Assessment of Coronal Microleakage of Different Temporary Restorative Materials Used for Endodontic Access Cavity Restoration

Introduction

Achieving a hermetic seal of the root canal access cavity between appointments and after the accomplishment of therapy is a vital element in the success of root canal therapy. A commonconcern in day to day dental practice of conservative dentistry and endodontics is coronal leakage. Such complication often leads to the failure of endodontic treatment.^1,2,3,4 Failure of root canal therapy usually occurs when the access cavity of the tooth is momentarily restored with a material which has intermediate ability to provide a complete seal. Pathway created by the fluid from the oral cavity into the tooth through the restorative material is referred as microleakage.² Microleakage is of considerable.

importance for an endodontist as it takes place in and around the temporary restorations put in the access cavity leading to failure.^2,3 Zinc oxide eugenol is an age-old material which has been in use since more than 50 years as a temporary restorative material (TRM). Literature has revealed that it provides a hermetic seal. But there are many studies reporting that this material can lead to coronal microleakage when used for long term.⁴ If by any chance in some cases, if permanent restoration cannot be placed soon after the treatment, then temporary restoration ought to be placed in a manner that it seals the coronal aspect of the endo access cavity hermetically and provides superior sealing ability of the margins.⁵ Preference of any temporary restorative material should be considered with great efforts and care. The material selected should be resistant to abrasion and should have ample dimensional stability. Meanwhile, the material should also possess the ability to avert the contamination of intracanal medicaments by the fluids of oral environment.6 The emergence of recent materials and technology tried addressing this issue by addition of different materials and modifying the currently available materials.Therefore this invitro study was carried out to compare zinc oxide eugenol cement with the two recent materials Intermediate restorative material (IRM) (Dentsply Sirona) and CAVIT G (3M ESPE) for their ability to prevent coronal microleakage. The main aim and objective of this invitro study was to assess the potentiality of different TRM in preventing coronal microleakage during inter-appointment period inthe course of root canal therapy.

Materials and Methods

A total of 60 premolar teeth that were extracted for orthodontic treatment were stored and used in this study.

The materials used in the study included:

Zinc oxide eugenol (ZOE)

Intermediate restorative material (IRM by Dentsply Sirona)

CAVIT G (3M-ESPE) Study groups were as following: Group

1 - teeth filled with zinc oxide eugenol Group

2 - teeth filled with IRM Group

3 - teeth filled with CAVIT G

Endodontic access cavity was designed and a cotton plug was kept in the chamber without instrumenting the canal and was then filled with respective material in different study groups. Then the specimens were soaked in the Indian ink stain upto a specified time duration. After the 1st, 2nd, 4th and 7th day, the specimens were taken out, sectioned and were observed under the stereomicroscope and were scored as per the scoring criteria stated below. (Supplementary table) (Supplementary figure)

Results

Mann Whitney U test was used to analyze the data obtained.The results demonstrated variable leakage pattern in all the groups at all time intervals. Significant statistical difference in dye leakage between Group 1 and Group 2 was observed. Also, a significant statistical difference in dye leakage between Group1 and Group 3 was observed. The difference between Group 2 and Group 3 was not statistically significant. The microleakage observed in ZOE was significantly more on the second day than on the first day.There was not much difference in microleakge on the 2nd and 4th day. IRM and CAVIT G showed less penetration of dye during initial days but later it gradually increased and there was no significant statistical difference in scores among all the groups on the 7th day. By 7th day, all the groups showed penetration of dye into the cotton pellet.

Discussion

A crucial factor that predicts the prognosis of endodontic therapy is the selection of TRM. The purpose of TRM is to provide a temporary seal for the endo access cavity and to restrict the ingress of fluids, microorganisms inside the root canal system. It is recommended to permanently restore the access cavity immediately at the end of the root canal treatment to avoid microleakage.^1-8 Information perceived from the existing literature denotes that a provisional restoration with well adapted margins can prevent ingress of microorganisms and significantly enhance the prognosis of even a poorly root filled tooth.^9-14

Hagemeier et al.,¹⁵and Jensen et al.,¹⁶ have proven that sealing capabilities of Ketac Molar is lower than CAVIT, though the former exhibits better properties when subjected to load.¹⁷ CAVIT exhibits excellent sealing abilities even in extensive access cavities. According to a study by Pankaj et. al., CAVIT showed lower microleakage after 1, 2, 3, and 4 weeks when compared to Ketac Molar.¹ 

Indian ink dye was utilized in the present study because it was simple and inexpensive than other methods like radioisotope. Outcome of the study showed that dye penetration into the endo access cavity was prevented by the temporary material only till 2nd or 4th day. By 7th day, all the teeth used in the study showed dye penetration into the access cavity regardless of the group to which they belonged. Numerous previously reported studies suggest that microleakage in the zinc oxide eugenol group is extensive after the 3rd day. Zinc oxide eugenol is frequently used as TRM in endodontic access cavities. Though many of the previous studies suggest that even zinc oxide eugenol can provide a tight seal preventing microleakage upto 7 days, the effectiveness and ability of the zinc oxide eugenol to forbid microleakage mainly depends on the powder liquid ratio. Though the other materials utilized in the study showed better ability to restrict microleakage, it was only observed till the 4th day. All the materials employed in the study failed to avert microleakage upto 7 days. The reason for better prevention of microleakage by CAVIT G and IRM is because of reinforced polymers. To correlate the results to clinical use, thermocycling was not performed in the present study. It was suggested that when these TRM were exposed to thermocycling, it extensively damages these restorations and leads to microleakage within 24 hours.

Conclusion

Within the limitations of the present study, it was proven that none of the TRM could prevent microleakage upto 7 days. Hence it is better to undertake early replacement of endo access cavity with permanent restoration. Furthermore, clinically oriented studies need to be carried out to discern and improve the sealing potentiality of TRM to avert microleakage.