INDEX • • • • INTRODUCTION TERMINOLOGY PRINCIPLES OF CONNECTOR DESIGNCONNECTORS I. RIGID CONNECTORS CAST CONNECTORS SOLDERED CONNECTORS WELDED CONNECTORS LOOP CONNECTORS II. NON-RIGID CONNECTORS KEY AND KEYWAY SPLIT PONTIC CROSS PIN AND WING • CONNECTORS FOR1. TEMPORARY RESTORATIONS 2. ALL METALLIC F.P.DS 3. METAL CERAMIC F.P.DS 4. ALL CERAMIC F.P.DS 5. TOOTH IMPLANT SUPPORTED PROSTHESIS 6. SPECIAL SITUATIONS -PIER ABUTMENTS -TILTED MOLARS -CANTILEVERED BRIDGES • • • CONNECTOR FAILURES AND REMEDIES CONCLUSION REFERENCES 1 2 INTRODUCTION Connectors basically link different parts of fixed partial dentures (i.e. pontic and retainers). Thus constitute an important part of F.P.D. Their designing determines the fate of periodontal ligament under F.P.D. They may be either rigid /non-rigid type of connectors. TERMINOLOGY 1. Connector- the portion of fixed partial denture that unites the retainer’s and pontics. 2. Rigid connector: - a cast, soldered /fused union between the retainers and pontic. 3. Non-rigid connector: - a connector that permits limited movement between otherwise independent members of a fixed partial denture. 4. Internal connector: - a non-rigid connector of varying geometric design’s using a matrix to unite the members of a F.P.D. 5. Sub-occlusal connectors: - an interproximal non-rigid connector positioned apical to and not in communication with the occlusal plane. 6. Soldering: - to unite, bring into/restore to a firm union, the act of uniting two pieces of metal by the proper alloy of metals. PRINCIPLES OF CONNECTOR DESIGN The connector design determines the success of F.P.D to a certain extent. The factors to be observed while fabricating a connector are: • Type of connector -Rigid connector -Non-rigid connector. • • Size of connector Shape of connector 3 Type of connectors 1. Rigid connector-they are the ideal choice of connectors for F.P.D’s. They provide maximum rigidity and accurately transfer occlusal forces to abutment teeth. 2. Non rigid connector- they are usually used for pier abutments due to differences in physiologic tooth movement and difference in arch position of abutment. It provides a scope for flexing of mandible during opening and closing movements but it is technically sensitive. Size of connector The size of connector is important in maintaining the periodontal health of the abutment teeth. The recommended occusogingival height of connector is, ideally 3-4 mm. It should be sufficiently large to prevent distortion /fracture during function. It should not be too large which interfere with effective plaque control. Pulp size and crown height (young teeth) may be a problem in designing non-rigid connector. Shape of connector Connector’s should have a concave shape mesiodistally (appear as meniscus) and Convex buccolingually4. In cross section it appears as ellipse. For effective functioning the long axis of ellipse should be parallel to direction of force, this leads to encroachment of gingival embrasure, so usually the long axis of ellipse is placed perpendicular to long axis of force. It should be highly polished. For anterior teeth connector should be placed lingual and use of large connector /inappropriately shaped connector result in display of metal leading to esthetic failure of F.P.D. CLASSIFICATION OF CONNECTORS Connectors are basically classified as: - 4 F. Access for proximal margins impeded so removal of patterns from die is difficult. There should be 1 mm of gap between connector and gingiva.D. simple in processing. Rigid connectorsCast connectors Soldered connectors Welded connectors Loop connectors 2.P. 3. Simple in fabrication but difficult in seating. Difficulty in reflowing proximal margins. 2.1.P. Non rigid connectors Key & keyway (dovetail) Split pontic Cross pin and wing RIGID CONNECTORS Cast Connectors They are commonly used type of connector. full veneer preparations. Disadvantages: 1. They are usually indicated for 3-unit F. Partial veneer F.D’s more than 3 units 2. Contraindications: 1. 5 .D’s Preparation: Cast connectors are prepared by waxing the interproximal area before reflowing the margins and investing the pattern.P. 105 m). Use of bench set with thermal expansion is better than hygroscopic expansion. 5 unit fpds. No opportunity to verify fit of individual retainers in mouth.Prosthet. 5. then sectioned and seated with duralay resin.P.dent 55(2). With normal casting procedure the castings are larger facio-lingual The 6 .D – 176 µm highest 3 units F.D cast in a Ceramo-metal gold alloy. Initially were prepared as cast. Increased number of units caused increased amount of mean marginal opening (54.92.P. 2.D do not seat properly after routine adjustments then: .P. 4. 3.P.4. Cut the pontic and recast the cut parts 21 (J.studied the accuracy of different length of multiunit F.It is better to cut the connector and resolder. If F. Investment expansion and pattern distortion can affect fit of castings. 4. 50% improvement in seating was found after sectioning.P. They used 3. mean vertical discrepancy found with as cast specimens were: 4 units F. Precautions in processing of cast connectors:1. So the distortion is not uniform across the fpd. 195-197. They advised use of oval casting ring than cylindrical casting ring. which produces more uniform expansion.D – 20 µm lowest.D greater than 3 units should be cast in 2 piece and soldered. It is advisable to use large casting ring (60 mm). The vertical marginal discrepancies and dimension at gingival axial line angle’s were measure before and after.1986) Burno Es et all (1985) 9: . Any F. And oval casting ring preferable (uniform expansion) than round casting ring. The greatest amount of opening was found at mesial finish line of mesial abutment and distal finish line of distal abutment. It contains a lingual loop and designing should include adequate plaque control.is joining of 2 metal parts using a filler metal with melting point <4500 c. Loop is cast using sprue wax /shaped from platinum-gold –palladium alloy. repair of fractured connectors.D and alteration of stress with addition of multiple abutments (finite element analysis study) They found that – 1. when F.D’s with cast connectors are exhibiting high marginal discrepancy. The most common connector after cast connectors are soldered connectors. less medio-distal dimension(casting contracted mesiodistally).studied the stress levels in the teeth and supporting structures of F. Soldered Connectors Soldering . 4. The connector material should nave high yield strength and rigidity. Connectors in long span fpd’s should be of greater dimensions. Brazing . Hong So Yang et al(1999): .P.D’s more than 3 units.D. They are commonly indicated for F.is joining of 2 metal parts using a filler metal with melting point >4500 c But for theoretical purposes brazing is regarded as soldering. 7 . Increased number of abutments did not solve the mechanical problems of long span F.P. Loop Connectors They are rarely used and indicated when existing diestema is to be retained.8-298. 2.dimension. Dental Solders They are intermediate filler alloy used to join parent metal parts.P. High stress concentration was found at connector (215.P.9 kg /cm 2) 3. Requirements of dental solders: 1.730. 6. 2.5 % Zinc –6. If solder is indicated as585 fine – fineness of solder 180 carat –to be used with 18-carat parent metal Pre.0.5% Tin-4. It should have free flow Silver –increases flow Copper –decreases flow High fusion solder –show high flow Low fusing solder show decreased flow 6. Strength should be similar to a parent metal.615.650. It should have same color as parent metal. 3. Corrosion resistance (minimum 580 fineness) Lower fusion temperature than alloy (60 0 less) Non –pitting (pitting occur due to over heating which cause vaporization of components 5.585.5-2.0% Fineness. Fusion temperature of gold solders –780-8300c They are commonly used with gold alloys.flow Copper –23-12. Fusion temperature is 600-7500 c 8 .5 –9%.490. 2) Silver solder: Composition –Silver Copper Zinc &cadmium-decrease the fusion temperature.ceramic soldering. Commonly used dental solders are: 1) Gold soldersComposition: -Gold –49-73%-corrosion resistance Silver –17.3. Cr. They are available as powder.Ni oxides Composition: . . liquid and pastes. Soldering Investment 9 .Borax glass – 55% Boric acid –35% Silica-10% Fluoride Flux: .They are used with base metal alloys. 