Monthly Archive for April, 2007

The anatomy dissection hall… Found it on my fren’s friendster photos… “Grabbed” it… Hehehe… This picture was lost after transfer to this blog (actually the fact is – blogger lost it, LOL), thanks to Yi Han who answered my “call” in fb and uploaded it.

So this is it, no AC, and the windows are directly facing the corridor (outside of class room) I shown last time… For us this room doesn’t gives you any creepy feeling at all… Haha… Say hi to the two fellas people there…

Just as I said… Gotta show you all what we did over here after the cube making shit… Hehe…

Now we are constructing a removable complete denture (those people wear when they lose the whole set of dentition), which is the exercise for 1st year… Before going any further, I should clarify some terms I’m going to use… Hehe… Obviously for construction of denture, we can’t just work on the patient’s mouth, thus we have to replicate the oral cavity so that the patient can go back home first while we are working on that replica, right? Thus here comes the term impression and cast.

– Impression –
Not the abstract impression, but the concrete thing. It’s made by using some kind of soft material (where the consistency is something like play dough, or better if less viscous) and press it on the oral structure and then let the material becomes hard (mostly chemical setting reaction) and then take it out.

The correct definition for impression is ‘the negative replica of oral cavity made by using impression material’.

– Cast –
So the impression is made, and it’s something like the ‘negative’ of oral cavity, where those empty space in oral cavity is filled (in impression) and those filled space of oral cavity is empty (in impression). We can’t work in a ‘negative’ right? Just like the negative of pictures we take, we just can’t make out who the h*** is the person in a film unless we develop it back into a ‘positive’ right?

Ok so now we’ll be pouring something into the impression which will set inside the impression… Yeah, you can call the impression as a “mold” at this point… No no, we are not going to pour metal, haha… but just plaster, or gypsum (we have a whole chapter for gypsum, hehe)…

So as you can imagine, cast is the ‘positive replica of oral cavity’, and the material used is usually rigid after setting. Yeap, we desired the impression material to be rigid too after setting, but one more thing is we want the impression material to be easily removed, or the cast can be easily obtained… Yeah, yeah, we have to study the ideal properties of all the materials…

– Procedure –
Yeah, here comes the main part… Of course the first thing in denture construction is to make an impression by using what we call tray (impression material is loaded on the tray then only we take impression, don’t tell me you imagined a dentist to stuff a whole chunk of dough-like substance in the mouth for the impression… Hahaha…)… There’re a few types of trays also, but I’m going to tell you the two types – Stock tray and custom tray… You should be able to guess by the name – One is available in the market and one is custom made…

And what’s the different? Yeah, the proper procedure after making the 1st impression is to pour Plaster of Paris (Type II gypsum product) to get the cast, we call it as Primary cast… Then on the primary cast we’re going to construct the custom tray (using acrylic resin or shellac base plate, explained below), and then using the tray, together with another more proper impression material, we’re going to make the impression again, which by right should be more accurate lah, known as secondary impression… So again we pour the cast and now it’s known as the secondary cast or master cast on which we are going to work …

Shown below is a metal stock tray (you can see tray only, the impression material’s supposed to be on the tray, but was completely destroyed when recovering the cast) with a cast poured using dental stone (Type III gypsum product)… Oh ya anyway, we are now learning the pre-clinical work, so no real patient mouth is involved… Hehe… These are made using models provided by the lab…

So let’s assume that we’ve gotten the master cast… The next step will be constructing what we called temporary denture base (denture base is the part of a denture without the artificial teeth) by using shellac base plate (brown colour one) which has the thermoplastic property (soften after heating), I can’t take the picture of the temporary denture base alone because that time Vidya (the bitch) wants us to do fast fast… And she actually broke my first work because she’s not satisfied with it… (Yeah.. Blardy bitch she is..)

So we gotta continue the next step… Known as occlusal rim, using wax… We are to build the wax-made occlusal rim on top of the temporary denture base, the occlusal rim is going to be a base where the artificial teeth lodge… Hard to tell you in words but see the pictures below and you shall understand, the brown part is the denture base and the red part is the wax-made occlusal rim… If you wonder how come the cast is soooo beautiful, yeah, it’s different cast… Haha… Vidya wants us to get this cast to work on only… It’s made by the lab lah, using molds – that’s why it’s so cantik-molek…

And several pictures when the upper and lower part is put together…

And now we are going to mount the cast together with the occlusal rim on a err… machine known as articulator, because by mounting it on articulator, the upper and lower part is fixed in a fixed position, thus we can open and close the casts as if it’s in a real person’s mouth, or put it in another term, to simulate the temporomandibular joint (it’s the joint of your mandible to the skull)…

Oh ya, the mounting is done using plaster again… Hehe… If you can’t imagine how the thing can open and close… Err… The purple thing is the fulcrum point, and the metal bar in front there is attached to the upper piece, ok? Still cannot? Nevermind, I’ll show it in the final process where all the teeth has been arranged on the occlusal rim…

So now… The whole thing is ready for teeth setting…

Those are just acrylic teeth, or put it in another term, plastic teeth… In which the plastic is no ordinary plastic… Quite hard and durable instead… Plastic is a very broad class you know… We called it resin… Hehe… In case you wonder what the denture base is made up of, it’s also acrylic resin…

We start with the upper anteriors because the teeth of upper anteriors have to follow a plane (occlusal plane) where the tips of certain teeth (central incisors and canines) have to touch the plane while the lateral incisors have to be slightly above the plane… And also all the inclinations is another headache… Because the blardy lecturers have different comments everytime… Sometimes today after you let him (the ngiau ji)/her (the bitch) correct the arrangement and don’t touch it, tomorrow you let them see again they say it’s wrong… Duhh…

So after the upper anteriors we’ll arrange the lower anteriors according to the upper ones… Now only I know the relationships of upper and lower ones are supposed to be like this…

My own teeth are not like tat… Far away from normal… Haha… The lower should be behind of upper (known as overjet, while mine is opposite) as well as the lower and upper does overlap (known as overbite)…

And now we are ready for the posteriors… [to be continued]

*: Exams coming, internet’s lousy, I’ve used 3 days to upload the photos here… Haha… So expect another delay again…