Effects of camphorated parachlorophenol on human periodontal ligament cells in vitro

Comparative Evaluation of Cytotoxicity, Anti-inflammatory, and Drug Release Profiles of Allicin-incorporated GO-AgNP Hydrogel: An In Vitro Study

AIM

This study evaluates the cytotoxicity, anti-inflammatory effects, and drug release profiles of an allicin-incorporated graphene oxide-silver nanoparticle (GO-AgNP) hydrogel as an intracanal medicament.

MATERIALS AND METHODS

The allicin-incorporated GO-AgNP hydrogel was synthesized and characterized using transmission electron microscopy. Human periodontal ligament (PDL) fibroblasts were used for 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assays, assessing cell viability at 10, 25, 50, and 100 µg/mL concentrations over 24, 48, and 72 hours. Anti-inflammatory effects were evaluated by analyzing interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α expression in lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells via quantitative polymerase chain reaction at 24 hours and 7 days. Drug release was assessed using ultraviolet-visible spectrophotometry over 168 hours in root canal-treated teeth.

RESULTS

The allicin-incorporated GO-AgNP hydrogel exhibited concentration-dependent cytotoxicity, with cell viability exceeding 90% at 10-20 µg/mL but decreasing significantly at 50-100 µg/mL (p < 0.05). The half-maximal inhibitory concentration was approximately 45 µg/mL. Anti-inflammatory assays showed a reduction in IL-6 (45%), IL-8 (38%), and TNF-α (42%) compared with the LPS-treated control (p < 0.05). Drug release analysis revealed a sustained release pattern, with the 20 µg/mL hydrogel demonstrating a higher cumulative release than the 10 µg/mL hydrogel.

CONCLUSION

The allicin-incorporated GO-AgNP hydrogel demonstrates potential as a biocompatible intracanal medicament with anti-inflammatory properties and controlled drug release. Further optimization is required for clinical application.

CLINICAL SIGNIFICANCE

This allicin-incorporated GO-AgNP hydrogel shows promise as an intracanal medicament due to its biocompatibility, anti-inflammatory properties, and controlled drug release. By modulating the inflammatory response, it may contribute to reduced postoperative discomfort and improved periapical healing. Additionally, its bioactive properties may support tissue repair and regeneration, making it a potential candidate for regenerative endodontic procedures. How to cite this article: Piriyanga R, Ranjan M, Bathla S, et al. Comparative Evaluation of Cytotoxicity, Anti-inflammatory, and Drug Release Profiles of Allicin-incorporated GO-AgNP Hydrogel: An In Vitro Study. J Contemp Dent Pract 2025;26(1):71-76.

Efficacy of in vitro antimicrobial intracanal medicaments against C. albicans and E. faecalis in primary teeth

To exclusively evaluate, in vitro, the efficacy of five intracanal medicaments against Candida albicans and Enterococcus faecalis in infected single-rooted primary teeth. Forty-three teeth were selected, out of which 42 were simultaneously contaminated with C. albicans and E. faecalis, verified by measuring the initial quantification (IQ), whereas one tooth was used as sterile control. Forty-two teeth were then randomly assigned to six groups (n = 7 teeth in each); one was the control group, while the others received calcium hydroxide (CH), camphorated paramonochlorophenol (CMCP), CH/CMCP, chlorhexidine (CHX), or iodoform paste (IP). Two samples from each group were then randomly selected and evaluated under a scanning electron microscope along with the sterile control (n = 1) for qualitative analyses (n = 13). The remaining samples (n = 30) were collected after 7 days of intracanal medicaments (final quantification - FQ) and 7 days after medicament removal (residual quantification - RQ). ANOVA and Tukey's and c2 tests (p £ 0.05) were performed for the statistical analysis. All the medicaments, except CMCP, significantly reduced the levels of C. albicans from IQ to FQ (p = 0.046). Only CHX (p = 0.000) and IP (p = 0.007) showed a significant reduction from IQ to FQ against E. faecalis. The 2% CHX and IP demonstrated a favorable performance as an intracanal medicament, with a good antimicrobial activity against C. albicans and E. faecalis.

