Troubleshooting Crown and Bridge Technique
Contents
1. Use runner bar for larger pieces Attach sprue to thickest part of wax up Do not taper sprues towards casting Use carbon free investment such as Castorit Use casting crucibles for one metal only Remove slag from crucible and replace old crucibles Use melting crucibles for one metal only Keep them clean Burn out modelling wax and plastic completely Extend burnout time raise temperature ENGLISH Ring heated too quickly Metal cast too hot Liner Kera Vlies used incorrectly Investment processed too cool Ratio of powder to liquid not observed Secondary parts of telescope crowns were made with plastic caps that were not cut Wrong concentration of mixing liquid for powder Castorit super Platorit Heating rate 5 C 41 F per minute Holding time 250 C 482 F for 60 mins Do not overheat melt otherwise rough surface and tighter fit Place layer of Kera Vlies moistened in the metal ring Room temperatures and temperature of powder and liquid should be between 18 C 64 F and 20 C 68 F See instructions for use less liquid gives looser fit more liquid gives tighter fit When plastic caps are used these must be cut to release tension If the expansion of the liquid for a certain alloy is not sufficient the next higher concentration liquid should be used i e liquid B instead of liquid A or C instead of B Liquid must be used i2. crucibles Frame stained after oxide bake Discolouring of porcelain Chipping of ceramic coating poor adhesion ENGLISH Incorrect grinding materials used for preparation Contamination by incorrect blasting and cleaning Unsuitable solder used Wrong crucible used different alloy Frame not cleaned between bakes Wrong grinding materials Wrong solder used Old metal reused Casting metal overheated 10 Use grinding material for one metal only Use clean grinding material Observe recommendations of porcelain manufacturer for cutting tools e g carbide burs for CARMEN Use clean Aluminium oxide Ultrasonic cleaning with distilled water Use Rema Sold solder Use crucible for one alloy only Clean frame between bakes brush under running water after every porcelain bake Use grinding materials for one metal only Use only clean grinding materials Use Rema Sold solder or laser welding Use new metal only Release centrifuge sooner 18 Chipping of ceramic coating poor adhesion Chipping of cervical edges Chipping of cervical edges during blasting of inner crown sides after glazing ENGLISH Did not use separate crucible Remanium CS CD Remanium 2000 Remanium G soft Frame surface not properly prepared Blasting media too fine Unsuitable opaque paste used Cooling phase in porcelain furnace unsuited for
3. Troubleshooting Crown and Bridge Technique ENGLISH Dear Customer Thank you for selecting Dentaurum products for crown and bridge dental prostheses You decided to purchase high quality products that are precisely adapted to one another and produce accurately fitting attractive dental prostheses The production of high quality dental prostheses is dependent on precision workmanship and close attention to the processing instructions However should you have difficulty in using our products we would like to assist you in finding a solution This brochure contains useful information to help you avoid mistakes in using our products and to identify the cause of problems that might occur Should you require further assistance do not hesitate to call our customer service department The phone number is 49 72 31 80 34 10 ENGLISH Contents Page Problem analysis during processing 4 13 Wax up and spruing 14 Storage of investment 15 Problem analysis alphabetical index See number Beads on surface of casting 7 Breaking of pontics i e crown flooded 10 Bridge is rocking 14 Bubble formation in the porcelain 21 Casting investment material inclusions 8 Casting not completely filled round holes in crowns and or rounded cervical edges 5 Casting porous shrinkage 11 Cast surface beads 7 Cast surface rough 6 Ceramic bubble formation 21 Ceramic coating chipping poor adhesion 17 Ceramic discolouring 16 Cervical edges chipped 18 C
4. alloy Frame not sufficiently cleaned after sand blasting Opaque firing done with one bake only Frayed edges in cervical area Blasting pressure too high 11 Use separate crucibles Remanium CS CD Remanium 2000 Remanium G soft Follow porcelain manufac turers recommendations for grinding instruments e g carbide tipped burs for CARMEN Grind in one direction only Use coarser Aluminium 125 250 mu blasting pressure 2 3 bar Use opaque suitable for ceramic system Longer cooling for Remanium CD and possibly also Remanium 2000 see instructions for processing Ultrasonic cleaning with distilled water Opaque firing with two bakes Bake 1 wash bake Bake 2 covering See porcelain manufacturer s instructions Minimum metal thickness 0 2 mm Use less pressure for blasting cover edges with wax Cracks in the porcelain ENGLISH Slow cooling not observed Faulty frame wax up Baking of base material at low temperature opaque Individual teeth not sepa rated down to the opaque at time of dentin bake Bonding agent used Wrong solder used Bridge buffed or polished at too high a temperature after glazing 12 Slow cooling of non precious metal alloys according to instructions of the porcelain furnace manufacturer Allow dentin and glaze bake to cool to 600 C 1112 F in the baking chamber approx 8 minutes When wax
