RESTORATIVERESTORATIVE DENTISTRY DENTISTRY

Clinical Considerations for Adhesive Bridgework

RICHARD IBBETSON

Abstract: is well controlled. It may be Many dental practitioners do not use adhesive bridges because of concerns favoured by patients who have an over high failure rates. Techniques for these restorations should be based on the appreciation of the disadvantages fundamental principles of design which require rigid, accurately fitting frameworks and careful control of the occlusion. The abutments generally require inherent in the tooth preparation little if any tooth preparation. Greater security will result from more extensive required for a conventional metal- coverage of abutment teeth: the routine use of relative axial tooth movement is a ceramic bridge using full coverage predictable method for creating the space that this approach requires. retainers. The adhesive bridge is not Dent Update 2004; 31: 254–265 appropriate in all situations where a Clinical Relevance: The adhesive or resin-bonded bridge should be one of the fixed bridge is the treatment of choice. routinely-used methods for replacing missing teeth, based upon traditional principles Adhesive bridges should not be used in for fixed bridgework and relative axial tooth movement. patients who have significant bruxist or parafunctional activity. The loads are considerably higher than in normal function and this is likely to have adverse consequences for the retention of the framework and its ability to withstand distortion. any dentists are deterred from these restorations have a part to play in Adhesive bridges are generally Mproviding adhesive bridges for their own clinical practice. The modern contra-indicated when the abutment their patients on the grounds that they adhesive bridge is very different from teeth are heavily restored. The presence fail. Some reports in the literature the first ones described by Howe and of restorations is not an absolute support this depressing picture.1 In a Denehy in 1976.3 contra-indication but, where large multi-centre study in Europe, debond This paper will consider adhesive amounts of the functional surfaces of rates increased with time following bridges and their successful use under the abutment teeth consist of restorative placement up to nearly 50% after five the following major headings: material, conventional retainers may be a years.2 Faced with such data, even the better option: these are better able to greatest enthusiast for this type of l Case Selection; provide stable occlusal contacts and prosthesis could find themselves l Framework Design; protection for the remaining tooth. wondering if the adhesive bridge is such l Bridge Design; One further contra-indication is a lack a good idea. However, the experience l Occlusal Management; of clinical height in the abutment gained over nearly 20 years of providing l Try-in, Cementation and Finishing. teeth. Adhesive bridges are often adhesive bridgework for patients, described as being suitable for the coupled with useful information young patient: this is true in so far as accumulated from research, may be CASE SELECTION they avoid significant preparation of the helpful to practitioners who feel that abutments. However, lack of crown height is a contra-indication to any fixed Indications and Contra- bridge as it limits both the production of Richard Ibbetson, BDS MSc, FDS RCS(Eng.) indications FDS RCS(Edin.), FFGDP(UK), Professor of Dental good retention and resistance in the Primary Care and Director, Edinburgh The adhesive bridge has wide retainers and rigidity in the bridge as a Postgraduate Dental Institute, University of application, particularly where potential whole: fixed bridges on short teeth do Edinburgh. abutment teeth are sound and the not perform very well.4

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considerably increased. The three most likely reasons for the detachment of the retainer from the canine were:

l Insufficient coverage of the canine and therefore a lack of retention. l Every time the mandible made a left lateral excursion, the mandibular Figure 1. Labial view of an adult showing a Figure 3. Labial view of the Rochette bridge missing maxillary lateral incisor and a large canine rubbed from the metal-work immediately after cementation. vertical overlap of the anterior teeth. onto the maxillary canine and eventually pushed the tooth buccally out of the framework. l There was considerable difficulty in finding space for the framework on the palatal aspect of the maxillary canine with the result that the framework was very thin: this allowed it to flex leading to failure of the cement lute. Figure 4. Palatal view of the Rochette bridge Figure 2. Palatal view showing the presence of showing the extent of the framework that could proximal restorations. This paper concentrates on three be retained after occlusal adjustment. aspects of the design and construction of adhesive bridges that are important to their success. These are: Common Reasons for Failure Figures 1 and 2 show a 35-year-old man l Framework design; who presented in the early 1980s l Bridge design; requesting that a bridge be made to l The fit of the framework. replace his missing maxillary lateral incisor. The prospective abutment teeth FRAMEWORK DESIGN had Class III restorations but the patient Figure 5. A modern framework for an anterior was anxious to avoid having a bridge adhesive bridge. made that used conventional retainers. A significant difficulty was the depth of Modern Frameworks vertical overlap of the anterior teeth. The design of frameworks has changed However, the decision was made to radically since the early days of these this. However, the principle of provide an adhesive bridge using the bridges. The retentive wings of early maximal coverage is an important maxillary canine and central incisor as adhesive bridges often resembled little one. For anterior retainers, the abutments. Figures 3 and 4 show the more than pads of metal tacked onto the framework should cover from the bridge in place. It was a perforated palatal surfaces of maxillary anterior incisal edge to the area of the framework in the old Rochette style, but teeth. Such bridges were often anatomical crown apical to the the most notable feature is the small surprisingly successful but a cingulum (Figure 5). amount of metalwork remaining on the considerable proportion, unsurprisingly, l Retainers that wrap around the abutment teeth, particularly the palatal failed rapidly and completely. tooth as much as possible. The aspect of the maxillary canine. It had Good framework designs have: retainer should extend onto the proved impossible to retain more metal proximal surface of the abutment on this tooth owing to the extent of the l Retainers that cover as much of the adjacent to the pontic area while, if vertical overlap of the anterior teeth. crown of the abutment tooth as possible, coverage of the tooth’s The bridge remained cemented for 6 possible. There is no doubt that an other proximal surface will also months before becoming uncemented on anterior adhesive bridge would be enhance retention and resistance the maxillary canine. There are three extremely well retained if it covered form. The use of occlusal rest seats possible theories as to why this may both the palatal surface of the is essential for adhesive bridges have occurred. If these are identified abutment tooth and the labial supported by premolar or molar and avoided in adhesive bridge design, surface down to the survey line, teeth: extension of the framework to the likelihood of successful outcomes is although aesthetics would prohibit cover a greater part of the occlusal

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increase, the greater become the requirements for connector height. Two millimetres is the minimum that is acceptable in a reasonably short span. Figures 6 and 7 show a 16-year- old patient for whom an adhesive bridge was made to replace a first premolar. The patient had undergone Figure 6. A posterior adhesive bridge where the framework has reasonable extension but is thin. a surgical crown lengthening procedure because the teeth would Figure 10. Two abutments requiring have been too short to allow preparation of the proximal surfaces facing the pontic area if connector height is to be adequate strength to be produced in appropriate. the connectors. The lingual view of the final bridge shows that, despite the surgery, there was only just enough crown height for provision of the bridge with a connector of appropriate height with an adequate Figure 7. The lingual view showing how the relative lack of crown height compromises the embrasure for cleaning. The need to thickness of the framework and connector height. keep the embrasure open, together with the lack of crown height, has resulted in a thin framework: this bridge was consequently likely to fail. Figure 11. Following preparation of the mesial surfaces of the maxillary right central incisor and A thicker and stronger framework is the maxillary left canine. shown in Figures 8 and 9, but there is more available crown height than in Figure 6.

Figure 8. An occlusal view of the bridge showing Framework Design for Anterior extensive occlusal coverage. Bridges

Minor Abutment Modification

Techniques where minimal preparation, if Figure 12. Cementation of the bridge. The any, is undertaken are based on covering framework is well extended. as much of the functional surface of the tooth as possible such that the teeth are not pushed out of the framework. the resin is bonded to the dentine, this is Features of preparations designed to less likely to be the case and there may increase retention and resistance form be an increased risk of secondary caries. Figure 9. An adhesive bridge made on teeth have been shown in vitro to increase Tooth preparation can be limited to with useful crown height facilitating a framework 6 having appropriate thickness. retention and resistance. However, little or none for the vast majority of clinical studies do not confirm these anterior adhesive bridges. The only area benefits.7,8 The preparation of anterior where preparation is sometimes surface can be beneficial in teeth should only be undertaken after necessary is on the approximal surfaces increasing retention. Such coverage due thought as to its consequences. The of the abutments adjacent to the pontic contributes towards rigidity of the enamel on the palatal surfaces of area. Figure 10 shows a situation where prosthesis, but this will only be the maxillary anterior teeth is relatively thin9 the abutments are inclined towards each case if the retainer has appropriate and any significant degree of preparation other; it would have been impossible to thickness. (Figure 6). is likely to penetrate dentine. Resin establish connector height without l Frameworks that are as rigid as cements generally remain less effective preparation of the proximal surfaces. This possible. The thickness of the on dentine than enamel, while adhesive was carried out and the proximal surfaces retainers should not be less than 0.7 bridges continue to carry a failure rate. made as parallel as possible (Figure 11). mm. Rigidity is also maintained by The cement failure at the framework- The final bridge shows the extension of having height in the connectors of enamel interface is virtually always the framework into the proximal areas the bridge.5 As the span or the loads between the metal and the resin. Where adjacent to the pontics (Figure 12).

