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Lab procedure cast partial
contact the opposing teeth or - remain slightly out of contact to avoid interference with natural tooth guidance. b. Posterior teeth should not contact during excursive movements. 8323-01-2015 Ivanhoe JR, Plummer KD. Removable partial denture occlusion. Dent Clin N Am. 2004;48:667–83 23-01-2015 84 Ivanhoe JR, Plummer KD. Removable partial denture occlusion. Dent Clin N Am. 2004;48:667–83 Occlusal schemes for removable partial dentures: 1. Balanced occlusion 2. Canine
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Introduction to lab procedures for cast partial dentures including various techniques.
Highlights the significance of lab techniques and addresses common errors in RPD fabrication.
Steps for taking impressions and the necessary work authorization details for denture processes.
Methods for surveying master casts, ensuring proper design mimics the diagnostic cast.
Different blockout methods for clear denture bases including arbitrary, parallel, and shaped blockouts.
Discussion on procedures involved in duplicating casts and materials used for duplication.
Types of investment materials including gypsum, phosphate, and silica bonded investments.
Detailed methods for investing and associated procedures for preparing the mold.
Steps in waxing the framework for maxillary and mandibular partial dentures.
Processes related to spruing, cutting off sprues, and finishing ornate details on partial dentures.Discusses the casting process and considerations including alloy ductility and reactions.
Surface preparation methods like sand blasting and pickling after casting.
Techniques and steps for creating corrected cast impressions for denture frameworks.
Information on the arrangement and setting of artificial teeth in dentures.
Details on determining occlusal schemes for different classes of removable partial dentures.
Overview of the steps in processing following artificial teeth arrangement.
Recent advancements in the fabrication of removable partial dentures utilizing new technology.
Comprehensive listing of references used in the presentation for detailed procedure documentation.
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Lab procedure cast partial
- 1. Lab procedures in CastPartial Dentures Presenter Bejoy Zachariah I MDS Department of Prosthodontics and Crown & Bridge 23-01-2015 1
- 2. Contents • Introduction • Impressionswith work authorization forms • Requisites for casts • Surveying the master casts • Block and Relief Arbirary block out Parallel block out Shaped block out • Duplication • Investment materials Gypsum bonded Phosphate bonded Silica bonded • Waxing and Spruing Maxillary Mandibular • Investing Vaccum mix Hand investing 223-01-2015
- 3. • Wax eliminationand heating • Casting • Cutting off Sprue, Finishing and Polishing • Corrected cast technique • Artificial teeth setting • Processing • Advancements • Conclusion • References 323-01-2015
- 4. Why lab procedureis important? 23-01-2015 4 Introduction “ G o o d t e c h n i q u e p a y s o f f.” T h e s e w o r d s a r e n o t m e r e l y a m o t t o t o h a n g o n t h e w a l l i n t h e l a b o ra t o r y b u t w o r d s o f w i s d o m
- 5. Possible errors inRPD Everyone who participates in any step of the fabrication of a removable partial denture must share in the success or failure of the restoration. Some seemingly innocuous deviations can be accumulative and cause serious problems, so everyone should review the procedures that they use on a regular basis. 23-01-2015 5 Rudd and Rudd. A review of 243 errors possible during the fabrication of a removable partial denture: Part I J Prosthet Dent 2001;86:251-61
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- 7. Impressions with workauthorization forms 723-01-2015 Bomberg TJ, Hatch RA, Hoffman W. impression material thickness in stock and custom tray. J Prosthet Dent. 1985;54(August).
- 8. (1) The signatureand license number of the dentist (2) The date the authorization was signed (3) The name and address of the patient (4) A description of the service or material ordered. 23-01-2015 8
- 9. Requisites for casts 923-01-2015 voidsor nodules hard dense denture support. 3 to 4 mm deep peripheral roll Vertical side walls 15 mm thick •Dental laboratory procedures vol 3;Rudd KD 2nd edition.
- 10. 23-01-2015 10 Surveying themaster casts Dental laboratory procedures vol 3;Rudd KD 2nd edition.
- 11. 23-01-2015 11 Dental laboratoryprocedures vol 3;Rudd KD 2nd edition.
- 12. 23-01-2015 12 Design shouldmimic the design on diagnostic cast
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- 14. Block out andRelief 1423-01-2015
- 15. Arbitrary block out 1523-01-2015 Dentallaboratory procedures vol 3;Rudd KD 2nd edition.