2. Solvent –dissolves and carry away any surface oxides present.Borate Fluoride. Soldering Antiflux They limit spread of solder to unwanted areas.They are commonly used for base metal alloys. They dissolve Co. Reducing agent –reduces any oxides present 3. They have type I and II function. Surface protective – cover metal surface and prevent access to oxygen. Commonly used soldering fluxes are Borax Flux: -(Na2 B4 O7) it is commonly used for pre soldering. They are used with noble metal alloys due to high affinity for copper Composition. Commonly used antifluxes are: Graphite –economical & evaporates at high temperature. liquid and pastes. Soldering Flux (Flow) They are used to provide a clean surface for soldering and increase wetting of solder they are available as powder. as they are too fluid in nature. Types of fluxes: 1. Iron oxide (rouge) +turpentine –it is painted on casting with small bristle brush. metal –ceramic restorations are preheated to avoid porcelain cracking. When gas. Different type of heat source used are: . Lower heat content indicates need of long time to melt the alloy.air torch is used to melt solder. Heat Source It is needed to melt the filler metal.<0.Composition of soldering investment is similar to routinely used gypsum and phosphate-bonded investment. Heat content –amount of heat /cubic feet of flame (calories /cubic foot). To prevent uneven heat distribution flame should never be concentrated in one area. Always melting is to be done with reducing zone. Different types of flame torches: 1) Gas –air 2) Gas –air 3) multi-orifice. Flame It is commonly used flame is gas-air/gas –oxygen torch. Type of fuel used Flame temperature with oxygen Hydrogen gas Natural gas Propane Acetylene 2660 2680 2850 3140 Heat content 275 1000 2385 1448 Flame temperature indicates the temperature.1) Flame 2) Oven 3) Infrared light.1% at temp >7000 c. But the refractory component used is fused quartz (it shows least thermal expansion. Oven 10 . 4. It needs specially designed apparatus and requires more processing time. 2. Infrared Soldering It is used with low fusing connectors . 5. et all (1992): .the joints produced have similar strength as conventional soldering. Cleaning and preparing the surface (smoothening done using abrasive discs) to be joined. Soldering Basic steps of soldering involve – 1.the soldering assembly is placed in horizontal muffle with affixed floor.P. Control of time to ensure adequate flow of solder. 3.Furnace /oven soldering is done under vacuum /air .Ds) with as cast connectors and infrared soldering. Connector area of soldering assembly must be positioned precisely relative to the focal point of the reflector that concentrates the heat.9(infrared soldered connector) it was also observed the F. Then muffle is opened and solder is fed unto joint space.2(for cast connectors) 18. preceramic soldered joints.b. They found that mean marginal gap was – 65. Gerard . Maintain proper position of parts.P. 11 . temperature is raised above fusion point of solder. Preparation and fluxing the gap surfaces between the parts.compared accuracy of fit of castings (F. the operator observes soldering procedure through protective dark screen and stops electric supply once solder flows . Assembling the parts to be joined (gap width). infrared energy from tungsten iodide lamp –3400 0 c.Ds with infrared soldered connectors showed better fit than as cast connectors and to similar to single retainer castings . 3. With decreased gap width there is increase flux inclusion. If flow temperature is very near/higher than solidus temperature of parent mental it causes alloying and decreased strength.if done for less time it causes incomplete flow. Selection Of Soldering Technique Selection of appropriate soldering technique needs a through understanding of fusion ranges of all materials involved in F. The main advantages are metal try-in can be 12 . increased porosities. Type III & IV gold retainers are soldered –using gold solders (615 –650 fine) and gas-air torch /furnace. If soldered for longer duration it causes alloying . 4. Temperature –50-600c less than melting point of parent metal.P.P.Ds Bade metal alloys are difficult to solder due to easy oxidation of its elements (silver solders). 2. Mid pontic soldering.time –flame should be used till the solder flows and little tome more to remove flux on parent metal.Factors affecting soldering: 1. decreased strength due to increased amount of solder. With increase gap width there is decreased capillary action.2 mm wide gap should be present between adjacent parts with surfaces parallel to each other. Flame –reducing zone is to be used for soldering.it mainly needs gas-oxygen torch.D. Metal-Ceramic F. Gap width – an average of 0. Pre-Ceramic Soldering The procedure of soldering before application of porcelain . If flow temp is very low it shows low wetting. Soldering All-Metallic F.P.Ds Soldering of metal –ceramic restorations involves two techniques: 1) Pre-ceramic soldering 2) Post-ceramic soldering. recasting of cut parts may be used to increase strength of joint in base metals. done in unglazed state.P.061 Stone 0. sticky wax.0. Harper r j et al (1979) 25: . polyvinyl siloxane polymer (putty). they are finished properly.033 Polyether –0. 052 After wax pattern is prepared and casted.The technique described is used contour 13 . But gold alloys have a low sag resistance. Various materials used are plaster. Post-Ceramic Soldering It involves soldering done after porcelain application and glazing. such as a hygienic . auto polymerizing acrylic resin (cause polymerization shrinkage).055 Sticky wax 0.088 Acrylic resin:-0. Mean distortion than other indexing system (in mm): ZOE:. the framework should have high sag resistance. Its main disadvantages is.Ds Indexing -maintains the relationship between parts of F. proximal embrasure in porcelain can be adjusted. ZnO-eugenol.052 Plaster 0. 4-meta. Soldering All-Metallic F. High palladium alloy and base metals have high sag resistance.P. Its main disadvantage is when porcelain is applied to long structure.P. the temporary restoration is removed and the parts of F.D are checked in mouth for individual fit and occlusion is corrected. Polyether.D till soldering investment is done. They reported that ZnO Eugenol indexing system produced a narrow range and significantly smallest mean distortion than other indexing system. Then using pop as index material index is prepared. if correction of porcelain is needed the joint has to be separated. It is done using gas-air torch.determined the accuracy of different indexing materials. Indexing A two-piece casting can be used to fabricate a fixed partial denture with a solid pontic. do not leave the other unit in place.pontic unit is soldered to the larger retainer. The index must accurately maintain that relationship until the parts if the fixed partial denture have been embedded in soldering investment. However excess bulk of a resin index will diminish accuracy because of additional polymerization shrinkage. plaster. Perform preliminary finishing procedures on the retainer margins. Make sure that there is a small gap between the pontic and the retainer to which it has not yet been soldered.for soldering three unit posterior fixed partial dentures. Smooth off the occlusal surface with a rubber sulci disc. This provides for the most accurate relationship between the retainers and between the retainers and between each retainer and its abutment tooth. Place it on a plastic index tray or a 14 . Numerous materials have been described for transferring the relationship of the fixed partial denture components from mouth to laboratory bench. Into polish the castings at this point. Procedure Remove the provisional restoration from the patient’s mouth and make certain that there are no traces of temporary cement left on the tooth preparations. The pontic is cast with the smaller retainer. The rough surface left on the casting by a greenstone index. utilizing an index of the relationship of the fixed partial denture components in the patient’s mouth. sticky wax. which has been shown to be a highly accurate material for indexing. auto polymerizing acrylic resin (duralay). the most accurate and consistent results will be obtained if the castings are not removed from the index prior to investing.Eugenol. On the first try in for each. since polishing rouge is iron oxide a specific anti-flux for soldering. Then the retainer. Verify the marginal fit of each retainer first. if they are accessible.pontic combination. Resin indices are as accurate as those made of plaster if the components are separated from and reseated in the plaster. 