Comparative Scanning Electron Microscopic Study of the Marginal Adaptation of Four Root-End Filling Materials in Presence and Absence of Blood

OBJECTIVES

The aim of this study was to evaluate marginal adaptation of mineral trioxide aggregate (MTA), calcium enriched mixture (CEM) cement, Biodentine and BioAggregate in presence of normal saline and human blood.

MATERIALS AND METHODS

In this in-vitro experimental study, 80 extracted single-rooted human teeth were instrumented and filled with gutta-percha. After resecting the root-end, apical cavity preparation was done and the teeth were randomly divided into 4 groups (N=20)(a total of 8 subgroups). Root-end filling materials were placed in 3mm root-end cavities prepared ultrasonically. Half the specimens in each group were exposed to normal saline and the other half to fresh whole human blood. After 4 days, epoxy resin replicas of the apical portion of samples were fabricated and scanning electron microscopy (SEM) analysis was performed to find gaps in the adaptation of the root-end filling materials at their interface with dentin. The Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis of data with P<0.05 as the limit of significance.

RESULTS

There were no significant differences in marginal adaptation of the 8 tested groups (P>0.05).

CONCLUSION

Based on the results, blood contamination does not affect the marginal adaptation of MTA, CEM cement, Biodentine or BioAggregate.

Effect of acidic environment on dislocation resistance of endosequence root repair material and mineral trioxide aggregate

OBJECTIVE

The aim of this study was to compare the effect of an acidic environment on dislocation resistance (push-out bond strength) of EndoSequence Root Repair Material (ERRM putty and ERRM paste), a new bioceramic-based material, to that of mineral tri-oxide aggregate (MTA).

MATERIALS AND METHODS

One-hundred twenty root dentin slices with standardized canal spaces were divided into 6 groups (n = 20 each) and filled with tooth-colored ProRoot MTA (groups 1 and 2), ERRM putty (groups 3 and 4), or ERRM paste (groups 5 and 6). The specimens of groups 1, 3, and 5 were exposed to phosphate buffered saline (PBS) solution (pH=7.4) and those of groups 2, 4, and 6 were exposed to butyric acid (pH= 4.4). The specimens were then incubated for 4 days at 37°C. The push-out bond strength was then measured using a universal testing machine. Failure modes after the push-out test were examined under a light microscope at ×40 magnification. The data for dislocation resistance were analyzed using the t-test and one-way analysis of variance.

RESULTS

In PBS environment (pH=7.4), there were no significant differences among materials (P=0.30); but the mean push-out bond strength of ERRM putty was significantly higher than that of other materials in an acidic environment (P<0.001). Push-out bond strength of MTA and ERRM paste decreased after exposure to an acidic environment; whereas ERRM putty was not affected by acidic pH. The bond failure mode was predominantly cohesive for all groups except for MTA in an acidic environment; which showed mixed bond failure in most of the specimens.

CONCLUSION

The force needed for dislocation of MTA and ERRM paste was significantly lower in samples stored in acidic pH; however, push-out bond strength of ERRM putty was not influenced by acidity.

Subcutaneous tissue responses to three endodontic irrigants: a comparative study

INTRODUCTION

This study aimed to compare the subcutaneous tissue responses to MTAD (mixture of a tetracycline isomer, an acid, and a detergent), 17% EDTA, and 2.6% NaOCl.

MATERIALS AND METHODS

Thirty-six Wistar albino rats were used for this study. Test solutions were injected subcutaneously into predetermined areas on the animal dorsum. The rats were then randomly divided into three groups of twelve each and sacrificed at 2 hours, 2 days, and 2 weeks. The severity of inflammation induced by each irrigant at different time intervals was assessed histologically. The data were analyzed using Kruskal-Wallis and Friedman tests.

RESULTS

The difference in severity of inflammatory reactions induced by tested irrigants at the different time intervals was statically significant (P<0.05). There was no significant difference between the severity of inflammation induced by MTAD and 2.6% NaOCl at the various time intervals (P>0.05). Subcutaneous tissue responses to MTAD were not different from those observed in 17% EDTA specimens at 2-hour and 2-day intervals (P>0.05).

CONCLUSION

Under the conditions of this study, MTAD has the same toxicity as 2.6% NaOCl.

The effect of two post-space preparation techniques on the seal of resilon and gutta-percha obturation materials

INTRODUCTION

The aim of this study was to compare the effect of post space preparation with Gates Glidden drills or hand files on the sealing ability of gutta-percha or Resilon obturation materials.

MATERIALS AND METHODS

One-hundred and four single-rooted human teeth were instrumented and divided into four experimental groups (n=21 each) and two groups of positive and negative control (n=10). Forty-two roots of experimental groups were obturated with gutta-percha and Dorifill sealer; and 42 roots with Resilon/Epiphany self-etch using lateral compaction technique. Each gutta-percha or Resilon group was divided into two subgroups (n=21) and post-space prepared with either Gates Glidden drills or hand files and chloroform. After post space preparation, 5 mm of apical gutta-percha or Resilon was left intact. The whole system was sterilized with gamma-rays. Saliva leakage was tested using a split-chamber model. Specimens were monitored every 24 hours for 30 days. The data were analyzed using log-rank test and Cox regression analysis.

RESULTS

There were no significant differences between the sealing ability of gutta-percha and Resilon. Furthermore, no significant difference was found between two different methods of post space preparation (P>0.05).

CONCLUSION

Under the limitations of this ex vivo study, there were no significant differences between the sealing ability of Resilon and gutta-percha after post space preparation using Gates Glidden drills or hand files with the aid of chloroform.

Relationship between human cytomegalovirus transcription and symptomatic apical periodontitis in Iran

BACKGROUND/AIMS

Apical periodontitis of endodontic origin may develop as a result of cooperative interactions among herpesviruses, specific pathogenic bacteria and tissue-destructive inflammatory mediators. This study sought to identify the presence of Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) transcripts in symptomatic and asymptomatic periapical lesions of individuals living in Iran.

MATERIAL AND METHODS

Fifty endodontic patients (28 with symptomatic periapical lesions and 22 with asymptomatic periapical lesions) were included in the study. In each study subject, a microbiological periapical sample was collected using a curette in conjunction with periapical surgery. A reverse transcription-polymerase chain reaction assay was used to identify transcripts of EBV and HCMV.

RESULTS

Human cytomegalovirus transcript was detected in 15 of the 28 (53.6%) symptomatic and in six of the 22 (27.3%) asymptomatic periapical study lesions (significant difference between symptomatic and asymptomatic lesions; P = 0.03, chi-square test). Epstein-Barr virus transcript was identified in one symptomatic and in two asymptomatic periapical lesions.

CONCLUSION

This study establishes that HCMV transcription is common in apical periodontitis and is most frequent in symptomatic lesions. The high frequency of active herpesvirus infections in severe apical periodontitis changes the pathogenic paradigm of the disease and may also have preventive and therapeutic implications.

Antimicrobial Effects of AH26 Sealer/Antibiotic Combinations Against Enterococcus Faecalis

INTRODUCTION

The purpose of this in vitro study was to evaluate the antimicrobial effects of two antibiotics added to AH26 sealer against Enterococcus faecalis (EF).

MATERIALS AND METHODS

The antimicrobial effects of two antibiotic (amoxicillin and doxycycline) that were added separately to AH26 sealer was evaluated by using the agar diffusion test and in vitro human root inoculation method. The freshly mixed sealers were placed in prepared wells inside agar plates inoculated with EF, and were incubated at 37(°)C. The zones of inhibition were measured at 24, 48, 72 hours and 7 days. Root specimens were prepared and obturated with lateral condensation technique. Samples were collected from infected root canals after 2 and 7 days of incubation and the number of colony-forming units (CFU) was determined. The data were analyzed using one-way and two-way ANOVA.

RESULTS

The findings of this study revealed that sealer-antibiotic combination containing amoxicillin and doxycycline had a significant difference in the mean zones of inhibition when compared to AH26 sealer alone in all of the time periods (P<0.05). The minimum effective concentration against EF was one percent of sealer powder weight for both of amoxicillin and doxycyline. The mean log10 CFU in AH26-doxycyline combination group was significantly lower than other groups at 48 h incubation period (P<0.05). AH26-doxycycline combination group and AH26-Amoxicillin combination group killed bacteria (mean CFU=0) in the dentinal tubules at 7 days incubation period.

CONCLUSION

In vitro root fillings carried out with gutta-percha and AH26-antibiotic combination were effective in killing EF in dentinal tubules.