- 16. Parallel block out 1623-01-2015 Dentallaboratory procedures vol 3;Rudd KD 2nd edition.
- 17. Shaped block out 1723-01-2015 Dentallaboratory procedures vol 3;Rudd KD 2nd edition.
- 18. Relief 1823-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition. Not used in complete denture bases, bead retention, open retention
- 19. 23-01-2015 19 Stewart’s clinicalremovable partial prosthodontics. Rodney D. phoenix.4th edition.
- 20. 23-01-2015 20 Dental laboratoryprocedures vol 3;Rudd KD 2nd edition.
- 21. 2123-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition. Duplicating procedure
- 22. 23-01-2015 22 Stewart’s clinicalremovable partial prosthodontics. Rodney D. phoenix.4th edition. Agar : complex polysacharide extracted from sea weed Primarily consists of 15% colloidal suspension of agar in water Borates- 0.2-0.5% Potassium sulphate- 1-2% Wax- 1% Thixotrophic material 0.5% Water- around 84%
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- 26. Investment Materials 2623-01-2015 Gypsum bonded Phosphatebonded Silica bonded Robert G. Craig & John M. Powers : Restorative dental materials (Tenth edition)
- 27. Gypsum bonded • mixedwith water • composed of a mixture of silica (SiO2) and calcium sulphate hemihydrates (gypsum product) • Three types of gypsum bonded investments can be identified as follows: -Type 1 thermal expansion type; for casting inlays and crowns. -Type 2 hygroscopic expansion type; for casting inlays and crowns. -Type 3 casting complete and partial dentures. 2723-01-2015 Robert G. Craig & John M. Powers : Restorative dental materials (Tenth edition)
- 28. Phosphate bonded • powdercontains silica, magnesium oxide and ammonium phosphate • Can be mixed with water or colloidal silica • Two types of phosphate-bonded investment can be identified as follows: -Type 1- for inlays, crowns and other fixed restorations. -Type 2- for partial dentures and other casts. removable restorations 2823-01-2015 Robert G. Craig & John M. Powers : Restorative dental materials (Tenth edition)
- 29. Silica bonded • consistof powdered quartz or cristobalite which is bonded together with silica gel. • On heating, the silica gel turns into silica so that the completed mould is a tightly packed mass of silica particles. 2923-01-2015 Robert G. Craig & John M. Powers : Restorative dental materials (Tenth edition)
- 30. 3023-01-2015 Robert G. Craig& John M. Powers : Restorative dental materials (Tenth edition)
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- 34. 3423-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 35. 3523-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 36. 3623-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
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- 38. Waxing the framework- Maxilla 3823-01-2015
- 39. 3923-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 40. 4023-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 41. 4123-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
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- 44. Waxing the framework- Mandible 4423-01-2015 Dental laboratory procedures vol 3;Rudd KD 2nd edition.
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- 48. 4823-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 49. 4923-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
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- 51. 5123-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition. Hamda et all. Investigation of the effect of three sprue design on the porosity and the completeness of titanium cast removable partial denture frameworks. J Prosthet Dent. 1999;82(1):15–21
- 52. 5223-01-2015 Hamdi et all.Button versus buttonless castings for removable partial denture framework. J Prosthet Dent. 1994;72(4):433–44.
- 53. 23-01-2015 53 Dental laboratoryprocedures vol 3;Rudd KD 2nd edition.
- 54. • Mechanical mixingunder vacuum removes air bubbles created during mixing and evacuates any potentially harmful gases produced by the chemical reaction of the high-heat investments. Investing Vacuum Mixing 5423-01-2015
- 55. • For gypsumbonded investments, temperature can be either 4680 for the hygroscopic technique or 6500C for the thermal expansion technique. • With phosphate bonded investments, the maximum temperature setting may range from 7000C to 8700C, depending upon the alloy selected.. Wax elimination and heating Monika nemet. Laboratory fabrication procedures of a metal partial denture framework. acta stomatol crot 2003;37:95-98.5523-01-2015
- 56. • It isalso advisable to begin the burn out procedure while the mold is still wet. • This process is facilitated by placing the ring with the sprue hole down over a slot in a ceramic tray in the burnout furnace. Shah SA. Influence of time of placement of investments for burnout and the type of rings being used on the casting accuracy. J Indian Prosthodont Soc.2014 Mar;14(1):67-71. 5623-01-2015
- 57. Casting •Monika nemet. Laboratoryfabrication procedures of a metal partial denture framework. acta stomatol crot 2003;37:95-98.5723-01-2015
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- 59. co-cr alloy isa commonly used investment material for casting of partial dentures.this metal doesnot have adequate ductility for adjustment purposes but are light in weight, strong and corrosion resistant. superheating the alloy before casting can increase the ductility of the alloy. superheating the alloy can cause the metal to react with the mold and a close adhering green scale is formed. this green scale is very hard to be removed and requires a lot of machining. 23-01-2015 59 Allan FC, Asgar K, Alligato RDE, Cobalt FDE, Con EC. Reaction of Cobalt-Chromium Casting Alloy with Investment. J Dent Res. 1966;45(5):1516–28.