4-META adhesive resin and zinc oxide. Adjust the occlusion wit green stones or other appropriate abrasives. If plaster is used. Try in the single retainer first and then the retainer. Mix a small amount of fast setting impression plaster. 006 inch is recommended for some greatest accuracy. If the crowns separate from the index when it is removed from the cast. If the castings touch there is a likelihood of increased distortion. A conflict arises in determining the proper gap dimension for a solder joint. the stronger the joint apparently because there is less porosity in the joint. Arrange the index material on the carrier so that sharp ridge of material runs the length of the depressor or tray. Therefore a gap width of . In another study. Obviously there is a need for 15 . A plaster index is most accurate when the crowns stay in it. Scrub the occlusal surface of the crowns and clean them in the ultrasonic cleaner before repositioning them in the index. This guarantees a symmetric Uniform bulk of investment surrounding the units to be soldered and should minimize distortion . Trim the area around the imprints enough so that a substantial part of the axial walls will be covered by investment. The wider the solder joint gap. Carefully trims it with a laboratory knife with a no.25 blade so that all margins are exposed by at least 1. The index should extend at least 3 mm easily and distally past the crowns being soldered.thoroughly wet tongue depressor.the plaster index should be approximately 6mm thick.012 inch is recommended for strength. This ridge facilities getting index material into the central grooves of the casting. Place the index on the bench and carefully try the castings in their respective imprints. however it was determined that increased gap width produced an increase in distortion.the slightest bit of debris between the index and crown will keep the crown from seating in the index and will make the relationship inaccurate. trim off excess that might prevent the casting from seating completely back into the imprints. When the material has set remove the index. Then clean the index thoroughly with compressed air . vibrating gently as you seat it.0 mm. For this reason. it has been suggested that there be a gap of at least . If the casings come out with it so much the better. A gap width of .005 inch between the pontic and the retainer. Carefully position the index on the occlusal surface of the castings. A gap width of . since the average business card is 0. Run a triangular-shaped extension of utility wax from the lingual side of the solder joint area of the index. In addition wherever there is contact.8 bur to cut small ‘well’ on the facial and lingual edges of each imprint in the ices. Indeed some investigators have used this distance as a standard. It is often necessary to use a no. solder will be more likely to stick to one surface or the other. there will be harder to solder since capillary action is more difficult to achieve .1 instrument. and apply sticky wax to each casting using the PKT no.008 inch would appear to be optimum since it is intermediate between the narrow in distorted joint and the wide string joint. This permits pace for a bulk of sticky wax without forcing it over the margins. the resulting wedge shape of the solder joint may produce distortion. The opposing surfaces of the retainer and pontic on either side of the solder joint should parallel and each other. leaving approximately 3. Investing Pontics and retainers that have come off the index should be luted back on the index with sticky wax.2 instrument to prevent the joint area from being filled with investment. Flow utility wax into the joint with a PKT no. There should be a slightly smaller one on the facial. In these surfaces diverge. Do not allow the sticky wax to cover occlusal margins (if any) on the facial surfaces. Furthermore.some compromise. Any margin covered by wax at this point will not be covered by soldering investment.as a result.0mm all around the perimeter. This could cause the margin to melt when heated by the bow pipe during soldering. it can be determined easily by inserting a business card into the gap . instead of filing the gap and adhering to both surfaces. Use a cast trimmer to remove excess from the edge of the index. Separate the tongue depressor from the index if they have not already come apart. The waxed area should be slightly larger than the solder joint will be.008 inch thick. Allow the index to dry. These wax wedges will be narrow in the solder joint area than at the edge of the 16 . Use a nop. Flush out the remaining wax with boiling water from a boil-out tank. Overzealous vibrating could jar one of the castings loose. Use of laboratory knife with ano. Paint into the castings and carefully vibrate it into the castings and carefully vibrate it into the boxed area. add flux paste with an explorer. 17 . Allow the investment to set for 1 hr and then remove the boxing wax. While the castings are still warm. It will melt. A separating medium (super-sep. The investment should measure 2. an incomplete solder joint is likely to result. Inspect the block of investment containing the fixed partial denture castings. Separate the index and the investment with a heavy laboratory knife. Mix a small amount of soldering investment. If either of these notches is not placed.index. Also.5cm top to bottom. trim off the excess from the bottom on a cast trimmer. The wax extension placed on the lingual earlier will facilitate this step. err dental manufacturing co. and capillary action will draw it through the entire solder joint.25 blade to cut a v. There should be 3. MI) may be painted over the index outside the castings to insure easy separation later. Hold the index so that there is a finger between it and the vibrator. Romulus. surface oxidation may occur before the protective flux is applied. Place boxing wax around the index. Check again to make sure that the castings are completely seated. Run hot water over the investment and index to soften the sticky wax. If flux is applied later when the castings are hot.0mm of space between the castings and the boxing wax. because the solder will be fed into the joint area from the lingual. This will act as an antiflux and will prevent solder from flowing onto the occlusal surfaces.shaped notch buccal and lingual to the solder joint. The lingual notch is larger than the facial. it will bubble up and stick where it is applied rather than flowing into the joint where it is needed. If it is more. The facial notch is necessary to gain access for heating the castings during soldering.2 pencil to draw heavy line across the marginal ridges adjacent to the solder joint area. Concentrate the tip of the blue cone on the buccal side of the block near the open space between retainer and pontic. The investment block can be placed in an oven and brought from room temperature to 815 0c. the uneven heat distribution that will occur when the blowpipe is applied to a cold block may produce distortion of the finished joint. The bottom of a casting well is good for this purpose. they are set on a tripod and screen over a fisher burner. Aim the blowpipe obliquely at the investment. since an obliquely directed flame results in more even heating and less distortion.Soldering - the invested castings should be preheated to insure even heating. Continue to preheat the castings for 10-15 min. and brush the flame over the entire investment block repeatedly until it is so hot that the castings glow red when the flame is held on throughout this process. In an alternative method of preheating the invested castings. If too much solder is used. direct the torch into the buccal notch and keep it there while the solder flows through the joint. or it will not flow through the entire joint. They will be milted by the heat of the castings. Turn off the flame. covered with flux. the solder will “ball up” and not flow at all. Leave the flame there a few seconds longer while the solder shimmers and appears to “ roll” in the joint. Remove the investment block from the tripod with casting tongs and place it someplace where there is no chance or someone picking it up and getting burned. and not by the blowpipe. When the solder starts to flow. If the blowpipe is used to melt the solder directly the following difficulties can be expected. Begin heating with the blowpipe. Wedge two or three pieces of solder 2*3mm. it may run onto the occlusal surface. The solder on the lingual side of the casting will flow toward the source of heat on the facial. and a larger bulk of solder is more likely to produce distortion. select an area where there 18 . If the castings are not preheated. If you must place it on a bench top . into the lingual embrasure of the joint area. Do not quench immediately.ceramic fixed partial denture. or 4) type III partial veneer retainers are used in an other wise metal. 