After reading this chapter, the student will be able to:
Explain the objectives of root canal obturation.
Explain the rationale for single-visit versus multi-visit endodontic treatment and identify cases when each approach would be indicated.
Explain the rationale for smear layer removal.
List the ideal properties of an obturation material.
Identify obturation materials that have been used historically and explain why these materials are no longer used.
Describe the properties, advantages, and disadvantages of gutta-percha.
List the ideal properties of a root canal sealer.
Identify types of sealers available on the market and describe their properties.
Explain how to perform different obturation techniques using gutta-percha as an obturation material.
Explain the advantages and disadvantages of different obturation techniques used with gutta-percha.
Describe how obturation materials and techniques are evaluated through research studies.
Describe how the results of obturation are clinically evaluated and the impact of obturation on treatment outcomes.
Explain the rationale for intraorifice barriers and identify materials used as barriers.
Explain the importance of restoration following endodontic treatment and list materials used for temporization.
Objectives of Obturation
Success in endodontic therapy is dependent on adequate instrumentation, disinfection, and obturation of the root canal system. The objective of obturation is to create a watertight seal along the length of the root canal system from the orifice to the apical termination. Obturation prevents leakage of microorganisms and their byproducts into the root canal system from a coronal direction and leakage of periapical tissue fluids into the root canal system from an apical direction. This seal allows for prevention and healing of apical periodontitis (Question 15.1). After adequate obturation, an adequate coronal restoration is also necessary and significantly affects the healing of apical periodontitis and the success of root canal therapy.
Interestingly, a periapical lesion may heal at least temporarily after root canal débridement without obturation. Research has shown that when bacteria are eliminated from the root canal system before obturation, healing of a periapical lesion occurs regardless of the quality of obturation. However, if bacteria remain before obturation, healing is related to the quality of obturation. Although failure to obturate or poor obturation are not desirable treatment options, these results demonstrate the important concept that what is removed from the root canal system is more important than how it is filled.
When to Obturate
One versus Two Visits
The endodontic community has long debated the number of visits in which root canal therapy should be completed. Should a tooth be obturated during the same visit when it is instrumented? Factors influencing the answer to this question include the pulpal and periapical diagnoses, the radiographic presentation, the patient’s signs and symptoms, the degree of difficulty, patient management issues, and logistic concerns. In some cases, the degree of difficulty of the case dictates that the treatment be completed in more than one visit, for example, very calcified cases when additional time is needed to locate and instrument canals. Patient management or medical issues may also dictate that treatment be completed in more than one visit, for example, a patient who cannot recline for an extended period of time. Finally, logistic issues may dictate that treatment be completed in more than one visit, for example, a patient presents on an emergency basis, and the dentist has limited time in their schedule to treat the patient.
Opinions vary regarding the advantages and disadvantages of single- versus multiple-visit endodontic treatment when it comes to pulpal and periapical diagnoses, radiographic presentation, and patient signs and symptoms. Consensus exists that a tooth with a vital pulp may have root canal therapy completed in one visit (if time permits), because the canals are not infected. Cases with a vital pulp include those with a pulpal diagnosis of symptomatic irreversible pulpitis, asymptomatic irreversible pulpitis, reversible pulpitis, or a normal pulp. When root canal therapy is performed using proper infection control and disinfection protocols, completing treatment in one visit further precludes the possibility of recontamination of the root canal system caused by coronal leakage between visits. Consensus also generally exists that root canal therapy should not be completed in one visit when the patient has swelling associated with an acute apical abscess, or when the canal cannot be dried as a result of exudate draining from the periapical tissues. In these cases, the clinician should wait until the swelling has resolved and the canal can be dried completely before obturation.
There is disagreement on whether teeth with a necrotic pulp and asymptomatic apical periodontitis, symptomatic apical periodontitis, or a chronic apical abscess should be treated with single- or multiple-visit root canal therapy. The debate centers on the importance of disinfection of the root canal system. The rationale for completing treatment in two visits is that the intracanal medicament placed between visits facilitates disinfection of the root canal system (Question 15.2). This approach is supported by evidence from clinical studies looking at microbial sampling of the root canal system. In a study investigating the role of infection at the time of obturation in teeth that were treated in one visit, teeth were sampled for bacteria before obturation, and all teeth were treated in one visit. After 5 years, complete healing occurred in 94% of cases with a negative culture and in 68% of cases with a positive culture before obturation. These results highlight the importance of completely eliminating bacteria from the root canal system before obturation, which may be aided by an intracanal medicament between visits.
Despite the microbiologic rationale for completing root canal therapy of necrotic teeth in multiple visits using an intracanal medicament, the available outcomes studies do not support an improved prognosis with two-visit treatment. Multiple systematic reviews have found no significant difference in radiologic success of root canal therapy between single- and multiple-visit treatment. , However, there is some evidence that patients having single-visit root canal therapy may be more likely to experience pain or flare-up and use analgesics in the short-term after treatment. , Unfortunately, the overall quality of the evidence is poor, because many studies have limitations including low power and risk of bias. Thus the debate is ongoing, and the decision to treat in one visit or two is ultimately at the discretion of the clinician for each individual case.
Smear Layer Removal
The smear layer is a combination of organic and inorganic debris present on the root canal walls after instrumentation. When viewed under scanning electron microscope, the smear layer has an amorphous, irregular appearance that represents dentinal shavings, tissue debris, odontoblastic processes, and bacteria and their byproducts. Historically, whether or not to remove the smear layer has been debated; though there is now generalized agreement that the smear layer should be removed before obturation. This is because the smear layer may contain microbes and their byproducts, which would remain in the canal if not removed, and because the smear layer may inhibit adhesion of filling materials to the dentin walls and penetration into dentinal tubules, thereby compromising the seal (Question 15.3). The smear layer is typically removed by irrigation with ethylenediaminetetraacetic acid, which serves as a chelating agent. Proprietary formulations may also be used (e.g., MTAD, SmearClear, QMix).
Ideal Properties of an Obturation Material
Grossman suggested the ideal properties of an obturation material ( Box 15.1 ). Currently, no material or combination of materials satisfies all of these criteria.
Grossman suggested that the ideal obturation material would have the following properties:
Be easily introduced into the canal
Seal the canal laterally and apically
Not shrink after insertion
Be impervious to moisture
Be bactericidal, or at least not promote bacterial growth
Not stain tooth structure
Not irritate periapical tissues or affect tooth structure
Be sterile or easily sterilized
Be easily removed from the root canal
Core Obturating Materials
Core obturating materials are the primary materials used in obturation and occupy the bulk of the space within the root canal system. Core obturating materials are classified as either solid or semisolid. Solid materials are introduced into the canal as a solid, and they require a sealer to completely seal the canal. Semisolid materials are introduced into the canal in a liquid, paste, or softened form, and then set up within the canal.
Gutta-percha has been used as a root canal filling material for over 160 years. , It is by far the most popular core obturation material ( ).
Commercial gutta-percha contains the following ingredients: zinc oxide 59% to 76%, gutta-percha 18% to 22%, waxes and resins 1% to 4%, and metal sulfates 1% to 18%. The gutta-percha is the matrix, and the zinc oxide is the filler. The waxes and resins are the plasticizers, and the metal sulfates, such as barium sulfate, provide the necessary radiopacity.
The stereochemical structure of gutta-percha is 1,4 trans polyisoprene, whereas the stereochemical structure of natural rubber is 1,4 cis polyisoprene. , Even though gutta-percha and natural rubber have similar stereochemical structures, studies have shown that there is no cross-reactivity of gutta-percha and natural rubber latex in individuals who have a latex allergy. ,
Gutta-percha has two crystalline forms, alpha and beta. , Depending on the temperature, gutta-percha can be in different crystalline forms and exhibit different physical characteristics. Commercial gutta-percha comes in the beta crystalline form at room temperature. When the beta form is heated to 42°C to 49°C, it transitions into the alpha phase. When alpha phase gutta-percha is heated above 53°C to 59°C, it transitions into the amorphous phase. This is important when the clinician needs the amorphous form of gutta-percha to flow into all parts of the root canal system utilizing thermoplastic techniques.
