Endodontic Topics 2005, 12, 2–24 All rights reservedCopyright r Blackwell Munksgaard ENDODONTIC TOPICS 2005 1601-1538 Methods of filling root canals: principles and practices JOHN WHITWORTH Contemporary research points to infection control as the key determinant of endodontic success. While epidemiological surveys indicate that success is most likely in teeth which have been densely root-filled to within 2 mm of root-end, it is unclear whether the root canal filling itself is a key determinant of outcome. It is also unclear how different materials and methods employed in achieving a ‘satisfactory’ root filling may impact on outcome. This article provides an overview of current principles and practices in root canal filling and strives to untangle the limited and often contradictory research of relevance to clinical practice and performance. Introduction Successful root canal treatment depends critically on controlling pulp-space infection. In evaluating root canal-treated teeth, it is unusual for external assessors to have full information on the methods used and the detail of infection-controlling steps. Attention therefore tends to focus on aspects of treatment which can be readily identified and measured, such as the radiographic nature, length and density of root fillings, with the assumption that these are good proxy markers of the overall package of infection-managing care. It is not surprising that the majority of epidemiological surveys in endodontics have focused on radiographic appearances alone (1), despite our recognized limitations in radiographic interpretation (2, 3), and acceptance that the radiographic ‘white lines’ reveal only limited information. The classic ‘Washington study’ (4), although never published in a peer-reviewed journal, set the tone by observing that 58.66% of endodontic failures were caused by incomplete obturation. Other well-established undergraduate textbooks have emphasized that ‘lack of adequate seal is the principal cause of endodontic failure’ (5), positions based on the best clinical scientific evidence at the time. Contemporary research points to cleaning and shaping of the root canal as the single most important factor in preventing and treating endodontic diseases (6), and it is difficult to endow root canal filling with the same primary importance. But to take such views too rigidly, and to use reports of periapical healing without definitive root filling as evidence that root canal filling is unnecessary (7–10) is to miss the important role it may play in securing short- and long-term health (11, 12). In technical terms, we anticipate that ‘success’ will be associated with root canals (prepared and) densely filled to within 2 mm of radiographic root end (1, 13). However, the body of high-quality clinical research on which such conclusions are founded is limited (14). Even less clear is whether a technically ‘satisfactory’ root canal treatment will deliver health regardless of the materials and methods, or whether some are inherently ‘better’ than others in terms of predictability, safety, consistency, healing, and tooth longevity. Commercial pressures and glossy advertising have never been more prominent, but the debates are not new. As early as 1973, Brayton et al. (15) noted that ‘Many techniques have been advocated for filling root canals. Controversies and disputes have arisen, dividing practitioners into different schools of thought. To date, there is still very little evidence other than clinical impression to support or deny any particular technique.’ As no single approach can unequivocally boast superior evidence of healing success (13), decisions may be based on such factors as speed, simplicity, economics, or ‘how it feels in my hands.’ For some, there may be other issues at stake, such as the desire to keep ‘up to date,’ to demonstrate ‘mastery,’ to keep ahead of referring 2 Methods of filling root canals: principles and practices colleagues, or to enliven the working day by ‘the thrill of the fill’ (16) as unexpected canal ramifications are demonstrated more consistently. For others, issues such as root strengthening, or a fundamental lack of confidence in established materials may be critical (17–19). The role of root canal fillings in endodontic success The shaped and cleaned canal space represents an environment in which microbial communities have been eliminated or seriously disrupted and can no longer promote periradicular disease (6, 20). But how is this condition preserved? Undue reliance on a coronal seal is probably unacceptable without first filling the canal system (21–23) with materials that control infection: 1.Directly: by actively killing microorganisms (24) which remain (25) or which gain later entry to the pulp space, and 2.Ecologically: by denying nutrition, space to multiply, and correct Redox conditions for the establishment of significant biomass of individual microbes, or the development of harmful climax communities. They should do so long-term and without damaging host tissues. Fig. 1 Classic spectrum of filling techniques, emphasizing the desirability of minimum sealer volume, from (A) paste only (least desirable), through (B) single cones with paste, and (C) cold lateral condensation, to (D) thermoplastic compaction. Basic approaches Textbook accounts describe a spectrum of filling methods (Fig. 1) ranging from paste-only fills, through pastes with single cones of rigid or semi-rigid material, to cold compaction of core material and finally, warm compaction of core material with sealer paste. It is likely that most accounts have assumed the materials involved to be traditional sealer cements (such as zinc oxideeugenol pastes) in combination with metallic or gutta percha cones. Sealer cements are usually regarded as the critical, seal-forming ‘gasket’ of the root canal filling (26), but paradoxically, as the weak link of the system whose volume should be minimized by core compaction (27, 28). Paste-only root fillings Paste-only root fillings have a poor reputation in clinical endodontics. Notable approaches have included highly toxic resin cements such as ‘Traitement SPAD’ and the original, formaldehyde-containing Endomethasone (Septodont, St Maur des Fosses, France), which were advocated for rapid results in minimally prepared canals. Although success was reported, in some cases after deliberate apical extrusion with a spiral paste-filler (29), such ‘quick and dirty’ approaches appeared to deny the biological perspective that what came out of the canal was more important to success than what went in. Inadvertent accidents of over extension into vital structures such as the inferior alveolar canal left a distressing legacy for affected patients. Concerns were compounded by the all too frequent insolubility and hardness of such materials, making removal for retreatment a challenge to the most skilled of operators (30, 31). Even with fluid materials which are regarded as bland and biocompatible, risks of erratic length control 3 2). Equally. Laboratory evidence in fact suggests comparable cross-sectional area of canal occupied by gutta percha using single-matched taper cones compared with lateral condensation. unacceptably porous. After reaming a circular. Some commercial Trioxide Aggregate presentations of Mineral systems may serve to promote single-cone cementation techniques (Fig. the sealer-heavy root fillings associated with single-cone root fillings have not been regarded well. Smith et al. 3. (35) have recently reported that single-cone obturation was still the method of choice for 16% of Flemmish dentists. at least in the apical part of the canal. 3) has challenged the view that paste-only root canal fillings are difficult to control. Fannibunda et al. ergonomic shaping files and filling cones may inadvertently promote single cone filling techniques. dimen- 4 . Hommez et al. silver. Are our views on paste-heavy fills still valid? Mineral Trioxide Aggregate (MTA) (Fig. and may make accurate apical cone fit a possibility in many cases (40). all those who accept endodontic referrals are very familiar with single-cone removal from canals in which a large volume of surrounding sealer has leached away or dissolved under the action of tissue or oral fluids. Single-cone obturations For similar reasons. In a retrospective clinical study. stop preparation in the apical 2 mm of the canal. Porosities in large volumes of fluid paste. and within the context of infection control. Matched.Whitworth during application are recognized. Concerns were compounded by the realization that canal transportation is common and that damaged roots are difficult to seal (38). a single gutta percha. Fig. Contemporary advertising on ergonomic. setting contraction with loss of wall contact. Single-cone obturations came to the fore in the 1960s with the development of ISO standardization for endodontic instruments and filling points (34). 2. which followed the inadvertent extrusion of molten gutta percha. All experienced dentists have witnessed success following the use of such techniques in skilled hands. matched file and cone Fig. The advent of nickel titanium makes predictably centred preparations more realistic than ever in curved canals (39). and dissolution with time have all reinforced the negative views of such approaches. but clinical trial data is hitherto unavailable. and in significantly less time (41). (37) demonstrated 84% success following cementation of an apical silver cone with sealer. and 81% with a full-length silver cone and sealer. Even 1% shrinkage of a material after setting has been recognized as a potentially significant problem in terms of seal and success (33). (32) reported a case of inferior alveolar nerve paraesthesia.2% of those qualified 3 years regularly used single-cone techniques (36). Data from the UK has indicated that 49% of dentists qualified more than 20 years and 13. sectional silver or titanium point was selected to fit with ‘tugback’ to demonstrate inlay-like snugness of fit. The cone was then cemented in place with a (theoretically) thin and uniform layer of traditional sealer. to the nonsurgical management of wide open apices.Methods of filling root canals: principles and practices Fig. the white version appears to be less ‘gritty’ and more cohesive. In a narrow. often supplemented by ultrasonic (48) or sonic vibration with the intention of improving settlement and adaptation. although the merits of vibration remain contentious (49). probably due to difficult manipulation and concerns about re-treatment. A medical-grade Portland building cement (44). Fig. MTA has not yet found widespread acceptance in curved and relatively narrow canals. The consistency and behavior may be adjusted by varying the powder:liquid ratio (45). 5 . Further consolidation can be achieved by tamping the material with the broad end of paper points to wick out excess water which could retard the curing process (Dentsply/Maillefer). 4). Londrina. 4. Gathering Mineral Trioxide Aggregate ( on the end of a plugger from a ‘Lee’ block. and ongoing treatment may then proceed. or after expressing a pellet of material from a gun (47) (Fig. MTA is firmly established as the material of choice for open apices (precisely those where length control is likely to be an issue. where there is no risk of wash-out during the lengthy setting period. MTA is mixed into a stiff paste with sterile water. On the end of a plugger after wiping material into the grooves of a dedicated teflon ‘Lee’ block (46). and perforation repairs (51). Volumetric change and leakage (53) have not been identified as significant issues. Although the composition of the grey and white forms is broadly comparable (44). ProRoot MTA (Dentsply) is then usually overlaid with moist cotton wool or sponge to Fig. Material is then compacted with pluggers set to extend 2–3 mm short of working length. The need for this action has not been established. 2. Material may be carried to the canal: 1. Setting is checked by re-entry at least 4 h after placement. Wide canal with a blown-out root end filled with Mineral Trioxide Aggregate ensure a humid environment for the hydration setting reaction (Dentsply/Maillefer). Another commercial version. 3) is claimed to set within 15 min and may therefore require no overlay or re-entry. But its adoption in a range of challenging applications suggests that concerns about root canal filling cements are not universal. MTA carrier (or ‘apicectomy’ amalgam gun). Unpublished data (43) indicates that endodontists worldwide have adopted this material as first choice in a range of applications from pulp capping. A question that research must answer is whether other classes of cement can be used safely and effectively in thick section during root canal filling. It is possible that MTA may supersede calcium hydroxide ‘apexification’ procedures in the management of traumatized immature teeth (52). 5) (50). MTA Angelus (Angelus. Brazil) (Fig. and premature desiccation is prevented by covering the mixed material with moist gauze (Dentsply/Maillefer instruction guide REF A 0405). sionally unstable and unacceptably soluble (42). 5. biocompatibility (59). fluid paste. Germany) is a white. it was associated with 91. 6).3% healing at 14–24 Glass ionomer cements Ketac Endo (3M ESPE. root-reinforcing root canal sealer to be applied in thick section with a single gutta percha cone. 6. Evidence on root reinforcement was equivocal (17. Urethane methacrylates EndoRez (Ultradent. Silicone rubbers Addition polyvinylsiloxanes are well established in dentistry as inert. RoekoSeal (Roeko. but one clinical trial which included both single cone and cold laterally condensed root canal fillings provided outcomes comparable to those of other materials and techniques (58). Laboratory investigations indicate 0.Whitworth matching the apical preparation size are seated to length in the sealer-filled canal. MN. 64) and to seal as well as other established materials in vitro (65). 57). 30 gauge ‘Navitip’ needle (Fig. The mixed material is deposited into the canal by passive injection through a narrow.2% setting expansion (33). and acceptable wall coverage (60). UT. or by passive injection through dedicated plastic cannulae (Fig. Formulations with reduced hydrophobicity are now widely available. USA) was developed as an adhesive. GuttaFlow expressed from the end of a cannula after trituration. whereas GuttaFlow (Roeko) appears to be based on RoekoSeal. No clinical data are available on paste-only or single-cone EndoRez root canal fillings. although in combination with cold lateral condensation. USA) is a hydrophilic urethane methacrylate resin capable of good canal wetting and flow into dentinal tubules. including two developed specifically for endodontics. The material is reported to have acceptable biocompatibility (59. A single cone is again floated to length to encourage material flow and provide a pathway into the canal for re-entry. Materials are mixed with automix tips similar to impression materials (RoekoSeal) or by trituration (GuttaFlow) before carriage to the canal on a gutta percha cone. 6 . 63. 7. The optimal canal preparation and shape of cone to ensure adaptation and carriage to length without extrusion has not been established. South Jordan. Langenau. dimensionally stable materials. 54. Fig. Single gutta percha cones Fig. Can all cements be viewed like traditional endodontic sealers? Limited evidence exists that other classes of material may also be suitable for ‘sealer heavy’ or minimal compaction techniques. with the addition of powdered gutta percha. EndoRez expressed from a narrow Navitip applicator needle. Silicone rubbers provide long-term seal in a range of wet environments and sealing root canals may be a valid new application (62). A clinical trial comparing silicone sealer with zinc-oxide eugenol in lateral condensation revealed comparable healing outcomes (61). 7) which is claimed to minimize pressure buildup and over-extension. but outcome studies on the single-cone method are not yet available. 55) and concerns have been expressed about long-term solubility (56. encouraging flow to the apical region and into lateral ramifications. St Paul. presented like AH26 as a powder and liquid for control of material viscosity. EZ-fill/single cone root canal filling. AHPlus is specifically advocated with the single-cone Lightspeed SimpliFill technique (Lightspeed Technologies. months (66). 8B). Resin tags were demonstrated impregnating canal walls. (B) 6-months follow-up (courtesy Barry Musikant). results comparable to other materials. Following the preparation of an apical stop and parallel. 73). In vitro tests have demonstrated comparable seal in thin and thick section (65. which appears to demonstrate canal complexities well and in vitro studies have shown it to seal as well as other established techniques (75). EZ-fill is a rapid method. Review of clinical cases managed in a multi- 7 . and the handle removed by unscrewing anti-clockwise (Fig. TX. 10). Carpules with 27 gauge needles which form part of a dedicated injection system are then filled with sealer. a size matched gutta percha (or Resilon) apical tip is selected which fits snugly just short of working length in a moistened canal. 9). South Hackensack. San Antonio. One or more gutta percha points may be added if desired. Mixing with a warm spatula decreases the material’s viscosity. (A) SimpliFill device seated fully to length with sealer before unscrewing the handle. (A) Immediate postoperative radiograph. (67) have recently described the use of resin coated gutta percha cones in combination with a dualcuring EndoRez in an effort to enhance bond and seal. USA). 9. cylindrical preparation in the apical 5 mm of the canal with Lightspeed instruments. USA) is a similar material. Fig. (B) preparing to backfill by injecting sealer. 8. insolubility and dimensional stability (70). Innovative bi-directional spiral for controlled sealer placement.Methods of filling root canals: principles and practices Fig. Epoxy resins Epoxy resins are well established as effective root canal sealers. and coronally in the apical 2–3 mm. the apical tip is seated firmly to length. A recent in vitro leakage study has suggested that backfill with AHPlus alone provided a better seal against coronal leakage than AHPlus compacted with injection-molded gutta percha (74). and the canal backfilled with cement (Fig. displaying acceptable biocompatibility (68. EZ-fill (Essential Dental Systems. Tay et al. 8A). The bi-directional spiral controls apical flow of sealer cement by virtue of its blades which drive material apically in the coronal region. 