PROVISIONALRESTORATION IN FIXEDPARTIAL DENTUREDR IRFAN
INTRODUCTIONIt is important that the prepared tooth or teeth beprotected and that patient be kept comfortable while acast restoration is being fabricated by successfulmanagement of this phase of the treatment, the dentistcan gain the patients confidence and favourableinfluence for the ultimate success of the finalrestoration.If the provisional restoration is not up tothe mark, it may lead to unnecessary repairs as well asnead to treat gingival inflammation and it can furtherprolong the treatment schedule.
One of the foremost reasons to be careful duringpreparation of provisional restoration is that due tounforeseen events such as lab delays or patientsunavailability it has to function for extended period so ithas to be adequate to maintain patients health in otherwords it should be healing matrix for the surroundinggingival tissue and adjacent gingival mucosa.It can be said that provisional restoration isfrequently the patient’s first impression of finalprosthesis so it should be representative of the finalesthetic result. In some cases it is used to help correctthe etiologic factors of T.M.J or periodontal disease.
SYNONYMSProvisional restoration,Treatment restoration(Temporization), Interim prosthesis, Provisionalprosthesis.The word provisional means established forthe time being pending a permanent arrangement . Thistype of a restoration has also been known for manyyears as temporary restoration . Unfortunatelytemporary often convey the notion that requirement areunimportant . Experience reveal that time effortexpended fulfilling the requisites of provisionalrestoration are well invested.
DefinitionA fixed or removal prosthesis designed toenhance esthetics stabilization and function for alimited period of time after a which it is to bereplaced by definitive prosthesis.(GPT-7 1999) .
A PROVISIONAL MATERIAL SHOULD SATISFYFOLLOWING CRITERIAConvenient handling: adequate working time,easilymoldability, rapid setting time.Bicompatibility: nontoxic, nonallergic, nonexothermic.Dimensional stability during solidification .Ease of contouring and polishing .Adequate strength and abrasion strength.Good appearance,transclucent,color controllable,colourstable.Good patient acceptance,non irritating ,odorless.Ease of adding to or reparing .Chemical compatibility with provisional luting agent.
Requirements of a Provisional Restoration:1. Fit: a temporary crown mustfit closely at the finish line of thepreparation. This will help preventtooth sensitivity and promotehealth of the surrounding gingiva.In the picture at right, theprovisional restoration will beworn for an extended period oftime while the tissues heal fromperiodontal surgery. Note that themargins of the temporary fitclosely to the finish line of thepreparation.
This provisional hasoverextended margins thathave caused gingivalirritation. This inflammationwill progress during the timethat the provisional is wornand could result in necrotictissues or bone destructionaround the tooth
2. Occlusion: Theprovisional should establish ormaintain adequate occlusalcontacts. Without occlusal contacts,the prepared tooth may extrude.This will make the permanentrestoration too high in occlusionand further adjustment of the finalrestoration may result in an occlusalsurface that is too thin or that isperforated.Occlusal contacts on the provisionalmust not be too high. This willcause occlusal disharmony and mayresult in tooth sensitivity.
3. Proximal contacts:The provisional must establishor maintain adequate proximalcontacts to prevent movementof the prepared tooth in alateral direction. Withoutproximal contacts, the toothmay drift. This will result in apermanent restoration that willnot fit due to excessive ofdeficient proximal contacts.Proximal contacts must bepresent also to prevent foodimpaction in those areas.
Adequate esthetics:The temporary must haveadequate contours, color,translucency and texture. Thisis especially important inanterior teeth. Because acrylictends to darken and discolorover an extended period oftime, a different provisionalrestorative material may needto be selected if the temporaryis to be worn for a long period.A smooth polished surface isimportant for esthetics as wellas plaque removal
5. Proper contours: Aprovisional must haveproper contours foresthetics and for gingivalhealth. The emergenceprofile must be the sameas the original tooth tofacilitate plaque removal.Embrasure areas must becontoured to allow for theinterdental papilla.In a fixed partial denture,the pontic must becontoured so that it is asself cleansing as possible.
The photo at rightshows an improperlycontoured fixedpartial denture. Thereis not enoughembrasure space. Thedental papilla areimpinged upon andsigns of gingivalinflammation arepresent.
At left is anexample of tissuedamage that canoccur fromovercontoured oroverextendedmargins on aprovisional
6. Strength: Thestrength of mostprovisional materials isfar less than gold alloy.Provisionals must be ofadequate thickness towithstand occlusal forceswithout cracking. In afixed partial denture, theconnector area may needto be slightly enlarged toprevent breakage.
MaterialsMaterial used to fabricate provisionalrestorations can be classified as acrylics or resincomposites. Subcategories are based on method ofpolymerization (e.g., chemically activated, lightactivated, dual activated).Acrylics These materials have been used to makeprovisional restorations since the 1930s and usuallyconsist of a powder and liquid. They are the mostcommonly used materials today for both single-unitand multiple-unit restorations. In general, theirpopularity is due to their low cost, esthetics, andversatility.
They produce acceptable short-term (i.e., threemonths) provisionals but tend to discolor over time.Other disadvantages include an objectionable odor,significant shrinkage and heat generation duringsetting, and messiness during mixing. The three typesof acrylics are polymethyl methacrylates,poly-R’methacrylates(where R’ represents eitherethyl,vinyl,or isobutyl groups), and epimines.
Type Brand Manufacturer Advantages DisadvantagesPoly(methylmethacrylateAlikeCr & Br ResinDura layGC America LDCaulk RelianceDental LangDental ParkellBiomaterialsGood marginal fitGood transversestrengthGood polishabilityDurability~ High exothermicheat increaseLow abrasionresistanceFree monomer toxic topulpHigh volumetricshrinkagePoly( ethylmethacrylate)JetSnapParkell Biomaterials Good polishabilityMinimal exothermicheat increaseGood stainresistanceLow shrinkageSurface hardnessTransverse strengthDurabilityFracture toughness
Poly(vinylethylmethacrylate)Trim Harry Bosworth GoodpolishabilityMinimalexothermicheat increaseGoodabrasionresistanceGood stainresistanceSurface hardnessTransverse strengthEstheticsFracture toughnessBis-acrylcompositePro temp II ESPE-Premier Goodmarginal fitLowexothermicheat increaseGoodabrasionresistanceGoodtransversestrengthLowshrinkageSurface hardnessLess stain resistanceLimited shade selectionLimited polishabilityBrittleMarginal fit
VLCuerthanedimethacrylateTriad Dentsply York High surfacehardnessGoodtransversesirengthGoodabrasionresistanceControllableworking timeColor stabilityLess stain resistanceLimited shade selectionExpensiveBrittle
1 . Polymethyl MethacrylatesPolymethyl MethacrylatesAdvantages -low cost ,good wear resistance ,goodesthetics ,high polishability ,good color stability .Disadvantages- significant amount of heat given off byexothermic reaction , high degree of shrinkage (about 8%),strong, objectionable odor -short working time , hard torepair , radiolucent2 Poly-R Methacrylates (R = ethyl, vinyl, isobutyl)Advantages-low cost ,less heat given off during reaction thanpolymethyl methacrylates , less shrinkage than polymethylmethacrylatesDisadvantages -extended working time ,less esthetic thanother currently-marketed materials , poor wear resistance,poor color stability , strong, objectionable odor hard torepair ,radiolucent
3.Epimines These were the first two-pasteacrylics, commercially introduced in 1968 as Scutan(ESPE). Although Scutan had relatively low shrinkageand heat production, it was weak and could not be alteredor repaired.4 . Bis-Acryl Composites Bis-acrylprovisional materials are resin composites and representan improvement over the acrylics because they shrinkless, give off less heat during setting, and can be polishedat chairside. Conveniently, the majority of these productsare provided in cartridges for use in an automixdispenser gun. However, there are at least two types ofguns for provisional materials, so you should not assumecompatibility between one manufacturers cartridges andanother manufacturers gun.
Provisionals made with bis-acryl resins can bepolished to a smooth finish, but are generally notglossy like the acrylics. They also have a pronouncedair-inhibited layer that should be removed (usuallywith alcohol-saturated gauze) prior to finishing andpolishing. Although they are provided in fewer shadesthan the acrylics, they can be characterized usingflowable or traditional resin composites. The bis-acrylcomposites can be subcategorized according tomethod of activation (e.g., chemically activated,visible light activated, or dual activated).
Advantages-less shrinkage than acrylics ,minimal heatgenerated during setting reaction ,relatively highstrength ,minimal odor ,excellent esthetics ,mostproducts use automix delivery ,can be repaired orcharacterized using resin composite ,easy to trim ,good color stabilityDisadvantages - radiopaque ,greater cost thanacrylics ,some do not have a rubbery stage ,viscositycannot be altered ,sticky surface layer present afterpolymerization ,may be more brittle than acrylics
Specific Product Information Protemp 3 Garant isavailable in four shades (A1, A3, B1, B3). Aspecially designed dispenser syringe of AddOn, alow-viscosity light-cured resin, is also includedwith the product. AddOn is used to correct voids ordefective margins of the provisionals. Provisionalrestorations made with Protemp 3 Garant are saidto be more fracture resistant that those made withother composite products. 3M ESPE also claimsthat the restorations have excellent marginaladaptation and are fast and easy to polish.
Integrity is available in three shades (A1, A2, A3.).Two sizes of mixing tips are available: a small sizefor single-unit temporaries and a larger tip formultiple temporaries and fixed partial dentures. Theproduct has a snap set and should be usedexpeditiously; place it in the mouth within 45 secondsand remove it in another 45 seconds..Visible Light-Activated (VLA) Composites Veryfew provisional materials are available that arepolymerized solely by exposure to a light curing unit.One, however, is Revotek LC, introduced by GCAmerica in 2002.
Specific Product Information Revotek LC is a VLA,single-component, sculptable resin composite. It issupplied in a Putty Stick form in a lightproof plastictray. To make a provisional restoration, a smallportion of the material is cut from the stick andadapted to the preparation directly in the mouth. It isthen sculpted using hand instruments after which thepatient is instructed to occlude into it to establish afunctionally-generated occlusal scheme. The RevotekLC provisional is then light-activated for 10 secondsin the mouth, removed, and given a final 20-secondlight exposure. After finishing and polishing, therestoration is cemented with a temporary cement.Revotek LC is available in only one shade (B2).
Dual-Activated Composites One example is Unifast(GC America), which goes through a chemically-activated, rubbery, setting stage and is then VLA forfinal set. Other such products have appeared in thepast such as TempCare (3M) and Provipont DC(Ivoclar Vivadent) but have since discontinued.Preformed materialsPreformed provisional crowns or matrices usuallyconsist of tooth-shaped shells of plastic, celluloseacetate, or metal. They are commonly relined withacrylic resin to provide a more custom fit beforecementation, but the plastic and metal crown shellscan also be cemented directly onto prepared teethusing a stiff luting material following adjustment..
They are commercially available in various toothsizes and are usually selected for a particular toothanatomy. Nonetheless, available sizes and contoursare finite which makes the selection processimportant for clinical success. Compared withcustom fabricated restorations, this treatmentmethod is quick to perform but is more subject toabuse and inadequate treatment outcome. This canresult in improper fit, contour, or occlusal contactfor a provisional restoration
Polycarbonate resinPolycarbonate resin is commonly used for preformedcrowns and possesses a number of superior propertiesrelative to polymethyl methacrylate materials.Thesecrowns combine microglass fibers with apolycarbonate plastic material. Practitionerscommonly use polycarbonate resin shell crowns as amatrix material around a prepared tooth that isrelined with acrylic resin to customize the fit. Thismaterial possesses high impact strength, abrasionresistance, hardness, and a good bond with methyl-methacrylate resin.
MetalMetal provisional materials are generally estheticallylimited to posterior restorations. Aluminum shellsprovide quick tooth adaptation due to the softness andductility of the material, but this same positive qualitycan also promote rapid wear that results in perforationin function and or extrusion of teeth.
