Maggio / Giugno 97                            PROSTHESIS
A New   Thermal Treatment of  precious and palladinized   Alloys    






By Rosario Muto

  As  well  known,  the fusion  process of dental  alloys in  the laboratory consists of      putting  the solid  metal  in  a  furnace  at  controlled temperature, or  using the system  of crucible  with oxygen and propane. The  metal,  made liquid   that way,  gets   immediately put  in  a  previously  heated  fireproof cylinder.    On getting  cold   the   alloy  get  its   solid  state again, reproducing the fixed shape. During  the  phase ransition  (solid -> liquid -> solid)  the  metal  undergoes  stability  variations, then the  (solid) object  is  treated by a thermal procedure, that is  said by experience to be able to guarantee stability.  This procedure is generally followed with  all kinds of prosthesis  with noble or  palladinized alloys.   After  the polishing treatment to make it  fit the alloys for ceramics undergo a further thermal treatment to produce a chemical bond with ceramics.  

As well known, the metal treated that  way provokes oxidationreduction  pheno mena in the buccal cavity    that weaken the harmlessness of the object. After variousresearches and experiences about the phases of metal manufacturing in 1992 I begun to stabilize alloys  by the help of a gelatinoid compound I have created, which cuts down surface   oxides heavily, and above all prevents them from forming again in the  following bakings.  Rosario Muto was       born on the 6/9/58       in Naples and got a  diploma in 1979 at  Istituto professionale "Casanova"in Naples   He has been  in   charge of a dental technology laboratory  since 1981.   At pres-  ent he works in Prato     (PO)  and collaborate      with Odontologist  Dr.Marco Cipriani.  He has taken part in several advanced refresher courses as to gnathology, prosthesis implant and metallurgy.  He  has attended ceramics- metal master courses in Italy and abroad, cooperating with several firms about electro medical system projects and realization.

  Consequently a dark surface structure   is   got,        which provokes   negative       conse- quences     owing     to      the ceramics  -  metal   adhesion, beside   influencing  the final effect    of    colour   and    its brightness.                               This      happens   with   pal- ladinized  alloys particularly, because   they   favour   the creation   of  oxides  during the    repeated   baking   of ceramics..



  N. 1 - The gelatinoid product for alloys tratment

          RASSEGNA ODONTOTECNICA            pag. 33
N. 2 - Crowns (2%Au palladinized      alloys) at the and of the thermal treatment N. 3 - Remember to apply the product also iside the crowns N. 4 - As it can be easily noticed, cats have got a light appearance after the thermal treatment

This means a lower  absorption of these  substances by the   body and therefore a lower potential chronic toxicity. The object, moreover, shows a clearly higher  aesthetic quality if treated that way. It's also important to deal the  alloys used in resin-gold work so that oxidation-reduction phenomena that damage the bond  are prevented. In fact they create a space that may be infiltrated by saliva, causing the detaching eventually. The product is a gel, so that it can be applied easily and quickly thanks to its physical-chemical properties.   Actually the gel but creates a glassy layer, under thermal  effect, so that the metal lacks  oxygen when the temperature for the thermal treatment is reached. This enables a stabilization of the crystal lattice  of the alloy, while bonds between oxygen and metals, that provoke oxides, are prevented.  

  N. 5 a /5 b / 5 c - Example of mized work : postceramized welding, between ceramics-gold and richmond in resin-gold
N. 5 b --/> N. 5 c  --/>
N. 6 a / 6 b / 6c - Example of work by precision bar, junctures incluted, welding on richmond, bound to get on overdenture N. 6 b  --/>
  N. 6 c  --/>
N. 7a / 7 b / 7 c  - Ceramics-gold structure before the thermal treatment  
N. 7 b  --/>  
  N. 7 c  --/>
N. 8 a / 8 b  - Resin-gold work: the brightness of the metal treated by thi product is noticeable  
N. 9 - Close-up of a ceramics group with milling: the product has been applied in order to eliminate surface oxides, and  make rectifying and polishing easy --/>  
N. 10 - The product is fit for all the metals used in the buccal cavity, therefore for stunp pins too --/> N. 11 - After the treatment --/>