Gutta-percha is formed into either standard or nonstandard cones of different tip sizes and tapers ( Fig. 15.1 ). Standardized cones conform to the requirements of the International Organization for Standardization (ISO) or the American Dental Association/American National Standards Institute (ADA/ANSI). Nonstandardized (conventional) gutta-percha cones do not conform to the standards set by ISO or ADA/ANSI. Standardized gutta-percha cones are manufactured to have the same tip size and taper as the corresponding endodontic instruments used in the preparation of the root canal system. The original specifications called for gutta-percha to have a taper of .02 mm per millimeter increase in length. With the advent of various tapers in endodontic files, gutta-percha cones now come in various tapers, including .04, .06, and so on. Nonstandardized gutta-percha cones end in a feathered tip. Gutta-percha used with thermoplasticizing devices is manufactured as pellets or contained in cartridges ( Fig. 15.2 ). The pellets or cartridges are inserted into a thermoplasticized gutta-percha injection system, and the gutta-percha is heated before dispensing.
Gutta-percha is by far the most popular and widely accepted root canal filling material. Although it does not meet all of the criteria for an ideal filling material, it satisfies most of them. Gutta-percha has a number of advantages. First, because of its plasticity, gutta-percha adapts well when compacted into prepared root canals, especially when thermoplasticized. Second, gutta-percha has good handling characteristics and is easy to manipulate with multiple obturation techniques. It is relatively stiff and easily placed into canals. Third, gutta-percha is relatively easy to remove from the root canal system, either to create post space or for retreatment. Fourth, gutta-percha is regarded as a very acceptable material with good biocompatibility with the periapical tissues (Question 15.4).
To produce an adequate seal, gutta-percha must be used with a sealer. Gutta-percha does not adhere to canal walls, so the space between the gutta-percha and the canal wall must be sealed with a root canal sealer. Additionally, the application of heat or solvents to gutta-percha during different obturation techniques can cause gutta-percha to shrink, further increasing the space between the canal wall and gutta-percha core.
Other Additives to Gutta-Percha
Other ingredients have been added to some brands of gutta-percha to increase its antibacterial properties. Calcium hydroxide has been added to gutta-percha points by Coltene/Whaledent (Langenau, Germany). Activ Point (Coltene/Whaledent, Langenau, Germany) contains chlorhexidine. Other gutta-percha has been introduced that contains iodine-polyvinylpyrrolidone. Although these additives to gutta-percha have been shown to be effective against various bacteria, long term clinical studies have not been conducted.
Several brands of carrier-based gutta-percha are on the market ( Fig. 15.3 ). Carrier-based obturators are composed of gutta-percha surrounding a carrier that is heated and then placed into the canal. The handle of the carrier is cut off and removed, leaving the gutta-percha and carrier in the canal. Many obturators are designed to fit corresponding file systems. Several carrier-based obturators are marketed by Dentsply Sirona (York, PA), including GuttaCore, GuttaCore for WaveOne Gold, WaveOne Gold Obturators, ProTaper Next Obturators, ProTaper Universal Obturators, Thermafil Plus Obturators, Vortex Obturators, GT Obturators, and GT Series X Obturators. Soft-Core is a similar carrier-based obturator marketed by Kerr Endodontics (Orange, CA). SimpliFill (Kerr Endodontics) is a 5-mm apical plug of gutta-percha on the end of a metal carrier. It has the advantage of not leaving the carrier in the canal, as the carrier is twisted off and removed, leaving only the apical plug of gutta-percha. SuccessFil is a carrier-based gutta-percha system that is combined with the UltraFil thermoplasticizied injection system to create what is marketed as the Trifecta System (Coltene/Whaledent, Langenau, Germany). JS Quick-Fill (JS Dental Manufacturing, Inc, Ridgefield, CT) is an alpha phase gutta-percha coated titanium core in ISO sizes 15 to 60. The carrier-based material is spun into the canal at low speed, and the core may be left in the canal or slowly removed.