Expert consensus on irrigation and intracanal medication in root canal therapy

Chemical cleaning and disinfection are crucial steps for eliminating infection in root canal treatment. However, irrigant selection or irrigation procedures are far from clear. The vapor lock effect in the apical region has yet to be solved, impeding irrigation efficacy and resulting in residual infections and compromised treatment outcomes. Additionally, ambiguous clinical indications for root canal medication and non-standardized dressing protocols must be clarified. Inappropriate intracanal medication may present side effects and jeopardize the therapeutic outcomes. Indeed, clinicians have been aware of these concerns for years. Based on the current evidence of studies, this article reviews the properties of various irrigants and intracanal medicaments and elucidates their effectiveness and interactions. The evolution of different kinetic irrigation methods, their effects, limitations, the paradigm shift, current indications, and effective operational procedures regarding intracanal medication are also discussed. This expert consensus aims to establish the clinical operation guidelines for root canal irrigation and a position statement on intracanal medication, thus facilitating a better understanding of infection control, standardizing clinical practice, and ultimately improving the success of endodontic therapy.

Endodontic infection control practices among Pakistani general dental practitioners: A national cross-sectional questionnaire survey

Objective

This study was aimed at evaluating the self-reported endodontic infection control practices of general dental practitioners in Pakistan.

Methods

An e-questionnaire was sent to 619 general dental practitioners in several WhatsApp groups. Sixteen questions associated with various infection control measures recommended by the ESE were asked, including the use of various isolation methods/rubber dams, the selection of canal irrigants and anti-bacterial solutions, and practices regarding hand hygiene and use of examination gloves. The e-questionnaire also included questions associated with demographics. Data analysis was conducted in SPSS-24. Descriptive statistics were documented as percentages and frequencies.

Results

Of 619 GDPs, 350 responded (56.5% response rate), of whom 43.7% worked in private dental practices. The majority were women (64%), had graduated after 2010 (81.1%), and were 24-34 years of age (78.9%). A total of 72.3% of GDPs used cotton rolls, and 17.4% routinely used rubber dams for endodontic isolation; 89% did not disinfect the operative field; 80% reported using different concentrations of NaOCl during root canal instrumentation; and 0.9% reported not using any irrigant during endodontic procedures. A total of 61.7% reported always using intra-canal medication during multi visit endodontic treatment, among whom 82.5% reported using Ca(OH)2. Finally, 100% of respondents reported using gloves during endodontic treatment.

Conclusion

The results indicated that the GDPs tended to follow some of the endodontics quality standards recommended by the ESE, but the overall implementation of all guidelines requires improvement.

Evaluation of antimicrobial efficacy of ethanolic extract of Cuminium Cyminium as intracanal medicament on common bacteria of endodontic infections: An in vitro study

Context

Antimicrobial intracanal medicaments play a vital role in successful outcome of any endodontic procedure. One such plant extract Cuminium cyminium, as intracanal medicaments needs to be researched.

Aims

The purpose of this study was in vitro assessment of the antibacterial activity of ethanol extract of C. Cyminium in comparison to Calcium hydroxide (Ca[OH]2) as intracanal medicament against the pathogens of endodontic infection, at an interval 1 h, 24 h, 48 h, and 72 h.

Settings and Design

The study was conducted in the central research laboratory of our institute. Freshly prepared C. cyminium extract was procured from AYUSH approved laboratory and direct contact test (DCT) was utilized, which is based on turbidometric determination of microbial growth in a 96-well microplate, carrying 6 times for each bacteria.

Methodology

Three groups were assigned for each material in a 96 microwell plate for DCT. Bacterial growth kinetics was monitored at intervals of 1 h, 24 h, 48 h, and 72 h using spectrophotometer at 595 nm. The optical density of T2 (Test group), P2 (Positive control), and N2 (Negative control) was considered.

Statistical Analysis Used

After compiling the data, based on the normality of data, further statistical analysis was conducted using Kolmogorov-Smirnov test, Paired t-test, and pairwise comparisons by Turkey's multiple post hoc procedures. The level of statistical significance was set at P = 0.05.

Results

The comparison of mean optical density values of C. cyminium in comparison with Ca(OH)2 against the microorganisms of endodontic origin showed a statically significant decrease in bacterial viability at the end of 24 h, 48 h, and 72 h.

