and the distolingual wall of the proximal box

CAPPING CUSPS • If the preparation outline is extended 2/3 of the distance or more • To protect the weak, underlying cuspal structure from fracture caused by masticatory forces • To remove the occlusal margin from a region subjected to heavy stress and wear •

Counter bevel or reverse bevel ✓ A bevel of generous width is prepared on the facial/lingual margin of a reduced cusp ✓

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30 marginal metal

Cusp reduction appreciably decreases retention form because it decreases the height of the vertical walls ✓ Proximal retention grooves are recommended Including portions of the facial and lingual smooth surfaces affected by caries or other injuries

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Caps all the cusps of a posterior tooth Maybe designed to help strengthen a tooth that has been weakened by caries or a previous restoration Capping is mandatory, if the cavity outline extends 2-3 the distance from any primary occlusal groove up to the cusps slopes to: 1. Protect the weak underlying cuspal structure from the fracture due to masticatory forces 2. Remove the occlusal margin from a region subjected to be heavy stress and wear Designed to distribute occlusal load over the tooth that greatly decreases the chance of future fracture More conservative of tooth structure than a full crown preparation Its supragingival margins, when possible are less irritating to the gingiva

MODIFICATIONS ON AN ONLAY TOOTH PREPARATION:

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Facial or lingual groove extension • The extension sometimes is indicated to provide additional retention form even though the groove is not faulty • Inclusions of portions of the facial and lingual smooth surface affected by caries, fractures cusps or other injury Enhancement of resistance and retention form Retention form: • Minimal amount of taper (2 per wall) in addition to proximal retention grooves • Preparation of the facial or lingual surface groove extensions ❖ SKIRT PREPARATION: • Thin extension of the facial or lingual proximal margins of the cast metal onlay extending from the primary flare to a termination just past the transitional line angle of the tooth • A very thin extension for more retention providing a bracing effect • Conservative firm of improving both the resistance and retention form of the preparation • Usually prepared entirely on enamel (barely on dentin) • Often used for successfully for teeth exhibiting splittooth syndrome • The addition of the properly prepared skirt to three or four line angles of the tooth virtually eliminates the chance of post restorative fracture of the tooth because the skirting onlay is primarily an extra coronal restoration that encompasses and braces the tooth against forces that might split the tooth • Recommended when splitting posterior teeth together with onlays • Recommended when the proximal surface contour and contact area are to be extended more than the normal...