The success of endodontic treatment depends on three dimensional obturation of the root canal space with an inert filling material and creation of the hermetic seal, which will hinder the invasion of microorganisms. Washington studyhas attributed nearly 60 % of the endodontic failures due to incomplete obturation of the root canal system.1 A fluid tight seal in apical third is most difficult to achieve due to anatomy of that area for which the obturating material/technique need to possess specific qualities.
Lateral compaction of guttapercha is the most widely used technique of obturation of root canal system and often has been used as the standard to which the sealing ability of new filling techniques or materials are compared.2 The disadvantages of this technique as enumerated by Brayton et al as creation of voids, lack of homogeneity of the guttapercha mass a high percentage of sealer in the apical portion of the canal, spreader tracts, inadequate spreader penetration in curved canals, lack of adaptation to canal walls, cul-de sac, fins etc.3
The condensation pressure required for proper compaction in cold lateral condensation technique leads to higher incidence of vertical root fracture as reported byMeister et al,Gimlin et al.4,5 Furthermore the round and conical shaped canals are easier to obturate with this technique than the ribbon and oval shaped canals as the area beyond the reach of mechanical action of endodontic instruments in canal will frequently be left unfilled.6 These disadvantages of lateral compaction techniques can be overcome by plasticizing guttapercha for root canal obturation.
The injection moulded thermoplasticizedguttapercha technique was introduced by Yee et al in 1977.7 Heating of the guttapercha was done to plasticize the guttapercha so that it would flow. The technique “could obturate fins, cul de sacs and minute intracanal communications”. Though various authors have stated that the technique has disadvantages like lack of material control, excessive canal enlargement to accommodate the injection needles, lack of measurement guidelines to monitor the progress of filling procedure, the rapid cooling of the material, resulting in poor condensation and voids, the potential for equipment related problems such as needle breakage, or guttapercha leaks and presence of under condensed, slender filling in the apical third of the canal.8 This technique also causes a temperature rise on the external root surface which results in potential damage to the root cementum, periodontal ligament and alveolar bone because the excessive rise in intracanal temperature.9
The E & Q system is a relatively new introduction to the endodontic armamentarium for root canal filling, works on principle of continuous wave of compaction by Buchann in 1996 which is used in a similar manner as the System B technique for downpack of guttapercha in the apical region to prevent extrusion of guttapercha into periradicular area.2, 10 The system consists of a control unit with a pen grip device holding a heating tip, as well as guttapercha injection gun (like OBTURA II) for backfillthe middle & coronal portion of the root canal.2
In 1978, Johnson described a technique in which mynolguttapercha moulded on a last size of K file was heated in flame and carried to the root canal coated with sealer.11 This idea was later commercialised as Thermafil (Dentsply).Thermafilobturators are made of plastic core coated withalpha phase guttapercha. This stereoform of guttapercha is considered to have better flow characteristics when molten than beta phase guttapercha.
Apical seal is perhaps one of the prime determining factors in evaluating the success of an obturating technique. Dye penetration method is one of the most common methods used for detection of micro leakage as it is easy to use does not require any specialized equipment and is non time consuming.
The amount of dye leakage can be studied either by sectioning, or by clearing the teeth. Robertson (1980),revealed that the clearing technique used to assess the dye penetration is simple, inexpensive, allow three dimensional view and avoids the potential hazards of, loosing any tooth structure while sectioning.12 As it is possible to inspect the adaptation of guttapercha to the root canal walls directly in the cleared specimens and dye leakage to its maximum extent all around the specimen
The present in vitro study was undertaken to compare and evaluate the sealing ability of three different thermoplasticizedguttaperchaobturation techniques: injectable thermoplasticizedguttapercha, thermoplasticizedguttapercha with downpack and backfill, and core carrier thermoplasticizedguttapercha taking lateral condensation technique as the control in oval root canals. This was done by using the time tested dye leakage method and clearing technique.