Conclusion

Based on the results of the study, it can be concluded that C. cyminium has significant antibacterial action against endodontic origin, at interval of 24 h, 48 h, and 72 h.

Leptin attenuates hypoxia-induced apoptosis in human periodontal ligament cells via the reactive oxygen species-hypoxia-inducible factor-1α pathway

NEW FINDINGS

What is the central question of this study? Does leptin have an effect on hypoxia-induced apoptosis in human periodontal ligament cells (hPDLCs), and what is the potential underlying mechanism? What is the main finding and its importance? Hypoxia induces cell apoptosis and leptin expression in hPDLCs through the induction of hypoxia-inducible factor-1α and accumulation of reactive oxygen species (ROS). Leptin shows feedback inhibition on hypoxia-induced ROS-mediated apoptosis in hPDLCs, suggesting a new application of leptin for hypoxic damage in periodontal diseases.

ABSTRACT

Hypoxia-induced apoptosis of human periodontal ligament cells (hPDLCs) is an important contributor to the progression of various periodontal diseases. Although leptin has been shown to protect connective tissue cells against hypoxia-induced injury, whether it might do so by attenuating hypoxia-induced apoptosis in hPDLCs remains unclear. Here, using CoCl₂ treatment, we simulated hypoxic conditions in hPDLCs and explored whether apoptosis and reactive oxygen species (ROS) levels were related to hypoxia. After small interfering RNA (siRNA) inhibition of leptin and hypoxia-inducible factor-1α (HIF-1α), the levels of apoptosis, ROS and leptin expression were measured. We showed that in CoCl₂ -treated hPDLCs, significantly higher cell apoptosis rates and ROS accumulation were observed. Cobalt chloride also increased leptin and HIF-1α expression in hPDLCs. Further investigation of the pathway demonstrated that inhibition of ROS attenuated hypoxia-induced cell apoptosis and leptin expression, whereas siRNA inhibition of leptin aggravated hypoxia-induced cell apoptosis and ROS accumulation. Hypoxia induces cell apoptosis and leptin expression in hPDLCs through the induction of ROS and HIF-1α pathways, and leptin shows feedback inhibition on ROS-mediated apoptosis in hPDLCs. These findings suggest a new application of leptin for hypoxic damage in periodontal diseases.

The effect of different root canal medicaments on the elimination of Enterococcus faecalis ex vivo

OBJECTIVE

The aim of this study was to evaluate the antimicrobial effect of chlorhexidine gel (CHX-G) 2%, chlorhexidine powder (CHX-P) 1%, povidone-iodine (PVP-I), polyhexanide and camphorated-and-mentholated chlorophenol (ChKM) ex vivo.

MATERIALS AND METHODS

For every medicament group 10 root segments (15 mm long) of extracted human teeth were prepared to ISO-size 45 and sterilized (n = 50). The root segments were then inoculated with Enterococcus faecalis and aerobically incubated at 37°C. After 1 week, ten root canals were filled with one of the medicaments, respectively and aerobically incubated at 37°C for another week. Ten teeth served as positive controls and were filled with sterile saline solution. After 7 days, the medicaments were inactivated and all root canals were instrumented to ISO-size 50. The obtained dentin samples were dispersed in Ringer solution followed by the preparation of serial dilutions. 10 μl per sample were applied to an agar plate and incubated at 37°C for 48 h. The colony forming units were counted and the reduction factors (RFs) were calculated and statistically analyzed.

RESULTS

Compared with the positive controls all medicaments exhibited an antibacterial effect against E. faecalis. The RFs for CHX-G, CHX-P and ChKM were significantly higher compared to PVP-I and polyhexanide (P < 0.05). In contrast to PVP-I and polyhexanide, CHX-G, CHX-P and ChKM were able to eliminate E. faecalis from all dentin samples.

CONCLUSIONS

Within the limitations of this ex vivo investigation, 2% CHX-G and CHX-P were as effective as ChKM against E. faecalis. Thus, when choosing a root canal medicament the better biocompatibility of CHX compared with ChKM should be taken in consideration.

Antibacterial action of calcium hydroxide vehicles and calcium hydroxide pastes

AIM

To evaluate the in vitro action of vehicles alone and with calcium hydroxide against different bacterial species.