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chromium alloy is not likely to be good unless the preparation depth is over 0.5 mm. Whilst asking a technician to wax and cast in a non-precious alloy to a fine finish line will often result in a margin no finer than when no preparation was made. When the palatal surface of a maxillary anterior tooth has been prepared, contact Figure 13. The maxillary central incisor has with the antagonist in the intercuspal Figure 14. A framework for a posterior been prepared to receive an adhesive bridge by position may have been removed. It was adhesive bridge showing good proximal surface creating a cingulum rest seat, a chamfer finishing coverage with the occlusal rests adjacent to the line and an axial groove mesially. suggested that this space could be pontic area. maintained whilst the bridge was being constructed by bonding composite resin Significant Tooth Preparation to the preparation.10 This does not work: even if they appear so to the naked eye. Tooth preparation to enhance retention as the thin layer of composite is usually It is helpful to view the guide planes from of a framework was first described in either lost through wear or fracture before the side, either buccally or lingually, as detail by Simonsen et al.10 Any increased the bridge is ready. There are better ways their relative parallelism will be much coverage of the crown of the tooth that of dealing with occlusal contacts and easier to see. can be reasonably easily achieved is these will be described later. Occlusal coverage is important. This helpful,8 for example, the extension of the may be in the form of rest seats or can be framework onto the approximal surface of more extensive if the contacts with Framework Design for the abutment teeth adjacent to the pontic antagonist teeth allow. Rest seats may Posterior Bridges area. The shape and inclination of the not require preparation if the occlusion abutments can sometimes make Tooth preparation is generally, although permits but, if it is necessary, they must preparation essential if good coverage of not always, necessary for adhesive be definitive. The rests should always be axial surfaces is to be achieved. In bridges in the posterior part of the mouth. adjacent to the pontic area (Figure 14). It addition to guide planes, they described The shape and inclinations of the teeth is wrong to place them at the mesial and the use of axial grooves, cingulum rests often dictate that, without preparation of distal extremities of the bridge. They are and other resistant features prepared in axial surfaces, little coverage can be required to resist axial displacement of anterior teeth to improve retention of the achieved. The original suggestions made the bridge: placed too far from the pontic et al 10 framework. Simonsen et al.10 also by Simonsen ., that 180 degrees of area they will not be able to contribute described the preparation of axial finish the circumference of the axial surfaces usefully. They also make the framework lines to create definite margins and should be covered, make good sense. more rigid by providing bulk of metal at minimize axial contours. However, if there is an opportunity to the connectors, hence the need for them Preparation of anterior teeth to produce increase this, more coverage is likely to to be positioned correctly and to have axial grooves, extension of the framework be helpful. For example, it is very often adequate bulk. onto both the mesial and distal surfaces possible to extend the framework to the There must also be sufficient crown of the abutments, axial finishing lines and disto-buccal line angle of the more mesial height to develop adequate resistance cingulum rest seats is based on a abutment without compromising form in the framework. Crown height is particular concept of framework design aesthetics. Proximal guide planes should important for rigidity through increased (Figure 13). Many of these features are be parallel to each other, or very nearly height in both the retainers and intended to ensure that the framework is so. An average tapered diamond bur connectors. Adhesive bridges made on retained on the abutment teeth. used to make axial reduction in a crown short abutment teeth do not work. Significant tooth preparation will help preparation carries about 6–8 degrees of framework rigidity and may permit less total convergence: this is more than BRIDGE DESIGN incisal extension of the framework, enough to allow a framework to be thereby reducing the potential for the seated. Keeping tapers minimal improves framework to change the colour of the resistance form. Opposing guide planes Principles anterior teeth after cementation. The with approximately 6 degrees of taper will latter is, however, less of a problem with appear undercut when viewed from the There have been changes in the design modern opaque luting cements. occlusal surface. Therefore, it is helpful of fixed bridges which use conventional Any auxiliary retentive features need to to use the bur in the handpiece as a retainers. These have been based on be definitively prepared. Reproduction of surveying instrument and, if this research data where available and an axial grooves when cast in a nickel- indicates a lack of undercut of the improved understanding of the bio- prepared surfaces, they are not undercut mechanics of fixed bridgework. In