Mineral Trioxide Aggregate
Mineral trioxide aggregate (MTA) is a bioactive calcium silicate material that has many clinical applications in endodontics, including vital pulp therapy, perforation repairs, and root end surgery. , MTA is used as an obturation material in cases of immature or open apices ( Fig. 15.4 ). Attributes of MTA include biocompatibility, sealability, and a history of documented positive clinical outcomes. Similar to MTA, some of the more recently introduced bioceramic materials can also be used as obturation materials in this fashion. Teeth with open apices where obturation with MTA or other bioceramic material would be indicated are considered moderate or high level of difficulty cases, and referral to a specialist is typically recommended ( ). ,
Silver points were used historically in the mid-1900s and were manufactured to match the size and taper of endodontic hand files used in canal preparation at that time ( Fig. 15.5 ). Thus silver points had a 0.02 taper. Silver points fulfilled some of Grossman’s requirements of an ideal obturation material. They were easy to insert and had good length control. However, they did not seal well laterally or apically as a result of their lack of plasticity. Silver points did not adequately fill all of the canal space and could not be compacted into voids within the root canal system. The shape of silver points remained round after insertion, and canals are rarely prepared to a perfectly round shape. The remaining space was filled with sealer, leading to leakage. This leakage allowed for corrosion of the silver points and the formation of silver salts, which were found to be cytotoxic. With modern techniques, instrumentation and obturation of smaller canals with gutta-percha is predictable, so the use of silver points declined as a result of their disadvantages. Silver points are not recommended for use in modern endodontic therapy. The characteristic appearance of silver points make them easily identifiable on patients’ periapical radiographs ( Fig. 15.6 ). These teeth may require retreatment if pathosis is present or post space is needed; however, prophylactic retreatment of teeth obturated with silver points is not indicated.
Resin-based obturation materials were used in the early 2000s. Resilon and RealSeal were composed of a polycaprolactone core material with difunctional methacrylate resin, bioactive glass, bismuth and barium salts as fillers, and pigments. These products were used with a resin sealer (Epiphany or RealSeal) that was packaged with the core filling material. The rationale for the product was to create a “monoblock,” consisting of a resin sealer with resin tags that enter and bond to dentinal tubules on the canal wall, and which also adhesively bonds to the core material. The product was light cured and sealed coronally as well. The system consisted of a primer, a sealer, and synthetic polymer points or pellets. Research has shown no advantage of these materials over gutta-percha, and resin-based obturating materials are no longer on the market.
Pastes are a type of semisolid material that have been used as a core filling material. Zinc oxide is a major component of most paste materials. Because of the solubility of zinc oxide, these pastes do not make effective core filling materials. Other disadvantages of pastes include difficult length control, shrinkage of the material, voids in obturation, and toxic ingredients in some pastes.
One paste filling material is a resorcin-formaldehyde paste, which is a type of phenol-formaldehyde or Bakelite resin. , Because this material has been widely used in Eastern European countries, and because it stains teeth a characteristic dark red color, it is commonly referred to as Russian Red ( Fig. 15.7 ). This material has the advantage of being very antimicrobial, but has the disadvantage of shrinkage once placed in the canal. Additionally, retreatments can be very difficult if the resin sets completely and there is sufficient bulk to the material ( Fig. 15.8 ).
Paraformaldehyde-based pastes are another type of paste fill. The rationale for adding paraformaldehyde to pastes is to provide antimicrobial and mummifying effects. However, paraformaldehyde has severe toxicity to host tissues, and this negates the benefit of any antimicrobial effects it may possess in endodontic materials. These pastes are known as N2 (Indrag-Agsa, Losone, Switzerland), Sargenti, or RC2B, and are made of a liquid and powder. The powder contains zinc oxide, bismuth nitrate, bismuth carbonate, paraformaldehyde, and titanium oxide. The liquid consists of eugenol, peanut oil, and rose oil. N2 has changed in response to studies identifying toxic substances, such as lead oxide, and organic mercury. However, it still contains 4% to 8% paraformaldehyde. N2 is extremely toxic, , and because it is used as a paste, the extrusion of this material has caused permanent damage in many cases. The material affects bone and soft tissue and can cause permanent neurologic damage resulting in paresthesia, dysesthesia, and pain. Because of the toxicity, risks to patients, legal issues, and the fact that there are numerous other acceptable obturating materials available that provide a better outcome, the use of these materials in modern day endodontics is not acceptable. The Food and Drug Administration lists N2 as an unapproved drug that is not legally imported or shipped across interstate lines, and the ADA does not approve of its use. , In summary, use of paraformaldehyde-containing endodontic filling materials and sealers is below standard of care, as they have been shown to be both unsafe and ineffective.
Sealer is used in conjunction with a core obturating material and is necessary to fulfill the objective of creating a watertight seal in the root canal system (Question 15.5). In addition to the basic requirements for core filling materials, Grossman also identified the ideal requirements for a root canal sealer ( Box 15.2 ). As with core obturation materials, no sealer currently satisfies all of these criteria.