72). NJ. 10. Canals are rapidly filled with sealer before floating a pre-fitted 8% gutta percha cone to length without the need for further vertical or lateral compaction (Fig. 69). but interfacial leakage was not prevented. AH 26 and AHPlus (Dentsply) are classic examples with proven track records over many years of clinical use (71. Fig. Controlled delivery is achieved with an innovative ‘bi-directoral spiral’ paste filler (Fig. a light coating of sealer is applied. After conventional drying of the canal. There is little clear evidence on how it is ‘best’ done (61. injection.1% (76. Prerequisites Canal preparation Cold lateral condensation demands a canal which is continuously flared from apex to coronal opening (85). It is not established beyond question whether compaction methods benefit patients or dentists by preserving health better. encompassing a range of approaches in terms of master cone design and adaptation. 84). 8 . Accessory cones must occupy the space left by the spreader (A & B). Spreader selection Condensing tools must be selected and tried into the canals before compaction begins. The superiority of apical stop or tapering control zone preparations for lateral condensation has not been investigated clinically. This technology has been subjected to one clinical trial in which the radiographic quality of root fillings with AH 26 was comparable to that of conventional techniques (79). a spreader must be pre-fitted which extends deeply into Gutta percha compaction methods Despite the possibilities described. has indicated that compaction may reduce canal wall contact and seal of materials with insufficiently low minimum film thickness (26). 77). healing more disease or demonstrating more canal complexities. Conversely. One in vitro study Fig. For optimal deformation of material through the length of the canal. independent clinical trial data are not yet available. they could offer no improvement and risk adverse events such as root fracture or more frequent overfill.Whitworth surgery practice have indicated favorable clinical outcomes estimated at 94. although once again. choice of sealer and spreader application. The method is generic. or carriage on points of core material. A highly innovative approach is found in non-instrumentation technology (NIT). where the controlled development of a vacuum within the tooth allows fluid sealer to be drawn into the complexities of the canal system (78). spreader and accessory cone selection. 83. Cold lateral condensation Non-Instrumentation Technology The previous section has described the delivery of sealer cements by rotary instruments. 11. compaction methods continue to dominate clinical endodontics as practitioners strive to optimize density of the core material and minimize sealer volume. 80–82) and is regarded as the benchmark against which others must be evaluated. otherwise an air or sealer-filled space will result (C). Cold lateral condensation is probably the most commonly taught and practiced filling technique worldwide (35. 36. Incompatibility will result in the accessory cone ‘hanging up’ before full insertion. 11). Vertical loads in the range of 1–3 kg have been reported as typical (94).Methods of filling root canals: principles and practices the empty canal (86. 95). Hand spreaders encourage higher compaction forces than finger spreaders (88). Fig. (B) Heat severs the gutta percha points and allows consolidation deep into the canal. This is typically achieved by immersing the apical 2–3 mm of the master cone in chloroform or halothane for 2 s before seating it to length in an irrigant-moistened canal (Fig. Forces generated by vertical loading of the spreader are vertical and lateral. Laboratory investigations (83. 87) suggest that ISO master cones allowed deeper spreader penetration and a larger number of accessory cones to be inserted. Sealer selection It is not known which sealer works most effectively with cold lateral condensation. especially in curved canals. Solvent dipping has been shown to improve apical adaptation and seal of master cones in vitro (96). and adequate to deform gutta percha without undue risks to the tooth (88. and are usually tried in an irrigant-lubricated canal. Accessory cone selection In order to secure a dense filling. 13. 12). but clinical evidence suggests that sealer choice may not have a decisive impact on Fig. 87). Forces associated with lateral condensation should not be a direct cause of vertical root fracture (88). The greater the taper of the spreader. accessory cones must be able to fully occupy the space left by the compacting spreader (Fig. Lateral condensation works by vertical loading of the wedge-shaped spreader to move materials vertically and laterally. generate less internal stress (92) and distribute forces more evenly (93). Unstandardized cones may be trimmed to provide accurate apical sizing. (A) Condensation and addition of gutta percha cones continues until the spreader will reach no more than 2–3 mm into the canal. They should therefore be the same size or slightly smaller than the selected spreader (84). 9 . with the theoretical risk of root flexion or fracture (89). the greater the lateral component of force. In vitro evidence suggests that tapered gutta percha accessory cones may slide to length more predictably and be more forgiving in the hands of non-specialists than ISO accessory cones (84). Master cone selection There is no clear evidence whether ISO or unstandardized cones are preferred. Cold lateral condensation. 12. Chloroform customized master cone. 91). Nickel titanium spreaders may penetrate more deeply (90. although this did not result in a superior seal against microbial leakage. resulting in a cement pool at best or a void at worst. London). A slow setting sealer cement is generally preferred. Cold lateral condensation: the process (Fig. and compact it apically with a cold plugger (Fig. Condensation usually continues until the spreader will reach no further than 2–3 mm into the canal (Fig. fine injection needle. and case reports continue to be 10 . Compaction and accessory cone insertion continues. 