Inflammatory suppression by endodontic sealers after aging 12 weeks In vitro

Abstract

Dental endodontic sealers are in intimate contact with tissues around the root apex (periapical area) for extended periods. New endodontic sealers have been developed in the past decade, but the biological responses to many new products are not well documented. In this study, we assessed in vitro monocytic cytotoxic and inflammatory responses to several contemporary endodontic sealers. AH-Plus (AH), Pulp Canal Sealer (PC), Epiphany (EPH), Endo-Rez (ER), and an experimental Endo-Rez (ERx) were initially placed in buffered-saline for 12 weeks to simulate in vivo use. After "aging," specimens were placed in direct contact with THP1 monocytes for 72 h and their cytotoxicity (mitochondrial response; MTT) or ability to trigger or suppress cytokine secretion (ELISA; TNFalpha, IL1beta, IL=6; +/- lipopolysaccharide (LPS) exposure) were measured relative to Teflon (Tf) negative controls. Cellular responses among conditions were compared with ANOVA and Tukey post-hoc analysis (alpha = 0.05). Two of the five sealers, EPH and PC, still suppressed cell mitochondrial activity by 70% or more after 12 weeks of conditioning in saline. No sealer alone activated monocytic TNFalpha, IL1beta, or IL6 secretion (p > 0.05 vs. +LPS controls). When THP1 were activated by LPS after exposure to the sealers, differential suppression of TNFalpha, IL1beta, and IL6 secretion was observed for two of the five sealers tested. (EPH and PC) This data suggest that common endodontic sealers do not activate monocytic TNFalpha, IL1beta, and IL6 secretion in vitro by themselves, but degradation products of the sealers may suppress activation of monocytes.

Comparison of cytotoxicity, genotoxicity and immunological inflammatory biomarker activity of several endodontic sealers against immortalized human pulp cells

“…Thereby, in contrast to the present findings, Brackett et al . () indicated that AH Plus exhibited no immunological response on THP‐l monocyte cell determined TNF‐α, IL1‐β and IL‐6. Such difference might be attributed to different cell‐lineage tested.…”

Dysregulation of monocytic cytokine secretion by endodontic sealers

“…Although clinically relevant, freshly mixed sealers were not studied because previous studies have shown that they are uniformly cytotoxic in vitro, 9,10 making a change in secretion of inflammatory mediators difficult to measure. 11,24,25 The assumption of this strategy was that eluted components from the materials would change with time; previous studies with other materials suggest that elution from sealers decreases or stays the same with time. 11,28 The major goals of endodontic therapy are to remove infected soft and hard tissues and to seal the canal space against ingress of bacteria.…”

“…11,24,25 The assumption of this strategy was that eluted components from the materials would change with time; previous studies with other materials suggest that elution from sealers decreases or stays the same with time. 11,28 The major goals of endodontic therapy are to remove infected soft and hard tissues and to seal the canal space against ingress of bacteria. These goals are in place because of reports that failure of endodontic therapy is often caused by residual or invading bacteria that trigger inflammation and tissue destruction via secreted toxins including lipopolysaccharide (LPS).…”

“…8 Longerterm in vitro studies have shown that most sealers are initially cytotoxic and that some remain severely cytotoxic after 6-12 weeks ''aging'' in vitro; others may improve significantly. 9,10 Materials may alter monocytic secretory activity even after 12-week aging, 11 although effects on cytokine secretion are known for only a few cytokines.…”

“…Yet the 100%-plus increases in IL1b and IL6 observed for AHP in the ÀLPS condition are in direct contrast to previous work that reported no increases in these cytokines in the absence of LPS. 11 Causes for these inconsistencies are not known but could stem from antibodies raised against different epitopes in the array, or difficulties in the image analysis used to quantify the array results. Although the array is an attractive technology because of its high through-put, it is standard-less and relies on digital image analysis of the membrane for quantification; it also is expensive to the point that it limits the ability to get sufficient numbers of replicates for rigorous statistical analysis.…”