Additionally, the following two requirements could be added to Grossman’s original basic requirements: it should not provoke an immune response in periradicular tissues, and it should be neither mutagenic nor carcinogenic. ,
It should be tacky when mixed to provide good adhesion between it and the canal wall when set.
It should make a hermetic [sic] seal.
It should be radiopaque so that it can be visualized on the radiograph.
The particles of powder should be very fine so that they can mix easily with the liquid.
It should not shrink upon setting.
It should not stain tooth structure.
It should be bacteriostatic or at least not encourage bacterial growth.
It should set slowly.
It should be insoluble in tissue fluids.
It should be tissue tolerant, that is, nonirritating to periapical tissues.
It should be soluble in a common solvent, if it is necessary to remove the root canal filling.
Types of Sealers
The primary sealers in use today are those based on zinc oxide eugenol (ZOE), resin, calcium hydroxide, or bioceramics.
Zinc Oxide Eugenol S ealers
Zinc oxide eugenol (ZOE)-containing sealers have been widely used with success for many years. There are many formulations and brands of sealers with zinc oxide as the primary ingredient, differing only by other added components. ZOE sealers allow for the addition of chemicals, such as paraformaldehyde, rosin, Canada balsam, and others, all of which may increase the toxicity of that particular sealer. Grossman’s original formula contained zinc oxide, hydrogenated or Staybelite resin, bismuth subcarbonate, barium sulfate, and sodium borate (anhydrous), with eugenol as the liquid component. It has been marketed as Proco-sol sealer (StarDental, Lancaster, PA), as well as other product names. Roth’s 801 and 811 sealers (Roth’s International LTD, Chicago, IL) were essentially the same as Grossman’s original formulation, with the substitution of bismuth subnitrate for bismuth subcarbonate. Despite its popularity, production of Roth’s sealer recently ceased.
Rickert’s was one of the first zinc oxide sealers. The powder contains zinc oxide, silver, resins, and thymol iodide. The liquid is eugenol, and Canada balsam. One disadvantage is that the silver used to provide radiopacity can also cause staining of tooth structure. Another disadvantage is its rapid setting time in areas of high humidity and heat. Rickert’s sealer is marketed as Kerr Pulp Canal Sealer (Kerr Endodontics, Orange, CA), which has traditionally been popular with clinicians who use the warm vertical obturation technique. Pulp Canal Sealer Extended Working Time (EWT) (Kerr Endodontics, Orange, CA), with a working time of 6 hours, was introduced to lengthen the setting time over Kerr Pulp Canal Sealer.
Tubli-Seal (Kerr Endodontics, Orange, CA) was developed as a nonstaining alternative to the silver containing Pulp Canal Sealer. Tubli-Seal comes as two separate tubes. One tube contains a zinc oxide-base paste with barium sulfate for radiopacity, mineral oil, cornstarch, and lecithin. The catalyst tube contains poly-pale resin, eugenol, and thymol iodide. Tubli-Seal is easy to mix and has a short setting time. Tubli-Seal EWT was developed to provide extended working time.
Wach’s cement is made up of a powder of zinc oxide, bismuth subnitrate, bismuth subiodide, magnesium oxide, and calcium phosphate. The liquid consists of oil of cloves, eucalyptol, Canada balsam, and beechwood creosote. Wach’s cement has a distinctive odor of an old-time dental office. It has a smooth consistency, and the Canada balsam makes the sealer tacky. Medicated Canal Sealer (Medidenta, Woodside, NY) contains iodoform for antibacterial purposes and is to be used with MGP gutta-percha, which also contains 10% iodoform.
Calcium Hydroxide Sealers
Sealapex (Kerr Endodontics, Orange, CA) is a noneugenol polymeric sealer that contains calcium hydroxide. It is packaged in two tubes, one of which is a base, and the other a catalyst. Sealapex has zinc oxide in the base plus calcium hydroxide. It also contains butyl benzene, sulfonamide, and zinc stearate. The catalyst tube has barium sulfate and titanium dioxide for radiopacity, and a proprietary resin, isobutyl salicylate, and AEROSIL R792. Sealapex has similar sealing ability as Tubli-Seal. Apexit (Ivoclar Vivadent, Schaan, Liechtenstein) is a calcium hydroxide sealer with salicylates also incorporated into the formula. CRCS (Calciobiotic Root Canal Sealer, Coltene/Whaledent, Mahwah, NJ) is a calcium hydroxide-containing sealer that has a zinc oxide-eugenol and eucalyptol base. CRCS is a rather slow-setting sealer, especially in dry or in humid climates. It may require up to 3 days to fully set. The set sealer is quite stable, which improves its sealing qualities, but may mean that calcium hydroxide is not as readily released and the stimulation of cementum and bone formation may be severely limited.