13B). and accommodate revision and consolidation of the fill if voids are detected on intermediate radiographs. 13) Cold lateral condensation commences by liberally coating canal walls with sealer cement. Examples include: Warming spreaders before each use in a hot bead sterilizer Softening gutta percha with heat before insertion of the cold spreader (104) Mechanical activation of finger spreaders in an endodontic reciprocating handpiece (105) Application of an ultrasonically energized spreader (106. heat is always applied to sever the root filling at or below canal orifice level. Fig. although application on the master cone. Optimal time of spreader insertion has not been scientifically validated in the clinical setting. Although the technique is described as cold lateral condensation. 107). which will allow adequate lubrication for accessory point insertion. An unsuitable case for predictable filling by cold lateral condensation. The master cone is slid to working length and the measured spreader applied under vertical loading for 10–60 s to deform material apically and laterally (101. Appraisal Lateral condensation is regarded as safe. Withdrawal is with watch-winding motion to ensure that the master cone is not pulled free. Fig.Whitworth outcome (61. Lateral condensation supplemented with ultrasound in a complex upper molar (courtesy Dr Graham Bailey. Variants on cold lateral condensation A number of measures have been reported to enhance gutta percha adaptation and density in lateral condensation. 15. How closely general practitioners comply with such guidelines has not been scientifically evaluated. Figure 14 shows a complex canal system filled by lateral condensation. and the first accessory cone is slid promptly to length with a light coating of sealer. each spreader insertion being slightly less deep than the previous one mirrored by shorter and shorter accessory cone insertion. supplemented with ultrasound. 102). 13A). Leaving accessory cones with their tips immersed in sealer may soften them and compromise their ability to slide fully to length. as the filling develops. a paper point or a small file are popular alternatives. and Application of an engine-driven thermomechanical compactor which creates frictional heat and advances the material apically within the canal (108. cost-effective and user-friendly. This may soften and consolidate material several mm into the canal and improve seal (103). 97). or an ultrasonically energized file ensures the most complete wall coverage (98–100). In vitro evidence suggests that application with a spiral paste filler. 109). 14. 16. presenting compelling cases on the benefits and shortcomings of each (135). or a reliance on large volumes of sealer in some areas of the canal. 4. (3) showed that clinical radiographs may not reveal poor filling density.’ Shaping is considered to be sufficient when a Fine-Medium or Medium cone (137) or other taper-matched cone (e. 15). However. Warm vertical condensation was perfected and promoted by Herbert Schilder (136). Fig. Foramen diameter as small as practicable. The tapered canal preparations thus created allow softened materials to enter anatomical complexities as heat and pressure are applied in a canal of rapidly diminishing diameter. Adaptation may be equally limited in ribbon-shaped canals. 17. Numerous other clinical trials from around the world involving cold (39. Fig.g. and the package of care to achieve this included clear guidelines on canal preparation. A key limitation is when the root canal system has an abrupt change of diameter. Continuously tapered preparation. published showing successful healing after its use in a variety of clinical scenarios (61. 11 .Methods of filling root canals: principles and practices Warm vertical condensation Philosophical battles have long been waged between advocates of cold lateral and warm vertical condensation. rather than just the primary root canal. Such cases demand the application of heat to adapt gutta percha more thoroughly.’ indicating an intention to fill all ramifications of the pulp space. cone fit and condensation. where Thermafil obturation was found to be on average 20 min per tooth quicker (133). 110–114). Contemporary advocates of this approach (137) list the criteria for satisfactory canal shaping as: 1. F2 for a ProTaper F2 prepared canal) can fit to length in the canal. 3.. Scalpel-trimming an unstandardised gutta percha cone to conform to the ISO-gauged canal terminus diameter. and this was borne out in a recent clinical study. where Kersten et al. 2. A common criticism leveled at lateral condensation is that it is a time-consuming method. His approach to filling was described as ‘3-dimensional. 116) and it should also be noted that the majority of epidemiological studies on which we base our views on the predictability of root canal treatment have included canal filling by cold lateral condensation (117–123). But how much of the observed success was directly attributable to the filling technique is not known. recent clinical reports have confirmed the ability of high-quality laterally condensed root canal fillings to exclude the oral flora after long-term exposure (115. Position of the apical foramen maintained. Markings on the master gutta percha cone produced by insertion of a file into an adjacent orifice indicates confluence. Resistance to over-filling is achieved by the creation of an apical control zone as opposed to a traditional ISO ‘stop. Original anatomy maintained. 124– 133) and warm lateral condensation (134) have validated this approach in clinical practice. as seen in internal resorption (Fig. Heating and compaction occurs in three or more stages (A–C). however. or evidence of instrument markings on the side of the master cone indicates confluence (Fig. indicating that the cone tip is binding at the preparation terminus (141). Resistance to withdrawal which continues beyond 1 mm may indicate that the cone is binding along a greater length of canal wall and not apically. There is. the narrowest extending within 4–5 mm of root-end (142). Snugness of fit is usually confirmed by slight resistance to withdrawal from the canal (short tug-back). The master cone for the second canal is trimmed to the point of confluence with a scalpel. Romulus.0–0. little clinical evidence that other classes of material. Sealer selection Classic descriptions of warm vertical condensation have specifically advocated zinc oxide-eugenol sealers (Pulp Canal Sealer. Multiple wave warm vertical condensation Plugger and heater-tip selection In common with other filling techniques. 