METHODS

Agar plates were inoculated with the microbial suspensions, and wells were made and filled with the calcium hydroxide pastes and the vehicles used to prepare the pastes. The zones of inhibited bacterial growth were recorded, and the resulting measurements were statistically analyzed.

RESULTS

Enterococcus faecalis was the most resistant microorganism to all medicaments. Calcium hydroxide + p-monochlorophenol; calcium hydroxide + p-monochlorophenol-propylene glycol pastes; and p-monochlorophenol, p-monochlorophenol-propylene glycol, and chlorhexidine gluconate gel alone showed the largest zones of inhibition against all the tested microorganisms.

CONCLUSIONS

The vehicle used to prepare the calcium hydroxide paste might contribute to its antibacterial action. Chlorhexidine gluconate gel used alone, and camphorated p-monochlorophenol and camphorated p-monochlorophenol-propylene glycol as vehicles of calcium hydroxide, could be recommended, in an antimicrobial sense.

Novel molecules for intra-oral delivery of antimicrobials to prevent and treat oral infectious diseases

New molecules were designed for efficient intra-oral delivery of antimicrobials to prevent and treat oral infection. The salivary statherin fragment, which has high affinity for the tooth enamel, was used as a carrier peptide. This was linked through the side chain of the N-terminal residue to the C-terminus of a defensin-like 12-residue peptide to generate two bifunctional hybrid molecules, one with an ester linkage and the other with an anhydride bond between the carrier and the antimicrobial components. They were examined for their affinity to a HAP (hydroxyapatite) surface. The extent of the antimicrobial release in human whole saliva was determined using 13C-NMR spectroscopy. The candidacidal activity of the molecules was determined as a function of the antimicrobial release from the carrier peptide in human saliva. The hybrid-adsorbed HAP surface was examined against Candida albicans and Aggregatibacter actinomycetemcomitans using the fluorescence technique. The bifunctional molecules were tested on human erythrocytes, GECs (gingival epithelial cells) and GFCs (gingival fibroblast cells) for cytotoxicity. They were found to possess high affinity for the HAP mineral. In human whole saliva, a sustained antimicrobial release over a period of more than 40–60 h, and candidacidal activity consistent with the extent of hybrid dissociation were observed. Moreover, the bifunctional peptide-bound HAP surface was found to exhibit antimicrobial activity when suspended in clarified human saliva. The hybrid peptides did not show any toxic influence on human erythrocytes, GECs and GFCs. These novel hybrids could be safely used to deliver therapeutic agents intra-orally for the treatment and prevention of oral infectious diseases.

Biocompatibility of various formula root filling materials for primary teeth

The aim of this study was to compare the effects of different materials used in primary root canal fillings on the cell viability of human osteosarcoma cell lines. The experimental group contained six different types of root canal filling materials, including zinc oxide (ZnO) + eugenol + formocresol (FC), Ca(OH)(2) + FC, Ca(OH)(2) + Iodoform, Ca(OH)(2) + Iodoform + camphorated parachlorophenol (CPC), Ca(OH)(2) + CPC, and Vitapex. Cell viability tests were performed using tetrazolium bromide colorimetric (MTT) assay on human osteosacorma cell lines (U2OS). The results were analyzed using one-way analysis of variance (ANOVA) and Student-Newman-Keul's test with p < 0.05 showed statistical differences. The ZnO + eugenol + FC group and Ca(OH)(2) + FC group showed the lowest survival rates (p < 0.05). The Ca(OH)(2) + Iodoform + CPC group and Ca(OH)(2) + CPC group showed significantly lower survival rates at concentrations above 6 microL/mL (p < 0.05). The Ca(OH)(2) + Iodoform group and Vitapex group showed the highest survival rates (p < 0.05). We concluded that the use of calcium hydroxide with iodoform as a root filling base material is a better option than other medications.

