Evaluation of chlorhexidine toxicity injected in the paw of mice and added to cultured l929 fibroblasts

Research methods assessing sodium hypochlorite cytotoxicity: A scoping review

Sodium hypochlorite (NaOCl) cytotoxicity has been assessed using different methodologies, which has led to arbitrary interpretations. This scoping review aimed to discuss the different methodological protocols for assessing NaOCl cytotoxicity. A literature review performed in the PubMed and Embase databases up to July 2023 identified manuscripts reporting NaOCl cytotoxicity. The dataset identified 546 publications, further screened by 2 reviewers. Ninety studies were identified and mined methodologically to collect information on cell type, cytotoxicity assay, NaOCl dilution solutions, presence of fetal bovine serum (FBS), and NaOCl exposure time. The culture medium used in cytotoxicity assays contains buffering substances that neutralize the pH of NaOCl, thus reducing its cytotoxicity, an approach that may lead to bias when solutions with different pH are compared. For short exposure periods, as in simulations to evaluate the contact between irrigant and periapical tissue cells during chemo-mechanical preparation, NaOCl dilution should be performed with saline, which does not buffer the irrigant. For long exposure periods, as in simulations of irrigant extrusions, NaOCl should be diluted in the culture medium, to reproduce the expected buffering effect occurring in extrusions. The presence of FBS in culture medium can decrease NaOCl toxicity. There is no standardization of NaOCl cytotoxicity methodologies. This poses the risk of arriving at incorrect results and, therefore, pertinent tests must be refined.

Calcium hypochlorite cytotoxicity mechanism in fibroblasts and effect on osteoblast mineralization

AIM

To determine the cytotoxicity mechanism of 2.5% calcium hypochlorite [Ca(OCl)2 ] in L929 fibroblasts and the effect of this solution on human osteoblast-like cells (Saos-2) mineralization, compared to that of 2.5% sodium hypochlorite (NaOCl).

METHODOLOGY

L929 fibroblasts were exposed to Ca(OCl)2 and NaOCl at different dilutions for 10 min. Cell metabolism was assessed by methyl-thiazole-tetrazolium (MTT); lysosome integrity, by neutral red (NR) assay; type of cell death, by flow cytometry (apoptosis/necrosis); cytoskeleton, by actin and α-tubulin fluorescence and cell ultrastructure, by transmission electron microscopy (TEM). The alkaline phosphatase (ALP) activity and mineralized nodule formation were determined in Saos-2 by thymolphthalein release and alizarin red staining (ARS), respectively. The data were analysed by two-way anova and Bonferroni's post-test (α = .05).

RESULTS

Ca(OCl)2 promoted higher cell viability and a lower percentage of apoptosis and necrosis than NaOCl (p < .05). Ca(OCl)2 and NaOCl decreased cell metabolism and lysosome integrity, induced the breakdown of microtubules and actin filaments, promoted alterations of rough endoplasmic reticulum and disruption of mitochondrial cristae. Additionally, Ca(OCl)2 did not induce ALP activity and had no effect on mineralized nodules formation.

CONCLUSIONS

Although Ca(OCl)2 and NaOCl promoted the same cytotoxicity mechanism, Ca(OCl)2 was less cytotoxic than NaOCl. As for ALP activity, no differences were observed between NaOCl and Ca(OCl)2 . The production of mineralized nodules induced by Ca(OCl)2 was lower than those induced by NaOCl, but was not different from those induced by the control group.

In vitro cytotoxicity and antibacterial activity of hypochlorous acid antimicrobial agent

Background/purpose

Bacteria-associated oral diseases such as dental caries and periodontitis are widespread epidemics that cause oral pain and loss of function. The purpose of this study was to evaluate the in vitro cytotoxicity and antibacterial activity of different concentrations of hypochlorous acid (HOCl).

Materials and methods

Five different concentrations (100, 200, 300, 400, and 500 ppm) of HOCl were evaluated for their antimicrobial efficacy against Gram-negative (A. actinomycetcmcomitans and P. gingivalis) and Gram-positive bacteria (S. mutans and S. sanguinis) after treatment for 1 and 10 min. Sodium hypochlorite (NaOCl) and chlorhexidine (CHX) were used as positive controls. In addition, HOCl was examined for L929 cytotoxicity and RAW 264.7 growth.

Results

The bacteriostatic ratio of NaOCl was comparable to that of CHX and significantly (P < 0.05) higher than that of all HOCl solutions. Higher HOCl concentration had significantly (P < 0.05) higher antibacterial effect, and the bacteriostatic ratio of 10 min treatment was slightly higher than that of 1 min treatment. CHX and NaOCl seeded into L929 cells resulted in low cell viability with only 30-39%, much significantly (P < 0.05) lower than all HOCl groups (greater than 80%). All HOCl solutions met the recommendations of ISO 10993-5 and showed no cytotoxicity, although there was a concentration-dependent decrease in cell viability. All antimicrobial agents showed the same trend of response to RAW 264.7 as L929.

Conclusion

Within the limit of this study, 400 ppm HOCl disinfectant may be a potential antimicrobial candidate for mouthwash, endodontic irrigants, and periodontitis treatment.

Supramolecularly assisted chlorhexidine-bacterial membrane interaction with enhanced antibacterial activity and reduced side effects

Bacterial infection has emerged as a grievous threat to public health, and lots of antibacterial agents were developed to solve this issue. However, enhancing the antibacterial activity of antibacterial agents while reducing their side effects remains a challenge. Herein, a supramolecular antibacterial agent based on the host-guest interaction between cucurbit[7]uril (CB[7]) and chlorhexidine (CHX) was designed. CHX can be encapsulated in the cavity of CB[7] to form a 1:3 host-guest complex (CHX-3CB[7]). It was amazingly found that this supramolecular complex could display higher antibacterial activity than CHX alone. Electrospray mass spectrometry and UV-vis spectra revealed that the introduction of CB[7] promoted the protonation of N-atoms on CHX, resulting in stronger ion interaction with phospholipids and thus enhancing the destruction of the bacterial membrane. Scanning electron microscopy (SEM), surface ζ-potentials and outer/inner membrane integrity assays also reveal that the introduction of CB[7] aggravates the rupture of membrane. What is more, the cytotoxicity and irritation of CHX were decreased by forming the host-guest complex with CB[7]. This work provides a paradigm for enhancing antibacterial activity and reducing side effects of drugs through supramolecular chemistry.

