Root canal sealers are needed to adequately seal the root canal space to prevent microleakage. The sealer fills voids and irregularities of the root canal space left unfilled by the obturation core material [1]. Adequate sealing of the obturation material inside the root canal is important to the success of endodontic treatment, because up to 60 % of endodontic treatment failures are caused by the incomplete obturation of the root canal [2]. Root canal may leak and become exposed to periradicular tissue sealers; however, they are generally not very biocompatible [3–6]. Root canal sealers can vary greatly in composition and contain zinc oxide eugenol, calcium hydroxide, glass ionomer, composite resin, silipoint, urethane methacrylate, formaldehyde, and bisphenol A [7, 8]. The sealers are typically delivered by auto-mix syringes to reduce the risk of operator mixing errors. The most widely used sealers are AH Plus, Sealapex, RealSeal, BC Sealer, Apexit, and Pulpdent; the composition of these sealers is shown in Table 8.1.

The lack of biocompatibility of these sealers to periodontal cells is shown in the low numbers of cells which can attach to the sealers, as shown in Fig. 8.1.

The reason for the success of gutta-percha among dentists is because it is easy to manipulate into the root canal, it is radiopaque and easily seen on radiographs, and it can be removed from the canal and be replaced when necessary [17]. Fresh gutta-percha has good handling properties, while aged gutta-percha can become brittle. Gutta-percha is an isomer of natural rubber derived from the Taban tree (Isonandra perchas). The natural chemical form of gutta-percha is 1, 4-polyisoprene [18]. It was first used in dentistry in the late 1800s as a temporary restorative material and then to obturate root canal systems [19]. The semi-plastic physical properties of gutta-percha allow it to be reshaped and molded within the canal system by condensation forces [20]. Gutta-percha can be softened by heated instruments and chemicals such as chloroform and eucalyptol. This makes gutta-percha easy to obdurate the root canal and easy to remove from the root canal if a retreatment is needed. An advantage of gutta-percha is that it is inert to the periapical tissues if it should become extruded past the root apex [21]. The quality of root canal obturation with gutta-percha is important; if a root canal is poorly obturated, it can be associated with nonhealing periapical lesions in up to 65 % of treatments [22], and 60 % of endodontic treatment failures are caused by the incomplete obturation of the root canal [2]. The difference between a poorly obturated and a retreated well-obturated root canal can be seen in Fig. 8.2.

Some dentists prefer to insert the gutta-percha point into the canal without altering it [23], while other dentists like to soften the gutta-percha with heated instruments or chemicals. The softened gutta-percha can then be condensed into the canal using lateral or vertical condensation [24]. The separation of obturation methods into vertical or lateral condensations is unrealistic, since it is physically impossible to condense either laterally or vertically alone [25]. Often, the condensation procedure to insert the gutta-percha will vary according to the shape of the instrumented root. If the shape of the instrumented root matches the shape of the gutta-percha point, then not much condensation of the gutta-percha is needed to get a good obturation of the root canal. However, if the nearest size of gutta-percha point is a poor-fit, it might need to be condensed to fit the root canal space. Gutta-percha is most difficult to place into a minimally prepared narrow canal. Gutta-percha requires condensation pressure be applied in the apical third region of the canal, and it can easily become extruded through an open apex, leaving fragments in the periradicular tissues [26].

Gutta-percha filling techniques use a prefitted primary point procedure, verified by a radiograph to fit the full length of the canal and to still fit tightly in the apical region of the root canal [9]. Normally, if the instrumented canal has an adequate condensation space or flare has been prepared, it is often impossible to fill the length of the canal with a gutta-percha point that fits tightly at the root apical region. The largest possible gutta-percha point is normally selected according to the size of the last instrument used to the full length of the prepared canal. A radiograph of the root canal must be taken with the gutta-percha point inserted to check that it fits the working length of the root canal. If it does not fit, it may be necessary to reprepare the apical aspect of the canal or to select another gutta-percha point.

The root canal must be dried with paper points prior to its obturation, as residual irrigation fluids will leave voids [27]. The sealer is evenly coated on the prepared canal surface, with the last instrument used to spread it throughout the canal length using an up and down motion [28].

The fitted gutta-percha point is cut to the root canal working length, and a spreader is used to condense it into the root canal space. A radiograph is taken to evaluate the quality of the root canal obturation and to assess the need to reposition the point or apply more condensation pressure. In anterior teeth, if the filling is satisfactory, the gutta-percha should be removed to the gingival line or below it, because gutta-percha can discolor the tooth [29]. In posterior teeth, it is advisable to have a “bed” of gutta-percha on the floor of the pulp chamber; this can act as a guide for retreatment or to alert the operator that he is getting too close to the floor of the crown when making a final preparation [30]. It will also assist in the sealing of furcal accessory canals.

Because no one gutta-percha obturation technique could possibly satisfy all endodontic situations [31], it is necessary to consider some modifications of the basic technique. In a root canal where an adequate apical stop or constriction is impossible to achieve, as in an immature canal after apexification, the gutta-percha point can be custom contoured by dipping the apical 3–4 mm in chloroform and then placing it into the canal with pressure. By the repeated placement and removal of the apical softened point, this uses the apical canal space to mold the gutta-percha to accomplish a good fit. Thin root canals or canals with an extreme curve are more difficult to obturate with standard sizes of gutta-percha points. In these situations, heated instruments or chloroform can be used to chemically soften the gutta-percha for 5 s so that it can be more easily into the curvature and the minimally prepared apex. All of these gutta-percha obturation techniques must be considered to accomplish the goal of fully obturating the root canal. A summary of the terms and techniques for obturating root canals is shown in Table 8.2.

Situations when it is acceptable to fill the root canal:

Suggested gutta-percha obturation procedure: