In vitro evaluation of dentin tubule occlusion by three bioactive materials: A scanning electron microscopic study


Background: Dentin hypersensitivity (DH) is a common problem characterized by a short, sharp
pain. Reduction of dentin permeability by occluding dentin tubules is considered as a method for
treating DH. Many substances are available to decrease hypersensitivity. The aim of this study is
to evaluate the ability of three different remineralizing agents for occluding dentinal tubules in
comparison with positive and negative controls.
Materials and Methods: In this in vitro scanning electron microscopic (SEM) study, 75 extracted
premolars were cut into crown and root fragments with a bur and divided into five groups: group 1:
Sodium fluoride 5% varnish was applied (positive control), Group 2: No treatment (negative control),
Group 3: Treated with Remin Pro (contains hydroxyapatite and fluoride), Group 4: Treated with MI
paste (contains casein phosphopeptide‑amorphous calcium phosphate [CPP‑ACP]) and Group 5:
Treated with GC tooth mousse (contains CPP‑ACP). SEM images were obtained and mean tubular
diameter was measured in each group. One‑way ANOVA and Duncan’s tests were used for statistical
analysis. A significant level of α = 0.05 was set for comparison between the groups.
Results: Statistically significant difference was observed between Group 2 (negative control) and
other four groups (P < 0.05). There was no significant difference between Groups 1, 3, 4, and 5
(P > 0.05).
Conclusion: Under the limitations of the present in vitro study, it can be concluded that the
application of a CPP‑ACP paste as well as a paste which contains fluoride is effective on reduction
of dentin permeability.

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Root Canal Disinfection by Single- and Multiple-instrument Systems: Effects of Sodium Hypochlorite Volume, Concentration, and Retention Time

Journal Of Endodntics
Publication History
Published online: April 10, 2019


  • Bacterial reduction was compared between a single-file and a multifile system.
  • All protocols produced a highly significant intracanal bacterial reduction.
  • Counts of bacteria were 2.5 times significantly higher in the REC-2.5LOW group when compared with the BR-2.5HI group.
  • Disinfection was better with multiple instruments, high volume, and longer sodium hypochlorite exposure.



This ex vivo study evaluated the intracanal bacterial reduction promoted by chemomechanical preparation using a single-file technique varying the volume, concentration, and retention time of sodium hypochlorite (NaOCl) irrigation in comparison with a multifile system.


Palatal roots from extracted maxillary first molars were selected and anatomically matched based on microcomputed tomographic analysis for group distribution. The canals were contaminated with a fresh mixed bacterial culture grown in anaerobiosis and recently obtained from a tooth with apical periodontitis. Specimens were divided into 4 groups of 24 each according to the following preparation protocols: REC-6LOW (Reciproc R50 instrument [VDW, Munich, Germany], 6% NaOCl, low irrigant volume), REC-2.5LOW (R50, 2.5% NaOCl, low irrigant volume), REC-2.5HI (R50, 2.5% NaOCl, high irrigant volume), and BR-2.5HI (BioRaCe [FKG Dentaire, LaChaux-de-Fonds, Switzerland], 2.5% NaOCl, high irrigant volume). The total time of preparation was recorded. Intracanal bacteriologic samples were taken before and after preparation; DNA was extracted and subjected to quantitative polymerase chain reaction.


Bacteria were detected in 22 initial samples from the REC-2.5LOW group and in 23 from the other groups. Intragroup analysis showed that all tested preparation protocols were highly effective in significantly reducing the intracanal bacterial counts (P < .001). Intergroup comparison of bacterial reduction levels revealed a statistically significant difference between BR-2.5HI and REC-2.5LOW (P < .05). Counts of bacteria were 2.5 times significantly higher in REC-2.5LOW compared with BR-2.5HI. No other significant differences were found in quantitative findings (P > .05).


The concerted effects of multiple instruments, the high volume of irrigation, and the long retention time of NaOCl irrigant had a positive influence on intracanal disinfection during chemomechanical preparation.
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