An unpleasant taste is sometimes associated withaluminum materials. Iso- Form Crowns (3M DentalProducts, St. Paul, Minn) are manufactured withhigh-purity tin-silver and tin-bismuth alloys. Likealuminum, they possess reasonable ductility and canbe contoured quickly, but the occlusal table isreinforced so they are more resistant to wear relatedfailure. For longer-term use, nickel chrome andstainless steel crowns are available but may be moredifficult to adapt to a prepared tooth.
INFLUENCE OF MATERIALPROPERTIES ON TREATMENTOUTCOMEMarginal accuracyAccurate marginal adaptation of resinous provisionalrestorations to the finish line of a prepared toothassists in protecting the pulp from thermal, bacterial,and chemical insults. The accuracy could besignificantly improved by relining the restoration afterthe initial polymerization.
A number of studies have focused on the effects ofthermocycling on provisional crown margins.Theyreported that(1) acrylic resin provisional crowns demonstrateddimensional degeneration and enlarged marginal gapsresulting from thermocycling and occlusal loading;(2) marginal gap changes were greater after hotthermocycling than cold thermocycling;(3) improved marginal accuracy of PMMAprovisional restorations occurred when a shoulderfinish line was used compared with a chamfermarginal design;
(4) light-polymerized materials provided significantlyimproved marginal accuracy relative to autopolymerizing PMMA resin after thermocycling. Incontrast, Keyf and Anif concluded that the marginaldiscrepancy found with bis-acryl resin wassignificantly greater with a shoulder finish line after 1week relative to a chamfer design . composite materialswould provide a better marginal fit relative to unfilledpolymethyl methacrylate because of lesspolymerization contraction, but marginal fit is not theonly factor affecting the overall retentive quality ofprovisional restorations.
Nearly 20% improvement in the retention of interimcrowns made with polymethyl methacrylatecompared to those fabricated with compositematerials. They concluded that polymerizationshrinkage occurring with the polymethylmethacrylate material might have allowed for atighter fit of the restoration on the prepared tooth,which had a direct influence on improved retentivequality.
Color stabilityColor stabilityIn esthetically critical areas it is desirable forremain color stable over the course of provisionaltreatment. Discoloration of provisional materials canproduce serious esthetic complications, especiallywhen long term provisional treatment is required.Modern provisional materials use stabilizers thatdecrease chemically induced color changes, but thesematerials are susceptible to other factors that willpromote staining..
When provisional materials contact pigmentedsolutions such as coffee or tea, discoloration ispossible. Porosity and surface quality of provisionalrestorations as well as oral hygiene habits, can alsoinfluence color changes.Crispin and Caputo studied the color stabilityof provisional materials. They found that methylmethacrylate materials exhibited the least darkening,followed by ethyl methacrylate and vinyl-ethylmethacrylate materials. They also reported thatincreases in surface roughness induced increases inmaterial darkening and pressure polymerizing did notinfluence discoloration relative to air polymerizing.
Koumjian included a visible light-polymerizedmaterial in their investigation. They placed testmaterials into the flanges of complete dentures andconcluded that for short time periods of 5 weeks orless, all materials demonstrated acceptable colorstability . They stated, however, that the Triad VLCmaterial exhibited more adverse color changerelative to other materials at the end of 9 weeks.Yannikakis et al immersed provisionalmaterials in various staining solutions for up to 1month. They reported that all materials showedperceptible color changes after 1 week. The methylmethacrylate materials exhibited the best colorstability and bis-acryl materials the worst.
Gingival responseInflammation and recession of the free gingivalmargin associated with provisional treatment is acommon occurrence. Donaldson reported thefollowing observations regarding gingival recession:(1) the presence of a provisional restoration lead to atleast some recession at about 80% of the free gingivalmargin sites evaluated; (2) the degree of recession wastime dependant; (3) placement of the definitivetreatment commonly lead to gingival recovery; (4)10% of subjects demonstrated recession in excess of 1mm; and (5) in the presence of gingival recession,only one third of subjects demonstrated completegingival recovery.
In a separate report, Donaldson indicated that theoccurrence of gingival recession before provisionaltreatment was directly linked to further recessionobserved after the completion of definitiveprosthodontic treatment. He also found a direct relationbetween the degree of pressure applied by a provisionalrestoration and gingival recession. An anatomicallycontoured provisional restoration caused less recessionthan did a non-anatomically contoured one. periodontalinflammation associated with provisional treatmentcould be expected to be a reversible process providedthat the amount of gingival irritation is minimal andprovisional treatment occurs over a short time span.
PULPAL RESPONSEDental pulp inflammation can be caused byeither thermal or chemical insult resulting frommaterials used to produce direct provisionalrestorations. The results of the study suggest thepossibility of thermal damage to dental pulp tissueand odontoblasts during direct provisionalfabrication, They suggested that by use of air andwater coolants, as well as by use of a matrix material,that can dissipate heat rapidly, the pulp temperaturerise might be reduced. Additionally, the amount ofheat rise is dependent on the quantity of provisionalrestorative material used
Temperature rise was greatest with polymethylmethacrylate and vacuum adapted templates; least withbis-acryl and relined resin shells; and intermediatetemperature increases were recorded with polyethylmethac-rylate materials and either irreversiblehydrocolloid or polyvinylsiloxane impression materialsused as a matrix for holding acrylic resin provisionalmaterial against a tooth. The authors also identified thatfixed partial denture provisional restorations produced agreater temperature rise than did single-unit provisionalrestorations.Grajower et al showed that faster polymerizingacrylic resin materials could generate highertemperatures than slower polymerizing resins.
They indicated that external heat dissipation might beenhanced with a water spray or by polymerization ofrestorations in silicone impressions. Additionally, thisexternal heat dissipation caused retardation in thepolymerization, which further decreased heatproduction. The retardation resulted from thecooling effect of the spray and not the water itself,since moisture quickens the polymerization ofautopolymerizing acrylic resins that containtertiary amine accelerators. The authors concludedthat (1) provisional acrylic resin restorations might befully polymerized on prepared teeth by appropriatemethods such as in impressions or with externalcooling, without causing excessive heating of thedental pulp;
(2) removal of a provisional restoration beforecomplete polymerization, leading to potentialdeformation of the acrylic resin material, is thereforeunnecessary; and (3) a thin insulating layer shouldbe applied to a prepared tooth before contact withnon polymerized acrylic resin to avoid chemical .
