Diffusion ability of endotoxin through dentinal tubules

Clinical evaluation of culturable bacteria, endotoxins and lipoteichoic acid in teeth with vital normal pulp tissues

The objective of this study was to investigate the presence of culturable bacteria, endotoxins (LPS) and lipoteichoic acid (LTA) levels in teeth with normal vital pulp (NVP) with intact crowns (IC) and those with coronal restoration (CR) limited to the enamel level. A total of 20 teeth indicated for endodontic treatment due to prosthetic reasons were selected. Samples were collected from the root canals. The levels of cultivable bacteria, LPS and LTA were assessed. Statistical analyses were performed at significance level set at 5%. None of the teeth presented microbial growth. In the IC group, the LPS levels were limited to the lowest concentration of LPS. On the contrary, higher LPS and LTA levels were detected in teeth with CR. It was concluded that teeth with NVP and IC were negative for bacteria, LPS and LTA; while teeth with CR were positive for bacterial virulence factors.

Effect of Odanacatib on the release of NTX (Amino Terminal Telopeptide) from LPS contaminated type I dentin collagen

OBJECTIVE

To evaluated the Odanacatib inhibitor treatment on lipopolysaccharide (LPS) contamination effect on cathepsin-K mediated dentin degradation by analysis of type I collagen C- and N-termini telopeptides.

METHODS

Pulverized and disks of human dentin were demineralized and LPS contaminated, or stored in deionized water (DW) for 12 h. Samples were challenged with lactic acid (LA). Aliquots of dentin powder were treated with 1 mL Odanacatib or stored in DW for 30 min. Dentin collagen degradation was determined by sub-product release of C-terminal (ICTP and CTX) and N-terminal (NTX) telopeptides, normalized to total protein (tp) concentration (n = 3). Dentin matrix was evaluated for gravimetric (n = 8) and ultrastructural changes. Data were analyzed by Student t-test, one-way ANOVA and Tukey's test (α = 5 %).

RESULTS

LA incubation significantly increased telopeptide release compared with DW (p < 0.05). In untreated groups, significantly higher CTXtp, NTXtp telopeptide rates were observed for LA+LPS samples compared with DW (p < 0.01). Odanacatib significantly reduced ICTPtp, CTXtp, and NTXtp telopeptide release for LPS, LA, and LA+LPS conditions. In untreated groups, LPS and LA+LPS challenge significantly increased dentin weight loss (p = 0.02). Within each storage condition, Odanacatib treatment did not affect weight change (p > 0.05) of dentin disks.

SIGNIFICANCE

This study showed that LPS contamination resulted in significantly higher rates of NTX than CTX from dentin matrix. Odanacatib significantly reduced telopeptide release rates of LPS contaminated dentin matrix.

LPS levels in root canals after the use of ozone gas and high frequency electrical pulses

The present study aims to verify the effect of ozone gas (OZY® System) and high frequency electric pulse (Endox® System) systems on human root canals previously contaminated with Escherichia colilipopolysaccharide (LPS). Fifty single-rooted teeth had their dental crowns removed and root lengths standardized to 16 mm. The root canals were prepared up to #60 hand K-files and sterilized using gamma radiation with cobalt 60. The specimens were divided into the following five groups (n = 10) based on the disinfection protocol used: OZY® System, one 120-second-pulse (OZY 1p); OZY® System, four 24-second-pulses (OZY 4p); and Endox® System (ENDOX). Contaminated and non-contaminated canals were exposed only to apyrogenic water and used as positive (C+) and negative (C-) controls, respectively. LPS (O55:B55) was administered in all root canals except those belonging to group C-. After performing disinfection, LPS samples were collected from the canals using apyrogenic paper tips. Limulus Amoebocyte Lysate (LAL) was used to quantify the LPS levels, and the data obtained was analyzed using one-way ANOVA. The disinfection protocols used were unable to reduce the LPS levels significantly (p = 0.019). The use of ozone gas and high frequency electric pulses was not effective in eliminating LPS from the root canals.

Action of Chlorhexidine, Zingiber officinale, and Calcium Hydroxide on Candida albicans, Enterococcus faecalis, Escherichia coli, and Endotoxin in the Root Canals

AIM

The purpose of this in vitro study was to evaluate the antimicrobial activity of 2% chlorhexidine gel (CHX) as auxiliary chemical substance and intracanal medications on Candida albicans, Enterococcus faecalis, Escherichia coli, and their endotoxins in the root canals.

MATERIALS AND METHODS

The study was conducted on 48 single-rooted human teeth divided into four groups (n = 12), according to intracanal medications used: (1) Calcium hydroxide + apyrogenic saline solution (Ca(OH)2 + SS), (2) 20% ginger glycolic extract (GEN), (3) calcium hydroxide + 20% ginger glycolic extract (Ca(OH)2 + GEN), (4) apyrogenic SS (control). Collections were made from the root canal content before preparation (baseline-S1), immediately after instrumentation (S2), 7 days after instrumentation (S3), after 14 days the action of intracanal medication (S4), and 7 days after removal of the intracanal medication (S5). The antimicrobial activity and endotoxin content were analyzed for all collections. The results were statistically analyzed by the Kruskal-Wallis and Dunn tests at a significance level of 5%.

RESULTS

After instrumentation with CHX, there was complete elimination of E. coli and C. albicans, except for E. faecalis, which was significantly reduced and then completely eliminated after intracanal medication. There was significant reduction of endotoxin after instrumentation. Comparison of collection after instrumentation and intracanal medication revealed reduction of endotoxins in all groups; this reduction was greater in group Ca(OH)2 followed by the group GEN.

