Effect of ethylenediaminetetraacetic acid and sodium hypochlorite irrigation on Enterococcus faecalis biofilm colonization in young and old human root canal dentin: in vitro study.

INTRODUCTION: The alterations in dentin tissue depending on increasing age might cause different adhesion capability of bacteria, yielding differences in clinical approaches regarding root canal irrigation. This study, therefore, aimed to evaluate the effects of ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) on Enterococcus faecalis biofilm growth in root canal dentin of young and old individuals. METHODS: The root canals of extracted young (<30 years) and old (>60 years) single-rooted human teeth were sectioned at the crown and the apical parts. The root canals of the mid-root sections were enlarged with #2 Gates-Glidden burs. After treatment with 17% EDTA + 2.5% NaOCl, 17% EDTA alone, 2.5% NaOCl alone, or saline, the samples were incubated in E. faecalis suspension for 24 hours. Thereafter, root canal samples were enlarged again with #3 Gates-Glidden burs, and the removed dentin chips were collected. Bacteria were dispersed by using sonication, serially diluted, and then plated for counting on agar plates as colony-forming units. Scanning electron microscopy and confocal laser scanning microscopy investigations were also carried out to examine the biofilm formation on the dentin. Data were analyzed with Kruskal-Wallis test and Mann-Whitney U test with Bonferroni adjustment. RESULTS: Combination of EDTA and NaOCl significantly reduced the amount of intracanal biofilm in both age groups (P < .01). However, the bacterial counts of E. faecalis in the old group were still higher (P < .05). CONCLUSIONS: It might be suggested that root canals from elderly population are more susceptible to canal infection. However, combined application of EDTA and NaOCl significantly reduces the amount of intracanal biofilm.

Calcium ion diffusion from mineral trioxide aggregate through simulated root resorption defects.

The purpose of this study was to investigate the diffusion of calcium ions (Ca+2) through exposed dentinal tubules following intracanal application of mineral trioxide aggregate (MTA). Fifty-two single-rooted teeth were instrumented using 2.5% sodium hypochlorite for irrigation between each file size. Thereafter, standardized defects were created on the root surfaces so as to mimic external root resorption. The root canals and external defects received a final irrigation of 17% ethylenediaminetetraacetic acid and distilled water. MTA powder was then mixed with saline and placed into the canals. All root surfaces except the cavities were sealed with two coats of varnish. Teeth with unfilled canals (n = 26) served as controls. The teeth were immersed in saline after which the release of Ca+2 from the defects into the saline was measured at 1, 3, 7, 14, and 28 days. The results showed diffusion of Ca+2 through the defects in the dentin in MTA-filled roots with a significant increase in concentration within time.