16). such as slow-setting epoxy resins may not perform equally well in warm vertical condensation. 140). 17). MI. Warm vertical condensation – multiple wave.5 mm short of an electronically confirmed canal terminus (Fig.Whitworth Such preparations are now created rapidly and predictably with a range of hand and engine driven NiTi instrumentation techniques (138) and tapered. taking an increment of gutta percha from the canal each time and continuing until the apical 4–5 mm are ‘corked’ with gutta percha and sealer. or constant drying point (139. rather than ISO master cones are scalpel trimmed to fit snugly 1. USA) which are believed to set rapidly in the event of extrusion and hopefully become inert in the periradicular tissues (16). and it is usual to select three or more pluggers which will extend progressively deeper into the canal. Canal confluence may be confirmed by the insertion of a cone to working length before inserting a file or spreader into the adjacent canal. 12 . condensing tools must be selected before treatment. 18. Nickeltitanium instruments such as the double-ended Buchanan or Dovgan pluggers may be better suited to curved Fig. Failure of the instrument to advance to length. Kerr. The instrument for delivering heat must have a narrow enough tip to reach within 5 mm of root-end. The first wave severs the gutta percha cone at canal orifice level. Care should be taken to avoid contact of the plugger with canal walls.Methods of filling root canals: principles and practices canals than stainless steel Machtou or Schilder pluggers. coating its length before insertion and seating to length initially before withdrawing to inspect that its entire surface (and therefore presumably the entire surface of the canal) has a light coating of sealer 16. plunging the heat carrier or touch-and-heat tip 3–4 mm into the Fig. gently condensing material around the walls of the canal entrance before positioning in the centre of the mass of gutta percha and compacting apically with firm finger pressure. or more safely and neatly with an electronic touch-and-heat instrument. 20. taking care not to withdraw the master cone from the canal. 19. which is believed to carry an unacceptable risk of damaging force transmission to the root. In contrast with cold lateral condensation. Heat may be applied to the canal either with traditional ‘heat carriers’ which are warmed in a Bunsen burner flame. and often applied on the master cone. Ultrafil percha. sealer application is therefore sparing. The compaction process (Fig. 13 . low-temperature injectable gutta Fig. Calamus: engine-driven thermoplastic gutta percha in pre-dispensed cannulae (Courtesy Dentsply). The largest cold plugger is then applied. 141). 18) Downpack Compaction of the root canal filing occurs in multiple waves as the material is softened with heat and driven apically with cold pluggers. The second wave of heating follows. Sealer application Warm vertical condensation generates significant hydraulic forces and there is an increased risk that excess sealer may be extruded into the periradicular tissues (109). A variety of systems are available. 22) System B was the first of a new generation of electronic heat carriers which allowed rapid heating and cooling of tips to facilitate their use as both heat carrier and plugger (Fig. 21). A single tip is selected which will extend to within 4– 5 mm of canal terminus before binding on canal walls. Hygenic) (145) (Fig. which recent laboratory reports have suggested are superior to gutta percha compaction methods in terms of seal (74. and 12% taper.. Fig. although one laboratory study supported the deposition of increments up to 10 mm (146). and pressure is maintained for 5–10 s on the cooling mass of gutta percha in order to counteract cooling contraction. material removal and compaction proceed in a similar manner until the apical 4–5 mm of the canal is ‘corked’ with thermally compacted gutta percha and sealer. 148). Ultrafil. 19). Within 1 s. Radiographically seamless union with the downpack is more likely to be achieved if the needle of the gun system touches the cut gutta percha surface in the canal and is held in place for 5–10 s before commencing backfill injection. 23). including: Pre-heated carpule systems offering gutta percha in a range of viscosities (e. mass of compacted gutta percha and removing an increment of material from the canal. Backfill Empty canal space is most quickly and efficiently filled with injection-molded gutta percha. Injectable gutta percha is commonly deposited in 3– 5 mm increments. 20). heating gutta percha pellets and maintaining heat to the point of expression from the gun (e. Such systems are relatively inexpensive. Elements – combined System B and gun system in a single unit (Courtesy Sybron). delivered from a gun in increments of 3–4 mm and compacted by hand to counteract cooling contraction. with further compaction. using the next plugger. but offer limited working time before the carpule must be re-heated. the tip has reached working temperature and is swept in one fluid movement over the course of 2–3 s until it sits 2 mm short of the binding point. 23). The plugger now being locked into the canal by a solidifying 14 . Systems incorporating downpacking and backfilling devices (Fig. each marked at 5 mm intervals along their length (16) (Fig. 144). which offer the Tip selection System B is supplied with a variety of tips in 4%. 8%. Progressive heating and compaction is expected to drive gutta percha and sealer into all accessible canal ramifications during the downpack (143. sparing sealer application and cone insertion. Condensation proceeds in the same manner as previously. and sealer-only backfills. 