CONCLUSION

It was concluded that the instrumentation using CHX and intracanal medication used were able to eliminate the microorganisms from the root canal; the endotoxins were reduced, yet not completely eliminated.

CLINICAL SIGNIFICANCE

This study is important and relevant for searching alternatives during endodontic therapy, since it aims to study the effect of Zingiber officinale on microorganisms and endotoxins present in root canals.

Evaluation of the apical adaptation performance of various root canal instruments

OBJECTIVE

The aim of this study was to evaluate the apical root canal adaptation performance of various root canal instruments.

MATERIALS AND METHODS

A total of 40 freshly extracted single-rooted mandibular incisors were used in this study. Coroner parts of all teeth were removed from cemento-enamel junction and root canal of each tooth was explored with a size 8 K-file until the tip of the file was just visible at the apex. Working lengths (WLs) were determined as 1 mm short of these measurements. ProTaper, K-file, profile and hedstroem files were inserted into the root canals of 10 teeth to the WL following the flaring of the coronal and middle thirds. Instruments were fixed in the root canals with acrylic resin. The apical 1 mm of each root tip was ground on wet sandpaper to expose the canal and the instrument at the WL and the apical region of each tooth was examined under stereomicroscope. The stereoscopic images of the teeth were digitized and analyzed with software in order to determine the differences between the areas of root canals and file tips. Result data were analyzed using the one-way analysis of variance test (P = 0.05).

RESULTS

There were no significant differences between apical file/root canal areas of the evaluated instruments (P > 0.05).

CONCLUSIONS

None of the evaluated instruments performed a perfect adaptation with the apical root canal surface at the WL in mandibular incisors. Therefore, total removal of the debris from the apical canal surface may not be achieved when these filing instruments are used.

Influence of the apical enlargement size on the endotoxin level reduction of dental root canals

Gram-negative bacteria play an essential role in endodontic infections because they have virulence factors such as endotoxin. Due to its potential cytotoxic activity, special attention has been given to the removal/neutralization of this endotoxin in the root canal system.

In vitro evaluation of the action of irrigating solutions associated with intracanal medications on Escherichia coli and its endotoxin in root canals

OBJECTIVE

The purpose of this study was to evaluate the efficacy of auxiliary chemical substances and intracanal medications on Escherichia coli and its endotoxin in root canals.

MATERIAL AND METHODS

Teeth were contaminated with a suspension of E. coli for 14 days and divided into 3 groups according to the auxiliary chemical substance used: G1) 2.5% sodium hypochlorite (NaOCl); G2) 2% chlorhexidine gel (CLX); G3) pyrogen-free solution. After, these groups were subdivided according to the intracanal medication (ICM): A) Calcium hydroxide paste (Calen®), B) polymyxin B, and C) Calcium hydroxide paste+2% CLX gel. For the control group (G4), pyrogen-free saline solution was used without application of intracanal medication. Samples of the root canal content were collected immediately after biomechanical preparation (BMP), at 7 days after BMP, after 14 days of intracanal medication activity, and 7 days after removal of intracanal medication. The following aspects were evaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the Limulus Amebocyte Lysate test (LAL). Results were analyzed by the Kruskal-Wallis and Dunn's tests at 5% significance level.

RESULTS

The 2.5% NaOCl and CLX were able to eliminate E. coli from root canal lumen and reduced the amount of endotoxin compared to saline.

CONCLUSIONS

It was concluded that 2.5% NaOCl and CLX were effective in eliminating E. coli. Only the studied intracanal medications were to reduce the amount of endotoxin present in the root canals, regardless of the irrigant used.

Influence of 2% chlorhexidine gel on calcium hydroxide ionic dissociation and its ability of reducing endotoxin

OBJECTIVE

The aim of this study was to evaluate the influence of 2% chlorhexidine gel (CHX) on pH, calcium release, and Ca(OH)(2) capability of reducing endotoxin.

STUDY DESIGN

Calcium release was verified by atomic-absorbance spectrophotometry, and pH was measured with a pHmeter. For endotoxin quantification, extracted human teeth previously contaminated with standard endotoxin were filled with: group I, Ca(OH)(2) + saline solution; group II, Ca(OH)(2) + CHX; and group III, CHX for 14 days. The remaining endotoxin was quantified by using chromogenic quantitative test. Statistical analysis was performed with analysis of variance and Tukey post hoc test (P < .05).

RESULTS

Group II released more calcium than group I (P < .05) after 15 days. Groups I and II showed alkaline pH in all periods, and group I showed higher pH values than group II (P < .05) after 30 days. Groups II and III showed significantly more decreased endotoxin than group I.

CONCLUSIONS

CHX did not interfere with the chemical properties of Ca(OH)(2), in fact even improving its properties of reducing the endotoxin content in root canals in vitro.

Action of propolis and medications against Escherichia coli and endotoxin in root canals

This study evaluated the action of propolis and intracanal medications against Escherichia coli and endotoxin. Forty-eight dental roots were contaminated with E. coli. The root canals were instrumented with propolis and divided into groups according to the type of intracanal medication: Ca(OH)(2), polymyxin B, or Ca(OH)(2) + 2% chlorhexidine gel. In the control group, saline solution was used without application of intracanal medication. Counts of colony-forming units were carried out and the endotoxin was quantified by the chromogenic Limulus amobocyte lysate assay. The results were evaluated by analysis of variance and the Dunn test (5%). Root canal irrigation with propolis was effective to completely eliminate E. coli and reduce the amount of endotoxins. All intracanal medications contributed to the significant decrease in endotoxins. Only intracanal medications may reduce the amount of endotoxins in the root canals. The greatest efficacy was observed for medications containing Ca(OH)(2).