Enhancement of bactericidal effect of Chlorhexidine using choline augmentation as a natural additive

BACKGROUND

The long-term use of Chlorhexidine (CHG) at high concentrations has detrimental effects on health and the environment. This research was aimed to evaluate the antibacterial capacity of CHG in the presence of choline as a natural additive to reduce the amount CHG required for the activity.

METHODS

The newly obtained formulation was evaluated for its stability and efficiency under physicochemical stresses. The checkerboard test was also performed to evaluate the type of CHG-additive interaction in a combinational state.

RESULTS

The MIC of CHG was reduced up to five-fold in combination with choline at the concentration of 50mg/L and five log cfu/mL at 3 minutes of exposure. Chlorhexidine activity in combination with choline was preserved 20% more in the presence of interfering substances. The activity between CHG and choline was demonstrated as synergistic with FICI of 0.375. At sub MIC concentrations of both CHG (≤20 mg/L) and choline (≤6 mg/L) the observed interaction was synergy. While the significant interaction at high concentrations for both compounds was indifferent manner. The lysis effect of the CHG 20 mg/L was diminished in the presence of choline.

CONCLUSIONS

Our suggested CHG formulation demonstrated rapid antimicrobial efficacy which can be a useful adjunct to infection control strategies currently employed in healthcare facilities. In conclusion, CHG can be combined with natural compounds as additives for enhanced synergistic antimicrobial activity.

Antimicrobial effect of Red Roselle (Hibiscus Sabdariffa) against different types of oral bacteria

This study aimed to compare the antimicrobial effect of an aqueous extract Red Roselle calyx (RE), Chlorhexidine (CH), Amoxicillin-clavulanic acid (ACA), Tetracycline (Tet), and Metronidazole (Met)on Streptococcus mutans (S. mutans), Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) bacteria. The bacterial inhibition zones (BIZ)of the RE (25, 50, 75, 100) mg/ml and CH solutions (0.2%, 2%) were determined using the agar well diffusion method. Additionally, the susceptibility of the tested bacteria against (30 μg) of standard antibiotics of ACA, Tet, and Met was examined. The bacterial minimum inhibitory concentration (MIC) was measured using the Broth Micro dilution method (BMDM). All tests were carried out in triplicates, and water was considered the negative control. For S. mutans, the RE at 50 mg/ml or above concentrations displayed higher BIZ than 0.2% CH. 100 mg/ml of RE recorded a greater BIZ than the 2% CH. The greater BIZ against S. mutans was recorded by Tet. A comparable effect was found with 0.2% CH (75, 100) mg/ml of the RE against S. aureus. Greater BIZ for S. aureus and E. faecalis were reported for 100 mg/ml RE compared to the Tet and Met RE at 100 mg/ml inhibited the E. faecalis growth in a zone size comparable to the CH (0.2%, 2%).The RE with 50,100 mg/ml concentrations showed comparable antimicrobial effect to 0.2%, 2% concentrations of CH, respectively. As an herbal substitute for commercial disinfectants, the RE can be considered an effective final endodontic irrigant and dental mouthwash.

Synthesis, Drug Release, and Antibacterial Properties of Novel Dendritic CHX-SrCl2 and CHX-ZnCl2 Particles

This work demonstrated for the first time the synthesis of novel chlorhexidine particles containing strontium and zinc, to provide an effective, affordable, and safe intervention in the treatment of recurrent infections found in Medicine and Dentistry. The CHX-SrCl₂ and CHX-ZnCl₂ particles were synthesized by co-precipitation of chlorhexidine diacetate (CHXD) and zinc chloride or strontium chloride, where particle size was manipulated by controlling processing time and temperature. The CHX-ZnCl₂ and CHX-SrCl₂ particles were characterized using SEM, FTIR, and XRD. UV-Vis using artificial saliva (pH 4 and pH 7) was used to measure the drug release and ICP-OES ion release. The antibacterial properties were examined against P. gingivalis, A. actinomycetemcomitans, and F. nucleatum subsp. Polymorphum, and cytotoxicity was evaluated using mouse fibroblast L929 cells. The novel particles were as safe as commercial CHXD, with antibacterial activity against a range of oral pathogens. UV-Vis results run in artificial saliva (pH 4 and pH 7) indicated a higher release rate in acidic rather than neutral conditions. The CHX-ZnCl₂ particles provided the functionality of a smart Zinc and CHX release, with respect to environmental pH, allowing responsive antibacterial applications in the field of medicine and dentistry.

The High Impact of Staphylococcus aureus Biofilm Culture Medium on In Vitro Outcomes of Antimicrobial Activity of Wound Antiseptics and Antibiotic

The staphylococcal biofilm-based infections of wounds still pose a significant therapeutical challenge. Treated improperly, they increase the risk of limb amputation or even death of the patient. The present algorithms of infected wound treatment include, among others, the application of antiseptic substances. In vitro wound biofilm models are applied in order to scrutinize their activity. In the present work, using a spectrum of techniques, we showed how the change of a single variable (medium composition) in the standard in vitro model translates not only to shift in staphylococcal biofilm features but also to the change of efficacy of clinically applied wound antimicrobials such as octenidine, polyhexamethylene biguanide, chlorhexidine, hypochlorite solutions, and locally applied gentamycin. The data presented in this study may be of a pivotal nature, taking into consideration the fact that results of in vitro analyses are frequently used to propagate application of specific antimicrobials in hospitals and ambulatory care units.

Effect of Chlorhexidine Digluconate in Early Wound Healing of Human Gingival Tissues. A Histological, Immunohistochemical and Biomolecular Analysis

Chlorhexidine digluconate (CHX) is considered the gold standard for oral cavity antiseptic treatment. Nevertheless, several in vitro studies have reported detrimental effects in oral tissue repair. The aim of the present study was to evaluate the in vivo effect of post-surgical CHX mouth rinse on gingival tissue (G) 24 h after injury. G biopsies were obtained in three patients 24 h after surgery with the indication of post-surgical 0.12% CHX use and were compared with those obtained from the same patients without any antiseptic use. Changes in collagen production, cell proliferation, and apoptosis were examined by histological and Ki-67/P53 immunohistochemical analysis. Fibrotic markers (COL1A1, αSMA), proapoptotic protein (BAX) expression, and wound healing-related gene modulation (RAC1, SERPINE1, TIMP1) were analyzed by quantitative real-time PCR analysis. CHX was able to reduce cellular proliferation and increase collagen deposition, proapoptotic molecule and fibrotic marker expression, and myofibroblast differentiation, reduce expression of RAC1 and trigger expression of SERPINE1 and TIMP1, showing “scar wound healing response” pattern. This study assessed for the first time the in vivo effects of CHX on gingival tissue. The demonstration of a CHX-induced fibrotic transformation, leading to scar repair, supports the need for new post-surgical clinical protocols based on a strategic and personalized use of CHX.