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replacing a single missing anterior tooth right central incisor. using either adhesive castings or crowns l The framework demonstrates good as retainers. Where the span is of a inciso-gingival coverage and good length such that an abutment is needed wraparound onto the areas of the at both ends of the span, then two abutment teeth facing the pontic retainers should be used. For a areas. The framework is extended onto conventional bridge in the anterior part of the incisal edges of the abutment teeth Figure 15. Two adhesive bridges, one a the mouth where the arch is curved, this to provide greater security, whilst the cantilever, the other of fixed-fixed design would generally be of a fixed-fixed anterior view shows that such replacing three maxillary incisors. design. There is every indication for extension can, in some cases, be making the adhesive bridge using the compatible with reasonable anterior same design criteria. Figure 15 shows aesthetics. The important feature is contrast, it seems that much of this adhesive bridgework replacing one that the metal has been finished in this information has not been incorporated maxillary central incisor and two laterals. area intra-orally and is angled palatally into designs of adhesive bridges. The features are: much as it would be in an old- A fixed bridge is most stable when it is fashioned anterior gold partial . supported at each end of the span. In the l There are two bridges. If the l The only tooth preparation carried out anterior part of the mouth, a single retainers were made conventionally, was a small amount of modification of missing tooth may often be replaced by a it would be done in the same way. A the proximal surfaces of the abutment cantilevered bridge using only one one-piece bridge would make the teeth adjacent to the pontic areas. This abutment. Such a design spares the use right central incisor a pier abutment moved the survey line further of a second abutment. Single unit and would increase the likelihood of gingivally allowing the development cantilevers have proved very successful, loss of cementation on either of the of appropriate connector height. not only for conventional but also canines. adhesive bridges. Tay and Shaw11 l The right lateral has been replaced Fixed-Movable Designs showed that, where single missing as a cantilever. It is a short span The use of fixed-movable designs should anterior teeth were being replaced with anterior bridge and, were it to be be limited to hybrid bridges where one of adhesive bridges, this design worked made conventionally, the same the retainers is conventional and the best. design would be chosen. other adhesive. The desirability of these There has been a curious extrapolation l The left central and lateral incisors being fixed-movable is not related to of this concept to recommend that all have been replaced by a fixed-fixed mechanics but rather to the practicalities adhesive bridges are best made either as bridge. The span is certainly long of what happens if the adhesive retainer cantilevers or relative cantilevers. For enough to demand an abutment at becomes uncemented. The removal of a example, if the bridge span is longer and each end. It would be possible but hybrid bridge made of a fixed-fixed design demands an abutment at each end, the wrong to make the bridge as two would require the conventional retainer suggestion is made that a movable cantilevers. It would also be to be tapped off, a procedure best connector should be incorporated incorrect to place a movable avoided as there is risk of damaging the somewhere in the span. Such connector in the middle of the pontic abutment. recommendations misinterpret the area between the upper central Short span hybrid bridges containing research data whilst such designs are incisor and upper left lateral to movable connectors have proved from first principles without sound create a cantilevering effect. reasonably successful,8 but their use foundation. The available data indicate In cases where cantilever bridges are anteriorly does conflict with the general that cantilevers work best when a single made, the pontic should provide an principle that such bridges should be of missing anterior tooth is to be replaced intercuspal contact for the fixed-fixed design (Figure 16). In the and the span is short.9,11 antagonist tooth, but it should not posterior part of the mouth they should be involved in the excursive observe the basic essentials of movements of the mandible. If this conventional fixed-movable designs such Designs for Adhesive Bridges patient had been provided with three that the female part of the connector is cantilever bridges to replace the placed in the distal of the more mesial Fixed-fixed and Cantilever Designs missing teeth, the anterior guidance abutment. Together with the need to The principles of bridge design should be would have been virtually disabled, ensure that the adhesive portion is the same using either adhesive retainers being confined only to the right retrievable in the event of cementation or conventional ones. The earlier central incisor and possibly the failure, this means that they are most discussion has highlighted the essential canines. This would have left it easily used when the more mesial mechanical requirements for both types poorly distributed with the abutment requires the conventional of prosthesis. Cantilevers work well for possibility of high loading of the retainer and the more distal one the

