web viewlast year we talk about removable partial denture mainly laboratory steps. in this year we...

Aseel Salh

Sandra Al-trawnah

1

4/2/2015

Prosthodontics 2

Lecture No.

Date:

Doctor:

Done by:

Sheet Slides

Hand Out

Designed by: Hind Alabbadi

University of JordanFaculty of Dentistry

Fourth year – 2nd semester 2014-2015

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Aseel Salh Prostho II Sheet No 1 Date 4-2-2015

Last year we talk about Removable Partial Denture mainly laboratory steps. In this year we will talk about clinical part of fabrication of RPD.

Recommended textbook is McCracken's Removable Partial Prosthodontics, Twelfth Edition Carr, Alan B .

RPD it’s prosthesis which replace the missing hard tissue (teeth) and assiotated supporting structure (soft tissue ) and as the name indicate its removable so the patient can remove it by himself .

Partially edentulous patient: he is patient loss some of his teeth not all (some mean 1 teeth to 31 teeth ).

Treatment option for replacement of any missing teeth is :

-implants

-fixed partial denture: bridge

- Removable Partial Denture

The choice depend on case and patient desired .

Example :

In case 1 we can do implant or RPD on right side but in left side we can do bridge or implant or RPD .

In case 2, missing laterals we can do implant or bridge, no body will think in RPD as choice .

1 2


Classification of Removable Partial Denture

Metal ( CO-CR) RPD :

Components - Direct retainer ( clasp)

-Rests

-Major connector

-Minor connector: connect other components to major connector

-Saddle area : edentulous area where teeth are lost like mesh.-Guiding plane the adjacent proximal surfaces facing the edentulous area, we prepare them to have common path of insertion .

-Indications of the partial denture : (nowadays it’s limited due implants )

1)long edentulous span the patient has a long missing area of teeth e.g. a patient with a missing uppers 4,5,6 can’t have fixed bridge because what is left as anterior & posterior abutment teeth(3,7) are not enough for supporting the bridge . in this case the implant is choice if

- the medical history of patient allow that ( is he medically fit to do surgery or not )

- bone is enough

RPDMaterial acrylic metal CO-CR


-patient can pay for implant

2)free-end saddle

3)patient’s oral hygiene

oral hygiene should be good because there is no RPD design will prevent food trapped under it . so if the patient don’t have good OH he will end with caries on abutment and periodontal problem .

4)when there’s need to restore both soft & hard tissuesfor example the patient has neoplasm and when we do surgery we lost huge amount of bone and soft tissue and we need to replace them .also truma and maxillofacial patient need replacement of soft and hard tissue .

5) agewe cant do implant for young patient because the jaw still grow so we put RPD and we change it every year until 18 year then we do bone graft then implamt .

6)patient’s desire

some patient don’t have problem with RPD or cant pay for implant .

Acrylic RPD

actually acrylic RPD is temporary (transitional denture ) because it Mucosal-borne RPD so it will harm the tissue and that not meet with the aim of prosthesis which preserve what remain not replace what missing .

Indications

1)esthetic wise it will do the job.2)space maintainer for example the left upper central incisor is lost …in this case the RPD will prevent drifting of the right upper adjacent central mesially and the adjacent canine from drifting distally..3)reestablish the occlusal relationship4)intrem of restoration during treatment the acrylic RPD is a transitional state not permanent so as the patient to get used to the idea to wear a complete removable denture

5) to condition the patient for wearing denture


As example if patient has only lower anterior and we know after years he will lost them so we do acrylic RPD so the patient will accept complete denture later on .

*RPD are classified according from where they get the support to:

1- Tooth-borne RPD ,they get supported by adjacent teeth: for example when 6 is missing 5 and 7 will give support to the metallic partial denture. There will be two rests so it won’t sink into the mucosa ( rests will carry the partial denture).

2 - Mucosal-borne RPD ,as in acrylic partial denture , we don’t have stoppers or rests, so the denture will be supported by mucosa.

3-Tooth & mucosal borne RPD ,as in the case of free-end saddle either uni or bilateral. For example when there are no teeth distal to 4,, here the denture will resist the biting forces by abutment 4 as well as the mucosa.

Class one is Tooth & mucosal borne RPD but we can do something’s in design to decrease the effect on mucosa such we put the rest in opposite side of Guiding plane (we will put rest as show in image)


Classification of partially edentulous arches :

The purposes of classification :

Communication : as example if we say this case is class 1 any dentist in any where will know its bilateral free- end saddle .

Diagnosis of case easy and design the denture in proper way .

Requirements of an Acceptable Method of Classification 1. It should permit immediate visualization of the type of partially edentulous arch that is being considered. 2. It should permit immediate differentiation between the tooth-supported and the tooth- and tissue-supported removable partial denture. 3. It should be universally acceptable

Kennedy Classification according to Edward Kennedy in 1952.

Class I: bilateral free- end saddle an edentulous area behind the natural standing teeth…no abutment posteriorly

Class II: unilateral free-end saddle

Class III : Bonded suddle

Class IV: cross the midline

Class I Class II


Kennedy Classification is not enough so we have applegates rule

Rule 1 Classification should follow rather than precede any extractions of teeth that might alter the original classification. Rule 2 If a third molar is missing and is not to be replaced, it is not considered in the classification. Rule 3 If a third molar is present and is to be used as an abutment, it is considered in the classification. Rule 4 If a second molar is missing and is not to be replaced, it is not considered in the classification (e.g., if the opposing second molar is likewise missing and is not to be replaced).