Recent update on potential cytotoxicity, biocompatibility and preventive measures of biomaterials used in dentistry

Dental treatment is provided for a wide variety of oral health problems like dental caries, periodontal diseases, periapical infections, replacement of missing teeth and orthodontic problems. Various biomaterials, like composite resins, amalgam, glass ionomer cement, acrylic resins, metal alloys, impression materials, bone grafts, membranes, local anaesthetics, etc., are used for dental applications. The physical and chemical characteristics of these materials influence the outcome of dental treatment. It also impacts on the biological, allergic and toxic potential of biomaterials. With innovations in science and their positive results, there is also a need for awareness about the biological risks of these biomaterials. The aim of dental treatment is to have effective, yet safe, and long-lasting results for the benefit of patients. For this, it is important to have a thorough understanding of biomaterials and their effects on local and systemic health. Materials used in dentistry undergo a series of analyses before their oral applications. To the best of our knowledge, this is the first and original review that discusses the reasons for and studies on the toxicity of commonly used biomaterials for applications in dentistry. It will help clinicians to formulate a methodical approach for the selection of dental biomaterials, thus providing an awareness for forecasting their risk of toxic reactions.

Cytocompatibility Properties of an Herbal Compound Solution Support I n vitro Wound Healing

The aim of this study was to evaluate the cytocompatibility of an herbal extract compound oral rinse [StellaLife VEGA (SLife)] against relevant human cellular models of oral surgical wound healing. SL was compared to the gold standard for peri-/post-operative oral surgical use, i.e., Chlorhexidine (CHX) and to a commonly utilized essential-oil (EO) based antiseptic rinse. Fibroblasts and primary oral stem cells of the apical papilla (SCAPs) were employed to assess its comparative cytotoxicity to the active comparator antiseptic rinses and its effects on wound healing in vitro. In cytotoxicity assays, multiple timepoints were tested ranging from clinically relevant of 60-s rinsing to protracted challenge of up to 5 min, to determine dose-dependent toxicity. The SLife group consistently demonstrated minimal cytotoxicity as compared to active comparators across experimental timepoints and different cells lines. At concentrations up to 20% v/v SLife-challenged fibroblasts and SCAPs demonstrated no significant toxicity as compared to unstimulated controls (p > 0.05). When assessing wound healing, a scratch wound assay revealed significantly accelerated cell migration for SLife as compared to CHX (p < 0.05). Notably, all active comparator antiseptic rinses affected wound healing responses by significantly reducing total collagen deposition after intermittent “rinsing” intervals that simulated post-surgical oral rinsing. Nonetheless, intermittent as well as continuous challenge of cells with SLife had a positive effect in functional collagen assays. An herbal extract compound-based oral rinse was found to be cytocompatible to cells critical to oral wound healing and to promote fibroblast migration and differentiation, contrary to existing antiseptic rinses that lack selective cytotoxicity.

Mucosal Fenestration After 2% Chlorhexidine Extrusion Used in Substitution of Sodium Hypochlorite: A Case Report

This report describes a case of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) extrusion through the apical foramen, causing acute pain, swelling and mucosal fenestration. A 62-year-old woman was referred for endodontic treatment in the first left maxillary premolar with a diagnosis of necrotic pulp. After the root canal irrigation with 2.5% NaOCl, the patient felt a burning sensation and pain. Discrete swelling and redness were noted in the patient’s face at the end of the session. Antibiotic and corticosteroids were prescribed. In the next appointment, 2% CHX was used, but another episode of extrusion occurred, with a sudden acute pain and intense swelling within a few minutes after the injection. After 2 weeks, the patient exhibited a left-side facial swelling extending anterior and inferior to the left zygomatic arch and superior to the body of the mandible. Oral antibiotic and anti-inflammatory drugs were administered. After 10 days, the swelling had completely diminished, but a mucosal fenestration and tooth mobility were verified. A cone beam CT was requested and showed a periapical lesion involving both buccal and palatal roots. After a prosthetic evaluation, the tooth extraction was indicated. One week after tooth removal, the mucosa was completely healed.

Assessment of cytotoxic and antimicrobial activities of two components of Cymbopogon citratus essential oil

Background

There is a continuing search for compuounds to improve the chemical plaque inhibitory action of oral hygiene products. Although the antibacterial effects of chlorhexidine (CHX) and essential oils components, citral/myrcene, have been described, there is contradictory information regarding their cytotoxic effects in host tissues. This study aimed to evaluate the cytotoxic activity of the major components of the oil C. citratus, citral and myrcene on human periodontal ligament fibroblast (HPLF) cultures and their antimicrobial effect on different bacterial species present in supragingival biofilm.

Material and Methods

Cytotoxicity of the compounds to HPLF was determined by MTT assay. Antimicrobial activity was tested against reference strains of Enterococcus faecalis, Streptococcus mutans and Lactobacillus rhamnosus and for S. mutans clinical strains by broth microdilution assay. One-way analysis of variance (ANOVA) with Games-Howell post-hoc multiple comparison or unpaired t tests were used for inter- and intragroup comparisons.

Results

Overall, all of the compounds under study showed a cytotoxic effect to HPLF which varied in a dose-dependant manner. Whilst myrcene did not show bacteriostatic activity at tested concentrations, both citral and CHX exhibited bacteriostatic/bactericidal effects to all strains at specific concentrations, being CHX most effective to inhibit bacterial growth at lower concentrations than what observed for citral.

Conclusions

Based on these findings, it would possible to conclude that whereas myrcene might be ineffective to control bacterial growth, citral could have a promising antimicrobial activity against dental colonizers with low cytotoxicity, and may be useful for preventing the onset and progression of oral diseases. Key words:Antimicrobial activity, citral, cytotoxicity, chlorhexidine, myrcene.