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inter-occlusal space between the and a diagnostic wax-up to assist planning abutments and their antagonists. This has much to recommend it. was a reasonable suggestion but greatly If antagonist teeth are to be reduced, it limited the situations where they could be should be done correctly. Dentists are used. Most patients have contact often concerned that the teeth, between their incisors on closure into the particularly mandibular incisors, will look intercuspal position and there is often a shorter and try to minimize this by need to create space for the framework. bevelling the incisal edges towards the labial. This approach results in space Figure 16. An anterior hybrid bridge showing retrievability of the adhesive portion. There is a being created in the intercuspal position movable connector in the mesial of the maxillary Ways of Creating Space but, because the lingual part of the incisal right lateral incisor which has a ceramo-metal There are a number of ways of creating edge has hardly been reduced at all, retainer. space: excursive movements will allow this part of the tooth to contact the framework. l Preparation of the abutments; The maxillary tooth is thicker than it was adhesive. l Adjustment of antagonists; previously owing to the presence of the l Relative axial tooth movement. framework whilst the lingual portion of The Use of Multiple Abutments the mandibular tooth’s incisal edge is Double abutments at one end of a bridge Preparation of the Abutments barely shorter than it was originally. This span have been traditionally employed One suggestion was the creation of produces a protrusive interference with where either the loads on the bridge are space by preparation of the abutment. the resultant increased loading making high or where retention is in short supply. The potential difficulties with this the chances of loss of cementation of the Their use in bridgework is generally approach have been discussed earlier. bridge more likely. contra-indicated. If there appears to be a Adhesive retainers should generally not The opposing mandibular incisors lack of surface area for retention this will be less than 0.7 mm in thickness if must be shortened across the width of usually be because the abutment teeth resistance to flexure is to be adequate. their incisal edges. The motto is level not are short. Most bridges do not fail Removing this amount from a maxillary bevel! because of a lack of retention; it is tooth, not only from the site of resistance form that is more likely to be intercuspal contact but also from the Relative Axial Tooth Movement inadequate. They very rarely fail because guidance pathway, can often mean the The original works of Dahl et al.12 and of a lack of ‘straight pull’ retention, they loss of significant amounts of tooth Dahl and Krogstad,13 together with will fail by being twisted or torqued off structure. subsequent clinical practice, have the teeth. Adding a second abutment at demonstrated that moving teeth axially is one end of the span increases the surface a conservative and reliable way of area for retention but also increases the Adjustment of Antagonists creating inter-occlusal space. The radius of rotation of the bridge, thereby A regularly employed way of creating technique can be applied to adhesive decreasing resistance form, making loss space for the framework in the anterior bridgework and represents the most of cementation of the more distal part of the maxillary arch and allowing conservative method for creating the abutment more likely. control of the anterior guidance was by space necessary for the framework as no The solution lies in increasing the reducing the antagonist teeth at the time tooth reduction is necessary. available crown height of the primary of cementation of the bridge. Dentists There is evidence that increasing the abutment: not only does this increase generally view such suggestions with amount of coverage of the abutment retention but, by increasing the height concern, being anxious about taking up to teeth leads to increased success with available for the retainer, a significant 0.7 mm from the length of a group of lower adhesive bridgework.8 Using the increase in resistance will be produced. It incisors but, in contrast, being happy with framework to create the space necessary also allows taller connectors which make taking equivalent amounts or perhaps provides the opportunity to produce a the bridge more rigid. These more from the abutment teeth. There is high level of coverage of the abutment considerations apply as much to little wrong with a planned reduction of teeth. It may be used to create space adhesive bridges as they do to those antagonist teeth if there is no alternative either anteriorly or posteriorly and using conventional crowns as retainers. and as long as both the patient and the practitioners should not be deterred from dentist understand what the final result making these small planned changes to will be. The patient must be forewarned the vertical dimension of occlusion. OCCLUSAL MANAGEMENT otherwise it will appear that the dentist is Figure 17 shows two adhesive bridges Most early papers describing indications trying to compromise for an error in the replacing the first maxillary premolars in a for anterior adhesive bridges suggested bridge construction by adjusting the 17-year-old patient. The bridges that they should be used where there was opposing teeth. The use of study casts incorporated coverage of the palatal

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in the older patient there is relatively more intrusion of the teeth in contact with the bridge and less eruption of the teeth not in contact.