HypersensitivityHypersensitivity from provisional materials hasbeen reported but appears to be rare. Autopolymerizingmethacrylate materials have greater potential forproducing allergic contact stomatitis than similar heat-polymerized materials. The residual monomer in thematerial has been implicated as the causative factor.One report showed that the residual monomer contentin heat-polymerized acrylic resin ranges from 0.045%to 0.103%. Autopolymerized acrylic resin has aresidual monomer content of 0.185%. Over timeresidual monomer is gradually leached out, leaving afraction that is tightly bound to the resin materia1.
Allergic reaction to provisional materials willdemonstrate the following features: (1) the patient hashad previous exposure to the provisional material; (2)the reaction conforms to a known allergic pattern, suchas redness, necrosis, or ulceration; (3) the reactionresolves when a provisional restoration is removed; 4)reaction recurs when a provisional restoration isreplaced; and 5) a patch test for the material is positive.Patch testing has demonstrated less response withlight-polymerized materials relative toautopolymerizing acrylic resin. In-direct materialprocessing methods are recommended for individualsshowing evidence of hypersensitivity.
Strengthening provisional materialsThe studies clearly favors acrylic resin as thematerial of choice for provisional restorations. Mostresins used for provisional restorations are brittle.Repairing and replacing fractured provisionalrestorations is a concern for both clinician and patientbecause of additional cost and time associated withthese complications. Failure often occurs suddenly andprobably as a result of a crack propagating from asurface flaw. The strength and serviceability of anyacrylic resin, especially in longspan interimrestorations, is determined by the materialsresistance to crack propagation. Crack propagationand fracture failure may occur with these materialsbecause of inadequate transverse strength, impactstrength, or fatigue resistance.
Physical properties of strength, density, and hardnessmay predict the longevity of provisional restorations.Donovan et al examined methods to improve thelongevity of these restorations using variable indirectpolymerization techniques. They compared methylmethac-rylate material strength, porosity and hardnessunder the following polymerization conditions: (1) inair; (2) under water; (3) under air pressure; and (4)under water and air pressure. They found thatpolymerization with a pressure vessel with air andwater had the greatest influence on increasing strengthand reducing porosity.
Heat-polymerization of acrylic resin materials can beused when provisional restorative treatment will berequired for extended periods of time or whenadditional strength is required. This indirectlaboratory process results in materials that aredenser, stronger, more wear resistant, more colorstable, and more resistant to fracture than theirautopolymerizing counterparts. Both heat-polymerized acrylic resin and metal provisionalrestorations should last longer than autopolymerizedrestoration, but the expense and time required forindirect fabrication can make them less cost effectivefor routine use
Zuccari et al studied methods to promote a strongerresin matrix "by decreasing crack propagation. Theyreported that when admixed zirconium oxidepowders were added to unfilled methyl methacrylateresin, the resultant composite material exhibitedsignificant improvements in the modulus of elasticity,transverse strength, toughness, and hardness, eventhough water sorption over time had a negativeinfluence on mechanical properties.
In a study describing a negative influence on thestrength of provisional materials, Chee et al studied theeffect of chilled monomer on the working time for 3autopolymerizing acrylic resins. They found that theworking and setting times increased by up to 4 minuteswhen chilled monomer was used, but the transversestrength for the materials were decreased by 17%.
Provisional luting materialsProvisional luting agents should possess goodmechanical properties, low solubility, and toothadhesion to resist bacterial and molecular penetration.The most important function of these materials is toprovide an adequate seal between the provisionalrestoration and prepared tooth. This is necessary toprevent marginal leakage and pulpal irritation. Thereare a variety of luting materials used for interimpurposes. The most common include (1) calciumhydroxide; (2) zinc-oxide and eugenol; and (3)noneugenol materials. Generally, all of these possesspoor mechanical properties that likely worsen overtime.
This can have a negative influence on marginalleakage but also provides an advantage byallowing easier dislodgment and removal ofprovisional restorations from teeth.The retentive requirements for provisional lutingmaterials are that they be strong enough to retain aprovisional restoration during the course of treatmentbut allow easy restoration removal when required.This paradoxical necessity for good retentive andsealing quality and easy restoration retrieval maylead to a compromise in material behavior,particularly regarding mechanical properties.
Baldissara et al recommended that interim restorationsbe frequently evaluated and used for only short periodsof time. Literature reports advise that if provisionaltreatment is required over a protracted time period, it isbest to remove and replace the provisional luting agenton a regular basis. Some of the most commonly usedcements with provisional prostheses are thosecontaining zinc-oxide and eugenol. They providesedative effects that reduce dentin hypersensitivity andpossess antibacterial properties. Unfortunately, freeradical production necessary for polymerization ofmethacrylate materials can be significantly hampered bythe presence of eugenol found in eugenol basedprovisional luting materials.
This can interfere with the acrylic resinpolymerization and hardening process .They can alsobe incompatible with some resin-based definitiveluting agents for the same reason.Eugenol-free provisional luting materials arecommercially available and have gained popularitydue to the absence of resin-softening characteristics .Gegauff and Rosenstiel, however, reportedthat Temp- Bond (Kerr Dental, Orange, Calif) a zinc-oxide and eugenol-based cement did not appear tohave a significant adverse effect on thepolymerization of acrylic resins. They postulated thatthe softening effect of eugenol on acrylic resin isdependent on the presence of unreacted eugenol,which may be minimal in Temp-Bond cement .