3) the fixed partial denture length is too great for an accurate single. 2) one retainer has inadequate margins and must be redone. If the invested fixed partial denture is allowed to bench cool for 5 minutes and is then quenched. Pre-ceramic pontic soldering 19 . This may occur is. which will increase hardness and strength while reducing elongation. That which does not flake off should be picked off with a sharp instrument and an old toothbrush. The resulting solder joint will be weaker. it can be trimmed down with a carborundum disc. distortion should be minimized. If all units of the fixed partial denture requiring soldering are of a metal.is little traffic and be sure the surface is heat resistant.ceramic alloy. If it is too bulky. Pre-veneer soldering uses a high-fusing solder that is melted by torch before porcelain is added. Evaluate the size. Soldering Metal –Ceramic Alloys Although an effort is made to fabricate metal-ceramic fixed partial dentures as a single unit. Quenching shortly after soldering will produce thermal stresses that will result in distortion. The fixed partial denture is ready to be finished and tried in the patient’s mouth.piece casting. the fixed partial denture may be assembled in one of two ways. Air abrade the castings with 50µm aluminum oxide. On the other hand. Leave a conspicuous sign to earn off “ lab lizards” who wander around picking up other people’s work. Inadequate bulk or the presence of pits requires reinvestment and resoldering. It is sometimes necessary to solder the units together. This allows time for the gold and solder to respond to an ordering heat treatment. Examine the solder joint to make sure that it is pit free. Place the invested block in water and remove the investment. allowing the investment block to cool slowly to room temperature may produce excessively recrystallization and grain growth. 1) there is distortion in a single –piece fixed partial denture castings. Certainly. In recent years a third method of soldering has been developed that utilized as infrared soldering machine. soldering was done with a gas. For many years. Oven soldered post-veneer solder joints are at least as strong as torch-soldered pre-veneer solder joints.air blowpipe. The high temperatures reached during the porcelain firing cycle would melt the type III gold alloy if it were soldered to the fixed partial denture before the porcelain and been added. With the development metal-ceramic restorations.allows a diagonal joint through the middle of a pontic. post-veneer soldering does present special problems. a need for oven soldering developed. a low-fusing solder is molted in the oven after porcelain has been baked on the fixed partial denture. This is because post-veneer soldering takes more time. and several investigators found that post-veneer joints to be stronger. Post-ceramic soldering compensates for any tooth movement in the mouth between final impression and restoration and it eliminates the significance of any distortion that might occur during porcelain firing. Soldering investment. flux. The device focuses a concentrated beam of infrared energy from a tungsten iodine lamp that operates at 3. which produces stronger joints than soldering in the interproximal connector area. and it is technically easier. If the fixed partial denture includes a type III gold alloy retainer. In post-veneer soldering. Pre-veneer Metal-Ceramic Alloy Soldering Although some investigators have found post-veneer to be stronger than pre-veneer solder joints. Pre-veneer soldering remains more popular with ceramists. and solder just be kept from contacting the porcelain to prevent discoloration or fracture of the porcelain. it can be assembled only by post-veneer soldering. flux and solder 20 . skill and attention to detail to keep the investment.4000 c in a closed chamber in porosity and strength have been found between torch-soldered and infrared-soldered joints although infrared soldering has been found to require more time than torch soldering. If any cracks appear in the plaster. Place monomer and polymer in separate dappen dishes or medicine cups. Make sure that the segments of the fpd are completely seated and stable in the mouth. Then dip the brush in polymer and apply a small amount of powder to the joint. tack them together with an auto polymerizing acrylic resin index. To accurately transfer the segments to be joined to the laboratory bench.from touching porcelain. with adequate separation for a solder joint with optimum strength and minimum distortion. and remake the index. Use a disposable brush to apply a few drops of monomer between the two retainers. a canine. fabricated as a five-unit FPD’S (canine to lateral incisor ) with the second retainer. made separately to facilitate margination of the proximal surfaces of the contiguous retainers. making sure that the material between the retainers is always wet. These restorations should be fabricated so that there will be parallel surface in the solder joint area. which in turn can require the reapplication of porcelain and resoldering. Dry the area with compressed air and isolate it with cotton rolls. wash the FPD thoroughly. remove the material. Continue alternating small quantities of liquid and powder. Apply it to the teeth while plaster is still fluid. creating a ridge of plaster that extends the length of the tongue depressor. Build the index as that it extends onto adjacent surfaces of the two retainers. Make a backup plaster index on a tongue depressor. hold it down with a finger. Mix quick-setting plaster and place it on wet depressor. if one is not stable. Hold the index until the plaster is completely set index. The example demonstrated her is of a six-unit metal-ceramic fixed partial denture with two retainers at one end. The apparent superiority of the post-veneer solder joints also may be offset by the fact that unlike the standardized joint size in the laboratory studies clinical post-veneer joints frequently are smaller because of the ceramist’s fear of causing damage to the ceramic by contacting it with solder. Hold the index until the plaster 21 . Remove the index along the path of insertion of the abutment preparations. With light finger pressure. Brush the investment with a gas-oxygen flame until the block glows if the flame is held in one spot for a few seconds. Hold the flame on the lingual surface of the block of investment. When the invested block has reached the desired temperature.150 0c.together castings into the investment. necessitating a remake. and place it into the top of the soft mound of the investment.is completely set. When it does. If the components are still firmly embedded in the plaster. Invert the framework. The resin will serve as filler in the solder joint. Add a little investment over the units that will not be directly involved in soldering. but do not disturb the resin. Several 2*3 mm pieces of solder in a hemostat can be fed into the embrasure after it gets hot. use casting tongs to transfer it to the mesh or some other area that will not be damaged by flame. Those who are more experienced at soldering may prefer to lift the components from the plaster. Preheat the invested castings in a burnout furnace at 650-8150c.050-1. Use your fingers as a cushion between the vibrator and the fpd components. trim the periphery to produce a near-even bulk of investment around the castings. Very carefully expose each pontic and retainer. Examine it thoroughly to see if the components are securely embedded. Place a quantity of investment large enough to contain the fpd on a ceramic or hard resin tile. The solder used should have melting range within 1. If the resin remains intact. the incisal half of the castings (approximately) should protrude from the investment. Carve the surface of the index surrounding the fpd exposing the pontics and retainers. Allow the investment to set hard. mix some investment and gently vibrate it into the retainers. they can be left there and invested from the plaster index using the technique previously described. Cut around. Then direct the torch into the 22 . it could shift or slip. partially submerge the luted. If left untended. whose retainers and filled with investment. cut the joint using the disk on a lathe. The best joint esthetically. is selected for separation. try the retainers in the mouth to see if they fit individually. must be completed before the soldering process.23 mm) disk. This allows the use of both hands to hold the fpd. Post-veneer Metal-Ceramic Alloy Soldering The technique that follows is for the soldering of a gold-palladium alloy. Remove the soldered FPD from the tripod and place it in a casting well or some other safe place where someone will not be able to touch it and be burned. Remove the fpd from the mouth. A soldering index can be made of quicksetting impression plaster. Try the units in the mouth and make whatever adjustments are necessary. strength wise. and the disks are very easily broken. 