In vitro evaluation of the susceptibility of endodontic pathogens to calcium hydroxide combined with different vehicles

The aim of this study was to investigate in vitro the antimicrobial activity of calcium hydroxide [Ca(OH)2] in combination with different vehicles against endodontic pathogens. For such purpose, a broth dilution test was performed. Pastes were prepared with Ca(OH)2 powder and the following vehicles: sterile water, glycerin, camphorated monochlorophenol (CMCP), CMCP + glycerin, polyethyleneglycol and CMCP + polyethyleneglycol. The time required for the pastes to produce negative cultures against the tested microorganisms was recorded and analyzed statistically using the Kruskal Wallis test at 5% significance level. Timing for pastes to eliminate the aerobic and facultative anaerobic microorganisms ranged from 6 to 24 h, while strict anaerobic microorganisms were inhibited within 30 s to 5 min. Microbial susceptibility, ranked from weakest to strongest, can be presented as follows: Enterococcus faecalis (the most resistant microorganism), Candida albicans, Staphylococcus aureus, Porphyromonas gingivalis, Porphyromonas endodontalis and Prevotella intermedia (the last two microorganisms required the same time to be eliminated). In conclusion, calcium hydroxide pastes needed more time to eliminate facultative than anaereobic microorganisms. These findings suggest that the antimicrobial property is related both to paste formulation and to microbial susceptibility.

Effects of enamel matrix protein application on the viability, proliferation, and attachment of human periodontal ligament fibroblasts to diseased root surfaces in vitro

OBJECTIVES

The purpose of this research was to examine the influence of enamel matrix proteins (EMP) on the viability, proliferation, and attachment of periodontal ligament fibroblasts (PDLF) to diseased root surfaces.

MATERIALS AND METHODS

Primary cell cultures of PDFL were obtained from clinically healthy third molars or premolar teeth. Viability and proliferation rates were carried out over a 10-day period. A total of 80,000 cells were plated in 24-well plates followed by EMEM with 10% FBS (positive control) and EMEM plus EMP at 25, 50, 75, and 100 micro g/ml. Cells were harvested on days 1, 3, 5, 7, and 10 and viability was performed utilizing an MTS assay. PDLF proliferation rates were assessed by a CyQUANT GR dye assay. SEM analysis was used to examine the qualitative effects of cellular attachment to diseased root surfaces following EMP compared to nontreated controls.

RESULTS

The results indicated that viability was negatively affected for higher doses over time while lower doses displayed viability effects similar to control. Proliferation, however, appeared to be ameliorated following exposure to EMP. The SEM analysis suggests that cellular attachment to diseased dentin was enhanced following EMP application.

CONCLUSION

These in vitro studies support the concept that EMP may act as a suitable matrix for PDLF.

Effects of parachlorophenol and camphorated parachlorophenol on the phagocytic activities of a murine macrophage cell line (RAW264.7)

The aim of this study was to determine whether the phagocytic functions of a murine macrophage cell line (RAW264.7 cells) may be altered by parachlorophenol (PCP) and camphorated parachlorophenol (CMCP). The adherence capacities of PCP- or CMCP-treated cells on plastic surfaces were much lower than those of untreated cells. When the PCP- or CMCP-treated cells were incubated with Actinobacillus actinomycetemcomitans, phagocytosis of these cells was significantly reduced in a dose-dependent fashion compared with that of untreated cells. Preactivation with bacterial lipopolysaccharide on PCP- or CMCP-treated cells failed to completely restore the phagocytosis of this periodontopathogen. The phagocytic functions of PCP- or CMCP-treated cells to this periodontopathogen opsonized with anti-A. actinomycetemcomitans were also reduced compared with those of untreated cells but were comparable with those of untreated cells incubated with unopsonized bacteria. The results of this study indicated, therefore, that both PCP and CMCP may, indeed, reduce the phagocytic activities of murine macrophages.

Mechanisms of cytotoxicity of nicotine in human periodontal ligament fibroblast cultures in vitro

