Connective tissue responses to calcium hydroxide-based root canal medicaments

Propylene Glycol Potentiates the Inhibitory Action of CTZ Paste on Antibiotic-Resistant Enterococcus faecalis Isolated from the Root Canal: An In Vitro Study

This study aimed to evaluate if the change of vehicle for CTZ (Chloramphenicol, Tetracycline, zinc oxide, and Eugenol) paste improves the inhibition of Enterococcus faecalis in vitro. The vehicles evaluated alone and mixed with CTZ were Eugenol, propylene glycol (PG), super-oxidized solution (SOS), grapefruit-seed extract (GSE), and 0.9% saline solution as a negative control. A clinical isolate of E. faecalis was morphologically and biochemically characterized, and its antimicrobial susceptibility was tested using 20 antimicrobial agents. Once characterized, the clinical isolate was cultivated to perform the Kirby-Bauer disc diffusion method with paper discs embedded with the different vehicles mixed or used alone, and incubated at 37 °C for 24 h. Data were analyzed using one-way ANOVA, and the means were compared using Tukey test with a significance level of p < 0.05. For vehicles used alone, GSE presented the greatest inhibition showing a statistically significant difference with the rest of the vehicles. When vehicles were mixed with the CTZ paste, PG showed a greater inhibition with a statistically significant difference from the rest of the vehicles. In conclusion, the vehicle used to mix the CTZ paste plays an important role in the inhibition of E. faecalis in vitro; therefore, we consider that this can be an important factor to achieve success in the use of this technique.

Nicolau Syndrome after Endodontic Treatment: A Case Report

Calcium hydroxide has been used successfully in root canal therapy for many years. However, it can cause serious damage if it is inadvertently displaced into surrounding vital structures, resulting in thrombosis if displaced into blood vessels, damaging connective tissue, and causing skin necrosis. These adverse reactions are known as Nicolau syndrome (NS) or embolia cutis medicamentosa. Very few case reports have been published about these adverse effects of injecting calcium hydroxide beyond the apex during root canal therapy. A 16-year-old female patient was referred to the endodontic department of Hamad Dental Center for assessment after treatment by the maxillofacial surgery department for swelling and tissue necrosis that occurred after endodontic treatment in another clinic. When the patient initially attended the maxillofacial surgery department, she presented with swelling on the left side in the region of the maxillary left first permanent molar. On examination, there was a change in the color of the skin of the left cheek in that area along with some reported paralysis of the left side of her lips. Analgesics and antibiotics had already been prescribed at the referring clinic. Two weeks later, the patient developed a necrotic patch of skin on the same area. Subsequent evaluation at the endodontic department of Hamad Dental Center led to a diagnosis of NS. NS is a very rare iatrogenic condition. Displacing calcium hydroxide beyond the apex might increase the chance of NS. Clinicians should avoid overinstrumentation and forced injection of calcium hydroxide to prevent NS.

Physicochemical properties and effect of bioceramic root canal filling for primary teeth on osteoblast biology

OBJECTIVE

Bio-C Pulpecto (Bio-CP) was recently developed as the first bioceramic root filling material for primary teeth. To evaluate the physicochemical properties of radiopacity, setting time, pH, cytocompatibility and potential of Bio-CP to induce mineralisation, compared with (1) Calen thickened with zinc oxide (Calen-ZO), and (2) zinc oxide and eugenol (ZOE).

METHODOLOGY

Physicochemical properties were evaluated according to ISO 6876. Saos-2 (human osteoblast-like cell line) exposed to extracts of the materials were subjected to assays of methyl thiazolyl tetrazolium, neutral red, alkaline phosphatase (ALP) activity and mineralised nodule production. The results were analysed using one-way or two-way ANOVA and Tukey's or Bonferroni's post-tests (α=0.05).

RESULTS

All the materials showed radiopacity higher than 3 mm Al. Bio-CP had lower pH than Calen-ZO, but higher pH than ZOE. Calen-ZO and Bio-CP did not set. The setting time for ZOE was 110 min. The cytocompatibility order was Calen-ZO > Bio-CP > ZOE (1:2, 1:4 dilutions) and Calen-ZO > Bio-CP = ZOE (1:12, 1:24 dilutions) and Calen-ZO = Bio-CP > ZOE (1:32 dilution). Bio-CP induced greater ALP activity at 7 days, and greater mineralised nodule production, compared to Calen-ZO (p<0.05). Conclusions Bio-CP showed adequate physicochemical properties, cytocompatibility and potential to induce mineralisation.

Novel calcium phosphate coated calcium silicate-based cement: in vitro evaluation

Calcium silicate-based cements are known for their wide applications in dentistry and orthopedics. The alkaline pH (up to 12) of these cements limits their application in other orthopedic areas. In this study, the effect of dicalcium phosphate dihydrate (DCPD) coating on set cement on pH reduction and biocompatibility improvement was examined. Samples with 0 and 10 weight ratio DCPD were prepared and characterized by XRD, FTIR, and SEM. The DCPD coating on the set cement was performed by a 7 d immersion in 1% monocalcium phosphate (MCP) solution and characterized by XRD, FTIR, SEM, and EDX. Also, the compressive strength and cytotoxicity of the samples were tested. The results showed that DCPD coating did not significantly change the compressive strength of the cement, but by decreasing the pH of the culture medium to the physiological range, it led to enhance adhesion, spreading and proliferation of human osteosarcoma cell line (Saos-2). The novel DCPD coated calcium silicate-based cement could be served as a bulk or porous bone substitute and scaffold.

Influence of the Vehicle and Antibiotic Formulation on Cytotoxicity of Triple Antibiotic Paste

INTRODUCTION

The aim of this study was to assess the influence of antibiotic formulations (tablet/capsule [TC] or United States Pharmacopeia [USP]-grade antibiotics) and vehicles (water [H₂O] or macrogol + propylene glycol [MP]) on the cytotoxicity and pH of triple antibiotic pastes (TAPs).

METHODS

L929 fibroblasts were exposed to TAPs prepared with TC or USP-grade antibiotics mixed with H₂O or MP for 72 hours. Each isolated antibiotic with each vehicle, each isolated vehicle, and the culture medium were used as controls. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and neutral red assays. The pH was measured after 3 and 8 hours of immersion of the pastes in water. Data were analyzed using analysis of variance, the Bonferroni or Tukey posttests (α = 0.05), and the Pearson correlation test (α = 0.05).

RESULTS

The pastes prepared with TC were less cytotoxic than pastes prepared with USP-grade antibiotics (P < .05), and pastes with the MP vehicle were less cytotoxic than pastes with H₂O (P < .05). TC TAP + MP showed the lowest cytotoxicity, whereas USP-grade TAP + H₂O showed the highest cytotoxicity (P < .05). All TAPs showed a pH ranging from 4.64-5.20. Irrespective of the vehicle, USP-grade TAP showed a lower pH than TC TAP (P < .05). TAPs with H₂O had a lower pH than TAPs with MP (P < .05).

CONCLUSIONS

The vehicle and the antibiotic formulations influenced the cytotoxicity and pH of TAP. The pastes prepared with TC and MP were less acidic and less cytotoxic than the type prepared with USP-grade antibiotics and H₂O.

Interleukin-6 expression on inflamed rat dental pulp tissue after capped with Trigona sp. propolis from south Sulawesi, Indonesia

