scr.2 - classification of partially edentulous spaces

37
Removable partial denture 10/2/2013 Abeer Abu sobeh 3esam-el3alem

Upload: cwt2010

Post on 01-Nov-2014

20 views

Category:

Documents


3 download

DESCRIPTION

prostho II 10-2-2013

TRANSCRIPT

Page 1: Scr.2 - Classification of Partially Edentulous Spaces

Removable partial denture

10/2/2013

Abeer Abu sobeh

3esam-el3alem

Page 2: Scr.2 - Classification of Partially Edentulous Spaces

Prosthodontics II: lec II.Title: Classification of Partially Edentulous Spaces.

Dr. said he will continue our previous lecture and he will repeat much of what he said in the last lecture for those who were absent.

the references for this lecture _ Stewart’s: Chapter 1 _ Kroll: part of Chapter 2 + 3(pg. 1+2+4, 13-20)

What is the definition of the removable partial denture ?It means that we essentially replacing missing teeth, you know replacing missing teeth doesn’t only refer to the replacement of the tooth structure, it’s also a replacement of the gum and the alveolar bone which is missing.

if you missing one tooth and you have the remaining 15 teeth in the arch, or you missing 15 teeth and you only have 1 tooth left in the arch they are both classified as a removable partial denture, one looks more like a bridge and the other looks more like a complete denture, but in terms of classification it’s a removable partial denture .there’s a wide variation in the types of removable partial denture that we have .

What are the main divisions in prosthodontics?

We have: 1-removable, 2-fixed, 3- maxillofacial, and some people say

2 | P a g e

Page 3: Scr.2 - Classification of Partially Edentulous Spaces

4-implant prosthodontics is a separate specialty that’s usually overlaps with other divisions.

because we can have implant retained -supported fixed, implant retained -supported removable, or implant retained - supported maxillofacial, it changes by dynamic so that’s what we do in dentistry ,but we leave it for more advanced part of your study later in your 5th year (we are interested here in these semester in removable prosthodontics).

Removable Prosthodontics are subdivided into two major categories:

o complete o partial

The removable partial denture is also subdivided into another

subcalcifications which is : o Temporaryo permanent

The words temporary and permanent are not scientific and they are not encouraged why?if you said something temporary for a patient it means it’s going to last for few hours and it’s a poor quality, so usually we say interim or transitional.

3 | P a g e

Page 4: Scr.2 - Classification of Partially Edentulous Spaces

and we don’t like say permanent because nothing in this life is permanent you might give the patient or insert something that is permanent today and it might fall out tomorrow morning so you call it definitive ( النهائي هو األبدي ليس . (هو

What are our treatment objectives? As an everything in dentistry we want to maintain oral health, restore and improve mastication, restore helping to get rid of poor quality of life (Do not underestimate improvement the quality of life).

Patients are very surprising, you can have patients who come to your clinic who are over the age of 80, 90 who tell you he care nothing about their appearance, Dr. said:” I’m not a very old dentist but I’ve been around enough to know that there’s not a single human being on the surface of the earth who’s not care about his appearance or the way his teeth look or his teeth function”. You ask the patient do you have any idea about the esthetics? The color? He says no, do you what do you want doctor, you are the specialist, you choose.. But The moment you turn your head they look to the mirror, they embarrass to say but everybody cares about the way they look, so the quality of life does have a large impact in turn of esthetics and function.

What options do we have for partial denture patient? What’s our first choice? Patient comes to you with a missing tooth or teeth what do you tell him? What are your solutions as a dentist? What’s your first choice? If the teeth are limited and the occlusion is stable, it is possible to give the patient the option for the interim ,or for a long period of time to face no replacement. you remember from your dental morphology Dr. Ashraf taught you that each tooth in the arch has two opposing teeth except:

4 | P a g e

Page 5: Scr.2 - Classification of Partially Edentulous Spaces

the upper 3rd molar and the lower central incisor, There is a wisdom from this design, if you’re missing one tooth in the arch sometimes the opposing two teeth can maintain the occlusion, so not every tooth we extract will result in drifting or supra eruption. In some cases if the tooth is extracted, if you examine the patient you can look and you can see that the patient can survive and that’s fine without a replacement (but he says dr. I’m not looking nice!! Yes you are right), but sometimes if tooth is posterior the patient may out of financial, for psychological, or for time reasons not to have a replacement, and I prefer as a dentist for functional reasons, for esthetic reasons, and for financial reasons to replace the tooth, but sometimes the ideal option for the patient to do nothing at all, especially if you are going to do something bad for his teeth. what is the next option that you see? It is a fixed partial denture –bridge, (you haven’t taken it yet, you will take this in your 4th year).

A bridge = is a tooth with a crown on it, we call it retainers, and we have something in the middle we call it “Pontic”.So essentially bridges from one tooth to the next, but what we have to do after sacrifice the lateral tooth structure behind and in front the missing tooth is to trim them down perfectly well, to maintain tooth that creates the bridge and put a crown on it, we sacrifice some tooth structure in order to replace tooth structure.

5 | P a g e

Page 6: Scr.2 - Classification of Partially Edentulous Spaces

Partial denture replaces one or more missing teeth, the question is: When do I choose to make Removable Partial Denture (RPD) and when do I Choose to make Fixed Partial Denture?

A simple basic rule the more teeth you have, the greater the probability of choosing a removable prosthesis, why?With fixed partial denture we take our support directly from the adjacent teeth. In term of terminology, the tooth which supports the prosthesis whether it’s fixed or removable is called an abutment.

So the teeth around the edentulous spaces are called abutments, so if my abutments are a canine and a third molar, how many missing teeth do I have?? 4,5,6,7 so they are 4 missing teeth being carried by a canine and a third molar. If we did a fixed bridge we have to prepare the canine (trim it down), and the third molar, and then put a retainer on the canine and the third molar, and in between we have 4 missing teeth that we call “Pontics”. In Latin pon means abridge so we have 4 bridging teeth. Now if you think about this we have six teeth (a six unite bridge) 3,4,5,6,7,8 ,but only 2 teeth are carrying the load, there is something you will learn in the future called Antes law, Antes is a dentist, who said that: (You have to make sure that the bridge isn't too long and the teeth can carry the weight) . Now we don’t actually follow it but the idea becomes logical, the longer the bridge the more impractical to place a fixed prosthesis, so

6 | P a g e

Abutments (teeth) supporting the prosthesis.

Page 7: Scr.2 - Classification of Partially Edentulous Spaces

generally (the more the missing teeth, the more directed we are to removable prosthesis).

So generally removable prosthesis are for long partially edentulous patients, fixed prosthesis for short partially edentulous patients, now implants can replace any of these cases.

the implant doesn’t require adjustment of the front tooth and the back tooth ,it’s just drilling the bone, place an implant in the bone, and after its integrate of bone to the bone, I attach the tooth to it ,it’s a bone standing self supporting to replace a natural tooth, so potential can afforded now, but if the patient won’t implant later so maybe doing nothing choice is a good option. -How about scarification teeth are going to drift? Well then we have the option of the removable partial denture,(Notice everyone we are talking about here is just missing one tooth so far), then we can extract all of the remaining teeth and make a complete denture ,if the teeth that are remaining are so week and they won’t support the denture, if I have a table with one leg I will remove that leg and just put it on the floor it’s better than looking for three other legs ,sometimes, but if you have more missing teeth then we have a balance, one missing tooth like two missing teeth fixed partial denture

7 | P a g e

Page 8: Scr.2 - Classification of Partially Edentulous Spaces

or an implant. the more the number of missing teeth the more complicated the solution will becomes, if we have lots of missing teeth in different parts of the mouth yes we can use the bridges, yes we can use an implants. but sometimes it’s more cost effective, and time effective if we replace with the removable partial prosthesis for the interim or for the long duration (there’s more profound discussion of this choice in the text book you can take a look at it ,this discussion will be repeated when you do a test prosthodontics and later in your education). Dr. said: “it is always a dilemma the patient comes and he’s missing a tooth, in most situations in my experience and everybody’s experience actually most people for psychological reasons prefer to have it fixed rather than removable, even some patients who we provide removable prosthesis for complete or partial dentures, refuse to take a mount for a personal reasons and because they embarrass to show it to others.”