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- 62. Cutting off CastingSprues and Finishing and Polishing 6223-01-2015
- 63. 6323-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 64. 6423-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 65. 6523-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
- 66. 6623-01-2015 Dental laboratory proceduresvol 3;Rudd KD 2nd edition.
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- 68. 23-01-2015 68 Stewart’s clinicalremovable partial prosthodontics. Rodney D. phoenix.4th edition. The unit pictured in is the Ti-Lectro Polisher (CMP Industries). The polishing occurs in a bath of 85% orthophosphoric acid, which is heated t o 49 ° C to 60 °C. The anode is attached to the cast and the cast is immersed in the solution. Each square inch of metal surface area requires 2 amperes of current for 6 minutes. The average setting is 6 amperes f o r 6 mins.
- 69. • A functionalimpression is generally made by adding an impression base to the removable partial denture framework. • Functional impressions may be made by a variety of impression materials. Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition Joanne N. Walton The corrected cast impression: An alternative technique. Quintessence Int 1993;24:779-781.6923-01-2015 Corrected cast impressions
- 70. Techniques for pouringcorrected cast impressions are boxing with a • 1)Plaster pumice mix and wax, • 2)Beading and boxing with wax, • 3)Beading with wax and the two stage pour. Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition Joanne N. Walton The corrected cast impression: An alternative technique. Quintessence Int 1993;24:779-781. 7023-01-2015
- 71. • 1. Arubber base corrected cast impression is received in the laboratory. • 2. Outline the master cast for removal of the ridge areas •Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition 7123-01-2015
- 72. • 3. Removethe residual ridge areas from the master cast • cut retention areas into the cast Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition 7223-01-2015
- 73. • 4. Placethe framework with its impression on the master cast and lute it Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition 7323-01-2015
- 74. • 5. Soak-the cast and framework in clear slurry water, and place it into plaster/pumice mixture. •Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition 7423-01-2015
- 75. • 6. Afterthe plaster/pumice mixture has set, shape it to the outline of the cast. • 7. Use a strip of boxing wax to complete the boxing of the impression and is seal with a wax spatula •Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition 7523-01-2015
- 76. 8. Soak theboxed impression in clear slurry water for 5 minutes in preparation for pouring 9. Pour the boxed impression in improved stone •Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition 7623-01-2015
- 77. •Stewart’s clinical removablepartial prosthodontics. Rodney D. phoenix.4th edition 7723-01-2015
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- 80. Determining occlusal schemes 1.Class III removable partial denture a. The occlusal morphology of the artificial teeth is selected to match that of the opposing teeth or surfaces. b. If the existing occlusion is physiologically healthy, the patient is restored to the existing occlusal scheme, which may be group function or mutually protected. c. A group function articulation is recommended if the patient’s natural canine is missing or periodontally compromised. d. A balanced articulation is recommended if the restoration is to oppose a complete denture. Some clinicians believe that balanced articulation is not desirable or clinically obtainable and select a monoplane or lingualized occlusion. 8023-01-2015 Ivanhoe JR, Plummer KD. Removable partial denture occlusion. Dent Clin N Am. 2004;48:667–83
- 81. 2. Class IIremovable partial denture The recommendations given for class III are appropriate, with the following exceptions: a. Group function articulation should be avoided when there are no remaining premolars. A canine-protected articulation reduces the destructive lateral forces that are generated on the distal extension during function. b. Except when opposing a complete denture, a balanced articulation should be avoided to prevent nonworking contacts on natural teeth. 8123-01-2015 Ivanhoe JR, Plummer KD. Removable partial denture occlusion. Dent Clin N Am. 2004;48:667–83
- 82. 3. Class Iremovable partial denture The recommendations given for classes II and III are appropriate with the following exception: a. Balanced articulation is recommended for patients for whom canine-protected articulation is not possible to provide bilateral occlusal contacts for increased denture stability. 8223-01-2015 Ivanhoe JR, Plummer KD. Removable partial denture occlusion. Dent Clin N Am. 2004;48:667–83