21.. The cold tip is presented to canal entrance before activating the heater. Third and fourth waves of heating.g. Single-wave vertical condensation (Fig. Obtura II). allowing the tip to cool rapidly. At this point.g. Alternative backfill methods include the incremental addition of ‘backfill’ lengths of pre-trimmed gutta percha which are heated and compacted as in the downpack (147).Whitworth advantage of unlimited working time. the System B is set for maximal rate of heat increase and to a working temperature setting of 2001C. the unit is deactivated. 10%. Manual gun systems which work on the same principle as a glue gun. in which temperature and flow rate can be regulated (Fig. 6%. Following cone fit. New-generation engine-driven gun systems. (B) Separation and withdrawal. The heater is therefore re-activated. Fig. mass of gutta percha. (A) Single wave downpack. opponents have historically argued that the cost in terms of dentine 15 . Evaluation of warm vertical condensation Compaction techniques of any sort require dentine removal to accommodate condensing instruments and the application of potentially damaging forces in nonphysiological directions.Methods of filling root canals: principles and practices Fig. Warm vertical condensation – single wave. 22. (C) Apical 4–5 mm ‘corked’ with gutta percha and sealer. classically by a 1 s ‘separation burst’ before smooth withdrawal. In warm vertical condensation. further heating is necessary to release the tip for withdrawal from the canal. Original System B heat source with a range of tips. 23. The apical gutta percha mass is then condensed further by hand before backfilling by any of the methods described previously (16). many warm vertically compacted root canal fillings may comprise of a single. and until recently. (A) Verification of the canal with a blank carrier. particularly if temperature guidelines are exceeded (149–152). 16 . A recent 20–27 year review on teeth with extruded of filling materials showed progressive periapical improvement with time (162). The consensus of recent laboratory reports is that heating and compaction within the apical 2–3 mm of the canal is required for optimal gutta percha adaptation to the canal terminus (155–159). However. there has been little to separate established methods.Whitworth removal to accommodate appropriate pluggers was excessive compared with that required for lateral condensation. However. and a welcome range of sufficiently narrow and efficient heat carriers. with most of the modeling taking place in the laboratory setting where the heat-buffering effects of a richly perfused periodontium cannot properly be taken into account. minimally distorted cone in the apical few millimeters. Perhaps as important are the questions of efficacy and control. 109. Additional concerns have been raised with regard to thermal damage to the periodontal ligament during thermal compaction techniques. Clinical studies (39. Carrier systems Carrier systems represent another convenient means of delivering thermally softened gutta percha to canal Fig. 132) and case reports (163. 24. This seems to be less of an issue in current practice with controlled canal flaring by contemporary instruments. and in reality. pluggers (including nickel titanium pluggers) and backfill needles. (B) Smooth insertion into a lightly sealercoated canal. There is little clinical evidence of adverse periodontal responses following thermoplastic obturation in clinical practice. Carrier obturation. a recent clinical report (160) found no association between sealer extrusion and postoperative pain. 125. The impact on clinical outcome is central to our choice of techniques. with significant (30%) differences in area of canal occupied by gutta percha following heat application to 2 or 4 mm from canal terminus (157). Warm vertical condensation techniques are designed to drive materials into anatomical complexities (16). whereas small extrusions of zinc oxide-eugenol sealers have been shown to resorb (161). Evidence on this appears to be equivocal (153. 154). Many laboratory studies have addressed how well warm vertically compacted gutta percha adapts to canal walls and reduces sealer-pools following heating and compaction to different depths. (C) Cut-back of the carrier. but a higher prevalence of sealer extrusion is recognized (109) with potential for further tissue injury and delayed healing. data from a recent longitudinal study suggests that root canal treatments involving minimal apical enlargement and warm vertical condensation may be associated with higher successes than large apical preparations and cold condensation (165). It is difficult to imagine that the majority of practitioners working in curved canals are able to consistently deliver heat and pressure to such depths. 164) have convincingly reinforced the view that warm vertical condensation techniques can enjoy comparable success to lateral condensation methods. Whether the filling technique or the overall approach to treatment was critical is hitherto unclear. and carrier devices (40. 169). A Thermafil device prepared for use. 24) Verifying the preparation In common with other techniques. Carrier methods and may be considered low temperature techniques with little risk of overheating tissues (168). Products from different manufacturers have differing degrees of taper.Methods of filling root canals: principles and practices Fig. 17 .5 mm of the tip of the carrier is visible. and as the excess apical to the tip of the plastic carrier is not accurately known. Preparing the device The majority of practitioners probably use Thermafil and other devices as supplied. Whole systems are available with matched shaping instruments. Clinical application (Fig. with the intention of limiting Fig. systems with some degree of control. reduced molecular weight gutta percha (167). The relative success of such systems in different configurations is largely unknown. where insertion occurs in one action. which has developed from a method involving the coverage of a conventional file with regular gutta percha (166) to contemporary plastic carriers coated with flowable. Such systems introduce an element of ergonomics to root canal treatment and may be welcomed by many. (A) Resilon. a biodegradable polycaprolactone with (B) matching sealer. with the reported intention of allowing more accurate carrier control during insertion and limiting excess gutta percha extrusion beyond the root apex (16) (Fig. some choose to trim back the apical extent of gutta percha until 1. This takes special importance in the case of carrier systems. which in the filling devices is covered with gutta percha) must first be tried in the canal to ensure that it will be able to carry and compact material to full length. absorbent points. the compacting tool (in this case. a plastic blank. As there is usually an excess of gutta percha on the carrier. which may make some systems more suitable with certain canal shapes than others. This approach is typified by Thermafil. with little opportunity to revise the result if the carrier does not go to length first time. 26. lower device trimmed to remove excess gutta percha apically and coronally. Upper device unaltered. 