Lecture 1, Introduction to Complete Dentures (Script)

8/4/2019 Lecture 1, Introduction to Complete Dentures (Script)

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Prosthodontics:Lecture # 1:Date: 27/9/2011

NOTE:I didnt have the slides when I wrote this lecture, so please, toavoid any confusion refer to the slides while studying.

Your Laboratory sections have been changed again, Its for yourown good..Is there anybody who is not registered for the course yet, but hesattending today?

There will be a list which will be turned around, I need you to sign

your name.. ok?If your name is not on the list, please write it, Ill understand that

you are not registered for the course yet.. In the future, Ill be takingthe attendance according to the seat number.. but for now, thenumber is not complete.. Ill give the seat numbers to your CR or Illput it on the e-learning.

I was informed yesterday that the maximum number of studentsallowed in each section is about 63 students, I think what they did is

they took the first 63 students in each section and kept them, and theones which are above 63 were moved into the remaining sectionswhich are not full (sections 3 & 4).

Ill hang the list outside the prosthodontics laboratory, section 2 ison Sunday, 3 is on Tuesday, 1 is on Thursday, section 4 is divided onMonday and Wednesday.

A lot of you asked me about the exam, we have a midterm examon the 19th or on the 12th of November, at 8:45 am , 10 H1,H2,H3 andH4.. so Itll be Saturday morning.

Now, very quickly I am going to repeat some of the things which Isaid in the lab (some of you have taken them), and some of the thingsthat Ive said during the last lecture.

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Quick introduction to the removable prosthodontics, and what thedivisions are for removable prosthodontics..You already know that prosthodontics in general is divided into:

Fixed ( Crowns & bridges )

RemovableIts not our business to discuss crowns & bridges during this

course, we said that we are (not) involved in bridges replacing specificteeth, fixed restorations which are cemented to the teeth , like this,which are made usually of enforced metal, or ceramic materials, ormetal materials.

Our job this semester will be to replace arches which have no teethat all (complete dentures) .. Complete dentures come in different

forms, we will learn about the conventional or the traditional techniquethis semester, there are also things called immediate dentures or overdentures, you may hear about them, and like I said these are moreadvanced, youll learn more about them in your 4th and 5th year.

An immediate denture.. If a patient comes, and we extract alltheir teeth, they have to wait for healing of the extraction sites beforewe can make a new denture, that means we have patients in society,stay 1, 2 ,3 ,4 and sometimes six months without any teeth, and for

some people that is unacceptable, depending on the patients age,occupation, and their social status, in such cases we can makesomething called an immediate denture.

We make impressions, we take records before the teeth areextracted, and the day the teeth are extracted we give the patient thedenture.

It sounds simple, but its more complicated than that, which isdelayed until we learn the conventional technique, thats what animmediate denture is. (, (

An over denture is a denture over roots, sometimes we canhave teeth in the mouth but we still can make a complete denture, wecut the tooth off the crown, and we leave the root, and thats why the

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denture instead of setting on the soft tissues of the gums, it has somesupport from the natural roots. Again, its not as simple as it sounds, ithas specific requirements and the way that we deal with it inside thepatients mouth.. Youll learn more in the coming years.

So essentially we are replacing the entire arch for patients withoutany teeth at all, like I said, next semester youll take a detailed courseon how to make removable partial dentures, I said in the lab, if youhave one tooth missing, or you have fifteen teeth missing, and onetooth left, the replacement is still called partial denture.) ( ,

These prosthesis (partial dentures) are usually two types: Is made entirely of acrylic or plastic. Is usually based on metal (cobal cronium alloyed) (not sure of the

spelling) With plastic.

So in this case you can see that we have a metal frame work tomake it stronger, and the acrylic is there just for the appearance notfor support.. ok?In this case we have no teeth on one side entirely, and you can see wehave partial denture going from one side to the other .. Youll learnthat we dont make removable prosthesis in only one side of the

mouth, if we have one or two teeth missing on this side, we cant makeremovable prosthesis just on this side, we have to extend to the otherside for balance and support, because if we make a small one on oneside, and its removable, it will come out of the patients mouth, or theymight swallow it, or chock, so we have to take advantage of the otherside.

Whereas fixed prosthesis, because they are not removable, can bemade unilaterally, or on one side.

And there are two branches of removable prosthodontics which youwill take a lecture or two about in your undergraduate education butyou wont practice.