23 . All phases of the porcelain addition. as solder is red into the facial notch. Heat will draw the solder through joint area. break the investment by pickling it up with casting tongs and tapping it on the bottom of the casting well or a heat resistant bench top. remove the restoration from the mouth and relieve the affected area. resin. When the restoration is tried in all margins should be closed without any special force needing to be applied anywhere. i. a fixed partial denture is carried to completion in expectation of cementing it without any type of try-in.lingual notch. This technique is often employed without prior intent. Check for any encroachment on the interdental papilla on the facial or especially on the lingual. or both. using a very thin (0. If they do.009 in 0r 0. when it has cooled to room temperature. Retrieve the fpd from among the bits of soldering investment and clean it up. including glazing.e. continue with the soldering procedure. After separation of the two parts of the prosthesis. or zinc oxide-Eugenol bite registration paste as previously described. The solder has a melting range of 710-7400c and it is used with flux. only to find that it does not seat. aspect. Air abrade the surface 50µm aluminum oxide. If there is any. Use no rouge or polishing compounds. pour monomer and polymer into separate containers.2 pencil. Stabilize the index until the plaster is completely set. making sure that the material between the retainer and the pontic is always wet. Apply it to the teeth while the plaster is fluid. if the resin index has come loose. Outline the area to be soldered with ano. without any spaces. Reseat the components of the fixed partial denture in the mouth. Zapit is the material of choice when indexing on a cast in the laboratory. With the two parts of the fpd firmly seated. place a 1. but it should not be used in oral cavity because it’s safety has not been proven. Remove the index along the path of insertion of the abutment preparations. The wax for this step and those following should 24 . Build the index so that it extends onto adjacent surfaces of the two castings. Rearrange the parts of the fpd on the plaster index. Squeeze a cyanoacrylate liquid resin in and around the joint while holding the parts securely. Next dip the brush in polymer and apply a small amount to the joint.0mm thick layer of ivory wax over the gingival one half to two-thirds of the facial surfaces of the retainers and pontic. which will serve as an antiflux. Continue alternating small quantities of liquid and powder.Finish those areas of the crown that are to be soldered with extra-fine sandpaper discs. Then spray the zapit accelerator over the joint. To prevent investment from contaminating the ceramic veneer covering mush of the fixed partial denture. Arrange quick –setting plaster on a wet depressor. Use a disposable brush to apply monomer between the retainer and the pontic. Dry the area with compressed air and isolate it with cotton rolls. making a ridge of plaster that extends the length of the length of the tongue depressor. creating a flat surface with shallow imprints. make sure that it is back in place between segments of the fpd. Duralay is the material of choice for use in the mouth. Fabricate a secondary plaster index on a tongue depressor. Carve the surface of the index around the fpd components. continue raising the temperature in the oven until it reaches 870 0c. After the wax has been removed. When the fps was embedded in investment.mm of the castings. Place the invested castings in front of a porcelain oven to warm slowly for 10 minutes.0mm. and raise the temperature to 8150c at the rate of 42 0c/min. the wax prevented contact between investment and porcelain. there is a space surrounding the porcelain. making surf that they contact only the metal framework of the fixed partial denture. check the castings for completion of soldering. Then carve a vshaped notch on the lingual aspect to insure adequate access to the solder joint.25 blade. Since this is the major support for the crowns in the block. Be sure to use the solder recommended by the manufactures for the specific ally being used. The final temperature used will vary with different solders. Flush out the wax with boiling water.overlap the metal by 1. 25 . into the investment. Place the castings in the oven. Open the muffle of the oven and warm the castings for 5/ or more minutes. Build a mound of investment on a flat surface and set the inverted margins first. Create a wide bevel around the entire periphery of the invested block with a laboratory knife equipped with a no. If the solder has not yet fused. Add a couple of 2*3mm pieces of fluxed solder to the solder joint. Be sure to apply wax to any exposed ceramic that is part of a porcelain shoulder . When the investment has set. Push up a ridge of investment with a spatula to cover most of the lingual surfaces of the retainers and pontic. turn on the vacuum. avoid vibrating the castings directly to prevent the cr0wn from being loosened. add wax to the joint area to insure access for the solder after the restoration has been invested. Turn the restoration over and apply a coat of wax to the gingival and lingual aspects of the pontic. Mix a small amount of soldering investment and carefully vibrate it into the crowns are filled completely with investment. trim it to within 30. including any all-porcelain shoulders. High power neodymium laser with very high power is used. Silver solder joints become porous from corrosion along the interface between the solder and the nickel-chromium substrate. with variable results. While restorations of base metal alloys can be soldered. Argon gas source. Parts:Glove-hax –laser tip. Allow the casting to cool to room temperature. The castings cannot be quenched. Laser welding has low thermal influence on parts and is effective.Break the vacuum and remove the invested fixed partial denture from the oven. Cover the porcelain with masking tape and air abrade the fpd. Soldering can be done on abase metal fixed partial denture with gold solder n a manner similar to that used for gold-palladium metal-ceramic alloys. as the porcelain may fracture. Gold solder use with high resistance nickel-chromium alloy prevents corrosion. 1970 Gordon te28 1st demonstrated use of laser welding form fpd’s. while others have blamed surface oxides. This does not occur with gold solder.Forms an o2 layer at higher temperature. Closed vacuum furnaces were suggested as a solution for this problem and testing by lima verds and stein confirmed that soldering under vacuum resulted in mean tensile strengths that were as much as 40% greater than those soldered in air. using neodymium lasers. While silver solder use on the same alloy permits corrosion. So soldering is ineffective. they tend to be quite technique sensitive. 26 . When the fixed partial denture has cooled. Welded connectors In 1967 orange memorial hospital was started at Florida. High and lowtemperature solders are capable of producing joints with adequate tensile strength that will not lose that strength in a corrosive environment. Overheating of the metal substrate and excessive flux have been faults. CPTI: . They found that the results were satisfactory. remove the investment. Anterior teeth show increase movement in buccolingual movement than mesiodistal 27 . Sjogren g et al (1980) 9: . (U) a. The laser used was neodymium glass laser unit.studied the laser fusion of selected dental casting alloys. But are mainly contraindicated when the abutment tooth show significant mobility. He evaluated the optimum energy levels needed for fusing ceramic compatible alloys Precious alloys. Then non-rigid connectors are to be used.studied effect of laser on titanium properties and found decrease in % elongation and increase in tensile strength.5mm. They have a maximum penetration depth of 2. They are mainly indicated when two abutments cannot be prepared for common path of insertion. J d Preston et al (1975) 18 : .4jooules / 4msec. The energy values were(C) a.4 joules / 6msec. They do not cause damage to ceramic /polymer material. The loss of attachment increase crown: root ratio and tooth mobility due to bone loss.