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Dana Younes Prosthodontics / Sheet #6 March 25, 2014

Major Connectors As a continuation for the series of lectures about removable partial denture components, today we are going to talk about major connectors.

Major connector: component of partial denture that connects parts of the prosthesis located at one side of the arch with those located on the other side of the arch.

Because the partial denture has to be bilateral component even if the missing teeth are only on one side, it has to cross to other side for cross arch stabilization. Basically you need to think of all possible movement that will affect the denture and provide components that give stability for the denture because if it was unilateral it will be easily displaced by forces acting on the denture that’s why you cross the arch to the other side to provide components of the other side to provide stability and resistance to movement away and towards the tissues that’s why we use cross arch stabilization and that’s why we need major connector to connect the components of one side to the other side .

Small components are connected to the major connector through minor connectors, so major connector don’t connect between small components, it connects one side to the other side.

In order to fulfil this major function, major connectors should have certain requirements:

1. Biocompatible and comfortable : This is very important because they cross the arch to the other side, so they are in direct contact with tissues so they have to be comfortable for the patient, so we need to do minimal coverage as possible for the major connector so not to irritate tissues.

2. Rigid : It has to be rigid because connection needs a rigid component (the only flexible component in partial denture is the retentive tip of the direct retainer) and also it provides support which is the resistance against movement toward the tissues.

If there is flexibility in the major connector not only it will not connect properly , it will also cause improper stress distribution at function , stresses on the teeth , causing teeth mobility , loss of teeth and bone resorption.

3. Do not interfere with or irritate the tongue :Particularly for mandibular major connector and also for maxillary major connector.

4. Do not impinge on oral tissues during removal or insertion of the RPD :

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It has to be fit with the tissues but doesn’t cause any kind of impingement or irritation to the tissues.

5. Do not cause food retention or trapping ( self-cleansing ) :If there is tissue coverage, it has to be in intimate contact with the tissues. On the other hand, if there is a space, it has to be big enough to self-cleans, not to cause food trapping, dust, caries and periodontal diseases.

6. Contribute to support of the prosthesis and preferably indirect retention :The major function of major connector is to connect the components from one side to the other side, but it can also provide support (basically the maxillary major connector because it has the palate and it’s on a horizontal surface so it can provide support and retention).

7. Have as minimum tissue coverage as possible :We have to use the smallest coverage (don’t extend it on areas we don’t needed to extend it on).The more coverage, the more you deprive the tissues from normal stimulation of oral flora, also the more irritant for the patient.

8. Possess smooth rounded edges to avoid discomfort, stress concentration and fatigue.

Mandibular major connectors:

1. Lingual Bar : Number one of choice, if there’s a contraindication in using the lingual bar, we use other types.

2. Lingual Bar with Continuous Bar (Open Kennedy)3. Lingual Plate4. Labial Bar5. Swing lock :

It’s a variation of labial bar.6. Sublingual Bar7. Dental Bar

Lingual bar : Found in the depth of the sulcus Looks like half pear shaped Minimal height or thickness of major connector = 5mm

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Seated vertical with the thickest part in the depth of the sulcus and the thinnest towards the upper part

The distance from the most apical part of gingival margin to the upper border of the lingual bar should be 3mm , this is to safe the biological width of the tooth and not to cause periodontal diseases and bone loss and also to be self-cleansing ( can’t be closer to the gingival margin than 3mm ) .

So we need 3mm distance and 5mm height or thickness for the major connector , so the distance between the gingival margin and depth of the sulcus must be 8mm ( as a minimal distance )

The more the distance (more than 8mm), the better it is especially if it is long span RPD, 5mm might not be that rigid so you might need to add thickness to prevent flexibility and provide sufficient rigidity.

Major contraindication: when you have less than 8mm distance.

Advantages :Number one choice for mandibular arch because:

1. It’s simplest design

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Major connector

(Lingual bar )

Miner connector

Clasp assembly connected by

minor connector

Major connector

Type of minor connector

I-bar

Minor connector carrying a rest

Not less than 8mm


2. Has minimal contact with the soft tissues so less plaque, more retention and better soft tissue stimulation. 3. It doesn’t contact the teeth (away from teeth by 3mm), so it’s better for plaque control and also for patient’s acceptance.