Rule 5 The most posterior edentulous area (or areas) always determines the classification. Rule 6 Edentulous areas other than those that determine the classification are referred to as modifications and are designated by their number. Rule 7 The extent of the modification is not considered, only the number of additional edentulous areas. Rule 8 No modification areas can be included in Class IV arches. (Other edentulous areas that lie posterior to the single bilateral areas crossing the midline would instead determine the classification; see Rule 5.)

Examples

Class III Class IV

Class II mod 2


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When the patient come to your clinic you should take proper history and examination also we need full mouth series for the patient .then you put your treatment plan .lets say you plan to do RPD :

First : select size of special tray

As we know we have different types of tray some of them use for complete denture and some for partial denture

Complete denture tray :shallow and rounded but partial denture tray box like with high flanges to accumedate the teeth and sulcus .

Second : make primary impression

We can use any elastomer material to make impression, usually we use alginate .then we pour it with stone

Class III mod 1

Here we have 2 senarios:

1)7 is missing in upper and lower and I don’t want to replace them … class3 mod 1

2 )7 is missing but the opposing present so we need to replace it … class 1 mod 2


Third: Diagnostic cast - study cast

Its advantages

1) it will help us educate the patient and explain the treatment plan to him also to let him know the final outcome … to avoid misunderstanding, some patients don’t know the status of their teeth as example patient come with multiple missing teeth and he say he never extract them but when you show for he the cast and say your mouth looks like that he will appritiate and will be more cooperative and accept the treatment plan .2) enables initial surveying .3) enables technicians to do the specific design of the RPD.4) to construst a special tray.5) medico legal issue ,by law you should keep the study cast 10 years before you discard them .if the patient come and say you extract my teeth you will show the cast and be in safe .

Fourth : initial surveying


*Denture Surveyor :a mechanical device that used to design the plan of partial denture making, it help us in measuring the relative parallelism between teeth surfaces and undercut areas in relation to common path of insertion and removal .

Surveying: The procedure of analyzing and delineating the contours of the abutment teeth (Hard tissues) and associated structures (soft tissues) before designing a RPD.

Components :

Base

vertical arm

Horizontal arm

mandrill

Accessories :

Analyzing rod:cylindrical metal rod placed in the mandrill and checks where the undercut lies

Carbon/Graphite marker : we make bevel to be sure it contact with hard and soft tissue at same time .

Wax trimmer : to block unwanted undercut


Undercut gauges:British: American:0.25mm 0.01 inches 0.50mm 0.02 inches

0.75mm 0.03 inches

We determine the material type of clasp depend on amount of undercut .

Carbon marker sleeve to protect carbon marker . :

Some type of Surveyor that fix cast on base thus it has separate piece also it will help to determine the zero tilt .

Types of Surveyor :

Initial Surveyor : on study cast

Final Surveyor: on master cast to be sure the modification is done in proper way before we do metal framework on the lab .

The main aim of Surveyor is to be sure no rigid part of denture on undercut , the only part on undercut is the distal third of the retentive arm of clasp which is flexible .

This part is rigid , it will never enter


So we remove it but it will be not retentive and we will have food impaction

Others aims :

1.To mark the most bulbous parts of the teeth, where the terminal or the flexible part of the clasp should engage.

2.To identify undercut areas on the teeth and alveolar ridge relative to any given path of insertion, removal and displacement of the RPD.

3.To help in designing and locating the exact position of the clasp.

4.To block out the unwanted undercuts on the cast before fabricating the duplicating cast.

5.It help the clinicians to measure the depth of undercuts horizontally and in relation to the survey line, therefore, the dentist will decide which type of metal could be used regarding the clasps.

6.To identify the proximal tooth surfaces that may serve as guiding planes "G.P are proximal tooth surfaces that should parallel to each other to determine the path of insertion, contribute in denture stability and to ensure positive clasp action"..

7.To identify soft tissue undercuts that would act as interference ,as example if we have distal extention and 5 is abutment and we have huge soft undercut so we cant put I-bar clasp which gingival approach so the aesthetic will compromise .

Then we should determine the tilt:

Primary tilt ( Zero tilt ) is the tilt of the cast where the occlusal plane assumes parallelism with the horizontal plane. Secondary tilt (alternative tilt), we need it in some cases

Notes

-We draw the survey lines with 2 different colors, each color indicate one tilt .

-To be sure we draw correct survey lines the bevel should be at right angle to occlusal surface and touch soft and hard tissue at same time .

-If the ANTERIOR become DOWN so its ANTERIOR tilt .

- by using the surveyor we will give the patient RPD with path of insertion different from the path of displacement .

Recording degree of tilt :

Scoring by marking the cast from three sides (at least three marks)


Tripoding by marking three points at the same level inside the cast

These marks help you getting back your tilt whenever you use the surveyor again to get the exact tilt you got first .

Sorry for any mistake

The End

Anterior tilt.

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