Background: Propolis is a natural product of plant resins collected by honeybees from various plant sources. It is used as a remedy in folk medicine since ancient times because of its several biological and pharmacological properties. Recently, propolis has been used by dentist to treat various oral diseases. It was always mentioned as an anti-inflammatory agent. Cytokines are proteins that provide communication between cells and play a critical role in a wide variety of processes. It released from cells in an inflammatory process that active, mediate or potential actions of other cells or tissues. When dental pulp has inflammation, several pro-inflammatory cytokines including Interleukin-6 (IL-6) was released by innate immune cells. Objective: To analyse the expression of IL-6 on inflamed rat dental pulp tissue following application of propolis. Material and methods: Trigona sp. propolis was obtained from Luwu Regency, south Sulawesi Province, Indonesia. Flavonoid and non-flavonoid extracts were purified from propolis using thin layer chromatography. The study was applied on 80 male Sprague Dawley rats, 10–12 weeks of age, divided randomly and equally into 5 groups. Group I, as negative control group was not conducted any treatment. At group II, III, IV and V. A Class I cavity (Black Classification) were made on the occlusal surface of right maxillary first molar. The dental pulp was perforated using dental explorer and allowed in the oral environment for 1 h, after that, Ethanolic Extract Propolis (EEP) (Group II), Extract Flavonoid-Propolis (EFP) (Group III), Extract Non-Flavonoid Propolis (ENFP) (Group IV), or Calcium Hydroxide (Ca(OH)₂) (Group V) were applied on dental pulp. All cavities were then filled with Glass Ionomer Cement as permanent filling. The rats being sacrificed in 6 h, 2 days, 4 days and 7 days. Sample biopsy were obtained, IL-6 expression was detected by using immunohistochemistry method. Data was analyzed statistically using Freidman and Kruskal Wallis tests with significance level of P < 0.05. Results: All agent showed IL-6 expression in inflamed rat dental pulp tissue, and this expression was decreased with the longer of observation time periods. EEP more stronger to decreased IL-6 expression on inflamed rat dental pulp tissue than other agent. There is significant difference (P < 0.05) of IL-6 expression between group I and other groups in 6 h and 2 days but not in 4 and 7 days time periods. Conclusion: Trigona sp. propolis from south Sulawesi, Indonesia could suppressed the expression of IL-6 on inflamed rat dental pulp tissue.

Surgical management of damaged inferior alveolar nerve caused by endodontic overfilling of calcium hydroxide paste

AIM

To evaluate the neurosensory outcome of management of damaged inferior alveolar nerves caused by endodontic overfilling and to assess the efficacy of delayed surgical intervention.

METHODOLOGY

Nine patients who underwent surgical removal of extruded endodontic material were included. All patients were evaluated for neurosensory function using a set of standardized tests. The outcome of surgical intervention was evaluated through patient interview and quantitative statistical analysis.

RESULTS

Surgical procedures included foreign body removal, microsurgical external/internal decompression, excision of neuroma followed by nerve repair, and excision of damaged nerve segment with interpositional nerve graft. Seven of the nine patients had significant improvement according to the follow-up neurosensory assessment. Four patients reported significant improvement, three patients reported mild improvement and two patients reported no appreciable improvement in the Visual Analog Scale (VAS). Two patients who reported no appreciable improvement in VAS also did not achieve FSR. In these patients, calcium hydroxide was spread widely along the IAN and a surgical approach was obtained via sagittal spit osteotomy. The mean time to reach FSR was 222.7 (±41.8) days with a range of 106-397 days. In the early repair group who received surgery within 60 days, three out of five patients achieved FSR in a mean time of 198.0 (±76.2) days. The mean time to FSR in all four subjects who received surgical attention over 60 days after injury was 241.3 (±139.8) days with a range of 106-397 days. As all four cases in the late repair group with limited amount of nerve injury achieved FSR, only 3 of 5 early repair cases with wide-spread injury achieved a similar outcome.

CONCLUSION

The results of this case series confirmed the notion that surgical management of the inferior alveolar nerve is effective in the treatment of nerve injuries caused by endodontic extrusion of calcium hydroxide paste. Delayed surgical repair of the inferior alveolar nerve can be indicated and helpful for the neurosensory recovery of damaged IAN, however, the surgical management was less effective in case of widespread nerve injuries.