The use of tobacco products significantly contributes to the progression of periodontal disease and poor response to healing following periodontal therapy. The purpose of this study was to determine the effects of nicotine, a major component of cigarette smoking, on human periodontal ligament fibroblast (PDLF) growth, proliferation, and protein synthesis to elucidate its role in periodontal destruction associated with its use. Human PDLFs were derived from three healthy individuals undergoing extraction for orthodontic reasons. At a concentration higher than 2.5 mM, nicotine was found to be cytotoxic to human PDLFs (P < 0.05). Nicotine also significantly inhibited cell proliferation and decreased protein synthesis in a dose-dependent manner. At concentrations of 50 and 200 microM, nicotine suppressed the growth of PDLFs by 48% and 86% (P < 0.05), respectively. A 10-mM concentration level of nicotine significantly inhibited the protein synthesis to only 44% of these in the untreated control (P < 0.05). Furthermore, the effects of antioxidants (superoxide dismutase (SOD); catalase and 2-oxothiazolidine-4-carboxylic acid (OTZ) and buthionine sulfoximine (BSO) were added to search for the possible mechanism of action, as well as a method for the prevention, of cigarette smoking-associated periodontal diseases. The addition of OTZ, a precursor of cysteine that metabolically promotes GSH synthesis, acted as a protective effect on the nicotine-induced cytotoxicity. However, SOD and catalase did not decrease the nicotine-induced cytotoxicity. In contrast, the addition of BSO, a cellular GSH synthesis inhibitor, enhanced the nicotine-induced cytotoxicity. These results indicate that thiol depletion could be the mechanism for nicotine cytotoxicity. The levels of nicotine tested inhibited cell growth, proliferation, and protein synthesis on human PDLFs. This suggests that nicotine itself might augment the destruction of periodontium associated with cigarette smoking. In addition, these inhibitory effects were associated with intracellular thiol levels. Factors that induce glutathione synthesis of human PDLF may be used for further chemoprevention of cigarette smoking-related periodontal diseases.

Regulation of matrix metalloproteinase production by cytokines, pharmacological agents and periodontal pathogens in human periodontal ligament fibroblast cultures

Matrix metalloproteinases (MMPs). produced by both infiltrating and resident cells of the periodontium, play a role in physiologic and pathologic events. It is recognized that an imbalance between activated MMPs and their endogenous inhibitors leads to pathologic breakdown of the extracellular matrix during periodontitis. To date, little is known about the regulation of MMP synthesis and secretion in human periodontal ligament fibroblasts (PDLFs). The purpose of this study was to examine the effects of cytokines, pharmacological agents (protein synthesis inhibitor and protein kinase C inhibitors) and predominant periodontal pathogens (Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis) on MMP production in human PDLFs using gelatin zymography. The gelatin zymograms revealed that the main gelatinase secreted by human PDLFs migrated at 72 kDa and represents MMP-2. Minor gelatinolytic bands were also observed at 92 kDa regions that correspond to MMP-9. We found that A. actinomycetemcomitans, P. gingivalis and IL-1alpha can elevate MMP-2 secretion in human PDLFs. These results indicate that periodontal pathogens and inflammatory cytokines play an important role in tissue destruction and disintegration of extracellular matrix in periodontal diseases. Thus, activation of MMPs may be one of the distinct host degradative pathways in the pathogenesis of periodontitis. In addition, H7, staurosporine, cycloheximide and TGF-beta could suppress MMP-2 production. Agents that target protein synthesis or the protein kinase C pathway in human PDLFs inhibit MMP-2 production, and such inhibition may contribute to the pathogenesis of periodontal inflammation. Taken together, these findings suggest a possible new therapeutic approach, involving the use of drugs that modify host-response mechanisms to suppress or inhibit MMP-mediated tissue destruction.

Stimulation of matrix metalloproteinases by black-pigmented Bacteroides in human pulp and periodontal ligament cell cultures

Matrix metalloproteinases (MMPs) are a group of proteolytic enzymes capable of degrading most components of the extracellular matrix. Recently, evidence has shown that MMPs may play a role in tissue degradation in inflamed dental pulp. To date very little is known regarding the mechanism of extracellular matrix destruction at the site of bacterial infection. The purpose of this study was to determine the effects of the supernatants from Porphyromonas endodontalis and Porphyromonas gingivalis on the production and secretion of MMPs by primary human pulp and periodontal ligament (PDL) cell cultures in vitro. The results were evaluated by substrate gel zymography from long-term cultures. The main gelatinase secreted by human pulp and PDL cells migrated at 72 kDa and represented MMP-2. Minor gelatinolytic bands were also observed at 92 kDa regions that correspond to MMP-9. After an 8-day culture period, P. endodontalis and P. gingivalis were found to elevate MMP-2 production both in human pulp and PDL cell cultures. In addition, the stimulation was in a dose- and time-dependent manner. Both human pulp and PDL cells, however, treated with either P. endodontalis or P. gingivalis had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. These results indicate that black-pigmented Bacteroides species play an important role in tissue destruction and disintegration of extracellular matrix in pulpal and periapical diseases. Thus, activation of MMPs may be one of the distinct host degradative pathways in the pathogenesis of microbial-induced pulpal and periapical lesion. An understanding of the actions of these black-pigmented Bacteroides species on pulp and PDL cells may result in new therapies to augment current treatment of pulpal and periapical lesions.