Cytotoxicity and Gene Expression Changes of a Novel Homeopathic Antiseptic Oral Rinse in Comparison to Chlorhexidine in Gingival Fibroblasts

Most available antiseptic solutions available today have strong antibacterial effects, however most also possess major cytotoxic effects on human gingival tissues. The VEGA Oral Care Recovery Kit (StellaLife), previously evaluated in clinical studies, consists of 16 active ingredients that are monographed in the Homeopathic Pharmacopeia of United States (HPUS) and recognized for their accelerated healing properties (reduction in post-op pain). The aim of this study was to compare VEGA to chlorhexidine (CHX) in vitro on gingival fibroblast viability, survival at various concentrations, migration assay, proliferation activity, expression of both regenerative growth factors as well as inflammatory markers, and collagen synthesis. A 10-fold dilution of standard CHX (0.02%) led to cell death, whereas cell viability was significantly better in the VEGA group for all tested parameters. Furthermore, VEGA also induced significantly greater fibroblast migration and proliferation. CHX negatively impacted the cellular inflammatory response of gingival fibroblasts, and also led to a reduction in collagen synthesis (50% decrease). Findings from the present study provide support from basic laboratory experiments that validate the previous clinical studies supporting the use of the VEGA oral rinse on its superior biocompatibility and wound healing properties when compared to CHX.

Effects of octenidine applied alone or mixed with sodium hypochlorite on eukaryotic cells

AIM

To assess the effects of octenidine dihydrochloride (OCT) on eukaryotic cells and the cytotoxicity of OCT associated with sodium hypochlorite - NaOCl (NaOCl/OCT).

METHODOLOGY

L929 fibroblasts and human osteoblast-like cells (Saos-2) were exposed to 0.1% OCT, 2% CHX, 2.5% NaOCl, 5.25% NaOCl and mixtures of 5.25% NaOCl and 0.1% OCT (NaOCl/OCT) at 90 : 10, 80 : 20 and 50 : 50 ratios. Cell viability was assessed by methyl-thiazol-tetrazolium (MTT) and neutral red (NR) assays; type of cell death, by flow cytometry; cytoskeleton, by actin and α-tubulin fluorescence; and alkaline phosphatase (ALP) activity, by thymolphthalein release. The data were analysed by two-way ANOVA and Bonferroni tests (α = 0.05).

RESULTS

MTT and NR assays revealed that 0.1% OCT had the lowest cytotoxicity (P < 0.05), followed by 2% CHX (P < 0.05). The 2.5% NaOCl, NaOCl/OCT 80 : 20 and NaOCl/OCT 50 : 50 solutions had intermediate cytotoxicity. NaOCl 5.25% and NaOCl/OCT 90 : 10 had the highest cytotoxicity (P < 0.05). The OCT group had a higher percentage of viable cells than the NaOCl and CHX groups (P < 0.05), and induced apoptosis at higher doses. The cytoskeleton alterations were observed at 0.12%, 0.6% and 2.02% for the NaOCl, CHX and OCT groups, respectively. The solutions did not induce ALP activity.

CONCLUSION

Octenidine dihydrochloride was less cytotoxic, induced apoptosis at higher doses, caused few changes in the cytoskeleton and did not induce alkaline phosphatase activity. In addition, octenidine dihydrochloride reduced the cytotoxicity of 5.25% NaOCl when combined at 20 and 50%.

Comparison of the Antimicrobial Activity of Hibiscus sabdariffa Calyx Extracts, Six Commercial Types of Mouthwashes, and Chlorhexidine on Oral Pathogenic Bacteria, and the Effect of Hibiscus sabdariffa Extracts and Chlorhexidine on Permeability of the Bacterial Membrane

To determine and compare the antimicrobial effect of Hibiscus sabdariffa calyx extracts, six types of commercial mouthwashes, and chlorhexidine on Streptococcus mutans, Streptococcus sanguinis, Capnocytophaga gingivalis, and Staphylococcus aureus. Two varieties of H. sabdariffa cultivated in Mexico were used. Aqueous, methanolic, ethanolic, acetonic, and ethyl acetate extracts were obtained from H. sabdariffa calyces. Six different types of mouthwash (Astringosol^®, Colgate plax-ice-infinity^®, Crest pro-health^®, Dental max^®, Equate^®, and Listerine zero^®) and chlorhexidine (0.12%) were purchased at a pharmacy. The antimicrobial activity of the H. sabdariffa calyx extracts, mouthwashes, and chlorhexidine was determined by the agar disc diffusion technique. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of all solutions were determined by the broth dilution method and the pour plate technique, respectively. Also, the effect of H. sabdariffa extracts and chlorhexidine on permeability of the bacterial membrane was determined by the violet crystal assay. All H. sabdariffa calyx extracts and chlorhexidine showed antibacterial activity against all oral pathogenic bacteria. The mouthwashes showed lower antibacterial effect than H. sabdariffa extracts and chlorhexidine. Dental max showed no antibacterial effect. The MICs and MBCs, respectively, for H. sabdariffa extracts were between 5-20 and 10-20 mg/mL; and for chlorhexidine, between 3-4 and 3-5 mg/mL. For the Listerine^®, the MIC and MBC values were between 20-25 and 25-33 mg/mL, respectively. The results of the crystal violet test indicate that H. sabdariffa calyx extracts and chlorhexidine alter the permeability of the bacterial membrane. All H. sabdariffa extracts and chlorhexidine showed significantly greater antimicrobial effect than mouthwashes. This is the first report in which the antimicrobial effect of the H. sabdariffa calyx extracts, mouthwashes, and chlorhexidine is compared.