Disadvantages :1. May not be rigid if there is no enough space to place it correctly or if it’s too long:

sometimes it’s not that rigid that you have to add thickness and if it’s thicker it will irritate the patient.

2. Cannot be used in cases with tori: because mandibular tori can’t be relieved because of small thickness of major connector (5mm), if we relieve the tori then it will be too thin and will not be rigid.

3. Provides no bracing or indirect retention or reciprocation or any kind of support.

Lingual plate : Worst connector given to a patient Pear shape lingual bar with a solid metal piece extended on to the lingual surface of the

anterior teeth. It’s a lingual bar extended on the teeth covering just above the cingulum Extend on all anterior teeth Use it if we don’t have the 8mm from the gingival margin to the depth of the sulcus

(where we can’t use lingual bar): if you can’t provide 3mm cleansing area to have proper periodontal condition for the teeth, you should cover the whole surface, but the coverage must be with intimate contact with the teeth (scalloped just above the cingulum) to prevent food impaction.

Around the gingival margin and the embrasure must have slight relieve for the tissues to facilitate insertion and removal and to reduce the irritation during insertion and removal.

Biggest disadvantage :

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Usually have a rest extended at the end to provide indirect retention because the major connector itself doesn’t provide indirect retention, it helps in indirect retention but after all it’s on an inclined surface so if there is no rest at the end that provides indirect retention, it will not help in indirect retention.


It covers the teeth and when it covers the teeth the patient will always feel it because it’s an extra thickness on the teeth, it will be irritating for the patient and patient’s acceptance is not that good , and also the patient’s oral hygiene should be very good because it tends to trap food even though we have intimate contact with the teeth but it’s touching the teeth and surfaces of teeth and gum are not in indirect contact with the oral flora (which it’s self-cleansing ) so the chance of caries and periodontal diseases is more ( if the patient’s oral hygiene is not that good ) .So we can’t use lingual plate if patient’s oral hygiene is not excellent (patients with poor oral hygiene are not indicated for RPD).

If there’s spacing in the anterior teeth and you have to use lingual plate, we can do some cut backs around the gingival margins and between the embrasures in order not to be shown anteriorly.

Advantages :1. Rigid (even if relieved around tori): because it extended on longer distance so it must be rigid, so it can be used with mandibular tori only if the patient’s oral hygiene allows that.2. Can be used when there is insufficient space for lingual bar (less than 8mm): due to periodontal disease or there was a periodontal disease but now it’s controlled, so there will be loss of bone and gum recession.When the gum level is low or have gum recession, we can’t have the 8mm, so we use lingual plate.3. Can provide indirect retention and stability against horizontal forces (indirect retention

if rests are added at each end of the major connector).4. Especially useful with distal extensions with excessive bone resorption and loss:

because it can distribute some of the loads on the teeth, it also helps in providing indirect retention for the distal extension.

5. Can be used to splint periodontally involved teeth and mobile anterior teeth6. Can be added to the old RPD with lingual plate MC : The lingual bar is away from the teeth, so if one of the teeth is lost we can’t add it to the major connector because we must have metal component to connect so we have to redo another partial denture, but in lingual plate because it’s extended on the teeth, we can easily add a lost tooth to the major connector.

Lingual Bar with cingulum Bar ( Kennedy Bar / Open Kennedy bar ) : Used it we don’t have the enough 8mm distance It’s a little bit shorter lingual bar in the depth of the sulcus and a dental bar on the

teeth

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It doesn’t have to be 5mm in thickness ( it can be less, 3-4mm ) because there’s connection with dental bar on the teeth ( dental bar is around 1mm thick and 2-3mm in height ) resting just above the cingulum of the teeth , this provides additional support and helps in indirect retention .

Dental bar is connected to the lingual bar through longitudinal connectors and we extend rests at each end to provide indirect retention.

The bar itself because it’s located above the cingulum, it provides additional support, indirect retention and resistance to horizontal forces (provide reciprocation and bracing).