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The fist one is Maxillofacial prosthodontics, itssomething we usually teach in details in higher specialty courses.In Maxillofacial Prosthodontics we are not talking about missing toothor gum structure, we are talking about missing entire parts of the

mouth or the head and neck region, the entire palate maybe gone, forcongenital reasons, for traumatic reasons, or due tomalignancy after surgery.Sometimes patients lose a large part of their palate or jaw, or evensometimes their face, so in this case, which we can see on the screen,is an example of a soft palate obturator.

Everything in the body is there for a reason, even the appendix,regardless what they tell you, everything is there for specific reason, ifthe soft palate goes, you lose a very important valve, which divides theflow of air, water and food, nose and the oral cavity, if its removed,the patient can no longer swallow normally, no longer breathenormally, no longer speak normally.. So what we do is we replace it,its not as good as the original, but at least blocks ..Its calledobturator. ()

Here parts of the soft and the hard palate were gone, needs asurgery, and you can see we are making denture with an extension.Sometimes larger parts of the face are missing, if the plastic surgeon

or the surgeon is not able to replace certain parts of the face, and ifyou read the news, over the past few years, theyve been talking aboutentire or partial facial transplants, this is very recent, but in the past,many many decades ago, the only way to replace missing facialstructure is using the state prosthesis, and its based on silicon thatlooks very close to natural, but is not identical (not sure) , very difficultto fabricate but its also part of the prosthodontics specialty.And these procedures are done at the university.

And the second is Implant prosthodontics, hopefully ifyour course schedule doesnt change, in the 5th year you are going totake an entire course composed of two semesters. We will take a detailof the theory, not so much practice.. and itll be incorporated with thenumber of courses.The implant prosthodontics isnt yet called a specialty by itself, thereare few programs in the world that teach something called implant

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prosthodontics, but in general implant prosthodontics at the higherlevel is divided between different specialties, theres:

A surgical part.A restorative part (which is the prosthodontics part)

So, as a specialist I dont usually do the surgery, the surgeon does,he places the implants, then sends the patient to me, and then Icomplete the restoration on top of the implant.

Examples, if you are not familiar with what the dental implant is,its a screw or something that looks like a screw which is made ofmaterial, which is not only biocompatible, its bioactive.So the bone thinks its natural tooth structure, so it builds up against itand attaches to the body, the body is deceived into thinking its abone, so Itll attach to it, so once its attached to the bone, we can useit for support and attach teeth to it, and dentures..

Theres a misconception, some think Implant always means fixedprosthesis, I have an implant, I put the tooth on top of it, Its notnecessarily so, some patients cant afford 14 implants, so we place fewimplants, then we place a complete denture, so it becomes an overdenture ( , (, So most of the implants are made of Titanium, titanium is a very

special material: Its strong enough to support a prosthesis. The body thinks its a natural tissue.

There are implants in different shapes and forms, youll be surprised( , , , (

This is a process you will learn, its called oceo integration,Gold is not used in implants In implantation we use natural products,

so the body can attach to it.This is another prosthesis on the same implants, you can see an

entire arch was placed on these five implants, it was actually screwedin place, sometimes its screwed in place using cement.

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These are the basics of different procedures we use to makedifferent types of prosthesis in dentistry, youll learn about someprocedures next semester, and if you continue your education afteryour graduate youll learn more procedures.

Like I said that our job this semester is complete denture, andthose of you who came to the lab, have already seen this specificsequence that we talked about at the end of last lecture, you have torepeat it several times, because I want you to know it by heart, thesequence of fabricating a complete denture, Its very important, youneed to be able to close your eyes, and immediately visualize the stepsof complete dentures fabrication. So those of you who were with meduring last lecture and in the lab..How many steps are there for the fabrication of complete denture?

There are 9 steps; these steps are divided in between: Clinic Lab

Remember, complete denture is something called an indirectrestoration , unlike CONs where the patient walks into the clinic, hastheir tooth restored at the same day, these restorations require thehelp and the support of a dental laboratory technician.

And the problem with these is that they are made out of materials

that need to be polymerized or cured, we need high temperatures,these materials are poisonous when they are being processed, I cantmake these inside the patients mouth, its just not practical.

So if you were in the lab, youd also know my entire objective forthe first three clinics is just to take records to make a copy of thepatient, not just a copy of the arches, but also the relation between thearches, and we said for the first three visits we are just takingrecords, I havent made anything yet.

