British Dental Journal 190. 184 – 191 (2001)
Printed online: 24 Feb 2001 doi :10.1038/sj.bdj.4800919
J C Davenport 1. R M Basker 2. J R Heath 3. J P Make the most of 4. P-O Glantz 5 P Hammond 6
During this part, we’ll undergo
- Minor and major connectors
- Connectors for the upper jaw
- Connectors for the lower jaw
- Non-rigid connectors
- Connectors for acrylic dentures
All of the parts which comprise this series (that’s printed within the BDJ) are really incorporated (plus a amount of unpublished parts) within the books A Clinical Self-self-help guide to Removable Partial Dentures ( ISBN -904588-599) and A Clinical Self-self-help guide to Removable Partial Denture Design (ISBN -904588-637). Supplied by Macmillan on 01256 302699
This information describes the groups and operations of connectors for RPDs. In addition, it views the relative merits and limitations of people connectors.
Figure 1: Connectors
Connectors are either minor or major. The minor connectors (coloured red) join the little components, for example rests and clasps, for that saddles so that you can the main connector. In addition, they might lead for that functions of bracing and reciprocation similar to the RPI system (Figure 6.26 * ). Within the minor connectors joining rests having a saddle can change based on whether an ‘open’ or ‘closed’ design will probably be used (Figure 4.9 * ). The amount of minor connectors must be stored low to evolve for that key design principle of simplicity.
The main connector (coloured black) links the saddles and so unifies the dwelling within the denture. The rest of this chapter is devoted for the primary connector. The main connector may fulfil numerous functions.
In addition for the fundamental connecting role it leads to the support and bracing in the denture by disbursing functional loads broadly for that teeth and, in appropriate maxillary cases, for that mucosa. It will help to assist the denture by providing indirect retention, by contacting guide surfaces and, within the upper jaw, by coverage of palatal mucosa.
* A Clinical Self-self-help guide to Removable Partial Denture Design
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Types of connector for the upper jaw
A range of the form and of connectors is larger within the upper jaw due to the area created for coverage provided by hard palate.
A choice on selection of connector type depends on the needs of:
- Function (eg connection of components, support, retention).
- Physiological constraints.
- Patient acceptability.
Figure 2: Palatal plate
The fundamental functional reliance upon a considerable connector should be to link the different saddles along with other RPD components. During this tooth-supported RPD an easy mid-palatal plate was utilized. This really is frequently a really acceptable connector for such situations because it:
- Leaves all gingival margins uncovered.
- Might be created rigid.
- Includes a simple outline.
- Is well tolerated because it doesn’t encroach unduly across the highly innervated mucosa within the anterior palate.
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Figure 3: Palatal plate
In comparison, the higher extent within the saddles during this tooth–mucosa supported RPD presents really an assistance problem.
The key forces may be shared between teeth and mucosa employing a bigger connector that extends posteriorly for that junction of sentimental and hard palates. It’s still easy to leave the gingival margins of just about all teeth uncovered.
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Figure 4: Palatal plate
Where several teeth separate adjacent saddles you can preserve the border within the connector well within the vulnerable gingival margins. Where just only one tooth intervenes between two saddles (eg UR4 (14)) it will not be easy to find the gingival margin broadly enough to prevent problems of gingival irritation and patient tolerance. However, any chance to discover the gingival margin around only one tooth should normally be understood (A Clinical Self-self-help guide to Removable Partial Denture Design, Statement 15.10)
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Figure 5: Palatal plate
If coverage within the gingival margin using the connector is inevitable, close contact relating to the connector and gingival margin must be achieved whenever achievable. If ‘gingival relief’ is produced, the location is soon obliterated by proliferation within the gingival tissue this modification fit improves the depth within the periodontal pocket and so makes plaque control harder.
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Figure 6: Palatal plate
Full palatal coverage with cobalt chromium has two disadvantages. First, the responsibility of the giant metal connector can lead to displacement within the prosthesis. Second, inside the publish-dam cannot be altered should it finish off being poorly tolerated using the patient. Another approach that you simply are utilized to overcome these problems is highlighted. The posterior area of the casting includes a retaining mesh the polymer extension will most likely be attached.
