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Complex amalgam restoration

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Complex amalgam restoration

  2. 2. COMPLEX AMALGAM RESTORATION<br />Complex amalgam restoration refers to one that involves three or more surfaces of the tooth.<br />In recent years refer to an amalgam restoration that replaces one or more cusps.<br />
  3. 3. INDICATIONS<br />They are used:<br />To replace missing tooth structure due to fracture or caries or existing restorative material.<br />When one or more cusps needs capping.<br />When increased resistance and retention forms are needed.<br />
  4. 4. INDICATIONS<br />Used as an alternative to indirect restoration.<br />For periodontal and orthodontic patients.<br />Affordability.<br />For old patients <br />Used in tooth that have questionable pulpal prognosis.<br />Can act as a foundation for crown.<br />
  5. 5. If conventional retention features are not adequate pins, slots and bonded amalgam are used to enhance retention.<br />As more tooth is lost more auxiliary retentive features required.<br />
  6. 6. CONTRAINDICATIONS<br />If patient has occlusal problems.<br />If the tooth cannot be restored properly with direct restoration because of anatomic or functional considerations.<br />If the area to be restored is esthetically important to the patient.<br />
  7. 7. ADVANTAGES<br />Conserves tooth structure.(less cutting)<br />Less time required.<br />Resistance and retentive forms significantly increased by pins and slots.<br />Economics.<br />
  8. 8. Disadvantages<br />Dentinal micro fractures.<br />Microleakage.<br />Decreased tensile strength of amalgam.<br />Penetration and perforation.<br />Tooth anatomy cannot be replicated like that in indirect restoration.<br />
  9. 9. PERFORATION<br />
  10. 10. RETENTION AND RESISTANCE FORM<br />Non pin mechanical features<br />Pins<br />Amalgam bonding<br />
  11. 11. NON PIN MECHANICAL FEATURES<br />Parallel or convergent walls.<br />Box form.<br />Flat pulpal and gingival floors.<br />Grooves in proximal line angles.<br />Dovetails.<br />Reduction of undermined cusps.<br />Coves/locks.<br />Amalgapins.<br />Slots.<br />
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  16. 16. PIN <br />3 types of pins:<br />1.Self threading pins.<br />2.Friction locked pins.<br />3.Cemented pins.<br />
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  18. 18. PRINCIPALS FOR PLACEMENT OF PINS<br />Pinhole made the diameter of pinhole smaller then diameter of the pin being placed in threaded and friction locked.<br />Craze lines created in dentine (the more the diameter of the pin the more the dentinal craze lines).<br />Depth of the varies from 1.3 to 2 mm depending on the diameter of pin used.<br />Used in addition to non pin retentive features.<br />
  19. 19. SELF THREADING PINS<br />Self threading pins commonly used cause of its retentiveness.<br />TMS system used (thread mate system).<br />Threads engages the dentine as it is inserted into the dentine due to elasticity of dentine.<br />
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  21. 21. FACTORS AFFECTING RETENTION OF THE PIN IN DENTIN AND AMALGAM<br />Type <br />Surface characteristics.<br />Orientation number and diameter.<br />Extension into the dentin and amalgam.<br />
  22. 22. TYPE<br />Self threading are the most retentive followed by friction locked and then cemented.<br />
  23. 23. SURFACE CHARACTERISTICS<br />The number and dept of elevations (serrations or threads)on the pin influence retention of the pin in the amalgam restoration.<br />
  24. 24. ORIENTATION<br />Should be placed in non parallel fashion to increase retentiveness.<br />Bending pins in amalgam is not desirable if bending of the pin is done it should be done with a proper tool and at least 1mm of bulk of amalgam should be there between the pin and external surface of the finished restoration.<br />
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  26. 26. NUMBER<br />As the number of pins increases the retention in dentin and amalgam increases but the problems created also increases. Chances of <br />1.Crazing of dentin increases.<br />2.The amount of available dentin between the pins decreases.<br />3.The strength of amalgam restoration decreases.<br />Increasing the diameter also increases retention.<br />
  27. 27. EXTENSION INTO THE DENTIN AND AMALGAM<br />Pin extension into the dentin and amalgam greater then 2mm is unnecessary for pin retention and is contraindicated to preserve the strength of the dentin and the amalgam.<br />If more the 2mm amalgam or dentin is involved the chances of fracturing of pin increases.<br />
  28. 28. PIN PLACEMENT FACTORS AND TECHNIQUES<br />1.Pin size.<br />2.Number of pins.<br />3.location.<br />4.Pinhole preparation.<br />5.Pin design.<br />6.Pin insertion.<br />
  29. 29. PIN SIZE<br />Minikin and minim pins are used for severely involved posterior teeth.<br />Minim pins used as a backup if the pinhole is overprepared.<br />
  30. 30. NUMBER OF PINS<br />Factors considered when deciding how many pins are required <br />1.The amount of missing tooth structure.<br />2.The amount of dentin available to receive pins safely.<br />3.The amount of retention required.<br />4.The size of the pins.<br />As a rule, one pin per missing axial line angle should be used.<br />
  31. 31. LOCATION<br />Several factors aid in determining pin hole location:<br />1.Knowledge of the normal pulp anatomy and external tooth contours.<br />2.A current radiograph of the tooth.<br />3.A periodontal probe.<br />4.The patient`s age.<br />
  32. 32. LOCATION<br />Pins should not be placed directly under areas of contact with the opposing teeth as the restoration would fracture under the occlusal load.<br />Occlusal clearance should be sufficient to provide 2mm of amalgam over the pin.<br />Pinhole should be positioned no closer than 0.5 to 1mm to the DEJ or no closer than 1 to 1.5mm to the external surface of the tooth. <br />Pinhole should not be positioned very close to vertical wall as it would make condensation of amalgam difficult.<br />Interpin distance should be more for a pin with larger diameter.<br />
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  38. 38. PIN INSERTION<br />Can be done with conventional latch type contra angle hand piece or TMS hand wrenches.<br />
  39. 39. PIN INSERTION<br />
  40. 40. CEMENTED PINHOLE<br />
  41. 41. BONDED AMALGAM RESTORATION<br />Amalgam hydrophobic while dentine and enamel is hydrophilic.<br />4 meta based resin is used which has hydro philic and hydrophobic ends<br />
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  44. 44. REFERENCES<br />Principles of operative dentistry By A. J. E. Qualtrough, Julian Satterthwaite, Leean Morrow, Paul Brunton.<br />Lecture by barra eigbynia.<br />Art and science of operative dentistry.<br />Management of broken down teeth by doctor nasrien ateyah.<br />