CLINICAL CONSIDERATIONS FORPROVISIONAL TREATMENT INVOLVINGNATURAL TEETHThe fabrication of provisional restorations isextensive . Virtually all teeth receiving cast restorationsrequire provisional restorations. Properly executedprovisional restorative treatment rarely fails anddislodgment or fracture usually indicates that their formis unacceptable or that a tooth preparation is inadequate.Provisional restorations should be smooth, highlypolished, and alterable and for this reason custom madeprovisional restorations most consistently meet thebiological,functional, and esthetic needs of a patient.
Provisional restorations as part of comprehensivetreatmentProvisional restorations are not devoid ofinteractions with other modes of therapy. Patients oftenhave periodontal, endodontic, orthodontic, or surgicalneeds in conjunction with their prosthodontictreatment. Provisional restorations produceoutcomes that range from microscopic tissue effectsto psychological factors that change a patientsbehavior. Provisional restorations can providepatients with an increased confidence in treatment.
Diagnostic provisional treatmentIn the simplest situations, complete oral andextraoral clinical examinations, as well as radiographicevaluation, may be all that is necessary before commencingprosthodontic treatment. In more complex treatments,however, provisional restorations provide a means ofdesigning, improving, and assessing the occlusion,esthetics, and contours for definitive restorations, as well asto determine their effects on gingival health, phonetics, andpatient adaptability before the initiation of the definitivetreatment. Provisional restorations fit into 2 categories: (1)those that fit within an arch of fundamentally intact teeththat provide reference for their occlusion, contours, andesthetics; and
Those that become the reference for the entireprosthesis. Provisional treatment for patients with morecomplex prosthodontic needs demands fabrication andarticulation of diagnostic casts and completion of adiagnostic wax-up in the maxillomandibular relationshipin which definitive treatment is to be performed.Occlusal diagnosis and treatmentCasts of provisional restorations mounted oppositedefinitive casts transfer contours, clinical crowndimensions, and maxillomandibular relationships from apatient to a dental laboratory for developing occlusalfactors, especially anterior guidance, for fixedprosthodontic treatment.
Sometimes treatment feasibility can only be tested viafull-arch provisional restorations and occlusalproblems are best diagnosed during a functionaltesting period with provisional treatment .Esthetic and phonetic diagnosis andtreatmentProvisional restorations assist development andassessment of esthetic and phonetic values of theplanned fixed prosthesis. Matrixes created from adiagnostic waxing or from casts of provisionalrestorations are useful tools for producing specificcontours in a definitive prosthesis or communicatingthose concepts to the dental laboratory.
In certain situations phonetics and esthetics of a plannedprosthesis can be assessed before tooth preparation byuse of vacuum or pressureformed matrixes that holdautopolymerizing acrylic resin between unpreparedteeth and proposed tooth contours to provideintraoral treatment simulation.Periodontal treatment and maintenancePeriodontal treatment is commonly part ofcomprehensive prosthodontic care. These provisionalrestorations provide a matrix against which the tissueheals, guiding the generation of correct soft tissuearchitecture. According to Shavell, tooth preparationsand provisional restorations should be completedwith retraction cord in place.
It has been recommended that when the duration of theperiodontal treatment is less than 6 months, the use ofacrylic resin provisional restorations . Poorly fabricatedprovisional restorations have consequences for fixedprosthodontic treatment including gingival recessiondifficulty making impressions; difficulty fitting thedefinitive restorations; soft tissue damage; andinefficient use of time at prosthesis insertionSlightly convex facial and lingual contours ofprovisional restorations and a flat emergence profileare effective in promoting gingival health. Goodperiodontal health can be created by developing theappropriate contour and good gingival adaptation andembrasure space of the prosthesis.. Embrasure spacesthat are too broad can cause food impaction andblunting of the papilla .
Types of provisional restorations:Many different types of procedures are used toconstruct provisional. Provisional construction canbe categorized into two main methods:1 Custom temporaries - those that are madewith a matrix derived from the original tooth or amodified diagnostic cast. Custom temporaries canbe constructed in three different manners:Direct: these are constructed with a matrixlined with provisional material that is placeddirectly on the prepared tooth
Indirect: these are constructed by placing thefilled matrix over a model of the prepared tooth,thus the provisional is constructed out of thepatients mouth.IndirectDirect: these are made by forming atemporary in an indirect manner and then reliningthis directly in the patients mouth. This method isuseful when constructing temporary bridgesbecause most of the work can be done in thelaboratory.2 Prefabricated temporaries - these arepreformed crowns that can be purchased and may bemodified to fit a prepared tooth. In most cases theserequire relining with an acrylic material.
Direct fabrication. For select patients, a denturetooth secured in position and orthodontic wire may be asuitable provisional restoration for a missingmandibular incisor. For urgent situations, in the absenceof any matrix or opportunity to create a matrix, aprovisional restoration can be fabricated by adapting ablock of freshly mixed acrylic resin directly to a tooth.After the acrylic resin block has polymerized, the toothcontours can be carved with acrylic resin burs of choiceand the restorative margins perfected intraorally.Mostpatients, however, require a more conventionalapproach. Fabricating provisional restorations directlyon teeth using the "direct method" is suitable for singleunits and up to 4-unit fixed partial denture provisionalrestorations,
Three techniques encompass virtually all of the literatureon direct provisional restorations: (1) use of a premanufactured provisional sheIl (2) use of an impressionmaterial ,or pressure or vacuum formed translucentmatrix and (3) use of a custom, pre-fabricated acrylicresin shell. Direct provisional restorations madeparticularly of PMMA and, to a lesser degree, polyethylmethac-rylate (PEMA) must be cooled if the material isallowed to polymerize completely on a tooth;polymethyl methacrylate can increase pulpaltemperatures as much as 7°C. Cooling the materialduring polymerization by its removal at initialpolymerization and allowing complete polymerization tobe completed while it is off the tooth,
cooling with air-water spray, periodic removal, andflushing with water and use of a "heat sink" matrixmaterial such as alginate will limit temperatureincreases to less than 4°C, minimizing the exothermicrisk .Indirect fabrication. The indirect methodhas been indicated to fabricate multiple unitprovisional restorations to (1) avoid exposure of apatient to adverse properties of provisional acrylicresins; (2) optimize the properties of provisionalacrylic resins; (3) allow the use of materials that aredifficult to polymerize intraorally; (4) make significantcontour or occlusal changes; and (5) provide for thefabrication of hybrid provisional restorations.