Advantages :1. Provide indirect retention, horizontal stabilization and bracing to the teeth.2. It doesn’t cover the area around the teeth so the gingival margin and the teeth is still in direct contact with the oral flora ( still exposed)

Disadvantages : 1. It’s more irritant for the patient because it has too many bar (2 longitudinal and 2 horizontal), the patient can feel them, they are more annoying.

2. Entrapment of food debris 3. Complex design and difficult for the technician to make appropriately.

We must study each case separately to choose the most appropriate major connector to be used because each one has indications and contraindications.

Labial bar : Instead of having the connection lingually, the connection is labially in the labial slucus. Disadvantages :1. It’s too long because the labial sulcus is longer than the lingual sulcus so usually it’s not

that rigid (if we want to make it rigid, must increase the thickness but increasing the thickness in labial sulcus or buccal sulcus is irritating for patient.

2. It doesn’t provide any kind of reciprocation or bracing or encirclement to the teeth (don’t give additional support, indirect retention or stability).

Mainly indicated in large inoperable tori in the mandible (mainly bilateral) that we can’t relieve them and when we can’t use lingual plate because of poor oral hygiene.

Also indicated when the teeth are severely tilted lingually and we can’t do lingual bar or plate.

Runs at the Mucosa labial to the anterior teeth

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Indicated for malposed or lingually inclined teeth and where there are prominent inoperable tori.

Not commonly used because it’s flexible most of the time, it’s also irritating to the patients and doesn’t provide any kind of bracing or indirect retention.

Swing lock : It’s a modification of the labial bar, used when there are large inoperable tori or the

teeth are tilted lingually. Here there’s a joint that opens as a gate (anterior gate), we insert the denture when the

anterior gate is open and then we close it. There is vertical streaks in contact with the teeth , basically it can be used when we have

severely resorbed distal extension and mobile anterior teeth ( it provide some kind of splinting and proper distribution of forces between the distal extension and the teeth )

They found also that when there’s sever resorption and movement of distal extension , it will cause sever stresses on the anterior teeth because of vertical streaks moving up and down and thus will cause further mobility and periodontal problems to the teeth .

The advantages over the disadvantages, you have to weigh them whether the case is appropriate to use swing lock, but mainly if there’s inoperable tori or malpositioned, lingually inclined teeth we can use it.

It’s not esthetically pleasing so sometimes they are covered with acrylic in order not to show labially.

Has too much disadvantages and the main advantage that’s splinting mobile teeth, it might be actually causing further mobility and loss of mobile teeth because of extra stresses on anterior teeth , because of difference in support between tissues and teeth.

Sublingual bar : Used if there’s no 8mm distance from the gingival margin to the depth of the sulcus ,

you can place the bar horizontally ( the maximum dimension is horizontal not vertical)

It’s an excellent option if the space is 6mm or 7mm (not 8mm) because we still need a space above the upper border of the bar.

It’s half pear shaped located horizontally in the sulcus Can be used if the teeth are inclined lingually and have lingual undercuts. Need special impression technique to be able to record the depth and width of the

sulcus. Minimal thickness is 5mm

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Dental bar : Similar to open Kennedy but without the lingual bar It rests on the teeth above the cingulum slightly more than open Kennedy because it’s

the only bar that we are using. Also the upper part of the bar is scalloped with the teeth If there’s spaces between the anterior teeth , we can’t use dental bar because it will

show and we can’t do the cut backs so it will become too flexible Indicated if there’s insufficient space for lingual and sublingual bars and poor oral

hygiene (lingual plate is contraindicated) and if there are long clinical crowns otherwise we can’t extend the dental bar to minimum of 4mm on the lingual surface of the teeth.

Advantages :Provide good bracing, reciprocation, resistance against horizontal movements and some kind of indirect retention if there’s rests at the end.

Disadvantages : 1. Low patient tolerance because it’s covering the teeth, the patient can feel it all the

time.2. Poor aesthetics if spaces are present between the anterior teeth.3. Not rigid enough.