5. der to avoid chipping of the porcelain the lingual metal margin should be placed below the incisal region Contact surfaces provided for soldering should be flat O Rounding of the metal porcelain interface ensures cleaner margins and an esthetic colour The outstanding properties permit very thin connections to be used between the crowns and pontics During the later porcelain baking process the individual teeth can be seated clear of the the adjacent teeth This avoids a block appearance Spruing For large castings with up to four pontics use the indirect method Runner bar Casting button sprue 3 3 5 mm dia Runner bar 4 5 mm dia Connection to the crowns 2 5 3 mm dia length 3 5 mm Use the direct method for single crowns and small bridges For normal crowns sprue diameter 2 5 mm length 6 10 mm Larger crowns and connecting pontics 3 0 mm dia length 6 10 mm Sprue reservoir by the direct method distance to the object to be casted ca 1 5 mm 14 ENGLISH Storage of investment powder Mixing liquid Investment powder Measuring beakers Service Protect from excessive cold and direct sunlight Close the bottles immediately after use Store at room temperature 18 22 C 64 72 F In warm weather store the liquid in a refrigerator not in a freezer Liquid containing crystals or sediment should not be used Observe the date of manufacture Storage period in unopened bottl
6. e 15 months To avoid frost damage during transport the liquid should be ordered in November before the beginning of winter Close bag tightly immediately after removing powder Store in dry area Storage period in original unopened bags 24 months Replace soiled measuring beakers with new ones Order these from manufacturer In all processing matters not dealt with in the information brochure please contact our dental technology department Telephone 49 72 31 80 34 10 15 Z LU a ZO LO uewion wninezuaq Aq paud Q7 08 686
7. ervical edges chipped when blasting the inner side of crown after glazing 19 Cervical edges frayed sharp edged porosity in casting 9 Chipped cervical edges 18 Chipped cervical edges when blasting the inner side of crown after glazing 19 Chipping of ceramic coating poor adhesion 17 Crack formation in ring 4 Cracks in ceramic coating 20 Crowns fit too loose 13 Crowns fit too tight 12 Crowns flooded i e breaking of investment dies 10 Crowns round holes and or rounded cervical edges casting not completely filled 5 Discolouration of ceramic material 16 Fit of crown too loose 13 Fit of crown too tight 12 Frayed cervical edges sharp edged porosity in casting 9 Holes round in the crowns and or rounded cervical edges casting not completely filled 5 Inclusions of investment material in casting 8 Investment material does not set or sets too slowly 3 Investment material sets too quickly 2 Investment dies break off i e crowns flooded 10 Porosity in casting sharp or frayed cervical edges 9 ENGLISH Problem analysis alphabetical index See number Porous castings shrinkage 11 Ring cracked formation 4 Rocking of bridge 14 Rough surface on casting 6 Shrinkage porous castings 11 Stained frames after oxide bake 15 Dentaurum products Castorit super investment material for precious metal crown and bridge alloys Castorit super C investment material for non precious metal crown and bridge alloys Castorit super all speed crown and b
8. ical edges sharp edged porosity in casting Rough casting surface Rough casting surface 7 8 Sprues and funnel formers Correct waxing of sprues not properly waxed Wax surface tension Wax surface tension reducer not correctly used reducer must always be blown dry Ring pre heated too quickly See processing instruc tions for investment material Ring setting time too short Setting time 40 minutes or standing time too long ring must not be allowed to dry out ENGLISH Frayed cervical edges sharp edged porosity in casting Crowns flooded i e broken investment dies Porous castings contraction pits Solid plastic parts used Adhesive for retention beads not suitable Investment material inclusions Wax surface tension reducer used incorrectly Pressure investment Steam de waxing Pre heating of ring too rapid Poor metal flow due to incorrect spruing Use tapered sprues Investment compound used that contains carbon Incorrect or old crucible used Dirty crucible with metal residues from another alloy e g Pd alloy Incomplete burnout of alien residues Use plastic only when it burns without residue and is coated with wax Change retention adhesive Wax connections correctly Wax surface tension reducer Lubrofilm must be blown dry Not recommended Do not use See instructions for processing investment material Use thicker sprues
9. ing up frame ensure that not too much material is used when applying ceramic Maximum thickness of porcelain 2 mm follow processing instructions for alloy used After baking the opaque should have a silky finish Increase bake temperature Separate the porcelain down to the opaque with a razor blade or similar tool Do not use bonding agents Good adhesion is achieved if the frames are correctly prepared Use only Rema Sold solder Polish and buff with care Bubbles formed in porcelain ENGLISH Wrong torch setting when casting with torch Porosity in frame Overlapping in frame preparation 13 See instructions for casting alloy in question Use thicker sprues For larger workpieces use runner bars Attach sprue to the thickest part of wax up Grind in one direction only Follow porcelain manufac turer s recommendations regarding preparation of frame ENGLISH Waxing up Minimum preparation for metal and porcelain single crowns 1 3 1 5 mm bridgework 1 5 2 0 mm Before the wax up the preparations should be coated with release agent The size of the metal crown should be reduced to correspond to that of the final prosthetic crown missing portions of the teeth should be compensated for O A cross sectional wall thickness of 0 4 mm at the occlusal surface will ensure successful castings Uniform porcelain thickness ensures stress free bonding O In or