Indirect techniques generally use either approximatetooth preparations made on a duplicate cast or a cast ofthe actual tooth preparations made after the clinicalprocedure has been accomplished. One advantage ofthe indirect technique is that it can be allocated toauxiliary personnel. Fabricating a provisionalrestoration wholly or in part using an indirect methodreduces exposure of oral tissues to monomer, heat,shrinkage, and reduces the volume of volatilehydrocarbons inhaled by a patient. Creating an indirectacrylic resin shell of an unprepared tooth that is laterrelined intraorally is one method of reducing patientexposure.
It has been reported that provisional restorationsfabricated indirectly have superior margins to thosefrom direct techniques because the acrylic resinpolymerizes in an undisturbed manner. Polymerizingautopolymerizing acrylic resin under heat and pressureimproves the physical properties of the material.Reinforcing the vacuum or pressure formed matrixallows it to be secured to the cast on which theprovisional shell is polymerized.
Indirect method (Alginate impression technique)The overimpression frequently is made in thepatients mouth while waiting for the anesthetic totake effect. However, if the tooth to be restored hasany obvious defects, the overimpression should bemade from the diagnostic cast .When the alginate has set, the overimpression isremoved from the diagnostic cast and checked forcompleteness. Thin flashes of impression materialthat replicate the gingival crevice are removed toinsure that there will be no impediments to thecomplete seating of the cast into the overimpressionlater .
The impression is wrapped in a wet paper towel andplaced in a zip lock plastic bag for later use.When the tooth preparation is completed, anotherquadrant impression is made in alginate. Thisimpression is poured up with a thin mix of quick-setting plaster .Mix tooth-colored acrylic resin in a dappen dishwith a cement spatula. Place the resin in the overimpression so that it completely fills the crown areaof the tooth for which the provisional restoration isbeing made .
Seat the prepared tooth cast into the over impression,making sure that the teeth on the cast are accuratelyaligned with the tooth impressions.Once the cast has been firmly seated and theexcess resin has been expressed, hold the cast in placewith a large rubber band.
It is important that the cast be oriented securely inan upright position so that the space between thecast and the impression that is filled with the resinforming the provisional restoration will not bedistorted.If the cast is torque to one side by the rubber band,the cast may be forced through the soft tissue insome areas resulting in a provisional restoration thatmay be thin in those areas and thicker than desirablein others. The force used to seal the cast into thealginate impression is critical.
DIAGNOSTIC CASTSDIAGNOSTIC CASTSPUTTY INDEX TECHNIQUE
Putty index made from thePutty index made from thediagnostic wax up.diagnostic wax up.
Trimmed acrylic shells oriented in theTrimmed acrylic shells oriented in theputty indexputty index
Auto polymerizing resin filled inAuto polymerizing resin filled inthe putty indexthe putty index
The index stabilized on theThe index stabilized on theprepared sectional cast.prepared sectional cast.
Finished and cementedFinished and cementedprovisionals.provisionals.
2TEMPLATE METHODTo make a template, place a metal crown formor a denture tooth in the edentulous space onthe diagnostic cast . All of the embrasures shouldbe filled with putty to eliminate undercuts duringadaptation of the resin template.To facilitate removal of the template, a thin strandof putty can be placed around the periphery of thecast and on the lingual surface of the cast, apicalto the teeth . Use a large acrylic bur to cut a holethrough the middle of the cast (midpalatal ormidlingual). Place a 5 x 5-inch sheet of 0.020-inch-thick resin . Turn on the heating element ofthe machine and swing it into position over theplastic sheet .
As the resin sheet is heated to the proper temperature,it will droop or sag about 1.0 inch in the frame. If youare using coping material, it will lose its cloudyappearance and become completely clear. The castshould be in position in the center of the perforatedstage of the vacuum forming machine. Turn on thevacuum.Grasping the handles on the frame that holds theheated coping material, forcefully lower the frame overthe perforated stage . Turn off the heating element andswing it off to the side. After approximately 30seconds, turn off the vacuum and release the resinsheet from the holding frame . if a vacuum formingmachine is not available, it is still possible to fabricatea template for a provisional restoration.
Place the softened sheet over the cast. Forcefully seat thetray of silicone putty over the coping material . Toaccelerate cooling, blow compressed air on the plasticsheet and the impression tray. After about a minute, snapthe tray off the cast . If the silicone putty sticks to theresin sheet, the putty can be easily removed by pulling itoff in quick jerks. Rapid separation causes the siliconeputty to exhibit brittleness that will result in easyremoval. Replace the putty in its original container forlater re use. Separate the template from the diagnosticcast.
Upon completion of the preparations, make analginate impression of them and pour it in fast-settingplaster. Trim the cast so that it includes only onetooth on either side of the prepared teeth. Try on thetemplate to verify its fit .Coat the cast with separating medium and allow itto dry. Mix the acrylic resin in a dappen dish andplace some on protected areas of the cast, such asinterproximal spaces and in grooves and boxes. Asthe resin begins to lose its surface gloss and becomesslightly dull, fill the area for which the provisionalfixed partial denture is being made . Place some extrabulk in the portion that will serve as the pontic.
Wrap rubber bands around the template and cast,being careful not to place them over the abutmentpreparations, lest they cause the template tocollapse in that area . Place the cast in a pressurepot if one is available. Otherwise, place it in warm(not hot) tap water to hasten polymerization.Remove the fixed partial denture from the cast. Donot.hesitate to break the cast if necessary. Trim offthe excess acrylic resin. Use discs to trim the axialsurfaces down to the margins. Remove the saddleconfiguration that was created by the crown form inthe edentulous space . The pontic should have thesame general shape that the pontic on the permanentprosthesis has.