- 83. 4. Class IVremovable partial denture a. During excursive movements the anterior artificial teeth should either disocclude or have passive occlusal contact. b. A balanced articulation is recommended if the restoration is to oppose a complete denture. Some clinicians believe that balanced articulation is not desirable or clinically obtainable and select a monoplane or lingualized articulation with no anterior tooth contact in function 8323-01-2015 Ivanhoe JR, Plummer KD. Removable partial denture occlusion. Dent Clin N Am. 2004;48:667–83
- 84. Processing After the teetharrangement has been completed the flasking, processing, deflasking and finishing steps are followed. 8423-01-2015
- 85. Advancements In CastPartial Denture Fabrication 23-01-2015 85 3 D computer models Valplast RPD Milling of RPD
- 86. References 1. Nasser KSGA.Cast partial denture : Laboratory step by step. J Indian Prosthodont Soc. 2006;6(4):170–4. 2. Knezoviê-zlatariê D. Laboratory Fabrication Procedures of a Metal Partial Denture Framework. Acta Stomatol Croat. 2003;37:95–8. 3. Bomberg TJ, Hatch RA, Hoffman W. impression material thickness in stock and custom tray. J Prosthet Dent. 1985;54(August). 4. Howard S, Rudd KD, Dc U, Morrow RM, Powell JM. Comparision of effects of tap water and slurry water on gypsum casts. J Prosth Dent. 1970;24(5):563–9. 5. Hasaballa M. THE FEASIBILITY OF INDIRECT CASTING OF MAXILLARY REMOVABLE PARTIAL DENTURE. Saudi Dent J. 1993;5(3):114–20. 6. Hamda et all. Investigation of the effect of three sprue design on the porosity and the completeness of titanium cast removable partial denture frameworks. J Prosthet Dent. 1999;82(1):15–21. 7. Brudvik JS, Lee S, Croshaw SN, Reimers DL. Laser Welding of Removable Partial Denture Frameworks. Int J Prosthodont. 2008;21(4):285–92. 8. Allan FC, Asgar K, Alligato RDE, Cobalt FDE, Con EC. Reaction of Cobalt-Chromium Casting Alloy with Investment. J Dent Res. 1966;45(5):1516–28. 9. Hamdi et all. Button versus buttonless castings for removable partial denture framework. J Prosthet Dent. 1994;72(4):433–44. 10. Walton JN. The corrected cast impression : An alternative technique Prosthodontics. Quintessence Int (Berl). 1993;24(11):779–81. 11. Ivanhoe JR, Plummer KD. Removable partial denture occlusion. Dent Clin N Am. 2004;48:667–83. 12. Williams RJ, Bibb R, Rafik T. A technique for fabricating patterns for removable partial denture frameworks using digitized casts and electronic surveying. J Prosthet Dent. 2004;91(1):85–8. 23-01-2015 86
- 87. 13. Textbook ofclinical removable partial prosthodontics by Stewart, Rudd, Kuebker 2nd edition. 14. Stewart’s clinical removable partial prosthodontics. Rodney D. phoenix.4th edition. 15. Dental laboratory procedures vol 3;Rudd KD 2nd edition. 16. Mc Cracken’s removable partial prosthodontics, ninth edition 17. Joanne N. Walton The corrected cast impression: An alternative technique. Quintessence Int 1993;24:779-781. 18. Knapp J.G Technique for recording the cast surveyer. J. Prosthet Dent 1979; 41:352-354. 19. Yilmaz. G Optical surveying of casts for removable partial dentures J. Prosthet Dent.1975; 34:292-296 20. Richard E Coy. Survey and design of diagnostic casts for removable partial dentures J. Prosthet Dent.1974; 32:103 21. Sergio Reinaldo De Fiori. Transferring the path of insertion from the diagnostic cast to multiple master casts. J. Prosthet Dent.1983; 50:733. 22. Arthur M La Vere. A simplified procedure for survey and design of diagnostic casts. J. Prosthet Dent.1977; 37:680. 23. Robert G. Craig & John M. Powers : Restorative dental materials (Tenth edition) 24. Kenneth J. Anusavice : Philips’science of dental materials (eleventh edition) 23-01-2015 87
Editor's Notes
- #5 Good technique demands that everyone involved give adequate attention to all details required for safe and efficient operations. This means that good dentistry depends on the integrity, knowledge, and skills possessed by the entire dental team, which includes the dentist, dental nurse, dental assistant, office manager, and dental technician
- #7 Communication with technitian Must understand the lab procedures
- #8 Dental clinic and laboratory will not be in one place Sometimes in different cities Thus work authorization form acts as a medium of communication
- #11 the clinician determines a specific path of insertion and removal for the partial denture. This path is recorded by placing tripod marks on the diagnostic cast. In turn, the clinician prepares both hard and soft tissues of the mouth in harmony with this path. The technician must ensure that all framework fabrication steps are based upon this path of insertion and removal.
