The importance of appropriate temporisation and root canal treatment

Abstract

The purpose of root canal treatment is bacterial minimisation and the promotion of healing. Exogenous factors, including coronal leakage and poor fillings, are by far, the most significant contributors of bacterial ingress, despite adherence to good cleaning protocols. It is imperative to acknowledge the crucial role that a high-quality temporary restoration plays in root canal treatment procedures. An improperly positioned temporary restoration increases the chance that the root canal treatment will fail. Thus, in order to maximise the predictability and success of root canal treatments, "the deal is in the seal".

Keywords: Root canal treatment, temporary restoration, restorative material

Introduction

Dentistry has seen some major technological, biological and educational advances in achieving the clinical aims of root canal treatment (RCT). These advances have led to the development of treatment strategies in areas such as: vital pulp therapy;[1] contemporary instrumentation and disinfection procedures;[2] the use of the operating microscope in both surgical and non-surgical endodontic treatment;[3-5] and the adoption of more contemporary methods in undergraduate endodontic training.[6]

The role of bacterial infection in pulpitis and apical periodontitis is well established.[7] The goal of RCT is to decrease bacterial levels through cleaning and shaping, and prevent reinfection by obturating with gutta-percha and endodontic sealers. When executed effectively, this method promotes healing and the regression of periapical pathology.[8] To eradicate the microbial flora within a tooth and its root canal system, most dentists follow an eight step RCT protocol. These steps are: i) diagnose and remove the cause of the disease(s); ii) use an aseptic technique that includes the using rubber dam to prevent contamination; iii) mechanically instrument the root canals to enlarge them; iv) irrigate the canals with one or more antibacterial solutions; v) medicate the canals with one or more antibacterial agents; vi) temporarily restore the tooth to avoid bacterial ingress during and after treatment; vii) fill the root canal system once disinfected; and viii) restore the tooth to normal function.[9]

In the course of treatment planning for restoration, the tooth concerned must be assessed for any restorative challenges that might classify the tooth as unrestorable following RCT.[10] The following factors must be considered:[11] i) the amount of remaining tooth structure; ii) the anatomical position of the tooth; iii) the functional load on the tooth; and iv) the aesthetic requirements of the tooth. Continuous bacterial reinfection within the root canal system would significantly reduce the efficacy of the overall RCT success.[12] Therefore, a good temporary restoration is important if multiple appointments are planned for the RCT procedure,[10] and if long-term intracanal medication is planned.[13] Moreover, for successful RCT, an adequately placed temporary filling to seal the endodontic access cavities is vital.[14]

This paper reports some examples of patient cases to highlight the importance of temporisation and how this affects RCT outcomes.

Aim

To provide a brief analysis of the reasons for selecting appropriate temporary restorative materials in a series of root canal treatment cases.

Clinical Relevance

This paper highlights the importance of a good temporary restoration in preventing the entry of additional bacteria during and after root canal treatment, thereby influencing treatment outcomes.

Patient cases

Each patient presented with a tooth that required RCT and was temporised with a material chosen by the endodontist. These are shown in Figures 1 to 8. As there are a multitude of possible clinical scenarios, each with a specific temporary restorative treatment option, this paper cannot cover all the temporary restorative materials available. Permission was given for the use of photographs and radiographs.

Figure 1. Patient 1. LL6 presents with adequate tooth structure for temporisation with a glass ionomer cement (GIC) restoration (Fuji VII Pink).

Figure 2. Patient 2. The patient is a heavy bruxer and clencher. LL6 was diagnosed with a cracked tooth and temporisation with an orthodontic band was planned.

Figure 3. Patient 3. LR6 was diagnosed with crack lines and the patient consented to metal band cementation. Temporisation with a composite resin cuspal overlay was offered.

Figure 4. Patient 4. After removal of caries, LL6 was temporised with an orthodontic metal band to protect the tooth against fracture development during the RCT.

Figure 5. Patient 5. This young patient did not wish to have a metal band placed around her tooth so LL6 was temporised with a composite resin cuspal overlay.

Figure 6. Patient 6. Temporisation of LR6 was achieved with a GIC (Fuji II LC) to seal access through the existing crown.

Figure 7. Patient 7. UR2 was temporised with a triple layer of Cavit, Fuji IX GIC, and Composite resin restoration after a single-visit-retreatment with removal of a post.

Figure 8. Patient 7. This shows a 3-year follow-up of UR2 (Figure 7) following the single-visit.

Discussion

An effective temporisation can act as a shield to prevent bacteria and fluid from penetrating the periapical tissues. Numerous factors, including a poorly positioned coronal temporary restoration during and/or after the RCT, and lost or fractured restorations, can lead to bacterial contamination of root canals. This paper aims to demonstrate the significance of a quality temporary restoration in limiting the entry of bacteria both during and following root canal therapy and thus, impacting the course of treatment.

Single or multi-visit root canal treatment

The same theory underlies both single-visit and multi-visit endodontic treatment: root canal infection is caused by bacteria, and eliminating them will lead to healing. The primary distinction between the two approaches is how they handle bacteria remaining after root canal instrumentation. The multi-visit strategy uses intracanal medications to treat any residual bacteria while the one-visit treatment seeks to entomb any bacteria that remain after instrumentation.