Epoxy resin sealers have been used in endodontics for some time, including AH26, and its successor AH Plus (Dentsply Sirona, York, PA). AH26 is a sealer that has been used for many years. It is a bisphenol epoxy resin sealer that uses hexamethylenetetramine (methenamine) for polymerization. , A major disadvantage of AH26 was that the methenamine gave off formaldehyde as it set. It would also stain tooth structure and had an extended working time. One advantage of AH26 is it was not affected by moisture. AH Plus and ThermaSeal Plus (Dentsply Sirona, York, PA) are formulated with a mixture of amines that allows for polymerization without the unwanted formation of formaldehyde. , They have the advantages of AH26, which include increased radiopacity, low solubility, slight amount of shrinkage, and tissue computability. AH Plus is an bisphenol epoxy resin that also contains adamantine. AH Plus comes in a two paste system, unlike the liquid-powder system of AH26, and has a working time of 4 hours and a setting time of 8 hours. Additional improvements of AH Plus over AH26 include thinner film thickness and decreased solubility.
Mineral trioxide aggregate (MTA) is a calcium silicate bioceramic material, which has many applications in endodontics. MTA has been a very successful material because of its biologic and physical characteristics. MTA is extremely biocompatible and provides a good seal. Because of these biologic and physical attributes, several bioceramic sealers are now on the market. ProRoot Endo Sealer (Dentsply Sirona, York, PA) is an MTA-based sealer manufactured in a powder and gel form. The powder is MTA with enhanced radiopacity, which contains tricalcium silicate, dicalcium silicate, calcium sulfate, bismuth oxide, and a small amount of tricalcium aluminate. The gel is a viscous aqueous solution of a water soluble polymer. MTAFillapex (Angelus, Londrina, PR, Brazil) is a dual paste system. It contains salicylate resin, diluent resin, natural resin, bismuth oxide, nanoparticulate silica, MTA, and pigments. Endosequence BC Sealer (Root SP) (Brasseler USA, Savannah, GA) is a calcium silicate based sealer manufactured as a single paste system. It contains zirconium oxide, calcium silicates, calcium phosphate monobasic (CaH 2 P 2 O 8 ), calcium hydroxide, filler, and thickening agents. iRoot SP (Innovative BioCeramix Inc., Vancouver, Canada) is another calcium silicate based sealer that contains zirconium oxide, calcium silicates, calcium phosphate, calcium hydroxide, filler, and thickening agents.
Silicone Based Sealers
Silicone based sealers provide adhesion, a moisture resistant seal, and stability. Lee Endo-Fill (Lee Pharmaceuticals, El Monte, CA) is a silicone based root canal sealer. RoekoSeal (Coltene/Whaledent, Langenau, Germany) is a polyvinylsiloxane that is a white paste-like sealer and will polymerize without shrinkage, which results in less leakage. , It utilizes platinum as a catalyzing agent. GuttaFlow (Coltene/Whaledent, Langenau, Germany) is a polyvinylsiloxane that has finely milled gutta-percha particles added to the RoekoSeal sealer. GuttaFlow additionally contains silicone oil, paraffin oil, platin catalyst, zirconium dioxide, nano-silver as a preservative, and a coloring agent. It does not contain eugenol. GuttaFlow is a cold flowable gutta-percha filling system for the obturation of root canals. GuttaFlow is triturated in its cannula and passively injected into the canal and then used with single or multiple gutta-percha points.