- #12 Using carbon marker mark survey lines on master cast that will be contacted by metal
- #13 Metallic outline drawn in brown Rest, tripod, undercut cross lines, terminal end of the clasp in red Finish lines in blue
- #14 treated with a surface sealer. The sealer is a mixture of acetone, diethyl phthalate, and cellulose acetate. Impermeable seal that protects the drawn design multiple layer should not be applied Dry for 5 mins and block out
- #15 .5mm deep and becomes less distinct at gingival margins Prevents food particles from entering and creating discomfort Snugg fit against the palate
- #16 Done to prevent encroachment of metal on the soft tissues To withdraw block out cast from duplicating material
- #17 contoured in a predetermined relation to the prescribed path of insertion All tooth-supported removable partial dentures should be blocked out parallel to the path of insertion. Tooth-tissue-supported removable partial dentures may be blocked out in a similar manner, or they may be given a tapered blockout to allow increased freedom of movement in function Metallic block out instrument
- #18 Buccal or lingual surface to faciliate accurate placement of plastic or wax pattern It must be trimmed flush with the survey line If stone is trimmed off the final frame will not fit in the mouth
- #19 Relief is given in edentulous areas for adaptation of denture base and to form internal finish line Generally not needed except for unhealed ridges. The dentist should specify if relief is needed Advantages if relief is not used- eliminates one step and chances of error, no need for conventional internal finish line
- #20 Practically 1mm relief should be there for acrylic to flow A properly formed internal finish line permits formation of a butt joint between the framework and the acrylic resin denture base. This allows a smooth transition from metal to resin and minimizes the likelihood of trauma to the adjacent soft tissues. One thickness of baseplate wax makes an ideal relief pad
- #21 Ready for duplication
- #22 Cast is placed on the base of the duplicating flask. ¼ inch clearence in all direction Use modelling clay to fix the cast and close the body of the flask. Secure the junction between the base and body of the flask
- #23 Agar –basic constituent Borates- improves strength, also retards the setting of stone poured into the finished impression-disadvantage Potassium sulphate-counters retarding effect of borates Wax- filler Thixotropic-plasticizer Water-dispersion medium Coloring and flavour agent
- #24 Double boiler or storage unit A breakdown temperature of 100 °C and a working temperature of 63 ° C are suitable Pour the agar in a stream not more that one pencil size diameter
- #25 Run cool water at the base of the flask. Colloid cooling at the base alone will cause shrinkage in only that direction making it to adapt more closely to the cast 45 mins to 1 hr
- #26 The two wax knifes are used at the modelling wax depression area To loosen the cast blow air in between the colloid and cast The refractory cast is placed in oven at 93 C for 30-60 mins The dry refractory cast is dipped into beeswax at 1 3 8 ° C to 1 4 9 °C for 15 seconds. Once dipped, the cast is positioned on its end to allow excess wax to run off
- #27 Blockout philosophies and techniques are similar regardless of the chosen alloy. In contrast, duplication materials and techniques are alloy specific. refractory cast expansion determines the ultimate fit of the framework
- #28 Casts may be heated to 704 degrees celcius
- #29 The use of colloidal solution of silica instead of water for mixing with the powder has the dual effect of increasing the setting expansion and strengthening the set material. On heating the investment prior to casting, mould enlargement occurs by both thermal expansion and inversion of the silica. Thermal expansion is greater for the colloidal silica-mixed materials than for the water-mixed materials.