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Figure 7: Ring connector
A gem ring connector, outlined here round the cast, can be utilized in situations where you will find multiple saddles broadly distributed over the arch, where tooth support may be acquired. This connector can also be indicated in which a prominent palatal torus would contraindicate a mid-palatal plate.
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Figure 8: Ring connector
The ring connector exhibits good rigidity for almost any relatively low the majority of metal. Because the anterior and posterior bars may be situated in different planes to make certain that the ‘L’-produced girder effect is produced.
Of course this connector leaves a large part of the palate uncovered, it has the possibility disadvantage the anterior bar crosses mucosa that’s highly innervated that is contacted frequently using the tongue during swallowing and speech. The anterior bar may hinder these traits and become poorly tolerated consequently. Once the design is chosen the anterior bar needs to be carefully positioned and produced to combine while using the contours within the palatal rugae.
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Types of connector for the lower jaw
The primary physiological constraint for connector design within the lower jaw may be the relatively small distance relating to the lingual gingival margin along with the functional depth within the floor within the mouth. In relation to functional needs the mandibular connector doesn’t lead to aid by disbursing loads to the mucosa. It connects the RPD components and may provide indirect retention and guide surfaces.
With gingival recession there’s less room to manoeuvre and will also be difficult to make a connector that satisfies two primary needs: repair of dental cleanliness and rigidity.
Five within the common connectors are highlighted diagrammatically and clinically.
Figure 9: Sublingual bar
The sublingual bar is different from the lingual bar (see below) because its measurements be a consequence of a specialized master impression technique that precisely records the key depth and width within the lingual sulcus (A Clinical Self-self-help guide to Removable Partial Dentures, Figs 16.23 16.24 16.25 ). These sulcus dimension is retained across the master cast and so the specialist waxes inside the connector to fill the disposable sulcus width at its maximum functional depth. This results in a bar whose maximum mix-sectional dimension is oriented horizontally.
The rigidity in the lingual bar increases getting a square factor when its height is elevated having a cube factor when its width is elevated. The raised width within the sublingual bar connector therefore makes certain that the key factor reliance upon rigidity is satisfied. This isn’t generally the issue obtaining a standard lingual bar.
Because the vertical height in the sublingual bar is at lingual bar technology-not just in shallower lingual sulci and become stored not even close to the gingival margins.
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Figure 10: Lingual bar
The lingual bar, such as the sublingual bar, must be placed under the key depth within the lingual sulcus enables. This mix-part of the lingual bar is determined by the kind of the prefabricated wax pattern, either prescribed using the dentist office or selected using the dental specialist. Probably the most mix-sectional dimension in the connector is oriented vertically.
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Figure 11: Lingual bar
If whether lingual or sublingual bar will probably be used and extra bracing and indirect retention are crucial, bracing arms and rests may be incorporated within the design.
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You will find physiological constraints within the lower jaw that could prevent using sublingual or lingual bars. Mention have been created from insufficient space relating to the gingival margin along with the floor within the mouth. A respected lingual fraenum may compound the issue that makes it impossible to make use of either of people connectors. A mandibular torus might be of individuals a size the sublingual or lingual bar, sitting on the top within the bony protuberance, may be excessively prominent, creating major injury to the individual in tolerating the prosthesis.
Figure 12: Dental bar
Every so often, there’s inadequate room between gingival margin and floor within the mouth for whether sublingual or lingual bar. A lingual plate must be prevented whenever feasible since it could tip the fragile balance between medical health insurance disease for that second. Another connector, in which the clinical crowns are extended enough, may be the dental bar. Patient tolerance inevitably places some restriction across the mix-sectional part of this connector and so some decrease in rigidity might need to be recognized.
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Figure 13: Dental bar
Another connector (generally referred to as as ‘Kennedy Bar’ or continuous clasp) includes a dental bar, plus a lingual bar. This combination enables how big each part of be reduced having a limited extent without compromising the general rigidity within the connector. However, this really is frequently a comparatively complex design that is best prevented once the simpler alternatives are achievable. Tolerance within the patient needs to be assessed carefully before prescribing whether dental bar or maybe a lingual bar and continuous clasp.