Cytotoxicity of resin-, zinc oxide-eugenol-, and calcium hydroxide-based root canal sealers on human periodontal ligament cells and permanent V79 cells

AIM

The purpose of this study was to determine the cytotoxicity of three different types of root canal sealer on human periodontal ligament (PDL) cells and a permanent hamster cell line (V79 cells).

METHODOLOGY

Set specimens from two resin based sealers (AH26 and AHPlus), three zinc oxide-eugenol-based sealers (Canals, Endomethasone and N2) and one calcium hydroxide-based sealer (Sealapex) were eluted with culture medium for 1, 2, 3 and 7 days. Cytotoxicity was judged using tetrazolium bromide reduction assay on human primary PDL cells and V79 cells derived from a Chinese hamster.

RESULTS

The results showed that elutes from resin-based, zinc oxide-eugenol-based, and calcium hydroxide-based sealers were cytotoxic to primary human PDL cultures and V79 cells. Calcium hydroxide-based sealer was the least toxic sealer amongst the chemicals tested in both cultures. The cytotoxic response decreased in an order of N2 > Endomethasone > AH26 > AHplus > Canals > Sealapex.

CONCLUSIONS

The sensitivity of toxicity depended on the materials tested and the cell culture system used. Thus, the use of both permanent and primary cells is recommended for screening of the cytotoxic effects of root canal sealers. In addition, the results confirmed that root canal sealers constantly dissolve when exposed to an aqueous environment for extended periods, possibly causing moderate or severe cytotoxic reactions. Use of calcium hydroxide-based material as a root canal sealer initially may result in a more favourable response to periradicular tissues.

A comparison of the antimicrobial efficacy of three calcium hydroxide formulations on human dentin infected with Enterococcus faecalis

This study compared the antibacterial efficacy of three different formulations of calcium hydroxide by using human dentin specimens that were infected with Enterococcus faecalis. After exposure to three forms of calcium hydroxide (calcium hydroxide mixed with distilled water, calcium hydroxide mixed with 0.2% chlorhexidine, and calcium hydroxide mixed with camphorated paramonochlorophenol) for 7 days, dentin powder from the infected specimens was obtained and assessed for bacterial quantity by spectrophotometry. It was found that calcium hydroxide mixed with camphorated paramonochlorophenol killed all of the Enterococcus faecalis inside the dentinal tubules. This result was better than that obtained with calcium hydroxide mixed with distilled water or with 0.2% chlorhexidine (p < 0.05). Calcium hydroxide mixed with distilled water and calcium hydroxide mixed with 0.2% chlorhexidine were ineffective against these bacteria.

The effect of sodium hypochlorite and chlorhexidine on cultured human periodontal ligament cells

OBJECTIVE

The objective of this study was to examine the effects of sodium hypochlorite (NaOCl) and chlorhexidine (CHx) on cultured human periodontal ligament (PDL) cells in vitro.

STUDY DESIGN

The effects of irrigation solutions on human PDL cells were evaluated by propidium iodide fluorescence cytotoxicity assay, protein synthesis assay, and mitochondrial activity.

RESULTS

Both NaOCl and CHx were cytotoxic to human PDL cells in a concentration- and contact time-dependent manner. In addition, CHx inhibited protein synthesis in human PDL cells. Although NaOCl displayed cellular cytotoxicity, it showed no protein inhibition in the PDL cells. Furthermore, both NaOCl and CHx exhibited an inhibitory effect on mitochondrial activity on human PDL cells.

CONCLUSIONS

This study suggests that these irrigation fluids may cause detrimental effects on vital tissues. Its clinical significance, however, needs to be evaluated further because concentration used, exposure time to the agent, and exposure surface area are important factors affecting the resulting effect.