25) Remove the most coronal 2–3 mm of gutta percha from the carrier. 25. and in contrast to cold lateral condensation. Periapical extrusion has again been identified as a potential drawback of Thermafil (175) and Da Silva et al. It is critical for the development of adequate flow and to facilitate insertion that the device is heated to the correct temperature. Evaluation Laboratory evidence suggests that Thermafil obturation is a low-pressure technique (171. 26) Despite apparently satisfactory performance over many decades. Gagliani et al. excessive sealer application should be avoided to reduce the risk of large-scale apical extrusion. OH. capable of rapid. and to 1401C for Obtura (178). 173–175). (177) have shown 94. and are reported to be especially effective in long. Although few materials. USA) and Resilon Simplifill (Lightspeed Technologies). Two clinical trials have been reported recently. where excess sealer will slowly migrate coronally. reduced to 1501C for System B. and in a variety of guises. the extent of gutta percha and sealer movement can be controlled by the rate of carrier insertion (G. research continues to find alternatives which may seal better. with the subsequent insertion of further dry paper points to ensure that excess has been removed and that there is even. found to take 20 min longer on average per tooth than Thermafil. whereas Chu et al. Carrier devices are firmly established in clinical practice. Sealer application The insertion of a well-fitting Thermafil device is akin to inserting the plunger of a syringe to the root canal. In the hands of skilled and experienced operators. Carrier insertion When the carrier is adequately heated. but recent clinical research in dogs has confirmed that Resilon provides a better coronal seal against microbial ingress than laterally or vertically compacted gutta percha with AH26 (179). The shank may then be severed with a bur or heated instrument. Epiphany (Pentron. gutta percha and sealer filling techniques do not represent the universal ideal. it is removed from the heater without delay or distraction and smoothly seated to full working length in one smooth. 2005). a polycaprolactone core and sealer filling system has recently entered the market as Real Seal (Dentsply. light wall contact (16). have seriously challenged gutta percha and sealer in the majority of filling situations. Resilon (Fig. (133) showed comparable. CT. fluid movement. Claims on the in vitro sealability of Resilon were recently challenged by independent researchers (178). 80% success at 3 yr review in teeth filled with Thermafil or lateral condensation. with the exception of MTA. personal communication. This method has been shown in vitro to create dense root canal fillings while controlling apical extrusion of materials. Components were developed to bond with each other and with canal walls to produce an hermetically sealing (19) and root-reinforcing (18) monobloc of material. Melting temperatures are.Whitworth excessive gutta percha in the pulp chamber (16) (Fig. and avoid any potential for adverse responses in latex-allergic patients. and pellets for injection-molding are available. after pain. however. Sealer is generally applied sparingly on a paper point. and dense filling of root canal systems and their ramifications (11. Tulsa. where the insertion of conventional spreaders and pluggers may be compromised (167). Cones of ISO and increased taper. USA).2% healing in teeth without apical periodontitis. 25). and presumably. 24 months after treatment with Profile and Thermafil. Resilon. mechanically reinforce compromised roots. (176) have therefore described a modified carrier obturation technique in which a sealer-coated master gutta percha cone is first inserted to length before the heat-softened carrier. with the recommendation that the material can be used in any conventional technique. Cantatore. and laboratory evidence (170) has suggested that more rapid insertion captures apical detail better than slow insertion. and for the required time in the manufacturer’s recommended oven. Wallingfort. curved canals. Condensation pressure may be applied with a small plugger to compensate for some of the shrinkage which inevitably accompanies cooling. 18 . however. 172). As a consequence. Lateral condensation was. and 48. Clinical studies in humans are awaited.9% periapical health in teeth with apical periodontitis. Anecdotal reports suggest that the material is user-friendly but does not retain its softness after heating as well as gutta percha. J Endod 1999: 25: 364–368. Determining the optimal obturation length: a meta-analysis of the literature. References 1. 16. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005: 99: 628–636. There is a need to translate daily practice into research data to provide stronger evidence to support our care of patients. Prognosis of initial therapy. Weichman JA Chapter 1: Modern Endodontic Therapy. often of questionable clinical relevance and with little standardization of method. Schaeffer MA. 9. An evaluation of microbial leakage in roots filled with a thermoplastic synthetic polymer-based root canal filling material (Resilon). 19. Kersten HW. Teixeira EC. Zandi H. Endodontics. 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