Maxillary major connectors:

There are different types and different extensions for each type:1. Palatal Bar2. Palatal Strap3. Antero-posterior Palatal strap and Antero-posterior Palatal Bar4. U-shaped Palatal Connector ( ring ) 5. Complete Palatal Plate

Palatal bar : Narrow antero-posterior extension and large thickness Narrow, gently curved, half oval with its thickest point at the center Used only in interim prosthesis ( temporary prosthesis ) as it lacks rigidity : thin bar,

only used if we do partial denture immediately after extraction and we need a temporary prosthesis until the tissues heal and then we provide the permanent prosthesis .

To improve rigidity, should be made more bulky : more bulky mean that it’s more irritating for the patient because it’s on the palate and patient can feel it

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Provides little support because of its limited width ( Used only with very short span bilateral Class III, one or two teeth are missing on both sides )

Should not be placed anterior to first premolar as its bulk causes discomfort for the patient in the anterior area

Palatal strap : It has small thickness and large width Antero-posterior thickness is minimum of 8mm , so it’s fine to make it thinner

around 1mm Most versatile , most commonly used maxillary major connector If the premolars are missing , we can extend it further anteriorly ( broad palatal strap

) , so the width depend on the number of missing teeth Goes from one side to the other in intimate contact with the tissues ( no relieve ), so

there will be no food accumulation It provides support because the horizontal surface of the palate is covered so it

resists movement toward the tissues, in addition to the connection of components from one side to the other side.

It provides retention through adhesion and cohesion because it’s in intimate contact with the underlying tissues

The extension can be adjusted according to the number of missing teeth The width is increased as the width of edentulous saddle increases Should not be less than 8mm wide, but its cross-section is thin. Increased width

provides rigidity and support Used in bounded saddles , class II ( unilateral distal extension ) and class III not used

in class I and class IV

The anterior border should end posterior to the rugae area, if not possible it should end at the rugae valley (otherwise it becomes too bulky) : rugae area have valleys and elevations , we should be away from this area because it affects phonetics , it’s irritating and become bulky anteriorly , but if the edentulous area extends anteriorly , you have to extend it anteriorly ( should ends in the valleys not in the elevations of rugae area )

The posterior border should end short of the junction of the hard and soft palate (no need to extend it posteriorly )

Advantages :1. Great rigidity with less bulk2. Good stress distribution because of it has good width3. Offers little interference with the tongue because of small thickness4. Offers good retention through adhesion and cohesion

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5. Might give some indirect retention

Disadvantages : Because of small thickness, we must extend it of a minimal 8mm (even if the edentulous area is less than 8mm) so the patient may complain of excessive palatal coverage. Also might be associated with papillary hyperplasia with poor oral hygiene.

Antero-posterior palatal strap : Ring connector It has two straps and the inner area of the major connector is empty as a ring Used basically when there’s anterior components and posterior components and

multiple missing saddles ( so there’s components on anterior teeth must be connected with the rest of the major connector ) , at the same time we don’t want full coverage for this area , we want to expose it for good stimulation from oral flora

Consist of two horizontal straps ( anterior strap and posterior strap ) connected with each other with two longitudinal straps on the sides

Has Excellent rigidity because of the multiple straps Each strap is at least 8 mm wide but has thin cross-section

Borders should be 6 mm away from gingival margins or covering the lingual surfaces of teeth ( remember in lower teeth it was 3mm ) : if you don’t have enough 6mm , then you have to cover the whole surface So either you go away 6mm for the upper arch or 3mm for the lower arch or cover the whole palatal or lingual surface if you don’t have enough space because the border is in intimate contact with tooth so no entrance of food debris and easy to be cleaned (if there’s a small space then it will trap food, not self-cleansing, very difficult to clean and it will end up compromising the periodontal condition of the teeth)

The two straps joined by a flat longitudinal elements on each side of the lateral slopes of the palate

Indication :1. Widely separated abutments (multiple saddles with good abutments we can depend

on them to provide appropriate support).2. Cases with large inoperable palatal tori : torus palatinus mostly in the middle ,if it

doesn’t extended to the posterior part we can use this type of major connector3. Patients who want to avoid full palatal coverage.4. Long edentulous span in class II modification 1 arch.5. Class IV and bounded saddles ( if there’s different widely separated saddles)

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Don’t use it in class I because of few remaining teeth, so we need extra support through the major connector, so we might be using full coverage major connector depending on the condition of remaining teeth.