(C) a Non-precious alloy .Stereomicroscope with lens cross hairs for precise alignment of laser beam. for 5-unit fpd with a pier abutment and if one of designated abutment has good gold cast restoration and key and can be used.(U) a Type III gold alloy – (F) a They found that laser fusion of non-precious alloys could yield union that is superior to those in a conventional manner. NON RIGID CONNECTORS There are several situations when rigid connectors are not suitable. The tensile strength of joints by laser > conventional soldering. Douglas Clark et al (1989) 15 advised the use of non-rigid connectors following periodontal therapy. 0316 mm in 1 st bicuspid region. Key and keyway When a fixed partial denture is fabricated with a non-rigid connector. Goodkind r j et al (1973) closing movements”. Manipulate 17 : . Maxillary canine have shown good prognosis after periodontal treatment. This technique is best suited for relieving stress at mid span on long pontics. This defines the need to use non-rigid connector in FPD connecting anterior and posterior mandibualr segments. Adequate depth and a parallel path of insertion are essential when preparing the box form in the distal of this abutment. Key and keyway. And can be use as abutment using non-rigid connectors. and lock the mandrel that extends from the top of the key portion of the pattern into the vertical spindle of the surveying instrument. The wax pattern for the retainer on the pier abutment is fabricated on the working cast.“mandibular flexure in opening and 28 .direction. Place the working cast. Split pontic. a deep box form is carved into the distal surface of the wax pattern to create space for the placement of the plastic keyway pattern. Assemble the key and keyway portions of the connector.precision attachment.0768mm in 2nd molar region and 0. When a plastic pattern is used for the key and keyway. The mean amount of flexure was 0. There are different types of non-rigid connectors: 1. Cross pin and wing. 3. on the table of a surveyor. Studied the amount of mandibular flexural that occurs during mandibular movement. with the wax pattern seated. It was found that mandible width decreased during wide opening movements. .Semi-precious attachment. 2. it is necessary to align the path of insertion of the keyway with that of the distal abutment. invested. For a semiprecious attachment. is then removed. T this point the pontic wax pattern is attached to the pontic key. return it to the working cast. invested. carefully cut off any part of the keyway portion of the attachment that protrudes above the occlusal surface.170 l bur. Then trial set all of the units. The pattern is then invested. and cast.the surveying instrument. removed from the working cast. and cast. burned out. The pontic wax pattern. and the distal retainer. After the casting has been cleaned and air abraded. Because a precise fit is essential to prevent undue movement and stress in this ling-span fixed partial denture. After the acrylic key has polymerized. After the casting is recovered from the investment. incorporating the resin key. the rigid three-unit anterior segment is joined before try-in. The pontic pattern is completed. At the time of try-in verify the fir of each individual unit. the three-unit anterior combination with the distal pontic keyed into it. the pier abutment retainer. burned out. attach it to the wax pontic.169 l or no. lubricate the casting and form the key by placing acrylic resin in the keyway. burned out and cast. Then lower the plastic pattern to the middle retainer wax pattern and lute it in place with sticky was. Place the casting on the working cast. Manipulate the surveyor table until the mandrel and attachments are parallel with the path of insertion of the distal preparation. the mandrel and any excess on the top portion of the key are carefully reduced so the key and keyway are flush. Refine and finish the tapered keyway preparation in the casting with and no. Make a 29 . Cut a keyway or t. the wax pattern for the middle retainer is first completed. The path of insertion of the keyway can be checked against the path of insertion of the tooth preparation for the distal retainer by use of a surveyor or by visual examination.shaped preparation in the distal surface of the wax pattern with a no-170l bur. Remove the key portion and complete the middle retainer wax pattern by blending the distal surface with the keyway. and place the prefabricated plastic pattern for the key into the keyway. After the prepared wax pattern has been cast in gold. The mesial segment is delivered 1 st and then distal segment is seated with the key sliding in the keyway of the anterior retainer. The key is cantilevered distally on a structure of 10 : .keyway within distal surface of anterior retainer of mesial segment. surface of anterior retain. No cement should be placed in the keyway.as key is place extracoronally. Place the distal two units in their respective imprints and invest for soldering. Conventional orientation: . Keyway opening on occlusal surface with taper diverging occlusally. The keyway is also inverted and incorporated in the mesial surface of the pontic. 3) Flexibility of angulations: .soldering index of all the units with zinc oxide –Eugenol bite registration paste or fast-setting impression plaster. with the keyway sliding over the key of the anterior retainer. Physiologic axial contour: . stability and maintain pulpal integrity. Key is attached to distal surface of anterior retainer and is inverted so that it taper converges occlusaly.prevents over contouring of distalaxial improves retention. A flat emergence profile and physiologic contour of gingival 1/3rd can be developed. place the mesial three-unit portion immediately afterward. Advantages: 1) 2) Conservative tooth preparation: . The author described an alternative orientation by reversing key and keyway. the mesial segment is seated first at delivery followed by distal segment.the problem of paralleling the non-rigid connector to a mesially inclined posterior abutment can be resulted with the inverted orientation. with the pontic.“An alternate orientation of non-rigid 30 . When the restoration is cemented. Try in the finished soldering components in the mouth again at a subsequent appointment and make occlusal adjustments if necessary. Moulding m b (1992) connector in FPD”. The main disadvantage of this system is need of increased tooth reduction on distal surface of anterior abutment/ leads to over contouring of distal surface of mesial retainer. Caution must be exercised to ensure that no contact occurs between the porcelain of the 2 segments. The rigid fpd distributed stress vertically and evenly.the opening of key and key-way. lingually and gingivally.inverted orientation of non-rigid connection can be more esthetically pleasing in PFM FPD’S.“photo elastic analysis of supporting alveolar bone as modified by non-rigid connector” The study was done to qualitively compare the stress induced in periodontium of abutment teeth of 5-unit pier abutment fps with nonrigid connector on stress pattern loading conditions. 