We will talk about dental waxes; u can use dental wax in the lab or in the clinic for different purposes:
|In clinics |In laboratories | |Bite registration : to know the occlusal relationship between upper|Boxing techniques : when we want to make a base | |and lower teeth | | |we can use a wax sheet to set the teeth in complete denture we use |Baseplate for complete and partial dentures | |wax sheet we make adaptation of it on the cast Alterations and | | |adaptation for impression trays if the tray is too short ( not | | |reach all the teeth we can add wax to register all the area ) | | |so u alter the size and use the wax for this purpose | | |Direct waxing for cast restorations |Hold components before articulation | | ____________ |Indirect pattern for casting |
■ Natural waxes produced from:
■ Minerals: paraffin wax
■ Animals: beeswax
■ Synthetic waxes
■ Additional components: gums, oils, resins, fats just to change the properties .
1) melting range :Because waxes composed of different component they don’t have a melting temperature , they have a melting range so if u want to use the wax u have to know what is the melting range of it so u can manipulate correctly for example ( if u want to register the occlusal relationship between upper and lower teeth if the wax u use melt below 37 ( body temperature) then it will be soft if u put it in the patient mouth so the registration not accurate
2) flow : is also important for the same reason ,some waxes flow under high temperature so u have to know this temperature so u can manipulate correctly .
So these two properties can be represented in this diagram:
We have got three different blocks of wax on top of each wax we have certain amount of weight
*If we put the first wax in low temperature below its melting point so there is no change in the height of the block.
* if we increase the temperature the wax will start to flow because is getting closer to its melting range and because of the weight over this wax it is start to flow so flow increase .
* If you reach the flow temperature which is the melting range the block will melt with weight as time passing.
So flow and melting range are important properties for the manipulation of the wax.
3) excess residue : we mean with excess residue that if we use a machine for melting of the wax before using it when u are shacking crown and bridges making cast restoration these machine make to be clean properly from the wax because if they are remnant from the wax then u add new wax the melting range will be inaccurate so the properties of the wax will be change so this is the job of the technicians in the lab so machine that u use to melt the wax or process it need to be cleaned properly otherwise if excess wax remain it is called excess residue not all of it has been removed lead to inaccuracy and it will also affect our restoration later on .
4)Dimensional changes : wax expand when heated and contract when it cooled down, this properties is important when u are...
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