- #32 Add powder to water. Mechanical mixing 60 sec and vaccum mixing 30 sec
- #33 Add in increments. Use small portions for teeth that are to be clasped.
- #34 This mold is over filled and the investment touching the casts may be distorted because of restricted expansion
- #36 Place the cast in dry oven for at 200 farenheit for 2-3 hrs. Treating the cast with spray or bees wax. Make it less abrasive
- #37 Casting ring ¼ inch clearence
- #39 26 gauge major connector 14 gauge for outer strud, 18guage for cross struds
- #40 Blue casting wax into the beading. 2-3 mm wide. Reinfirments of wax added in the palate Tacky liquid applied on the cast for close adaptation of the pattern was to cast Spoon or roach carver is used to seal the wax and cast borbers
- #41 Out and cross struds
- #43 Undercut will lock resin in place
- #45 Tacky liquid applied 6 guage pear shaped wax
- #46 18 guage for lingual bar and onto anterior teeth
- #47 An opening to remove wax and introduce molten metal in sprue Also acts as a reservior
- #48 Vulcanite bur. In the center. The hole is bigger at the bottom. Use a bp blade
- #49 ticonium sprue cones. About 10 mm outside. Seal them
- #51 10 guage for sprue lead Auxilllary leads 16 guage
- #52 Tree, circular and ball The results of this study indicated that the ball-sprue design produced better castings than the tree and circular sprues,
- #54 Surface tension reduing agent is applied before investing
- #55 After investing the pattern, it is allowed to set for an appropriate period- approximately 1 hour for most gypsum and phosphate bonded investment. excessive vibration should be avaoided as heavy particles will get accumulated at the bottom and free water accumulation adjacent o wax pattern may occur Allowed to set for 1 hr
- #56 During burnout, some of the melted wax is absorbed by the investment and residual carbon produced by the ignition of the liquid wax become trapped in the pores investment If burnout is not done immediately place the invested ring in 100 %humidity (humidor)
- #57 Water trapped in the pores of the investment reduces the absorption of wax and as the water vaporizes, it flushes wax from the mold
- #58 Centrifugal force machine. Too less force will cause freezing of metal before it reaches the ends. Too much force will cause turbulance and air entrapment
- #61 Wet and dry Wet provides dust free and slight shine 250microns
- #62 Co cr castings are not pickled. Gold must always be pickled in acid pickling solution Removes the base metal deposits, oxidation and other contaminants If not removed can cause tarnish and corrosion
- #63 Sprue seperating disk As close as possible without nicking the frame work
- #64 Gring off the stumps with 7/8 inch stone
- #65 Barrel shaped mouted stone, fine tappered mounting stone or carbide bur to remove flash from clasp arms, minor connectors, rest and indirect retainers
- #66 Inverted cone to sharpen edges in undercuts
- #67 Rubber abrasives are used for fine finishing Small felt wheels with tripoli to remove traces of marks left by rubber wheel Polish with cloth wheel and tripoli
- #68 Chloroform can be used to remove traces of tripoli Check for fit To remove blockout wax from cast soak in warm water for 5 mins 49 celcius Then hot slurry water 95b celcius
- #69 Electrolytic polishing is a kind of electrolytic striping Atoms from the rough projections from the frame work fall into the solution before the atoms in smooth area
- #70 1. Usually, the functional impression is made for a distal extension base, whereas the master cast is adequate for most tooth-supported edentulous areas.
- #71 The laboratory procedure involves making a corrected. or altered, cast. Ridge area that were recorded in the functional impression arc removed from the cast. The framework is seated on the cast, and new ridge areas are poured in dental stone.
- #72 1. Use a sharp knife to trim away the excess impression material
- #75 Form this mixture around the impression
- #76 6. Paint the plaster/pumice area with a stone separating medium
- #78 10.Remove the boxing wax and plaster/pumice mixture from the cast.Remove the framework and impression from the cast.The corrected cast is complete
- #79 The dentist will generally specify the teeth. Trimming is needed in the ridge lap area, articulating paper can be used to detect where the trimming is needed
- #86 Sacrificial patterns Virtual patterns were then created for fabrication of frame work Flexible nulone poluamide denture base resin with conventional heat cure resin combinations is used