so briefly when we a patient comes to you with a missing tooth we have this treatment choices to consider: 1- No intervention by the dentist is indicated sometimes. Sometimes

your first choice is no replacement ,if the occlusion is stable ,there are no esthetic concerns,the patient is psychologically ok with the situation, and there are enough teeth in the arch so that the patient can function normally. there is actually no reasons to replace teeth functionally, so you give the patient the option that you don’t have to replace the teeth.

2- Replacement of the missing teeth by a denture, bridge, implant or whatever depending on the case.

There’s something called the shortened dental arch again you will learn more about this hopefully in the future ,the shortened dental arch is a concept means that not every person requires 16 teeth for arch to function . Kizer (I’m not sure about the name) did a many studies from the 1960 onward to prove that it’s correct, and to

8 | P a g e

Page 9: Scr.2 - Classification of Partially Edentulous Spaces

figure out the minimal number of teeth needed to achieve normal function.

Couple of examples: If the patient comes to you, and he’s missing his 3rd molars and he

only have a two sevens (which is like many people in the population) can they function? Yes, most of us do.

what if you are missing your sevens and you only have your sixes in the 12 teeth in your arch do you think they are function? Yes, exactly .(there’s a percentage in terms of function ,the six provides the majority of function antithesis to the 3rd molar).

so what if the six is missing and we only have five to five? Yes, properly they can function.

in the situation of patient in the 50,55 years old, with a sound dental arch, with a good arch in the mouth that he’s expecting his teeth to function in the next 20 ,30 years, it’s enough to have 20 teeth, he doesn’t need to replace the posterior teeth in every single case.

In such patients the discomfort or the psychological impact of wearing the removable prosthesis is sometimes hinder the patient from wearing prosthesis at all, and in terms of function he also accept to wear nothing at all,( but there are reasons we must have prosthesis to prevent drifting ,to had function.., we will talk about them later on ).but please understand that we have a concept called shortened dental arch, essentially the teeth are missing posteriorly ,but what if you have ten teeth on top and 14 teeth in bottom ,Could be acceptable not to replace the upper teeth? Here we have the problem, if the opposing arch are asymmetrical then it’s considered acceptable but we have to essentially evaluate case by case.

So here in the left picture: we have missing teeth in the back we have only premolars, it’s considered acceptable in this case. In the right picture: we have from canine up to 2nd molar in one side, we have not units here at least asymmetrically to function in the patient, (again this is more advanced

9 | P a g e

Page 10: Scr.2 - Classification of Partially Edentulous Spaces

than your state but it’s important to understand that this concept is available) .

This will be a bridge that you’re familiar with, this is the anterior bridge (3), this is a sound teeth (1) but we trimmed them down to place a bridge(2) . We replace what we trim down but we essentially affect natural tooth structure ,so it’s considered a non-conservative treatment it will be better if you just place an implant here ,and only one tooth without affecting the adjacent teeth.

(1) (2) (3)

everything we do in dentistry has an impact, Like place a crown on the tooth it’s not going to be sound as the original tooth, I can do the highest quality that’s possible, hopefully it will last for the rest of patient’s life, but once I touch the patient tooth it introduce a form of fracture in the patient’s mouth, maybe I made a mistake, maybe the patient doesn’t have a good oral hygiene ,every time I do something in the patient’s mouth it increases the risk level of what tooling in the patient’s mouth .

Here we a have a removable partial denture it’s a metal base partial denture ,and there’s some clasps here.

10 | P a g e

Page 11: Scr.2 - Classification of Partially Edentulous Spaces

In this case we are missing too many teeth to be able to replace with a bridge, so we have to replace with a partial denture.