1)In the first visit, Ill take something very simple, Ill make

something called primary impression , I cant just make a balland put it in the patients mouth like a chewing gum, I need to usesome kind of container to carry the impression material from mywork area into the patients mouth, we call this a tray .. ok?

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In the clinic:We put our impression material inside the tray, we take it to the

patients mouth, its soft, but inside the patients mouth it will

solidify, either because of temperature, itll cool down and becomestable and solid, or due to a chemical reaction.. it will set andbecome ready to be taken out of the patients mouth.

Now, In general, almost all impression materials last for about 2 10 minutes. Actually very few last to 10 minutes, most of thematerials between 2-6 minutes maximum, because the patientcant stand it, you cant keep your mouth open, and breathe andfeel comfortable with the material inside your mouth for so long, somost of the materials last for 2-6 minutes. In the lab well talk about

some examples of the materials that well be able to use.

So we take a tray, now, you are seeing the patient for the firsttime; the tray we have wasnt specifically designed for the patient.We said in the lab that this tray is one size, fits all, just like you walkinto a store and ask for small, medium or large clothes, when thepatient comes to our clinic, we first take the impression, I ask for asmall/ medium/large tray, its made by a company, it should fit inthe patients mouth closely, but not closely enough to take an

accurate impression, just good enough to be able to take a generalimpression, just to know how the patients mouth looks like whenIm in the lab..

So Ill take this impression using a moderately accurate material,not the most accurate materials, using a moderately accurate stocktray, so I take my stock tray and I take my initial or primaryimpression.

I am done in the clinic as a dentist, now I refer the work to mydental laboratory technician, I write a prescription, just like a doctorwrites a prescription for a pharmacist, I say (Hello Mr. technician,can you please . using plaster) , in this case we use (gypsumtype 2 (Plaster))

In the lab:

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So the technician mixes the dental plaster, pours the impression,and he ends up with a solid cast, so we have a negative replicaturning into a solid or a positive replica which is the initial cast.

We are going to use this cast to prepare for the next clinic, Ill

say this again in the lab today, I know its boring, sorry, I keeprepeating because I need you to fully understand it.Every clinic is the preparation for the next lab, and every lab is

the preparation for the next clinic.

So the technician will pour up the cast.. so again, we said its aprimary impression, which isnt that accurate, that means my mainobjective in the next clinic is to take a secondary (or final or moreaccurate) impression.How can I do that?

I take my primary cast, the one which I have here, and I canfabricate a special individually tailored custom tray ..

So the technician makes this tray using a cold or a light type ofacrylic, its a tray that I only use once.

So the technician makes this tray, well see the steps in a moment,and then he will send this tray to me in the clinic,

2)

In the clinic:Its the patients second visit.. and like I told you, you have totell the patient on the first visit, that he has to make 6-7 visits, youshould explain to him the steps, and why we are doing those steps..

This time, the tray is better, it fits better, and Ill use moreaccurate material to take the impression, well talk about that in thecoming two lectures..

So I take my second or my final impression of the upper andlower, using the custom trays, so I take the impressions, or letssay I make them, I dont take them , I make the impression, andnow Im done with the second clinical visit, I send them to thetechnician, and notice that the dental technician is very important inthis process.. so he will receive them, read my instructions..

In the lab:

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This time, just like the last time, hes going to pour it up with agypsum product, but this time Im going to use a material which isstronger, and more accurate.. Instead of gypsum 2 (plaster), hesgoing to use gypsum type 3 (stone)..

So he pours it waits for it to set, separates it.. now he has twoaccurate models of the patients mouth..

But the technician still cant do anything with these two modelsto make a denture, because he has to know the relation betweenthe upper and lower arches, which is specific to each individualpatient..

So he prepares for my next clinic, my next clinic is called Jawrelationship records/ Jaw registration records or the biteregistration..

In order to do this, he makes bases, covered with wax, we callthese bases Record blocks ..

Theres a plate which is made out of acrylic, and theres a RIM ofwax which looks like a teeth, well them in a moment, hes justgetting things ready for the next visit, hell send them back to me tothe clinic (this is my 3rd clinic)..