Antibacterial and Cytotoxic Activities of Pinus tropicalis and Pinus elliottii Resins and of the Diterpene Dehydroabietic Acid Against Bacteria That Cause Dental Caries

Considering the impact of dental caries on public health and the wide biological potential described for species belonging to the genus Pinus, here we investigate the antibacterial activity of the P. elliottii and P. tropicalis resins and of the diterpene dehydroabietic acid (DHA) against cariogenic bacteria. For this purpose, we have determined the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the resins and of the diterpene. We have also investigated the biofilm inhibition ability (through MBIC50 determination), as well as the synergistic effect (through fractional inhibitory concentration index) and the cytotoxic potential (through XTT assay) of the P. elliottii and P. tropicalis resins. The resins gave promising MIC and MBC values, which ranged from 12.5 to 400 μg/mL; DHA provided MIC and MBC values ranging from 25 to 400 μg/mL. The MICB50 values ranged from 0.78 to 400 μg/mL for the resins. Neither additive nor synergistic effects emerged for the combinations of one of the resins with chlorhexidine. The cytotoxic activity was ≥312.5 and ≥156.3 μg/mL for the P. elliottii and P. tropicalis resins, respectively. The resins showed antibacterial activity against planktonic and sessile cariogenic bacteria. These data are relevant and encourage further research into these plants, which may contribute to the discovery of new substances that can inhibit the growth of cariogenic microorganisms and reduce the incidence of dental caries.

Chlorhexidine Antiseptic Irrigation Eradicates Staphylococcus epidermidis From Biofilm: An In Vitro Study

BACKGROUND

Antiseptic and antibacterial solutions used for intraoperative irrigation are intended to kill bacteria and thereby decrease the incidence of surgical site infections. It is unknown if the concentrations and exposure times of irrigation solutions commonly used for prophylaxis in clean cases (povidone-iodine 0.35% for 3 minutes) are effective against bacteria in biofilm that are present in implant infections. Currently, povidone-iodine (0.35%), chlorhexidine (0.05%), sodium hypochlorite (0.125%), and triple antibacterial solution are all being used off-label for wound irrigation after surgical débridement for orthopaedic infections.

QUESTIONS/PURPOSES

Do commonly used antibacterials and antiseptics kill bacteria in established biofilm at clinically relevant concentrations and exposure times?

METHODS

Staphylococcus epidermidis (ATCC#35984) biofilms were exposed to chlorhexidine (0.025%, 0.05%, and 0.1%), povidone-iodine (0.35%, 1.0%, 3.5%, and 10%), sodium hypochlorite (0.125%, 0.25%, and 0.5%,), and triple antibacterial solution (bacitracin 50,000 U/L, gentamicin 80 mg/L, and polymyxin 500,000 U/L) for 1, 5, and 10 minutes in triplicate. Surviving bacteria were detected by 21-day subculture. Failure to eradicate all bacteria in any of the three replicates was considered to be "not effective" for that respective solution, concentration, and exposure time.

RESULTS

Chlorhexidine 0.05% and 0.1% at all three exposure times, povidone-iodine 10% at all three exposure times, and povidone-iodine 3.5% at 10 minutes only were effective at eradicating S epidermidis from biofilm. All concentrations and all exposure times of sodium hypochlorite and triple antibacterial solution were not effective.

CONCLUSIONS

Chlorhexidine is capable of eradicating S epidermidis from biofilm in vitro in clinically relevant concentrations and exposure times. Povidone-iodine at commonly used concentrations and exposure times, sodium hypochlorite, and triple antibacterial solutions are not.

CLINICAL RELEVANCE

This in vitro study suggests that chlorhexidine may be a more effective irrigation solution for S epidermidis in biofilm than other commonly used solutions, such as povidone-iodine, Dakin's solution, and triple antibiotic solution. Clinical outcomes should be studied to determine the most effective antiseptic agent, concentration, and exposure time when intraoperative irrigation is used in the presence of biofilm.

Evaluation of Calcium Release from Pulp-capping Material Using International Organization for Standardization Guidelines

Aims and Objectives:

Cytotoxicity assays are one of the methods used to assess the biocompatibility of dental materials. The objective of this study was to determine if surface area/volume ratios designated by the International Organization for Standardization (ISO) for biological evaluation of medical devices affects cytotoxicity and calcium release in an endodontic pulp-capping materials.

Material and Methods:

Human periodontal ligament fibroblasts (PDLFb) were treated with extractables derived from the calcium silicate pulp-capping material TheraCal LC at pellet surface area/culture medium volume ratios of 0.2, 0.5, and 1.0 cm2/mL. A colorimetric cytotoxicity assay (MTT) and phase-contrast microscopy was used to assess biocompatibility against the fibroblasts. The concentration of calcium leached into culture medium from TheraCal LC at pellet surface area/culture medium volume ratios of 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 cm2/mL after 24 hours was determined by colorimetric assay.

Results:

Both MTT assays and microscopy demonstrate that at a pellet surface area/culture medium volume ratio of 1.0 cm2/mL TheraCal LC extractable challenge to fibroblasts results in a significant decrease in cell viability ( P < 0.001) compared to control. TheraCal LC calcium release into culture medium varied with the surface area/volume ratio, with concentrations ranging from 2 to 8 times the calcium concentration in culture medium.

Conclusion:

Pellet surface area/culture medium volume ratios impacted parameters of TheraCal LC used in in vitro studies to determine biocompatibility with oral tissues. The ISO guidelines should be followed for all in vitro cytotoxicity studies of dental materials.

Antimicrobial Activity of a Cationic Guanidine Compound against Two Pathogenic Oral Bacteria

This study evaluated the potential antimicrobial properties of a polyguanidine (CatDex) on two oral bacteria. Chlorhexidine gluconate 1340 μmoL L-1 (CHX 0.12%) was used as control. Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) were grown in BHI media. Bacterial sensitivity and antimicrobial activity were determined by the minimum inhibitory concentration (MIC) and Kirby-Bauer methods. To study side effects, that is, toxicity, dental pulp stem cells (DPSCs) were used. Fluorometric cytotoxicity and confocal microscopy assays were used in order to test cell viability. CatDex inhibited growth of S. mutans at all concentrations and growth of P. gingivalis at all concentrations except 25 μmoL L-1. The MIC of CatDex was 50 μmoL L-1 for both S. mutans and P. gingivalis. The inhibition of bacteria exposed for 8 h at 50 μmoL L-1 of CatDex exhibited increased antimicrobial activity over time, with 91% inhibition in both bacteria. The antimicrobial activities of CatDex and CHX were similar when tested on two common bacteria. CatDex was significantly less toxic to DPSCs. CatDex toxicity depended on time and not on concentration. With regard to clinical relevance, CatDex may have potential as a novel antimicrobial agent. Further studies are in progress.

Tissue Reaction to Different Types of Calcium Hydroxide Paste in Rat

The purpose of this study was to compare the biocompatibility of two types of calcium hydroxide paste in subcutaneous tissue in rat. Twenty-two Wistar rats were divided into 4 experimental (n=5 each) and one control (n=2) group. A polyethylene tube filled with either Dentsply or Sure-Paste was implanted in each rat in the experimental groups, while an empty polyethylene tube was used in the control group. After 15 or 60 days, the animals were sacrificed and histopathological examination carried out. Tissue reaction was assessed by inflammatory cell infiltration using a 4-point scoring system, ranging from 0 to 3. Data were analyzed with the Kruskal-Wallis, Wilcoxon, and McNemar tests. Both types of paste induced an inflammatory response at each time point, although the intensity varied. A significant reduction in the number of inflammatory cells was observed at 60 days. Dentsply appeared to induce a more marked inflammatory response at both time points, although the difference was not significant. These results suggest that both types of paste are biocompatible with subcutaneous tissue in rat.

Evaluation of antimicrobial photodynamic therapy with indocyanine green and curcumin on human gingival fibroblast cells: An in vitro photocytotoxicity investigation

Recent investigations have suggested that antimicrobial photodynamic therapy (aPDT) can be an alternative treatment for the management of periodontal infections. However, currently there is very limited data regarding the photocytotoxicity of this method on human gingival fibroblast (HuGu) cells.

AIM

The in vitro optimal concentrations of indocyanine green (ICG) and curcumin as photosensitizers (PSs) and the irradiation time of diode laser emission were evaluated by assessing the photocytotoxicity of the treatment on HuGu cells.

MATERIALS AND METHOD

Monolayers of HuGu cells were incubated with various final concentrations of ICG (500, 750, 1000, 1250, 1500, 1750, and 2000μg/ml) and curcumin (3, 4, 5, 10, and 20mM). Three exposure times of the diode laser (30s, 60s, and 2×30s irradiation with an interval of 1min between each) and one of exposure time of 5min for LED were tested; cell viability was determined using neutral red assay. Chlorhexidine (CHX) as a gold standard antimicrobial agent for periodontal disease was considered as a control group.

RESULTS

ICG and curcumin significantly reduced HuGu cell viability at concentrations below 1000μg/ml and 10mM, respectively (P<0.01). Cytotoxicity was higher when the cells were treated for 2×30s irradiation with an interval of 1min and then again exposed to the laser for 30s (2% and 0.1%). CHX demonstrated no significant reduction in HuGu cell survival.

CONCLUSION

Photocytotoxicity is influenced by PS concentration, exposure time of PS, and time of irradiation. High doses of ICG and curcumin with lowest exposure time of light source and without cytotoxic effects may be an effective strategy for aPDT as an alternative treatment for periodontal disease.

Accidental injection of 2% chlorhexidine gluconate instead of an anesthetic agent: A case report

We report a case where 2% chlorhexidine (CHX) gluconate was mistaken for an anesthetic solution and infiltrated into the buccal vestibule during routine root canal treatment. Accidentally, 2% CHX gluconate solution was injected in the right upper buccal vestibule (16) of a 23-year-old male during routine root canal treatment. The patient experienced pain and a burning sensation over the injected area shortly after injection. Swelling with mild extraoral redness over the right cheek area was observed clinically. The patient was immediately administered dexamethasone intramuscularly, and was prescribed antibiotics, analgesics, and antihistamines. The patient complained of a loss of sensation over the right cheek by the 15^th day. The swelling reduced gradually over a period of 15 days. Reversal of sensation was attained after 35 days.

Antibacterial efficacy of Azadirachta indica, Mimusops elengi and 2% CHX on multispecies dentinal biofilm

Aims:

To check the antimicrobial activity of Azadirachta indica (Neem), Mimusops elengi (Bakul), and Chlorhexidine gluconate (CHX) on multispecies biofilm of common endodontic pathogens such as Streptococcus mutans, Enterococcus faecalis, Staphylococcus aureus and Candida albicans.

Settings and Design:

In vitro dentin disinfection model used to check the antimicrobial efficacy of herbal extracts.

Materials and Methods:

The in vitro dentin disinfection model was used to check the antimicrobial activity of the methanolic extracts of the medicinal plants along with Chlorhexidine gluconate. The polymicrobial biofilm was allowed to grow on extracted teeth sections for a period of 21 days. Remaining microbial load in the form of CFU/ml after the antimicrobial treatment was tabulated, and data were statistically analyzed using ANOVA and Bonferroni post-hoc tests.

Statistical Analysis Used:

SPSS version 17, one-way ANOVA, Bonferroni post-hoc test.

Results:

Both the plant extracts showed considerable antimicrobial efficacy as compared to negative control. 2% CHX was the most effective antimicrobial agent having statistically significant difference against plant extracts and negative control (saline).

Conclusion:

The methanolic extract of A. Indica, M. elengi, and Chlorhexidine Gluconate has considerable antimicrobial activity against polymicrobial dentinal biofilm of S. mutans, E. faecalis, S. aureus and C. albicans.

Antimicrobial and Cytotoxic Activity of Cuminum Cyminum as an Intracanal Medicament Compared to Chlorhexidine Gel

Introduction:

The aims of this study were i) to define the chemical constituents of Cuminum cyminum (cumin) essential oil, ii) to compare the antimicrobial activity of this oil to that of chlorhexidine (CHX) and co-trimoxazole on planktonic and biofilm forms of bacteria isolated from the teeth with persistent endodontic infection and iii) to compare the cytotoxicity of these medicaments on L929 fibroblasts.

Methods and Materials:

Three groups of microorganisms [aerobic bacterial mixture, anaerobic bacterial mixture and Enterococcus faecalis (E .faecalis)] were isolated from the teeth with persistent apical periodontitis. Zone of inhibition (ZOI), minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC) and time-kill tests were performed to assess the antimicrobial efficacy of the medicaments. Further, a cytocompatibility analysis of the medicaments was performed on L929 fibroblasts. The results obtained from disc diffusion test and mean cell viability values of the experimental medicaments were analyzed using two-way and one-way analysis of variance (ANOVA).