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Figure 14: Dental bar
Spaces relating to the incisors will likely preclude while using the dental bar or continuous clasp on aesthetic grounds because the metal may have while using gaps (arrows). A sublingual or lingual bar would avoid this issue, although a lingual plate getting its superior border notched where it passes behind the spaces can be a different.
When the space is small, composite may be incorporated for the adjacent teeth to close it and let a verbal bar for use.
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Figure 15: Lingual plate
The lingual plate covers many of the lingual regions of an individual’s teeth, the gingival margins along with the lingual part of the ridge. The dish terminates inferiorly inside the functional depth within the sulcus. Rigidity is achieved by thickening the lower border having a bar-like section. Among the primary drawbacks within the lingual plate is its inclination to inspire plaque formation. Plaque control should therefore be impeccable before a lingual plate may be prescribed with any confidence.
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Figure 16: Labial (or buccal) bar
Mention have been created from lingually inclined teeth creating a blockage for that insertion in the RPD, and exactly how an adjustment of path to insertion can every so often avoid this obstruction (A Clinical Self-self-help guide to Removable Partial Denture Design, Figs 3.23 and three.24). However, on rare occasions the lingual tilt is really severe you can’t really make use of the lingual connectors. Under such conditions a labial (or buccal) bar may be used. This mix-sectional part of the bar is seriously restricted using the short available space and through patient tolerance.
This mixture of short space for the bar that is elevated length because it travels over the outer circumference within the dental arch can make it hard to achieve rigidity although, during this example, rapid spans minimize this issue.
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All the the functions and essential characteristics within the mandibular connectors is presented in Table 1 :
Figure 17: Non-rigid (stress-breaking) connectors
During loading, an element found on a tooth will most likely be displaced greatly under one which rests on mucosa. In situation your denture is entirely tooth-supported, the displacement differential between teeth and mucosa is immaterial. The connector must be designed it’s rigid and so distributes the key forces using the structure within the denture and thence for that supporting tissues.
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Figure 18: Non-rigid (stress-breaking) connectors
A distal extension saddle gains numerous its support from teeth plus a handful of inside the tissues within the edentulous area. This support differential can lead to tipping within the denture when it’s loaded during function, causing an uneven distribution of load within the edentulous area. It’ll create a relatively greater be part of the burden being taken using the tooth. A way of minimising the issue is to refine a sense the top of saddle while using the altered cast impression technique (A Clinical Self-self-help guide to Removable Partial Dentures. Chapter 19).
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Figure 19: Non-rigid (stress-breaking) connectors.
Another approach is to create a design with ‘independent rear suspension’ employing a flexible connector similar to this split lingual plate. When the saddle component is able to exercise in comparison with tooth-supported component, a larger proportion within the load will most likely be transmitted for that tissues within the edentulous area and you will be more distributed. This can be truly the key the strain-damaged denture relies and offers been recommended that possibly it’s its finest application within the lower jaw. However, research evidence signifies that this preferred result’s not reliably achieved used.
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Inevitably, the strain-damaged design could be a harder construction and so more pricey. Additionally, it can pose greater demands on plaque control and become less well tolerated using the patient. Employing a rigid connector might make it less complicated to make a simple shape. Therefore it’s our preference to create distal extension saddle RPDs that have the next:
- A rigid connector.
- Charge of the duty distribution for that various tissues by: – lowering negligence the substitute occlusal table, – maximising coverage within the edentulous area, – while using the altered cast technique, – using most likely probably the most flexible clasp systems, – instituting a regular maintenance programme.
Of course this book is primarily worried about the development and style of dentures with cast metal frameworks, every so often when it’s appropriate to supply dentures made entirely in acrylic resin.
The primary benefits of acrylic dentures are their relatively affordable along with the ease that they are likely to be modified. They’re therefore most generally indicated in which the existence within the denture is anticipated to obtain short or where alterations for example additions or relines will most likely be needed. These two reasons will make the price of metallic denture hard to justify.
Indications for such treatment would be the following:
- Every time a denture is needed with the phase of rapid bone resorption following insufficient tooth, for instance an instantaneous denture replacing anterior teeth. During this situation a reline adopted by early substitute within the denture isn’t surprising.