Unquestionably, the development of apical periodontitis depends on bacteria.[7] Therefore, eliminating all the pulp tissue, bacteria, and their endotoxins from the root canal are the biologic goals of endodontic treatment procedures.[15] To accomplish the biologic goals, dentists must mechanically create a sufficiently shaped canal to enable an effective amount of irrigant to enter the canal system, and make it easier for instruments to compact gutta-percha during root canal filling.[8] Research indicates that even with the use of an intracanal medication, complete eradication of bacteria is not possible following chemomechanical debridement.[16] Overall, in cases where the culture was positive before root filling, treatment success was only 68%.[17] As a result, one-visit root canal therapy may be considered an alternative for treating teeth after the root canal system has undergone optimal chemomechanical debridement.[12] However, physicians may also decide to employ intracanal medication in a multiple-visit regimen to ensure consistent disinfection prior to canal obturation. There is currently insufficient evidence to conclude that one treatment strategy is superior to the other; each case needs to be evaluated to determine the best course of action. There is evidence that the single-visit approach is effective in preventing the growth of bacteria, which is the reasoning behind immediate root canal filling.[18] Alternatively, dentists may decide to employ intracanal medication in a multiple-visit regimen to ensure consistent disinfection prior to canal obturation.

Multiple-visit treatments require the placement of a temporary seal between appointments and this can cause additional problems.[12] For example, there is a chance of coronal leakage around the root canals, which has been linked to treatment failure.[19] While not without its drawbacks, such as placement of medicament dressings in cases with suppurative canals, single-visit endodontic therapy has the benefits of eliminating the need for inter-appointment temporisation and thus, reduces the risk of bacterial leakage into the root canal system. There is currently insufficient evidence to conclude that one treatment strategy is superior to the other. However, vital teeth are the best candidates for single-visit therapy, and with careful case selection, single-visit care can be just as effective as multi-visit care.[18]

Coronal leakage

From a biological standpoint, inflammation in the tooth's periradicular region is linked to endodontic failure.[20] Microorganisms found in the root canal system frequently contribute to the pathological process, and those living in the periradicular tissue may also be pathogenic.[15] Early failures are typically a consequence of the clinician's poor performance of root canal therapy and symptoms may appear soon after the start of treatment and include coronal leakage.[21] This underlines why a good temporary restoration that seals access to the cavity after the initial RCT appointment is important. In an in-vivo study on monkeys' posterior teeth, Madison and Wilcox[22] demonstrated that coronal leakage—which was shown by dye penetration—occurred shortly after the root canals were exposed to the oral cavity. This points to the potential for bacterial leakage to recontaminate the root canal system, which ultimately would cause treatment failure. Heling et al.[23] concur with findings of Siqueira[24] in that, if the coronal seal is broken, salivary bacteria and other irritants may enter the periradicular tissues and compromise the effectiveness of root canal therapy.

Temporary restoration

According to Warrier and Jayalakshmi,[25] the temporary restorative material should satisfy the following requirements: it prevents microleakage of bacteria, and entry of organic products and fluids from the oral cavity into the root canal system; it prevents leakage of the intracanal medication inserted in to the root canal system; it provides a stable seal and good marginal integrity with the hard dental tissues; it is easily shaped with the external contours of the tooth; it is easy to remove from the cavity; it has good abrasion resistance; it is insoluble in oral fluids; and it appears radiopaque on the radiograph. The materials used for temporary restoration, shown in Table 1,[26] can be classified into: light-cured materials e.g., Vertise flow (Kerr, USA); glass ionomer cements e.g., Fuji II (GC Corp, Japan); zinc oxide eugenol materials e.g., IRM (Dentsply Sirona, UK); and zinc oxide calcium sulphate materials e.g., Cavit (3M ESPE, USA). From an endodontist viewpoint, a double seal technique using Cavit and GICs, or Cavit and Composite resin restoration, with or without cementing an orthodontic band, is always employed as an interim restorative step between endodontic appointments.

Table 1. Different temporary restorative materials. Adapted from Bogomil A et al 2021.[26] A summary of the different temporary restorative material groups.

Cuspal coverage restoration

According to Panitvisai and Messer,[27] the largest cuspal deflections were observed following endodontic access after two surface (mesial and occlusal) and three surface (mesial, occlusal and distal) cavity preparations. The authors concluded that the cavity preparation's dimension influences cuspal stiffness. Cuspal coverage will, therefore, minimise marginal leakage and lessen cuspal deflections. These results supported the findings of Linn and Messer[28] regarding the significance of cuspal coverage for endodontically treated teeth. That is, complete coronal coverage of an endodontically treated molar led to a rise in cuspal stiffness and prevented cusp fractures. In a long-term observational study, Cheung and Chan[29] demonstrated that the most frequent cause of the rapid rate of decline in root canal treated teeth could be early failures, which typically indicate ineffective control treatment in the root canal. This suggests that improperly positioned temporary restoration increases the chance that the RCT will fail.

Key points to remember

When planning the type of temporary restoration for teeth having RCT, dentists should keep in mind a few fundamental guidelines:

• use a strong material that sufficiently seals the root canal system;

• preserve periodontal health; and

• for teeth without enough natural tooth structure for a direct dental filling, consider cementing an orthodontic band to lessen the chance of cusp fracture and support the provisional restoration.

Conclusion

It is critical to establish an effective coronal seal following the completion of the RCT for the period the patient is waiting for a definitive restoration. The achievement of a predictable RCT outcome is contingent upon the implementation of a well-executed temporary restoration.

Declarations:

Financial support: N/A

Consent: Informed consent has been given for the use of radiographs and photos of the tooth only.

Acknowledgements: None

Conflict of interest: No potential conflict of interest relevant to this article was reported.

Authors’ contribution: Thai Yeng (TY). Conceptualization: TY; Methodology: TY; Formal analysis: TY; Writing, reviewing, and editing: TY.

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Citation: Yeng, T. (2026). The importance of appropriate temporisation and root canal treatment