Here we have no posterior abutment it will be very difficult to place a bridge extends backwards there is a bridge called a “tilted bridge” but here it’s not a very good idea (the reasons we will learn about them later).

maybe there’s too much alveolar bone loss, you can see how far down the acrylic goes here, with removable prosthesis I can make a flange that goes to the depth of the sulcus which hides any deficiency in the

11 | P a g e

Page 12: Scr.2 - Classification of Partially Edentulous Spaces

residual ridge, now you might say why I don’t make a flange in fixed prosthesis?? Because as you will learn in the future in a fixed prosthesis you have to clean underneath the bridge with a special devices and if you have a flange it’s very difficult to do this, you can’t clean underneath the flange and go in and out, so the tissues become unhealthy. In conclusion if there is a difference between where the bone is and where the teeth should be, a removable prosthesis with a flange is better esthetically to the patient.

If the patient has a lot of ridge resorption sometimes you try to retain as much of remaining teeth as possible to delay extraction. This is an extreme case where the bone is negative due to extreme resorption. That there is a hole where the bone should be look at the picture.

-Dr. said”( so there is another indication and a complete denture we will jump ahead here- he didn't explain these slides).

12 | P a g e

Page 13: Scr.2 - Classification of Partially Edentulous Spaces

The different types of RPDs(removable partial dentures), I’ve mentioned this last lecture ,and I’ve told you this semester in terms of segregation we will divide them in two parts: the interim prosthesis ,and the definitive.( in the lab we divide them into interim and definitive ,in the lecture the only time I’m talking about the interim is pretty much next lecture it will be a short lecture just to understand what it is in theory.)

Interim Denture(Provisional; Temporary)In the text book and in most countries in the world, an interim is an” interim”, it’s there for a specific period of time, for specific purpose ,it would be replaced by definitive prosthesis, it’s usually easier to fabricate ,quicker to fabricate and financially it costs less because it’s just made out of acrylic and teeth like a complete denture (but few number of teeth), and it has some wires on it which we use for retention and clasps ,so in terms of cost it’s not that expensive . The worst thing about it usually 95% of the time is supported by soft tissue only (like the complete denture).

The definitive partial denture takes more time to fabricate, requires more expertise and it’s made out of metal base with acrylic and teeth and requires more procedures .

13 | P a g e

Page 14: Scr.2 - Classification of Partially Edentulous Spaces

Comparing interim with the definitive:

That’s why in Arab’s part of the world usually for financial reasons, and sometimes because of expertise, many patients used the interim like a definitive, but we lose out many advantages up the definitive with the interim. if you ever seen a spare tire, the spare tire of the car it’s usually about 2/3 of the size of the original tire And usually you can’t travel on this more than 50 km totally, using

14 | P a g e

interim (provisional

)

wrought wire for

retention

less time to make

cost less

life span is much more

than expected

definitive

no wrought wire

more time to make

cost much more

Page 15: Scr.2 - Classification of Partially Edentulous Spaces

an interim as a definitive is like travelling on your spare tire, Which wasn’t designed for definitive, use it can hurt the car and it wears down fast ,because it wasn’t intended for that, (unfortunate we use it like that in some parts of the world in many indications).

if you take a look at the photograph here, you notice that the interim made entire from acrylic, whereas a definitive has a metal base framework which is usually cobalt chromium , there are also components on the definitive which go over into the occlusal prosthesis of the teeth , which provide retention for the acrylic ,so if you look in the front here these is actually are a special teeth: lateral, central ,central, lateral and canine and we have pink acrylic, so the metal frame work partial denture is actually: part’s acrylic part’s teeth, and part’s metal.

The interim partial denture that’s usually provide for: Short time , esthetics , mastication and for occlusal supports.

15 | P a g e

Page 16: Scr.2 - Classification of Partially Edentulous Spaces

Usually we use it if we are going to provide definitive, fixed treatment or removable treatment later on, or the patient is in a rush.

The Dr. mentioned a couple of examples:

Let’s say a patient comes to you, he is going to lose his tooth and he’s urgent and Ask you to replace his missing tooth quickly,he says :Dr. I’m going to travel I don’t want to travel without teeth. And you know that the definitive partial denture will take several days if not a week, or two maybe ,or three, because there’s a lot of procedures involved, and it requires time it is an indirect procedure so you say: I will make you an interim, you can travel and when you come back and you have time I can make you the definitive.

In case of young patients. Let’s say a young patient is missing central incisors, these days the best option is to replace it with a single tooth implant (if the cost is reasonable for the patient).but the conventional way is to place a bridge, We trim each tooth on each side and place a crown over them and a retainer, with teeth in the middle, (let’s say having a three units bridge).what is the problem with this scenario for the young patient?When the patient is young the pulp is very large. As the child grows into an adult, will have secondary dentine and in case of trauma tertiary dentine, Progressively making the pulp chamber smaller. So if the pulp is large and you need to make lots of trimming you will expose the pulp, So Patient will need endodontic treat it means to avoid this, you will provide the young patient (13 or 14 years old) an interim prosthesis, until the gum, jaws, and pulp mature.

Another scenario : patient comes to you and he says: you know what.. I know I need teeth but I just don’t have enough money for the definitive is there something you can provide me with until I can save enough money or I can solve my solution ? Then you say ok we have an interim.

patient comes to you, all of his teeth need extraction for a pathological reason ,for example: advanced periodontal disease, you won’t extract all of his teeth in one goal ,you can but you give

16 | P a g e

Page 17: Scr.2 - Classification of Partially Edentulous Spaces

the patient the option of essentially sequencing the extraction, you say I will tell you what, giving a complete denture in one day is a big change ,what do you think about extraction teeth in two parts or three parts ?I will extract your back teeth and give you an interim denture for your posterior teeth ,and then I will extract your front teeth maybe a month later and then add those teeth to your interim prosthesis, and after healing maybe month or two later we will replace it by a complete denture.

So it is a phase going from a partial edentulous state to the fully edentulous state. So you are keeping something in the patient’s mouth so that psychologically, functionally, and emotionally the patient doesn’t degrade.

In case of trauma or any sudden loss of teeth , we need an immediate denture. So we use an interim prosthesis.

-Dr. said:”do you understand the logical that I’m talking about there are many scenarios where interim or transitional prosthesis solves our problem to the patient.Now we are going to talk about the partial denture we usually talks about the parts of the definitive partial denture, all of the choices of parts are available in the definitive but only some of the parts are available in the interim .so the full option of choices the definitive .the partial limited option choice, is the economic choice the interim.

17 | P a g e

Page 18: Scr.2 - Classification of Partially Edentulous Spaces

So what components do we need to know?

There’s something called the rest, and by the name, it’s something that rest on the occlusal surface of the teeth, but you will say: it means that I put just something on the top of the teeth, so what if the patient tries to close? there is going to be something in the way, but later you will see that in order to make a rest we have to trim part of the tooth, we prepare something called “the rest seat”,(it’s just like if you are rest in your rest seat, you as a human being will be the rest and the chair you’re seating on will be the rest seat). it looks a bit like class II but it’s shallow ,rounded, and it’s only within enamel we actually trim part of the tooth so the rest can go to the occlusal surface without interfering with the opposing arch (don’t worry we will learn more about this there’s entire lecture about each of this components).

we have a major connector: the major connector is like a skeleton of the prosthesis ,which connects the right with the left ,the anterior with the posterior, and all the small sections together .

we have a denture base connector you can see where the acrylic is, the denture base is essentially from acrylic so we have a meshwork which attaches the acrylic to the metal framework

Also we have something called the retainer (here we have a direct retainer) it is essentially something retains the denture onto the tooth , in partial denture the major method of retention is usually clasps ,there are many different designs .