Results:

Seventeen constituents were recognized in cumin oil (predominantly cumin aldehyde and γ-terpinene). Co-trimoxazole showed the greatest ZOI followed by cumin and CHX. The smallest MIC and MBC belonged to co-trimoxazole followed by cumin and CHX for all groups of bacteria except for E. faecalis for which the MBC of cumin was smaller than co-trimoxazole. The results of time-kill assay revealed that all medicaments totally inhibited the bacterial growth in all groups after 24 h. CHX was the most cytotoxic solution while there were no significant differences between the cytocompatibility of different concentrations of cumin essential oil and co-trimoxazole.

Conclusion:

Cumin exhibited a strong antimicrobial efficiency against the microbial flora of the teeth with failed endodontic treatments and it was biocompatible for L929 mouse fibroblasts.

Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances

The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG), Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract from Casearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide paste promoted the highest inflammatory response.

The effect of different concentrations of chlorhexidine gluconate on the compressive strength of mineral trioxide aggregate

Background and aims. Substituting chlorhexidine (CHX) for water has been shown to enhance antimicrobial activity of mineral trioxide aggregate (MTA). The purpose of this study was to compare the compressive strength of MTA mixed with distilled water, 0.12% and 0.2% chlorhexidine.

Materials and methods. MTA was mixed according to manufacturer's instructions in group I (n = 20). In groups II & III, 0.12% and 0.2% CHX liquid was substituted for water, respectively. Samples were condensed with moderate force into 20 tubes with 1.5×5 mm dimensions and were allowed to set for 72 hours at 37°C in 100% humidity. After being removed from the molds, their compressive strength was determined using Instron testing machine. Each group was divided into two subgroups according to the time of testing (at 72 hours, and one week). Fractured surfaces of 4 specimens in each group were then evaluated under Scanning Electron Microscope (SEM) to determine their microstructure. One-way ANOVA, Tukey, and paired sample t-test was used for statistical analysis. P < 0.05 was set as significant.

Results. There was no significant difference between three groups in terms of their compressive strength after 72 hours. However, the compressive strength of group II was significantly higher than group I (P = 0.034) and group III (P = 0.021) after one week. Crystalline microstructure was similar in all groups.

Conclusion. Substitution of 0.012% chlorhexidine for water significantly increased the compressive strength of MTA at 1 week without significant change in crystalline structure.

Antimicrobial and cytotoxic activity of Ferula gummosa plant essential oil compared to NaOCl and CHX: a preliminary in vitro study

Objectives

The usage of medicinal plants as natural antimicrobial agents has grown in many fields including dental medicine. The aim of this in vitro study was three-fold: (i) to determine the chemical compositions of the Ferula gummosa essential oil (FGEO), (ii) to compare the antimicrobial efficacy of the oil with sodium hypochlorite (NaOCl) and chlorhexidine (CHX), (iii) to assess the toxic behavior of FGEO in different concentrations compared to 5% NaOCl and 0.2% CHX.

Materials and Methods

Gas chromatography/mass spectrometry (GC/MS) was used to determine the chemical compositions of the oil. The disk diffusion method and a broth micro-dilution susceptibility assay were exploited to assess the antimicrobial efficacy against Enterococcus faecalis, Staphylococcus aureus, Streptococcus mitis, and Candida albicans. The cytocompatibility of the FGEO was assessed on L929 fibroblasts, and compared to that of NaOCl and CHX.

Results

Twenty-seven constituents were recognized in FGEO. The major component of the oil was β-pinene (51.83%). All three irrigants significantly inhibited the growth of all examined microorganisms compared to the negative control group. FGEO at 50 µg/mL was effective in lower concentration against Enterococcus faecalis than 5% NaOCl and 0.2% CHX, and was also more potent than 0.2% CHX against Candida albicans and Staphylococcus aureus. FGEO was a cytocompatible solution, and had significantly lower toxicity compared to 5% NaOCl and 0.2% CHX.

Conclusions

FGEO showed a promising biological potency as a root canal disinfectant. More investigations are required on the effectiveness of this oil on intracanal bacterial biofilms.

Positively charged imidazolium-based ionic liquid-protected silver nanoparticles: a promising disinfectant in root canal treatment

AIM

To synthesize and characterize silver nanoparticles (Ag NPs) with different surface charges in order to evaluate their cytotoxicity and antibacterial activity in the absence and presence of dentine compared with NaOCl and CHX.

METHODOLOGY

Ag NPs with positive, negative and neutral surface charges were synthesized and characterized. The first phase of the experiment determined the minimum inhibitory concentrations (MICs) of NPs against planktonic E. faecalis and compared them with that of NaOCl and CHX. The second phase tested the elimination of E. faecalis at different contact times (5, 20 and 60 min and 4 and 24 h), and the role of dentine in their inactivation was assessed. In the third phase, the most effective Ag NP solution was selected for cytocompatibility assessment. An MTT-based cytotoxicity assay was used to evaluate the cytotoxicity of the selected NP solution in different concentrations on L929 fibroblasts compared to that of 2.5% NaOCl and 0.2% CHX. Student's t-test and repeated measures manova approach were used for statistical analyses.

RESULTS

The characterization revealed synthesis of colloidal NPs in the size range of 5-10 nm in diameter. The results indicated that Ag NP with a positive surface charge had the smallest MIC against planktonic E. faecalis, and it was active in very lower concentrations compared to NaOCl, CHX and the other tested AgNPs. Positive-charged Ag NPs at 5.7 × 10(-10)  mol L(-1) completely prevented the growth of E. faecalis after 5 min of contact time, a finding comparable to 0.025% NaOCl. Dentine powder had variable inhibitory effects on all tested materials after 1 h incubation period, but after 24 h, NaOCl and the positive-charged Ag NPs were not inhibited by dentine at any concentration used. CHX was the most and the positively charged Ag NP solution was the least toxic solutions to L929 fibroblasts (P < 0.001).

CONCLUSIONS

Ag NP surface charge was important in bactericidal efficacy against E. faecalis. The positively charged imidazolium-based ionic liquid-protected Ag NPs showed promising antibacterial results against E. faecalis and exhibited a high level of cytocompatibility to L929 cells.

The antimicrobial activity of Azadirachta indica, Mimusops elengi, Tinospora cardifolia, Ocimum sanctum and 2% chlorhexidine gluconate on common endodontic pathogens: An in vitro study

Objective:

To check the antimicrobial activity of Azadirachta indica (Neem), Ocimum sanctum (Tulsi), Mimusops elelngi (Bakul), Tinospora cardifolia (Giloy) and Chlorhexidine Gluconate (CHX) on common endodontic pathogens like Streptococcus mutans, Enterococcus faecalis and staphylococcus aureus.