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3)In the clinic:

In the 3rd clinic, I take these record blocks and put them in thepatients mouth, they wont fit in the patients mouth well, because

the technician made the wax rims according to the averagenumbers, so in the clinic Ill modify them according to specificguidelines which well talk a lot more about in the future, in terms ofheight, support for the lip, statics, where the midline is, a lot ofthings

Well modify the wax so that the patients face looks normal, sothey can talk normally, smile and chew normally.. When I modifythem, I seal them together, then Ill send them back to thetechnician..

In the lab:Now the technician has a relationship..so now the information is

complete for the technician..

In the 3rd laboratory, the technician is ready to start making thedenture.. so what hes going to do now.. he has teeth which areprovided by the company, different shapes, different colors, hell set

the teeth according to specific guidelines, and then hell return themto me in the clinic, in the 4th clinic, so I can check to see if they lookgood in the patients mouth, and this is called the try-in ..

Again. 1st impression, 2nd impression, bite registration, try-in..

4)In the clinic:

So after the try-inif the patient is happy thats great, I need toturn the wax into the final acrylic which you learned in the dentalmaterials called polymethal methacrylic (PMMA)

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In the lab:So we send it to the lab, theres along procedure, we do whats

called flasking/ or dewaxing/polishing/finishing/packing/puring , its one form of the lost

wax technique, so weve turned the wax denture into a final acrylicdenture, its end of the 4th laboratory.

5)In the clinic:

Bach to the 5th clinic, now the patient gets the denture; its along road..In private clinics, they sometimes compress some of these steps,instead of taking primary impression and secondary one, they onlytake one, a good one.. but no matter how fast you are, itll take no

less than a couple of weeks..

In our clinics in the university, a denture usually doesnt takeany less than five weeks, If you are lucky, thats if you dont repeatsteps, so it takes a while..So when you treat patients, you need to make them aware of howmuch effort is placed into making a denture, its not a onetimeprocedure..

And like I said in previous lectures, the denture is not areplacement for natural teeth.. The tooth when its inside the mouth,its attached using a large periodontal membrane.. And we said thatthe periodontal membrane has a number of functions, its able totransmit force to the bone, the denture is not able to do this..

When you chew on the right, your left teeth do not touch, butwith the denture, the denture is one piece, and its not attachedusing a periodontal membrane, its just attached using certainatmospheric pressure forces.. will learn about that next lecture..

Were talking about a patient who is 60-65 years oldthey dontwant to get used to something new, its annoying, every time I chewmy teeth move, so its difficult for the patient to adapt to it.. So as aprosthodontist when youre a dentist, youre a part psychologist, youspend all of 4 or 5 visits preparing the patient for what they are

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going to receivebut regardless what you tell them, theyll besurprised at the end.. Unless they had an old denture, and you makea better one.. If they like there old denture more than yours, thenmay god help you :P Because you have to start from zero.

But the point is, its a challenging procedure, the rewards are verygood at the end, if you did everything correctly, If not, it can be verydisappointing and depressing..

Most students like doing prosthodontics preclinically (in the lab),and when they go to the 4th year, they stop liking it.. its a shame,because most dentists when they graduate, they dont make manyremovable prosthesis..

Actually, its a very relaxing part of dentistry, Im aproshtodontist, I was trained to do fixed and removable. Maybe for

every 10 patients I see, I make one complete denture, but I look forthem, because they relax me in clinic.. the amount of stress inmaking complete denture is much less for a partial denture, I knowhow to do it, because Im a specialist, but when I ask student whograduate, they are afraid to do it, because they had a badexperience during the clinical years..

In life, the things that take more effort, are usually the thingsthat give a larger reward..

Lets take a look at these steps..The patient comes in, we take a history of examination, we examinethe patient in detail, just like medicine, when you go into a medicaloffice, the doctor asks specific questions, as dentists, we do thesame..I am looking for information like, how long have you had your teethextracted? 1 month ago, 1 year ago10 years, 100 years ago???Dont laugh, I had a patient who had her teeth extracted when shewas 18and now shes over 100 years old.. and she was wearingthe same denture since she was 18.

So people can have dentures for a long long period of time, itmakes a difference to your treatment and how you proceed, youneed to make sure if your patient had previous dentures.. you tellme, a patient comes to you a says, I extracted my teeth 10 years

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ago, and Ive been wearing the same denture since that time, I wanta new one another patient comes and says, I had my teethextracted two years ago, and I made 8 dentures since then.. Whichone you think youll like better?