Precautions There are few contra-indications to this form of treatment. The only ones are: Figure 17. Two adhesive bridges with full Figure 20. An adhesive bridge framework waxed-up on a refractory cast. occlusal coverage replacing missing maxillary l It is sensible to avoid using this premolars. method in patients who have suffered from temporo-mandibular by electrolytic etching of base metal dysfunction. alloys15 and methods of increasing l Patients who are unable to co- surface roughness.16 The development operate with treatment that will of surface-active resin cements17 used in result in their tooth contacts feeling combination with sandblasted cast slightly strange during the first 48 nickel-chromium frameworks has hours after the bridge is cemented. provided a consistent method for securing the framework to the teeth. Additionally, the development of intra- Planning and Fabrication of oral sandblasting or ‘micro-etching’ Figure 18. The patient was unable to achieve the Framework on mandibular closure devices enables the final preparation of following cementation. This involves: the framework to be carried out immediately prior to cementation. This is l Using mounted casts to design the a major advantage as a delay between framework and to rehearse the effect sandblasting and cementation has been of increasing temporarily the shown to be deleterious to the bond vertical dimension. achieved.18 l Designing the framework to provide stable contacts on mandibular closure. Fit of the Framework The framework should fit the teeth When the framework is made, the precisely. This applies not only to the Figure 19. Three weeks later, full occlusion has technician increases the vertical margins but also to the overall been restored. dimension by an amount sufficient to adaptation of the framework to the allow the functional surface of the tooth teeth. It is not correct that the to be covered by the amount of wax composite luting agent will effectively surfaces of the canines and the occlusal necessary to provide a rigid framework. compensate for a poorly adapted surfaces of the second premolars: the At the increased vertical dimension, the framework. Research has indicated that, retainers were of the order of 0.7 mm occlusal contacts on closure and as the thickness of the composite thickness. This resulted in all the other excursive movements are checked for luting agent increases, the bond teeth being out of contact with their desirability. The framework is strength decreases.19 In a further study, antagonists on mandibular closure when subsequently cast, finished and the it was shown more accurately fitting the bridges had been cemented (Figure porcelain applied in the usual way. cast nickel-chrome castings could be 18). Figure 19 shows the teeth three made on refractory casts (Figure 20) weeks later, when all teeth had re- when compared with a traditional lift- established intercuspal contact. During TRY-IN, CEMENTATION AND off technique of a wax pattern from a this period the patient suffered no pain FINISHING stone die.20 A well-adapted framework or discomfort from the teeth, the will be stable when tried-in. If the temporo-mandibular joints or their clinician suspects that the framework associated musculature. Tooth Metal Preparation does not seat positively, it is movement tends to take place more The history of methods of preparing the worthwhile using a fast-setting quickly in the young than the old, framework has been a generally logical temporary cement or low viscosity mainly because the teeth in the young progression from Rochette’s original impression material to check how thick have greater eruptive potential: whereas perforated framework in 1973,14 followed the cement lute will be. If the film

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Cementation and Finishing tooth structure using a friction grip At the time of cementation, control of the handpiece and rotary instruments under operating field is essential. Adhesive copious water-spray. bridges are best fitted with a rubber dam Where the bridge is employing relative in place (Figures 21 and 22): anything axial tooth movement, the patient should other than this represents a compromise. have been previously advised that the Rubber dam makes removal of the excess tooth contacts will feel strange. This luting cement easier, keeping it out of the should be reinforced and the patient gingival crevice. Clearance of the uncured reassured before being dismissed from Figure 21. Rubber dam isolation prior to excess from the proximal areas is helped the surgery. In most cases, full occlusion cementation. by wrapping a length of Superfloss (Oral- will be re-established within a couple of B, Gillette Group UK Ltd, London) around months: the timing of this is not the pontic prior to cementation. Once the particularly important as the patient is not bridge is fully seated, the dentist can hold inconvenienced after the first two to the bridge in place whilst the nurse uses three days. Once full occlusion has been the floss to clear the embrasure areas. re-established, the occlusal contacts, Minimal finishing should be carried out both on mandibular closure and during at the cementation visit. Embrasures excursive movements, should be should be clear and excess cement reassessed to establish that they are removed but there should be little if any appropriate. Figure 22. The bridge having been cemented: finishing with rotary instruments. These glycol gel prevents air reaching the curing resin generate heat and stress and may damage cement. the composite bond to both metal and CONCLUSIONS tooth structure. Final finishing, which The adhesive bridge has a useful part to beneath the framework is thick, the should be done in all cases, is directed play as one of the restorative methods for bridge should be remade. towards blending metal margins into the the replacement of missing teeth. The

