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J Conserv Dent. 2019 Jul-Aug;22(4):381-386. doi: 10.4103/JCD.JCD_555_18.

Ex vivo microbial leakage analysis of polytetrafluoroethylene tape and cotton pellet as endodontic access cavity spacers.

Author information

Department of Clinical Dental Sciences, Princess Nourah Bint Abdulrahman University, College of Dentistry, Riyadh, Saudi Arabia.
Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.



The endodontic spacers are placed between the endodontic appointments or after completion of the endodontic therapy, and until the placement of a definitive restoration.


The aim of this study was to evaluate the sealing ability of polytetrafluoroethylene (PTFE) access spacer against microbial leakage and to compare it with that of a cotton pellet.

Materials and Methods:

Fifty-two extracted human single-rooted premolars were divided into two experimental groups (n = 20) according to the endodontic spacer; cotton pellet or PTFE tape, and two control groups (n = 6). Following standardized access cavity, cleaning, and shaping procedures, the access cavities received a standardized thickness of the spacer material followed by a Cavit restoration in all the teeth except for the positive controls, which were left empty. Negative controls had the root surfaces completely sealed with nail polish. A dual-chamber microbial leakage model was used with Enterococcus faecalis as the test strain. At days 7 and 30, samples of the lower chambers' solution were obtained and subjected to the quantitative real-time polymerase chain reaction (qPCR) analysis to quantify bacterial levels. Furthermore, broth turbidity in the lower chambers was recorded weekly. The Mann-Whitney U test and Wilcoxon test were used to compare E. faecalis counts between and within groups, respectively.


At days 7 and 14, the experimental groups leaked similarly as determined by broth turbidity. However, at days 21 and 30, a significantly higher number of cotton pellet samples exhibited microbial leakage. Analysis by qPCR revealed higher levels of E. faecalis counts in cotton pellet samples compared with PTFE samples. This difference was statistically significant at day 7, but not at day 30.


PTFE spacer showed improved sealing ability compared with the commonly used cotton pellet and may serve as an alternative endodontic access cavity spacer.


Cotton pellet; Enterococcus faecalis; endodontic spacer; microbial leakage; polytetrafluoroethylene

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