18 | P a g e

Page 19: Scr.2 - Classification of Partially Edentulous Spaces

-Dr said:(I say rests there are different types of rests, I say clasps or retainers there are different types of retainers, major connector there are different types of major connector, and we’ll learn in each lecture specifically what the types are, and I told you last time that the object of this semester will be to learn about each individual component, and be aware to know the different choices ,we’ll learn about design and then we as dentist will say well this patient is missing this ,this ,and this teeth, in this situation I should use this type of retainer, this type of major connector, and this type of rest. and the design should look like this so I will work as an architect designing the partial denture to the specific patient because again I told you the last week that there are so many different scenarios in missing teeth that is impossible to provide only one design for partial denture, unlike a complete denture patients come to you as an edentulous you’ll take an impression ,set the teeth ,there are some variation, but complete denture is a complete denture, but partial denture they can do with one tooth ,2 teeth ,2 teeth come from different sides ,they can be in the back or in the front, so the design varies the prosthesis individually for each individual patient.

19 | P a g e

Page 20: Scr.2 - Classification of Partially Edentulous Spaces

We have also a Minor connectors are those actually the small connectors who connect the major connectors with the other components.

The unit in the facial and the lingual with the rest, is report to the clasp unit consist of: clasp arm , reciprocal arm المكافئ ال ذراع )). And a rest(we’ll talk about it later).

So you can see a part of it goes into the undercut and part of it is not in the undercut . and we have something called the indirect retainer (at this

stage just know that there is something called the indirect retainer it’s a type of rest we’ll talk about it later) ,which prevents the rotation of the partial denture .

and then we have a denture bas, when we make this denture processing is done in two stages, with the complete denture you make the denture according to the most common process of fabrication in dentistry in the past was called the lost wax process you shape something into wax, you make a mould, you melt the wax ,you burn up the wax, and you replace it with the final material. the final material can be acrylic or it could be metal in

20 | P a g e

Page 21: Scr.2 - Classification of Partially Edentulous Spaces

this case we have two, we have metal and acrylic so we have to process twice, one process is to make the metal framework ,and the other lost wax process to arrange the teeth like a complete denture, so the work is double.

The classification system that we use to communicate with each other when describing partially edentulous patient is ” KENNEDY CLASSIFICATION” also Kennedy classification has some modifications, another dentist called O.C. Applegate said that Kennedy classification is not enough to describe the classification ,we need some more details to give us more information, so usually we talk about the Kennedy –Applegate classification for partial denture .Quick review for Kennedy's Classification, we have four Kennedy's classification, but Applegate came and said that those classifications are not detailed enough, so I have to make some modifications. You must remember that in Kennedy's classifications the order is essential. so in Kennedy's Classification the number is important, but in Applegate’s modification the number is not important.

KENNEDY CLASSIFICATION SYSTEM CLASS I - Bilateral Posterior Edentulous Areas, with remaining

teeth natural anteriorly.

21 | P a g e

Page 22: Scr.2 - Classification of Partially Edentulous Spaces

CLASS II - Unilateral Posterior Edentulous Area, with remaining teeth natural anteriorly.

Remember this:

Class I …. 2 edentulous areas

Class II….1 edentulous

area.

CLASS III - Unilateral or Bilateral Edentulous Area(s) Bounded by Remaining Tooth/Teeth.(it’s usually unilateral but if you refer to this as bilateral it wouldn’t be wrong)

22 | P a g e

Page 23: Scr.2 - Classification of Partially Edentulous Spaces

CLASS IV - Single Edentulous Area Anterior to Remaining Teeth, and Crossing the Midline. it’s bounded ,both central incisors must be missing, must cross the midline ,it shouldn’t be another spaces in the mouth it should be the only one to become class IV .

Sometimes there are other missing spaces, not the typical form that Kennedy talked about. For example if I have a tooth missing here (the star in the picture), what should I call it? There is an Applegate’s rule says that I always choose the most posterior edentulous part ,the one that is the most posterior is the distal extension ,which is Kennedy's class II, what should I call the other space (here it’s the star )? Applegate said that if I have an additional edentulous area I don’t care to the number of teeth, it could be one or two, and each additional missing space is called a modification space, not according to the number of missing teeth but according to the bounded spaces. So this is class II mod I.

23 | P a g e

Page 24: Scr.2 - Classification of Partially Edentulous Spaces

The other problem with Kennedy's classes is, here I have class IV, what if I have teeth missing, here the stars in the picture>>>

I take the most posterior edentulous area and the anterior space becomes a modification. Even though it crosses the midline which is another rule of Applegate (There is no modification space in Class IV). Class I,II,III can have a modification ,it’s common sense, if I have class IV modification I (which can’t happen) it should be class III any way, here is my explanation… any edentulous area other than the one in class IV will be for sure in the posterior part because class IV should cross the midline which means that it’s anterior to any edentulous areas and as Applegate said that we choose the most posterior, so if I have any additional edentulous area with class IV it will transform to a modification instead of a class by itself.

Sometimes there are teeth in the mouth that I don’t use in my design. What if I tell you that this upper 3rd molar has no lower 3rd molar so usually in Applegate modification you will see that if the third molar is not included in my design, it’s not included in the classification so if I’m not using the 3rd molar ,this becomes a unilateral extension of edentulous area which is Kennedy class II.

24 | P a g e

Page 25: Scr.2 - Classification of Partially Edentulous Spaces

Now this is true for 3rd and 2nd molar, unless I give you specific information then you have to take a specific default.

now let’s go to Applegate’s rules:

1) Classification should follow rather than precede extractions that might alter the original classification, (If a patient comes to you and has a periodontal disease extract the teeth then make the classification, or imagine the patient without that tooth or teeth).

2) If the third molar is missing and not to be replaced, it is not considered in the classification.

3) If a third molar is to be used as an abutment, it is considered in the classification,( if I want to use it I want to include it ,how it’s included in the design? Either to put a rest on it, or I replace the tooth).

4) If a second molar is missing and is not to bereplaced (that is, the opposing second molaris also missing and is not to be replaced), it is not considered in the classification.

5) The most posterior edentulous area(s) always determines the classification.

6) Edentulous areas other than those determining the classification are referred to as modification spaces and are designated by their number (not position).

25 | P a g e

If I delete this molar it becomes class II

Page 26: Scr.2 - Classification of Partially Edentulous Spaces

Classification According to Support?Now let's move to the second type of classification, this is more simple to talk about, where do I get my support, from where does the denture set? It can be:

o Tooth supported (tooth-borne)o Tissue supportedo Tooth-tissue supported (extension base)

In an acrylic partial denture and a complete denture usually when the patient bites down the forces goes directly to the tissue of residual ridge or the palate, so complete denture and most (not all) partial denture are called tissue supported prosthesis ,or tissue borne. However a metal framework partial denture has rests that are usually either, tooth supported or tooth-tissue supported.Which of Kennedy's classifications are tissue supported and which are teeth – tissue supported?

Kennedy's class III bounded areas and Kennedy class IV they are called tooth supported prosthesis and it’s important to the design.

Kennedy's class I has a rest in the front but no rest in the back, so tissues in the back, tooth in the front, so it's tooth-tissue supported.

26 | P a g e

Page 27: Scr.2 - Classification of Partially Edentulous Spaces

class III, class IV (Short span) are tooth supported, class I and II are tooth –tissue supported. In some cases if we have lots of missing teeth ,very rare class III ,but more commonly class II it can be tooth –tissue, why is that?? For example this case below, if you put a rest on abutments it will give support, but not that much that you cannot count on it, you need additional support from tissues.

classify the following arches:

Class I Mod III

27 | P a g e

Page 28: Scr.2 - Classification of Partially Edentulous Spaces

Class III Mod I

Class I Mod II

Class III Mod III

28 | P a g e

Page 29: Scr.2 - Classification of Partially Edentulous Spaces

Class II Class I Class III Mod III

Class III Mod I Class III Mod I Class I Mod II

Class IV Class II Mod II Class I

29 | P a g e

Page 30: Scr.2 - Classification of Partially Edentulous Spaces

Class III Mod I Class III Mod V Class III Mod III

Class I Mod I Class I Mod I Class II Mod I

Done by: Abeer Abu sobeh

30 | P a g e