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Eschmann Equipment, Peter Road, Lancing, West Sussex BN15 8TJ England Tel: +44 (0)1903 753322 Fax: +44 (0)1903 766793 http://www.eschmann.co.uk DU 264-65 7/6/04 2:50 PM Page 2

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principles for the design of the Services 1987–1997. Prim Dent Care 1999; 6: 21–24. preliminary report. Br Dent J 1982; 152: 378–380. frameworks are no different from those 2. Creugers NH, De Kanter RJ, van’t Hof MA. Long- 12. Dahl BL, Krogstad O, Karlsson K. An alternative for bridgework that uses crowns as the term survival data from a clinical trial on resin- treatment in cases with advanced localised retainers. There is a requirement to bonded bridges. J Dent 1997; 25: 239–242. attrition. J Oral Rehab 1973; 2: 209–214. 3. Howe DF, Denehy GE. Anterior fixed partial 13. Dahl BL, Krogstad O. Long term observations of consider the area of coverage of the utilizing the acid-etch technique and cast an increased occlusal face height obtained by a retainers, their thickness and control of metal framework. J Prosthet Dent 1976; 37: 28–31. combined orthodontic/prosthetic approach. J Oral the occlusal contacts. More recent 4. Roberts DH. The relationship between age and Rehab 1985; 13: 173–178. studies give data indicating survival failure rate of bridge prostheses. Br Dent J 1970; 14. Rochette AL. Attachment of a splint to enamel of 128: 175–177. lower teeth. J Prosthet Dent 1973; 30: 418–423. times that are good enough for these 5. Smyd ES. Mechanics of dental structures: Guide to 15. Livaditis GJ, Thompson VP. Etched castings: an restorations to be considered permanent, teaching dental engineering at undergraduate level. J improved retentive mechanism for resin-bonded whilst their non-invasive nature is an Prosthet Dent 1952; 2: 668–692. retainers. J Prosthet Dent 1982; 47: 52–58. added benefit because, in most instances, 6. Saad AA, Claffey, Byrne D, Hussey D. Effects of 16. Hudgins JL, Moon PC, Knap FJ. Particle-roughened groove placement on retention/resistance of resin-bonded retainers. J Prosthet Dent 1985; 53: there is no need to carry out significant maxillary anterior resin-bonded retainers. J Prosthet 471–476. preparation of the abutment teeth. The Dent 1995; 74: 133–139. 17. Yamashita A, Yamami T. Adhesion bridge, principle of relative axial tooth movement 7. Probster B, Henrich GM. 11-year follow-up study of background and clinical procedure. In: Proceedings resin-bonded fixed partial dentures. Int J Prosthodont of the international Symposium on Adhesive facilitates appropriate framework design 1997; 10: 259–268. . Gettlemam L, Vrijhoef MMA, and minimizes the need for preparation. 8. Djemal S, Setchell D, King P, Wickens J. Long-term Uchiyama Y, eds. Chicago: Academy of Dental The techniques for their construction and survival characteristics of 832 resin-retained bridges Materials, 1986; pp.61–67. cementation are, in many respects, more and splints provided in a post-graduate teaching 18. Asfour D. A Comparison of Two Methods for Surface hospital between 1978 and 1993. J Oral Rehabil 1999; Treatment of Nickel/Chrome Alloys. MSc Report, demanding than those for conventional 26: 302–320. University of London, 1989. fixed prostheses. 9. Shillingburg HT, Grace CS. Thickness of enamel and 19. Chana HS, Ibbetson RJ, Pearson GJ, Eder A. The dentin. J South Calif Dental Assoc 1973; 41: 33-36. influence of cement thickness on the tensile 10. Simonsen RJ, Thompson VP, Barrack G. Etched Cast strength of two resin cements. Int J Prosthodont Restorations: Clinical and Laboratory Techniques. 1997; 10: 340–344. REFERENCES Chicago: Quintessence, 1983. 20. Chana HS, Pearson GJ, Ibbetson RJ. A laboratory 1. Hussey DL, Wilson NH. The provision of resin- 11. Tay WM, Shaw MJ. Clinical performance of resin- evaluation of the construction of resin-bonded bonded bridgework within the General Dental bonded cast metal bridges (Rochette bridges). A cast restorations. Br Dent J 1997; 183: 130–134.

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