4) Esthetic potential.metal that becomes the connector and the keyway is positioned more distally within the pontic. Disadvantage. The porcelain can fracture as a result of shear stresses because of the slight unavoidable movement of the non-rigid connector Moulding (1998) demonstrated no significant difference exists in stress patterns with reverse orientation of key and keyway with photoelastic analysis study. However. They also resisted rotational movements and 31 . the porcelain metal junction are positioned on tissue surface of pontic with tissue.containing pontics the sprue between the key and the keyway is an area for plaque retention and resultant tissue irritation. This surface can be concealed by placing the guide planes at occlusal embrasure between the retainer and pontic. with porcelain coverage. The non-rigid distal on canines and non-rigid mesial of molar designs distributed stress almost similar to rigid fpd. The principles of biologic contours are then realized with physiologic emergence angles. This inverted orientation allows more flexibility in positioning the angled connector while maintaining the desired embrasure facially. This can be avoided b use non tissue-contacting pontic. Pier abutments: Moulding m b et al (1988) 8: . Since the keyway opening is open the tissue surface of pontic the only visual evidence do the connector is the interface between the metal guiding planes of the two segments. The nonrigid connector at pier abutment showed greater apical and horizontal stress especially with 1-point loading on the pier. pointing occlusally. The pattern of non-rigid connector orientation at distal aspect of pier abutment has no effect on stress pattern.resultant horizontal stress better than other non-rigid designed. The wax pattern of the anterior three-unit segment (mesial retainer-pontic –pier retainer) is fabricated first. periphery of the ceramic section. Invest. making adjustments as necessary. A surveyor is used to position either the key or the keyway segment of fpd pattern. followed immediately by the distal segment. it is particularly useful in tilted abutment cases. with a distal arm attached to the tissue-contacting area of a pontic. or down onto it (if the key was left facing upward on the pontic base). seat the cast segment on the working cast. Try it on the prepared teeth I the mouth. where the use of a conventional dovetail would necessitate the preparation of a very drastic box in the distal aspect of the pier abutment. Cement the mesial segment first. Wax the distal retainer and the disto-occlusal two-thirds of the pontic pattern. This segment must align with the distal abutment preparation. The design will find use primarily in accommodating abutment teeth with 32 . Split pontic This is an attachment that in placed entirely within the pontic. No cement should be placed between the two segments of the pontic. Cross-pin and wing The cross pin and wing are the working elements of a two-piece pontic system that allows two segments to be rigidly fixed after the retainers nave been cemented on their respective abutment preparations. Place the plastic pattern down into it (if the keyway is in the casting). The placement of non-rigid connector on least desirable on mesial aspect of pier abutment. After preliminary finishing. The pontic can be meta-ceramic. burnout and cast the mesial three-and –a-half –unit segment. A mold can be made by drilling a hole in apiece of aluminum with the machinist reamer and filling the hole with auto polymerizing resin. with draw the retainer-pontic wax pattern. with wing.disparate long axes.0mm thickness faciolingually.7mm hole through the wing with a twist drill in a hand piece. following he pilot hole produced by the 0. Invest. Use a tapered8/0 machinist reamer to ream a smooth. burnout. tapered hole through pontic and wing. burnout. and cast the distal retainer. Assemble the two parts of the fixed partial denture on the working cast. The wing should parallel the path of insertion of the mesial abutment preparation. Remove excess length from the pin both facially and lingually. cut out of a piece of base plate wax. the pin can be taped out and the parts dealt with separately. and replace the 0.0mm short of the occlusal surface.7mm pencil lead. Invest.7mm lead in the pontic pattern to maintain the patency of the hole during investing and casting. extend out 3. The path of insertion of each tooth preparation is made to parallel the long axis of that tooth. Remove the lead. Attach a vertical wing.Fabricate a pin of the same alloy used for the fixed partial denture casting.Cement the retainer with the wing first followed by the retainer-pontic segment. have a 1. and drill a 0. Seat the retainer on the cast. to the mesial surface of the distal retainer wax pattern. It must be long enough to extend all the way through the pontic –wing assembly. be 1. An impression of the reamer can be made with polyvinylsiloxane impression material and filled with resin or molten wax. If it is ever necessary to remove part of this fixed partial denture. and have an undersurface that follows the intended contour of the underside of the pontic. Seat the pin in the hole with a punch and mallet.7mm diameter pencil lead through the hole and build the wax pattern around the lead and the wing.0mm mesially from the distal retainer. This technique 33 . Place a 0. Try the pin for fit in the components on the cast. and cast it. And stress levels were higher in 3.00 mm at connector.5 12. Connectors for all ceramic fpd’s: Failure of all ceramic fpd’s was analyzed on model (1995) 12 it was found that the fracture commonly occurred at core veneer interface (70-78%). Connectors for provisional restorations: The connectors for provisional restorations should be carefully fabricated due to the low strength of the material usually used.0mm than in 4. Use high strength materials such cast metals. heat-processed resin fiber reinforced.4 12. which is the propagation of localized contact damage crack system.5 12. This is mainly due to Hertzian stress state. So they advised to increase the height of connector to increase the bulk and have good stress distribution. They should be slightly overcontoured for increasing strengthening.5 7. It was recommended to use 4*4mm connector size for ceramic 2*3mm for metal. Kamposiora p et al (1996) Material Gold Dicor Inceram 3mm 4mm 11 studied the stress concentration of all Maximum stress 20. and have smooth geometry as compared to angulated geometry in short connectors. Decrease the sharpness at the junction this relieves the stress concentration which may lead to fatigue failure of restoration.0 ceramic posterior fpd’s maximum stress found was Diameter of connector 3mm 4mm 3mm 4mm It was found that stress concentration was found more in region of force applied and at connector region.7 19. 34 . Higher stress was found in the apical region of connector & least in middle part of connector.requires no special patterns and does allow for a completely rigid prosthesis when completed. Cantilevered fpds should limit to replacement single tooth only and also use splinting of abutments.Connectors for metal ceramic: Berger Robert (1989) 16 described the esthetic and physiologic consideration in metal framework design The amount of beam distortion α 1 L 2 * D3 There should be no beam distortion to prevent porcelain fracture. increased marginal bone loss and loss of Osseo integration. Cohen s r et al (1994) advocate use of non-rigid connection between teeth and implants. To limit cantilever forces and direct occlusal loads axially to the implant. This difference can lead to intrusion of abutment. Connectors for cantilever bridges: Hong so yand et al (1996) 13 : . Design of fpd should be such that occlusal forces are limited to the connector’s ability to accept them. The interproximal zone should have adequate span for porcelain and connector placed lingually. Connectors for tooth implant supported fpd’s: Mahamoud h et al (2000) 7 performed a 14 yr comparison of connected and non-connected tooth-implant fpd’s. fracture of implant component. Studied the mechanical behavior of a cantilever fpd with normal and reduced bone support. 35 . Greatest stress was seen in distal cantilevered prosthesis and stress was seen distal to the most distal retainer and fracture may occur at this location. fracture of abutment teeth. Rangert et al (1997) stated that implant connected to tooth will act as cantilever. So for long span fpd’s connectors size should be increased. They found high stress concentrations were found around the connector of fpd.stress analysis of a cantilevered fps with normal and reduced bone support. The difference in mobility of tooth (50-200µm) and implant (10µm). and a casting can be cemented to stabilize the prosthesis. For this reason.Modifications of implant system to combat mobility difference:1) Imz implants. 2) Input of periodontal ligament mechanoreceptors. James v altieri(1995)14 – proposed augmentation of popular tooth – numbering connector. pontics are placed in a cantilevered relationship with the retainer casting. ii.(hypen) denotes the connector 36 . 2) Complaint keeper systems with silicon ‘o’ ring. implant supported crown. and a remake cannot be removed by cutting i endosseous implant p pontic` . 