10. n concentrated form Additional expansion of both investment materials can be obtained through hygroscopic investing Bridge rocks Frame stained after oxide bake ENGLISH Ratio of powder to liquid not observed Wrong concentration of mixing liquid for powder Castorit super Castorit super C Platorit Invested without ring Uncontrolled expansion Wax structure contained stresses Overall expansion of investment material too high Invested without metal ring For further problems see Fitting of crowns Wrong casting crucible or old casting crucible See instructions for processing investment material less mixing liquid gives a looser fit more liquid gives a tighter fit A tighter fit is obtained by diluting the liquid for the alloy type in question with distilled water The dilution may be as high as 50 Depending on the alloy the concentrated Platorit liquid can be diluted with up to 20 distilled water Use metal ring with a layer of Kera Vlies Kera Vlies must be dampened with water beforehand Wax up free of stress under uniform temperature conditions A lower degree of expansion of the investment material is achieved by diluting the liquid Use metal ring with a layer of Kera Vlies Kera Vlies must be dampened with water beforehand Use crucible for one metal only Use new crucible if level of residue is too high Only use ceramic
11. ridge investment for all alloys Platorit investment material for precious metal crown and bridge alloys Remanium CD CoCrMo porcelain bonding alloy Remanium Cs NiCrMo porcelain bonding alloy Remanium CSe NiCrMo porcelain bonding alloy Remanium 2000 CoCrMoW porcelain bonding alloy Remanium 2001 CoCrMo porcelain bonding alloy Remanium G soft crown and bridge alloy NiCrMo based ENGLISH Problem analysis after completion of work No Problem Mixing consistency too thick or too thin Investment sets too quickly Investment sets too slowly or not at all Cause Incorrect mixing ratio of powder to liquid Powder and or liquid too warm Mixing container dirty plas ter soap electrolyte oil Moisture in investment material Remedy Observe mixing ratio stated in instruction manual Ideal processing tempera ture 18 22 C 64 72 F Keep mixing container clean Do not allow powder bag to remain open Investment material or liquid Observe recommended too cold processing temperature Store investment and liquid at room temperature 18 22 C 64 72 F Formation of cracks in ring Setting time too short Ring allowed to bench set too long and has dried out Incorrect or too rapid preheating of ring Use of solid plastic parts Pressure investing Steam de waxing Liquid crystallized Liquid with red film bacteria formed Obser
12. s sary re calibrate burnout furnace Check burnout furnace temperature Casting delay time not over 40 seconds Pre melt metal Follow instructions for melting metal Heat crucible Check centrifuge If necessary attach air vents 1mm min Crowns should not be covered more than 8 mm with investment material air block Do not place crowns too close to ring edge Minimum thickness of wax up 0 4 mm Beads on casting surface ENGLISH Wrong or thin sprues Use thicker sprues or runner bar Metal overheated Cast colder With Care required with vacuum Remanium C B alloys and pressure casting devices use of high frequency in combination with high release centrifuge melting point alloys immediately when oxide skin begins to crack Take care when using electric arc melting machines Ratio of reused metal too Depending on alloy use at high least 50 new material With Remanium CS 2000 and CD use only new metal Ring held too long at Do not hold at final casting temperature temperature longer than 1 5 hours Incorrect use of wax Wax surface tension surface tension reducer reducer must always be blown dry Investment mixed without Use efficient vacuum vacuum or with inadequate mixing unit and stir for vacuum 60 seconds Wax surface was not Use wax tension reducer tension reduced Lubro film Important blow dry Inclusions of investment material in casting Frayed cerv
13. ve setting time of 40 minutes Place ring in burnout furnace after 40 minutes setting time Keep ring moist over weekend or dry on same day at 250 C 482 F Place ring in cold burnout furnace Heat up slowly 5 C 41 F per min and observe holding time of one hour at 250 C 482 F Solid plastic parts sprues must be coated with wax Not recommended Not recommended Use fresh liquid and keep tightly closed Liquid stored too long or not properly closed Use fresh liquid Cracks in ring Casting not complete Round holes in crowns and or round cervical edges ENGLISH Liquid stored too cold or ordered during cold weather Dirty mixing bowls and beakers Invested with liner without metal ring Wrong positioning of ring in burnout furnace Effect of impact Ring temperature too low Casting release of centrifuge delayed too long Melt too cold Ceramic crucible not preheated Insufficient torque in centrifuge Wrong position of casting object in ring Wax up too thin Order before beginning of winter Do not store liquid under 5 C 41 F Always keep bowls clean Do not use them for plaster or clean with soap Use metal rings Place rings in burnout furnace with casting funnel pointing downwards Allow ring to soak long enough at correct temper ature see instructions 30 minutes 1 hour Check final temperature of burnout furnace If nece
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