Materials and Methods:

The agar diffusion test was used to check the antimicrobial activity of the Methanolic extracts of the medicinal plants along with CHX. Six different concentrations of the tested agents were used for the study. The values of Zone of Inhibition were tabulated according to the concentration of the tested agent and data was statistically analyzed using ANOVA and Bonferroni post- hoc tests. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentrations (MBC) values were also recorded.

Results:

All the plants extracts showed considerable antimicrobial activity against selected endodontic pathogens. At 3mg. concentration, O.sanctum was the most effective against S. mutans, M. elengi showed highest zone of inhibition against E.faecalis, whereas CHX was the most effective agent against S.aureus. CHX was also the most consistent of all the medicaments testes, showing inhibitory effect against all the tree pathogens at all the selected concentrations.

Conclusions:

The Methanolic extract of A.Indica, O.sanctum, M. Elengi, T.cardifolia and Chlorhexidine Gluconate has considerable antimicrobial activity against S. mutans, E. faecalis and S. aureus.

Cytotoxicity and genotoxicity of chlorhexidine on macrophages in vitro

Chlorhexidine (CHX) is the most widely used antiseptic for wound, skin disinfection, and dental hygiene. The aim of this study is to investigate the possible correlation between CHX-induced cytogenotoxicity and alterations in normal cell cycle on RAW264.7 macrophages. The cytotoxicity, mechanism of cell death, mitotic activity, and reactive oxygen species (ROS) generation were determined by tetrazolium bromide reduction assay, flow cytometry, cytokinesis-block proliferation index, and superoxide dismutase-inhibitable reduction of ferricytochrome c, respectively. The genotoxicity was measured using comet assay and cytokinesis-block micronucleus assay. The cytotoxicity of CHX in RAW264.7 cells presented a dose- and time-dependent manner (p < 0.05). The mode of cell death shifted from apoptosis to necrosis when the dosage of CHX increased. The genotoxicity of CHX in RAW264.7 cells had shown DNA damage in a dose-dependent manner (p < 0.05). Prolongation of cell cycle and the increase of ROS generation also expressed in a dose-dependent manner (p < 0.05). Taken together, the data suggested that CHX-induced cytotoxicity and genotoxicity on macrophages may be via ROS generation.

Direct and transdentinal (indirect) antibacterial activity of commercially available dental gel formulations against Streptococcus mutans

OBJECTIVE

To evaluate the direct and transdentinal (indirect) agar diffusion antibacterial activity of different commercially available antibacterial dental gel formulations against Streptococcus mutans.

MATERIALS AND METHODS

The commercially available dental gel formulations were Corsodyl® (COG, 1% chlorhexidine), Cervitec® (CEG, 0.2% chlorhexidine + 0.2% sodium fluoride), Forever Bright® (FOB, aloe vera), Gengigel® (GEG, 0.2% hyaluronic acid), 35% phosphoric acid gel and distilled water (control). Direct agar diffusion was performed by isolating three wells from brain-heart infusion agar plates using sterile glass pipettes attached to a vacuum pump and adding 0.1 ml of the gels to each well. Transdentinal (indirect) agar diffusion was performed by applying gel to 0.2- and 0.5-mm-thick human dentin discs previously etched with phosphoric acid and rinsed with distilled water. Zones formed around the wells and the dentin discs were measured and analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni correction (p < 0.01).

RESULTS

Direct agar diffusion tests showed significant differences among all gel formulations (p < 0.01) except for COG and CEG (p > 0.01). COG and CEG exhibited higher antibacterial effects compared to FOB and GEG (p < 0.01) in both direct and transdentinal (indirect) testing procedures. GEG did not show any antimicrobial activity in transdentinal (indirect) testing.

CONCLUSION

Commercially available dental gels inhibited S. mutans, which may indicate their potential as cavity disinfectants.

Biocompatibility of intracanal medications based on calcium hydroxide

Objective. The aim of this study was to evaluate the rat subcutaneous tissue reaction to calcium hydroxide-based intracanal medicaments, UltraCal XS (calcium hydroxide, barium sulphate, aqueous matrix), Hydropast (calcium hydroxide, barium sulphate, and propyleneglycol), and Calen (Calcium hydroxide, zinc oxide, colophony, and polyethyleneglycol), used as a control. Methods. Forty-eight rats (Rattus Norvegicus Holtzman) were distributed in three groups: Calen, UltraCal XS, and Hydropast. Polyethylene tubes filled with one of the medicaments were implanted in the dorsal subcutaneous. After 7 and 30 days, the implants were removed and the specimens were fixed and embedded in paraffin. Morphological and quantitative analyses were carried out in the HE-stained sections. The numerical density of inflammatory cells in the capsule was evaluated and statistical analyses were performed (P ≤ 0.05). Results. At 7 days, all materials induced an inflammatory reaction in the subcutaneous tissue adjacent to the implants. In all groups, a significant reduction in the number of inflammatory cells and giant cells was verified in the period of 30 days. Conclusion. These results indicate that the calcium hydroxide-based medicaments evaluated present biocompatibility similar to Calen.

Response of mice connective tissue to intracanal dressings containing chlorhexidine

Substances containing chlorhexidine (CHX) have been studied as intracanal medicaments. The aim of the present study was to characterize the response of mouse subcutaneous connective tissue to CHX-containing medications by conventional optical microscopy. The tissue response was evaluated by implanting polyethylene tubes containing one of the substances evaluated: Calen paste + 0.5% CHX, Calen + 2% CHX, 2% CHX gel, and Calen paste (control). After experimental periods of 7, 21, and 63 days, the implants (n = 10) were removed along with the subcutaneous connective tissue. Tissue samples were subjected to histological processing, and sections were stained with hematoxylin and eosin. Qualitative and quantitative analyses of the number of inflammatory cells, blood vessels, and vascularized areas were performed. Results were analyzed by ANOVA and Tukey tests with the significance level set at 5%. We concluded that Calen + 0.5% CHX led to reparative tissue response in contrast with Calen + 2% CHX and 2% CHX gel, which induced persistent inflammatory response, pointing to the aggressive nature of this mixture. When Calen + 2% CHX and 2% CHX gel were compared, the latter induced more intense inflammatory response.