Shell-Fabricated Provisional RestorationA thin shell crown or fixed partial denture can bemade from any of the acrylic resins, and then thatshell can be relined indirectly on a quick-set plastercast. It also can be relined directly in the mouth. Ifthe reline is done directly, a methacrylate other thanpoly(methyl) should be used. This technique cansave chair time because the restoration is partiallyfabricated prior to the preparation appointment Caremust be taken not to make the shell too thick. If toothick, the shell will not seat completely over theprepared teeth and it will need to be trimmedinternally.
This can be time-consuming and defects anyadvantage gained by making it before the preparationappointment .An overimpression is made from adiagnostic wax-up before the preparationappointment. Trim off thin flashes of impressionmaterial created by the gingival crevice to producean extra bulk of resin near the margins. Use a plasticsqueeze bottle with a fine tip to deposit one drop ofmonomer on the facial and one drop on the lingualsurface of the overimpression. Keep the monomernear the gingival portion of the impression to preventexcess from accumulating in the incisal or occlusalarea. Extend the coverage by the resin to one toothimprint on either side of the teeth being restored.
When the teeth have been prepared, make aquadrant alginate impression and pour it with a thinmix of quick-setting plaster. Trim off excess plasteron a model trimmer. Save one tooth on either side ofthe prepared tooth, if possible. Remove areas of thecast that duplicate soft tissues.Try the shell gently on the cast to make sure itseats completely without binding. If it does bind,relieve the inner surfaces of the shells until therestoration seats completely and passively. Liberallycoat the tooth preparations on the cast withseparating medium and make sure it is dry beforemixing the acrylic resin.
Monomer and polymer can be added directly to theshell and mixed there. The resin also can be mixed ina dappen dish and then transferred to the shell,completeIy filling each tooth. Seat the shell onto theprepared teeth on the cast. Wrap a rubber bandaround the shell and cast, and place them in a plasterbowl full of hot tap water for approximately 5minutes, preferably in a pressure pot. The use of apressure pot will significantly increase the strengthof the restoration .
If the direct techniqueis employed, seat the shellon the prepared teeth in themouthA matrix can be made inmany different ways. Mostare from sheets of plasticthat are heated and formedover the diagnostic cast.Then the matrix is filled withacrylic resin and placed overthe prepared teeth in thepatients mouth.
Technique used in the fabricationTechnique used in the fabricationof provisionals using light curedof provisionals using light curedresin.resin.DIAGNOSTIC WAX UP& IMPRESSION.
Resin placed on the finish line forResin placed on the finish line forbetter adaptation.better adaptation.
Template is filled with light curedTemplate is filled with light curedresin.resin.
PREFABRICATEDCROWNPolycarbonate Crowns:These are available inincisors, canines andbicuspids. There is arange of sizes for eachtooth form.It should berelined with acrylic inorder to provide a goodinternal fit. After liningwith acrylic, they may betrimmed to provide agood marginal adaptationand further adjusted into
IMPROVING FIT WITH RESINIMPROVING FIT WITH RESIN
Cemented temporary in placeCemented temporary in place
Ion Crown Formers: These areshells made of cellulose acetateand are available in all toothforms. These shells come invarious sizes for each tooth formand are lined with acrylic resin.After the acrylic resin haspolymerized, the cellulose shellis peeled away from the crown.This usually necessitated thefurther addition of acrylic in theareas of the proximal contacts.
Tin Silver: Tin Silverpreformed crowns areavailable for posteriorteeth. This alloy is verysoft and the margin of thecrown can be flexed priorto seating with a swagingblock. This produces aclose marginal fit after theshell is trimmed with a bur.These should also be linedwith acrylic resin toprovide good internaladaptation and retention ofthe temporary.
Aluminum Shell Crowns:Similar to the tin silver,aluminum shell crowns areavailable in the anatomic form asshown here, or in a cylindricalform that requires extensiveocclusal contouring. Adjustingocclusion on an aluminum crownlined with acrylic sometimesresults in perforation of thealuminum into the layer ofacrylic beneath it as shown here
Provisional treatment for all ceramicveneer restorationsAll-ceramic restorations including laminate veneershave become a large part of dental practice. Most of whathas been published regarding provisional treatment forveneers has focused on technical procedures. Provisionalveneers are indicated when (1) esthetics and intelligiblespeech are important; (2) mandibular incisors areveneered; (3) dentin is exposed; (4) proximal contacts arebroken; (5) maxillary teeth are inverted lingually and theveneer surface affects occlusion; (6) the preparationmargin invades the gingival sulcus; and (7)the finalveneer is dependent on patient approval of form, color,contour, and position.
Provisional restorations allow patients to have atrial period for making notes about esthetics so thattheir desires can be taken into account with thedefinitive veneer . Preparations for porcelain veneersmay not have mechanical retentive features and thusone concern regarding a provisional restoration is toothattachment while avoiding irreversible contaminationor alteration of the luting surface of a prepared tooth.Elledge advocated placing 2 small dimples onopposing surfaces of the preparation to providemechanical retention for the provisional veneer that isluted with a cement of the clinicians choice. Onemethod that avoids excess cement while sealing themargin area is the "peripheral seal technique" that
uses a 3-second etch of the preparation periphery and thenbonding a provisional restoration primarily at the etchedperiphery. Similarly, a colored luting resin may facilitateremoval of excess resin and reduce contamination of atooth surface. Another technique known as the "spotetch" method incorporates provisional restorations that areluted with light polymerized acrylic resin to an etched spotnear the center of the preparation. In an in vitro study ofsurface contamination associated with provisionalbonding, a polyurethane isocyanate surface treatment leftthe cleanest tooth structure whereas a noneugenol provi-sional cement left: significant but removable residue; adual polymerizing resin cement left tenacious residue thatcould only be removed with a bur .
A variety of methods for fabrication of veneerprovisional restorations have been reported and are notunlike the methods advocated for conventionalprovisional restorations including, a removable"splint,"with hand-formed visible light-polymerizedmaterials, polycarbonate provisional crowns, acrylicresin shells, and splinting together adjacent provisionalveneers.