Urethane Methacrylate Sealers
EndoREZ (Ultradent, South Jordon, UT) is a hydrophilic urethane dimethacrylate (UDMA) resin sealer that reportedly has good canal wetting and flow into dentinal tubules. The hydrophilic property improves its sealing abilities if some moisture is still in the canal at obturation. EndoREZ is introduced into the canal with a narrow 30-gauge NaviTip needle (Ultradent). A single gutta-percha point, or the lateral compaction obturation technique, may be utilized. EZ Fill (Essential Dental Systems, South Hackensack, NJ) is a noneugenol epoxy resin sealer that is placed with a bidirectional spiral rotating in a hand piece. It may be used with a single gutta-percha point technique. It is nonshrinking on setting and is hydrophobic, rendering it resistant to fluid degradation.
Evaluation and Comparison of Sealers
Orstavik , has listed the various evaluation parameters for testing endodontic sealers. They include technologic tests that have been standardized by the ISO and ADA/ANSI internationally and in the United States. These technological tests include flow, working time, setting time, radiopacity, solubility and disintegration, and dimensional change after setting. Additionally, biologic tests, usage testing, and antibacterial testing are useful. Clinical testing should be included to establish outcomes of treatment.
What is the primary objective of obturation?
What is the rationale for completing root canal therapy in two visits versus one visit?
Why is the smear layer removed before obturation?
What are the advantages of gutta-percha as a core obturation material?
Why must a sealer be used when obturating with gutta-percha?
Obturation Techniques with Gutta-Percha
Gutta-percha is the most widely used and clinically acceptable obturation material, thus the techniques described in this chapter will focus on the use of this material. Gutta-percha is available in many different forms and sizes, both gutta-percha cones and gutta-percha for thermoplasticized injection systems (see Figs. 15.1 and 15.2 ). The choice of obturation method is primarily based on clinician training and preference, as well as the specific anatomy of each case. There are attributes and limitations of each technique, but no significant difference in outcomes has been demonstrated between contemporary obturation techniques using gutta-percha ( ) . ,
Cold Lateral Condensation
Cold lateral condensation (commonly referred to as lateral condensation or lateral compaction) is the most common obturation technique taught to predoctoral dental students. Advantages of lateral condensation are that it can be used in a wide variety of cases, does not require specialized equipment, and has a track record of clinical success. In addition, lateral condensation is safe and simple to learn for novice clinicians; it is less technique-sensitive than other methods and has predictable length control (less likely to overfill). A disadvantage of lateral condensation is that it requires more time than some filling techniques. In addition, it is challenging to use in some clinical cases (e.g., very curved canals, internal resorption, wide open apices, or other anomalous canal anatomy) (Question 15.6). However, these cases are considered “high difficulty” and are typically referred to a specialist for treatment. ,
The technique for lateral condensation, and all obturation techniques, varies slightly from clinician to clinician. The following is a description of a traditional lateral condensation technique.
The canal is dried. A paper point placed to working length should come out of the canal dry, with no irrigant, blood, or exudate on it.
A master gutta-percha cone is selected. Gutta-percha cones should be handled using cotton pliers (locking are preferred), and measured using a millimeter ruler. In classic cold lateral condensation, the master cone is a 0.02 taper cone and has a tip size that matches the master apical file size to which the canal has been prepared. The selected cone should seat to working length, not be able to be pushed beyond working length, and exhibit a sensation of slight resistance when removing the cone from the canal. This resistance (referred to as tug-back ) indicates that the cone is binding the walls of the canal ( Fig. 15.9 ). A master cone that does not seat all the way to working length is too large (i.e., it is binding short of working length). A master cone that can be pushed beyond working length is too small (i.e., it is not binding at working length and overfilling will result). A master cone that does not display any resistance upon removal is also too small (i.e., it is not snug at working length), though this sensation can be difficult to detect. Careful inspection should catch any cone that buckles when placed to working length and removed; this indicates that the cone does not fit well. A cone that buckles near the tip may be too small ( Fig. 15.10 ). A cone that buckles more coronally may be too large (it will appear that the cone is seating to working length because the cotton pliers seat to the reference point, but the cone will be short as a result of the buckling). Variations of selecting a master cone preferred by some clinicians include using a 0.04 taper cone or a nonstandardized cone with the tip cut to a custom diameter. Specialized instruments are available on the market to help cut the tip of gutta-percha cones to a specific diameter ( Fig. 15.11 ). Often the clinician may try multiple master cones, even of the same size, before selecting the master cone they want to use for obturation of a canal. As a result of manufacturing variations, there will be variations in gutta-percha cone actual sizes, even among those labeled as the same ISO size and taper.