3) Reduction of the number of implant abutment needed for restoration. Benefits of connecting teeth to implant: 1) Some occlusal support and relief of the tooth load on the teeth. When fracture occurs.intra-mobile zylender of polyoxymethelene. 4) Assistance in splinting of teeth. pontic implants. Occasionally. and this can allow excessive forces to be developed on the abutment tooth. For implant supported fpd i. implants in and restoration of tooth described modification nomenclature numbering system to include. failures of both cast and soldered connections have been observed and are generally caused by internal porosity that has weakened the metal. The study resulted in a finding with no difference between rigid and non-rigid connection with respect to long-term outcome. system He addressing pontic. tooth supported connected fpd. iii. CONNECTOR FAILURES A connector between an abutment retainer and a pontic or between two pontics can fracture under occlusal forces. an inlay like dovetailed preparation can be developed in the metal to span the fracture site. the prosthesis should be removed and remade as soon as possible. If this is not possible. If abutment castings can be removed. food impaction. they can be indexed. 2) Slot technique. The main causes of connector failure:Improper design Weak framework Incomplete flow /crystallization of the soldered joints. Fracture connectors cause dislodgement of retainer.remove fractured provisional restoration and traces of provisional cement. Porosities can result in either soldered/ cast connectors that may lead to failures. resoldered and recemented. 1) Brush paint on technique (bead –brush technique). If removal is unsuccessful it may be necessary to be remade some/ all of the units of the restoration. occlusal disharmony.“repair of fractured connectors in provisional fpd”. Remove the provisional components and prepare a class II preparation in each toot adjacent 37 . Modified sanitary pontic design gives optimum connector design with least gingival irritation. esthetic embrassement. Preventive care of fracture:1) Increase dimension of connector( rosensteil) 2) Reinforce connector with metal wire/plate 3) Fabricate connector with heat polymerized acrylic resin 4) Acrylic resin reinforce with cast metal substrate. and violation all the stated goals. David c Appleby(2001)6 : . Return then back in mouth.through the intact connectors. In special situations / where extensive restorations are involved an innovative techniques may be used with good results. mark the location of adjacent contact on either side of fracture. 5) Auto polymerizing acrylic resin with cast metal Common methods for repair broken provision fps connector. A temporary removable partial denture can then be inserted to maintain the existing space and satisfy esthetic requirements. Drill holes with hand in master cast with chips of stone dust frequently cleaned. The depression created 4mm wide. Keith e Thayer (1971) 20 : . Then do the finishing and polishing.“described the intraoral repair of complex cast restorations fracture” A case report was published who had a fracture between 11 and 21 (pontics) of a complex restoration. Depth of 1. Drilling on pontic and abutment done using Ney’s parallel pin drive assembly at slow speed. Pins are inserted in master cast holes and resin is poured over all pins and a matrix + pin assembly is recovered and checked for parallelism. Jaw relation record was made and articulation of master cast was done. 38 . Place the parts of restoration back in mouth and fill both cavities simultaneously with auto polymerizing resin. Thaxter k miller. The area pontic was prepared for parallel pin repair. casted and finished.5. A matrix with sleeves / brushings parallel to each other are placed using mandrel to position than (cold cure matrix) with sticky wax. The matrix containing the paralleling sleeve is placed in-patient.1mm in center of concave area no pinholes are placed at this time. Pin location was determined with 4 pins planned for pontic and on abutment care was taken to prevent pulp exposure. The matrix + pin + inlay wax is sprued.to the fracture in the marked area of contact (done extra orally). Porcelain and gold was removed from gingival 1/3 rd of lingual surface of fractured area. The margins are refined with inlay wax. The following innovative idea was wth the following steps. Matrix is removed. Secondary impression was made covering prepared area and fractured joint. After completely pinholes are made the casted repair is cemented using zinc phosphate cement. A special impression tray was fabricated. concave occluso-gingivally extending two teeth on either side of fractured joint. 731.f . The connector also plays a vital role in the success of the prosthesis.340-346.59.1 st Hong –so.Prosthet . This helps in avoiding long-term complications and embrassement before the patient. mosby –harcourt heath science company.D” J.pub 1997. 13.b.t.uang et all “Finite element analysis on the effect of w.Prosthet.P.et all “Within subject comparison between connected F.1999.509.goodarcrre cj. plillips rw “Crown and bridge–johnston” Thyer ke “fixed prosthodontics “Year book medical pub . splinting in fixed partial denture” J.saunders . Rosenstiel s. whisett ld “Fundamental of fixed prosthodontics” 3 edition quint.1988 39 . edition. Dent 263274.2001. 2001 .h. 3) 4) 5) 6) 7) Dykema rw .394.h.inc .535. land mr .company .c. The design features of the connector are to be kept in mind while fabricating the prosthesis.707.CONCLUSION Every part of the prosthesis has its own role in the long-term success. and non connected tooth –implant fixed partial prosthesis up to 14 year follow up study” IJP2000. REFERENCES 1) 2) Shillinburg.s. David .Appleby “Repair of fractured connectors in provisional Mahamoud . 8) Moulding mb et al “Photo elastic analysis of supporting alveolar bone as modified by non-rigid connectors" J. fujimotot j “Contemporary fixed prosthodontics” 3rd Edition.dent 86(4). 222-223.4th edition . rd hobo.449-50.dent 81(6).721-8.Prosthet . D” J. implants and restoration connector” Int J Maxillofac Implant 10 (5) 244 1995 15) Douglas c “The use of non-rigid connectors following periodontal therapy” Gen dent 37(4) 308-309 1989. 13) Hong so yuand et al “Stress analysis of a cantilevered fps with normal and reduced bone support” j.P. Dent 54(6)770-76. 236-8.D.9) Brumo es et al “Comparison of accuracy of multiunit one-piece castings” J. 16) Berger r “Esthetic and physiologic consideration in metallic framework design” DCNA 1989 33(2) 293-299.P.analysis and modeling” J. Fisher d w “Non-rigid connectors for fixed partial dentures” JADA 87 1195-1199 1973 23) O’connor r p et al “Use of split pontic non-rigid connector with the tilted molar abutment” j prosthet dent 1986 56 241-251 40 . 17) Goldking f j et al “Mandibular flexure in opening and closing movements” j prosthet dent 30 134-138-1973 18) Preston j d et al “Laser fusion of selected dental casting alloys” j dent res 1975 54 232 19) Foester j g et al “Mid-pontic soldering of modified sanitary pontic” j prosthet dent 1994 71 541 20) Miller t h.Dent.1995.prosthet dent 76(4) 424 1996 14) James y altieri “Proposed augmentation of popular tooth numbering system addressing pontics.Res 74(6). in vitro and in vivo. Dent68.701-706 12) “Failure of all ceramic F.1985 10) Moulding mb “An alternative orientation of non-rigid connectors in F.Prosthet.Prosthet.P. Theyer k e “Intra-oral repair of fpd” j prosthet dent 1971 25(4) 382-388 21) Fehling a w “Cast connectors an alternative to soldering base metal alloys” j prosthet dent 1986 55(2) 195 22) Shillingug h t.D” Qint .1992 11) Kamposiore et al “Stress concentration in all-ceramic posterior F. 1253-1258.int 27(10). 24) Eichiniller f c. Andersson m and Bergman m “Laser welding of titanium in dentistry” ACTA Odontol Sacnd 46 247-253 1988 30) Byrne g et al “The fit of fixed partial dentures joined by infrared soldering” j prosthet dent 68(4) 591-596 1992. “Tensile strength of mid-pontic soldering” j prosthet dent 57(6) 696-703 1987 27) “Glossary of prosthetic terms” j prosthet dent 81(1) 48-106 1999 28) Gordon t e. Nicholls j I “Distortion in indexing methods and investing media for soldering and remount procedures” j prosthet dent 42(2) 172179 1979 26) Ferenca j l. smith d l. 41 . Parry e f “Taper cross pin attachment for fixed bridges” Operta detn 1994 19 740 25) Harper f j. “Laser welding of prosthesis an initial report “j prosthet dent 24(4) 472-476 1970 29) Sjogren g.