Which one is probably going to give you more problems?The second one, theres a reason why he made all of these

dentures, he didnt choose you because youre the best dentist, itsbecause hes exhausted of all the dentist in the area, his problem ishe doesnt like dentures, you need to start thinking about otheroptions.

So the history of examination is very important, because itmakes you understand what your expectations are for the patient,

and what the patients expectations are..

So the patient comes in, you examine, take the primaryimpression, in the lab Im going to talk in more details about thiswe have different materials to take impressions, and we havedifferent types of trays..

Most of the materials can be used in 80% of the impressions,but some materials are only good for specific types of people..

The material that you see here on the screen is alginate, its asynthetic type of sea weed, not made of it, but based on sea weedproducts, its a complex of polysaccharide, technically, its knownas irreversible hydrocolloid..

So you examine the patient, see where the teeth whereextracted, and you will learn in the coming lectures, that when youlook at this ridge, and you look again after a year, it wont be thesame, does anybody know why?Because of resorption what do you know about resorption?

Do you know the concept of function-maintaining the bodystructure?If you dont use a part of your body, youll lose it.. the body has noreason to maintain it.

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The same for teeth, the reason you have alveolar bone isbecause there are teeth.. people who have congenital diseaseswho were born without teeth, dont have alveolar bone, so when

you extract the teeth, the body says ( I dont need this boneanymore), the root is no longer inside the alveolar bone, so slowlyand over time it resorps, specially in the first year, in the first yearwe lose a lot of bone..

Its one of the reasons why, when I make a denture today, theyhave to come 3-5 years later, and modify the denture and reline it.. ((

When taking the impression, the patient should be setting right,not laying back, not bend forward.. The position of the doctor in

relation to the patient is important, howyou approach thepatient for the mandibular arch we approach from the front,for the maxillary arch from behind..

We can use alginate for the impression compound, alginate ison the left, we just need a mixing bowl, or a rubber bowl, and onthe right we need a hot water bath.. the trays are different, they canbe plastic or metal, perforated or not, it depends on the material

used.Impression compounds have non-perforated trays,alginate has perforated trays, you can see we are mixing thealginate, and then we take our primary impressions..

We use different materials in different locations.. So theimpression compound is placed in the tray, seated inside thepatients mouth, and when we take it out of the patients mouth, itllrecord the ridge of the patients mouth, we have to help the patientto move their cheek and lips and tongue.. its not just a staticimpression, its a dynamic impression, we send it to the lab, mix thedental plaster, we pour it inside, and we end up with a model.. Thisis our primary cast,

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Type 2 plaster, we make a tray, a custom tray, and then using aspecial procedure called border molding well talk about it later,we take an accurate impression of the patients mouth

The secondary impression is taken in two stages We take an impression of the border. And we take an impression of the surface.

This is the border impression, and this is the surface impressionusing an accurate type of impression material.. this impression will bemore accurate than the primary impression..

Now, in the laboratory, they make record blocks ( ), we put these in the patients mouth, youll notice that whenthe patient loses their teeth they dont have lips support, their jaw willclose more than normal, its our job to put the patients face back tothe way it was when teeth were present, thats why we need therecord blocks, youll notice now that the patient has lips support..youll also notice that they have the correct relation between the upperand lower lip, we have to make a specific occlusal planes, so that whenthe patient smiles, they dont look like rabbits, or they look too oldwe need to know where the midline is, it needs to be lined with the

midline of the face, we need to know where the canines are..There are specific instruments and guidelines that you need tolearn about in the coming lectures

So we seal the upper and lower arches together using a specialwax, we select the teeth that we want, the teeth which are appropriatefor the patients skin color, age, habits, and then we put it on thearticulator, like the one you have, and then we do wax try-in, we checkthese teeth inside the patients mouth then we process.

Im not going to talk about the details of processing because its a littlebit complicated.

We process the dentures, then we give the denture to the patient,and we make sure that it fits correctly, and we give them instructionsand this is not the end of the story,

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Making the denture is half of the story, the patient need to comeback to frequent appointments..

This is called an articulating paper, because the lower and upper

teeth articulate together, so to make sure that the teeth meet evenly ,we place the teeth on it, and where it touches we can know its (not clear)

Forgive me if theres any mistake, I did my best =)

THANK YOU!!!

Done by: Katreen Suleiman

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Lecture 1, Introduction to Complete Dentures (Script)