EstheticsPatients may be highly motivated by esthetics andinstant improvement can be achieved throughprovisional restorations. Custom colored provisionalrestorations made with mixtures of acrylic resinpowders creating an incisal polymer, a body polymer,and a cervical blend are easier to fabricate with anindirect method. Esthetically enhanced provisionalrestorations can fabricated with visible light-polymerized labial veneers or denture tooth facings inconjunction with acrylic resin Gingival architecture andtissue contour are among the many factors other thanmaterials that influence esthetics.
Anterior provisional restorations should provide thefollowing esthetic benefits: (1) optimum periodontalhealth; (2) visualization of the anticipated estheticoutcome; (3) ability to test the incisal edge position andcervical emergence; (4) development of appropriateanterior guidance; and (5) determination of the need forperiodontal surgery. Methods for improving orcustomizing colors also include coloring provisionalluting cements and coloring a provisional restorationwith porcelain stains and visible light-polymerizedacrylic resin. In Custom color guides for provisionalrestorations have also been recommended.
REMOVAL OF PROVISIONALRESTORATIONThe provisional is removed when the patient returnsfor the definitive restoration or for continuedpreparation. The prepared tooth or foundation mustbe avoided. Risk of this can be minimized if removalforces are directed parallel to the long axis of thepreparation. The Backhans or hemostatic forceps areeffective for obtaining purchase on a single unit.Aslightl buccolingual rocking motion will help breakthe cement seal. Damage can occur when a FPD isbeing removed. If one abutment retainer suddenlybreaks loose, the other abutment can be supported tosevere leverage.
Care must be exercised to remove the prosthesis alongthepath of withdrawl. Sometimes it is helpful to loop dentalfloss under the connector at each end of the FPD,providing a more even force distribution for removal.RECEMENTATION OF PROVISIONALRESTORATIONIf provisional is to be recemented clean out the bulkof cement with aspoon excavator then place theprovisional in a cement dissolving solution in an ultrasoniccleaner. Line it with a fresh mix of resin if necessary(as when a toothpreparation has been modified, eg).The internal surface is relieved slightly and painted withmonomerto ensure good bonding of the new lining.
SUMMARYAlthough provisional restorations are usuallyintended for short-term use and then discarded, theycan be made to provide pleasing esthetics, adequatesupport, and good protection for teeth whilemaintaining periodontal health. They may befabricated in the dental office or in laboratory fromany of several commercially available materials andby a number of practical methods. The success offixed prosthodontics is often depends on the care withwhich the provisional is designed and fabricated.
In 1990, Ernest DaBreo et al gave "clinical report on aprovisional restoration for a patient with cleft lip andpalate. The provisional prosthesis provides onalternative treatment option that allows the dentist toplan the definitive restoration while providing thepatient with a temporary but esthetic and functionalrestoration.In 1991, Conrad Bodai described expedient andeffective interim restoration for compromised posteriorteeth.The restoration can beethyl methacrylate, visible-lightactivated resin, and a Bis-acrylplaced quickly,exhibits excellent adaptations provides exceptionalretention and maintains proximal and occlusal contacts.Review OF LITERATURE
In 1991, Jack Koumi Jian et al did a study on theColour stability of provisional materials in view.Colour stability of provisional restorations is animportant quality of the resin used, particularly forextensive reconstruction over a long period oftime.This study evaluated the invitro discoloration ofseven resins over a 9 week period. Resin specimenswere prepared and placed in the facialflange ofmaxillary complete dentures and the lingual flange of amandibular complete dentures. Patients were giventooth brushes and tooth paste and told not to use anychemical agents for choosing the dentures.Observations were made at 1, 5 and 9 weeks,
No change was detected at the first two evaluations.At the 9 week evaluation, four materials, methylmethacrylate, polyminylethyl methacrylate and bis-arylcomposite resin showed significantly less stainingthan did the other three resins tested. All materialstested were acceptable from the standpoint of colourstability for short term (5 weeks or less) provisionalrestorations. Therefore, the dentist using provisionalrestorations for a short period of time may considerother properties of the materials, such as resistance offracture, marginal accuracy, rase of fabrication andcost.
In 1991, Millstein et al studied the effect of aging antemporary cement retention in vitro. The primaryfunction of temporary cements isto act as an interimcementing media for provisional or fixed restorations.Temporary cements may be medicated and are oftenused for toothsedation as well as for retention. Retentionof restorations cemented with temporary cement varies.Some cements are adhesive and others are "work inretention. In addition, cement retention may vary overtime. this study determined:1. The retentive propertiesof four temporary cements. 2. The effects of aging ontemporary cement retention Retention of restoration wasstudied at 1 and 6 week intervals. Retention varied withthe 4 cements tested, and one cement (Temp-bond)became significantly less significant over time
In 1992, Timothy M. Campbell and Nagy describedthe use of avinyl polysiloxane to make interimrestorations.The rationals andprocedures is described.vinyl polysiloxane is a commonly used impressionmaterial that flows readily, is accurate and sets to a finsconsistency- properties that are useful a for thisprocedure .
In 1992, Douglass B. Roberts described a method ofmaking indirect interim restorations using flexiblecosts. A procedure isdescribed for making interimrestorations from a cast and dies made of polyvinylsiloxane impression, material. The use of theseflexible castsand dies facilitate the removal of thepolymerised resin from the cast especially in archesthat have significant undercuts caused by anatomicforor tooth alignment. The rapid set of the polyvinylmaterials reducesthe time involved in making, theindirect interim restorations.Thepolyvinyl cast isreusables if necessary. The polyvinyl cast is reusablesif necessary. One disadvantage of this procedure isthe cost of the material.
William H. Lienberg in 1994 described a technicalprocedure of wire reinforced light cured glass ionomerresin provisional restoration. aprocedure to use roundpractical provisional restorations is presented. Theviability of the use of glass ionomer resin cement andthe need forembrasure perfection in provisionalrestoration where extensive coronal destruction hasoccurred. The inherent disadvantage of the procedure isthe need to involve occlusal surfaces of the proximalteeth; thus its use isrestricted to mouth in which theadjacent teeth are to receive simultaneous restorativetreatment.