Advantages :1. Provides good rigidity for relatively low bulk because it has two straps in two

different planes one horizontal and the other vertical. 2. Used when the patient objects the large palatal coverage.3. Used with maxillary Tori if they are not extended posteriorly at the junction between

the soft palate and hard palate. 4. Provides good support because it’s extended on the horizontal part of the palate.

Disadvantages : 1. The anterior strap might interfere with phonetics if it covers the rugae area.2. Too many borders might be annoying to the patient (the anterior strap at highly

innervated area)

Never use two rests on one single tooth

The L-beam theory :Two straps in two different planes providing good rigidity even though with small bulk.

U-shaped palatal connector : U shaped with no posterior strap Basically used in class IV when there’s missing anterior teeth

Extend from the lingual or palatal surface of teeth down at the junction between the vertical and horizontal walls of the palate; you can extend it further if you need more rigidity.

Also used if there’s torus extended posteriorly because there’s no posterior strap All borders should be gently curved and smooth.

Indications :1. When many anterior teeth need to be replaced.2. With palatal tori extending to the posterior border of the hard palate.

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Advantages :1. Reasonably strong.2. Has moderate indirect retention because it covers horizontal surfaces.3. Has moderate support.

Disadvantages : 1. When vertical forces are applied on one or both ends it tends to flex and

deform (flexing causes pressure on the abutment teeth, this might cause periodontal problems and mobility of the teeth).

2. Cannot be used for distal extension RPD.3. Greater bulk is required to avoid flexing but results in discomfort for the

patient and interferes with phonetics.4. Poor cross-arch stabilization

Not commonly used because it’s not that rigid and it causes harmful forces on the teeth

Complete palatal plate ( complete palatal coverage ) : Only used when we have bilateral distal extensions with poor abutments, poor

periodontal condition for the remaining teeth that we can’t depend on them to provide the whole support for the whole arch.

Cover the whole palate and the lingual surfaces (extended with scalloped shaped coverage on the teeth), in this way we distribute the support and take if from the hard palate, distal extension and also from the teeth.

Not all class I need complete coverage , if the periodontal condition of the remaining teeth is good and they can provide sufficient support , we can use antero-posterior palatal strap , but if the periodontal condition is poor and there’s bilateral distal extension , we use this type for extra support .

Its anterior border should be 6mm away from the gingival tissues or extends up to the cingulum of anterior teeth

The posterior border should extend to the junction between the hard and soft palate : we give slight beading posteriorly like the post dam area to provide some kind of seal posteriorly and to prevent entrapment of food under the denture

Sometimes we can do the post dam area in acrylic if you expect the anterior teeth to be lost , by doing some kind of retention between the metals and then cover the area with acrylic , so in the future when there’s loss of anterior teeth we can add them and convert the denture to complete denture

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It provides extra retention through the intimate contact through adhesion and cohesion with the underlying hard palate

We need slight relieve on the gingival margin not excessive because it may cause hyperplasia to the gum and with poor hygiene there will be periodontal problems and caries.

Indication :1. Many posterior teeth are replaced and periodontally compromised abutments2. Kennedy class I with anterior teeth replacement ( class I with modifications )3. Patients with very strong muscles (developed muscles) and opposing natural

lower teeth because when ever have natural lower teeth , you have excessive forces on the denture

4. Flat highly resorbed upper ridge and shallow vaults where high stability is required

Advantages : 1. Best rigidity and support2. Better transmittion of temperature and thus better stimulation for underlying

tissues : they transmit heat because metal is conductive to heat 3. Little discomfort or effect on speech because of its minimal thickness

Disadvantages :1. Might interfere with phonetics if thick2. Soft tissue reaction (hyperplasia and inflammation with poor oral hygiene)

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Here we don’t need to cover the area because there is a space of 6mm available


Good luck

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