- Once the remaining teeth possess a poor prognosis additionally for their extraction and subsequent addition for that denture is predicted. A transitional denture might be fitted under such conditions and so the number of remaining teeth can stabilize the prosthesis for almost any limited period since the patient develops the neuromuscular skills essential to effectively control an alternate complete denture.
- Every time a diagnostic (or interim) denture is needed before a definitive treatment plan may be formulated. This type of appliance may be required, for instance, to find out when the individual can tolerate a lift in occlusal vertical dimension needed allowing effective restoration within the dentition.
- Every time a denture needs to be shipped to a youthful patient where progression of the jaws and advancement of the dentition remain proceeding.
In addition, acrylic dentures might also give a more permanent solution for instance, where only a couple of isolated teeth remain a polymer connector may function similar to effectively when you in metal.
Figure 20: Acrylic dentures
Where a polymer denture is supplied as being a extended-term prosthesis it really is significant it’s possibility of injuries is minimized by careful design. This is often easier to achieve within the upper jaw in which the palate enables extensive mucosal coverage for support and retention with no denture always dealing with cover the gingival margins. A typical type of the idea of the substitute of the couple of anterior teeth in youthful people may be the ‘spoon’ denture. It cuts lower on gingival margin coverage low, however a potential hazard is the chance of inhalation or ingestion.
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Figure 21: Acrylic dentures
A much more stable and thus more broadly relevant design may be the modified spoon denture. Here there is a selection of counting on frictional contact relating to the connector along with the palatal surfaces from the handful of in the posterior teeth, or of adding wrought wire clasps.
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Figure 22: Acrylic dentures.
Another acceptable design may be the ‘Every’ denture that can be used for restoring multiple bounded edentulous areas within the maxillary jaw. Its characteristics are the following:
- All connector borders will be in least 3 mm inside the gingival margins.
- The ‘open’ kind of saddle/tooth junction is needed.
- Point contacts relating to the artificial teeth and abutment teeth established you to ultimately reduce lateral stress low.
- Posterior wire ‘stops’ are incorporated to avoid distal drift within the posterior teeth with consequent opening within the contact points. These ‘stops’ may also lead for that retention within the RPD posteriorly.
- Flanges are incorporated to help the bracing within the denture.
- Lateral stresses are reduced by achieving just as much balanced occlusion and articulation as possible, or by counting on guidance inside the remaining natural teeth to disclude the denture teeth on trip.
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When thinking about in the event you produce an RPD in acrylic resin, the limitations within the material must be borne inside your ideas. These components is diminished and fewer rigid in comparison with metal alloys so the denture is a lot more susceptible to flex or fracture during function. To reduce these problems the acrylic connector should be relatively bulky. This, consequently, might cause problems with tolerance and provides less scope for almost any design that enables the gingival margins to obtain left uncovered.
Decision concerning problem with acrylic resin can it be is radiolucent to make certain that location within the prosthesis can be tough when the denture is ingested or inhaled.
Acrylic RPDs within the mandible frequently lack tooth-support making injuries highly probable. Such RPDs should therefore be prevented whenever achievable.
- Emeritus Professor, College of Birmingham, United kingdom
- Professor of Dental Prosthetics, College of Leeds and Consultant in Restorative Dentistry, Leeds Teaching Hospitals NHS Trust, Leeds, United kingdom
- Honorary Research Fellow, College of Manchester (Formerly Senior Lecturer in Restorative Dentistry, College of Manchester) and Consultant in Restorative Dentistry, Central Manchester Healthcare Trust, Manchester, United kingdom
- Consultant in Restorative Dentistry, Leeds Teaching Hospitals NHS Trust and Senior Clinical Lecturer, College of Leeds and Honorary Visiting Professor, Center for Services Studies, College of You can, You can, United kingdom
- Professor of Prosthetic Dentistry, Consultant in Prosthetic Dentistry, Faculty of Odontology, College of Malmo, Norwegian
- Professor of Informatics, Eastman Dental Institute for Dental Healthcare Sciences, College College London
Correspondence to: J C Davenport 1 5 Victoria Road, Harborne, Birmingham B17 0AG