Ex-vivo effect of intracanal medications based on ozone and calcium hydroxide in root canals contaminated with Enterococcus faecalis

This ex vivo study evaluated the antibacterial effect of intracanal medications in root canals contaminated with Enterococcus faecalis. Fifty single-rooted human teeth were contaminated with E. faecalis (ATCC 29212) and incubated at 37°C for 21 days. The specimens were randomly divided into 5 groups according to the intracanal medication used: OZ-PG: ozonized propylene glycol; CH/CPMC: calcium hydroxide/camphorated paramonochlorophenol; OZ-PG/CH ozonized PG/CH; PC: positive control group (no medication); and NC: negative control group (no contamination). The samples were collected after 7 days (post-medication) and 14 days (final). Bacterial growth was checked by counting the colony-forming units (CFU). OZ-PG and CH/CPMC reduced significantly the CFU counts compared with PC in the post-medication and final samples, with no statistically significant differences among them. On the other hand, OZ-PG/CH did not reduce significantly the number of bacteria compared with PC. In conclusion, among the evaluated medications OZ-PG and CH/CPMC were the most effective against E. faecalis.

Inflammatory effect of green propolis on dental pulp in rats

Pulpotomy in deciduous teeth is a controversial issue, especially with regard to alternative materials used for the direct pulp capping of the root canal pulp tissue. The aim of the present study was to perform a histological analysis of the initial reaction of the root canal pulp tissue in rats, following pulpotomy and pulp capping with (1) green propolis extract, (2) iodoform paste, (3) green propolis extract + iodoform and (4) calcium hydroxide paste with saline solution. Analyses were performed after 24 hours, 72 hours and 7 days. The substances containing green propolis extract and iodoform led to the production of an intense inflammatory infiltrate and necrosis in the root canal pulp tissue throughout the analyses. In the calcium hydroxide group, inflammatory infiltrate only prevailed at the 72-hour evaluation. Among the substances tested, calcium hydroxide paste induced the lowest intensity of inflammatory response in the root canal pulp tissue. Longer studies should be carried out to analyze the pulp repair process following pulpotomy and pulp capping with the compounds analyzed.

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.

Preliminary study of the inflammatory response to subcutaneous implantation of three root canal sealers

AIM

To evaluate the kinetics of the inflammatory tissue response to three root canal sealers using a physicochemical method for quantification of the enhanced vascular permeability and histopathological analysis.

METHODOLOGY

Twenty-eight male Wistar rats randomly assigned to four groups according to the evaluation periods (1, 3, 7 and 14 days) were used to assess the vascular permeability and histopathological reaction to RoekoSeal, AH Plus and Sealapex (new formulation) sealers, using saline and Chloropercha as negative and positive controls, respectively. Seven rats were sacrificed per period. The biocompatibility of the sealers was evaluated spectrophotometrically and histopathologically.

RESULTS

At day 14, Sealapex produced significantly more inflammatory exudate than AH Plus and RoekoSeal (P < 0.05); however, there was no significant difference between AH Plus and RoekoSeal (P > 0.05). Sealapex (new formulation) was the most irritating sealer, producing severe inflammation with the presence of multinucleated giant cells. RoekoSeal was the most biocompatible sealer, producing the least amount of inflammatory exudate.

CONCLUSIONS

RoekoSeal root canal sealer was biocompatible when implanted in connective tissue.

Subcutaneous connective tissue response to primary root canal filling materials

This study evaluated the response of the subcutaneous connective tissue of BALB/c mice to root filling materials indicated for primary teeth: zinc oxide/eugenol cement (ZOE), Calen paste thickened with zinc oxide (Calen/ZO) and Sealapex sealer. The mice (n=102) received polyethylene tube implants with the materials, thereby forming 11 groups, as follows: I, II, III: Calen/ZO for 7, 21 and 63 days, respectively; IV, V, VI: Sealapex for 7, 21 and 63 days, respectively; VII, VIII, IX: ZOE for 7, 21 and 63 days, respectively; X and XI: empty tube for 7 and 21 days, respectively. The biopsied tissues were submitted to histological analysis (descriptive analysis and semi-quantitative analysis using a scoring system for collagen fiber formation, tissue thickness and inflammatory infiltrate). A quantitative analysis was performed by measuring the area and thickness of the granulomatous reactionary tissue (GRT). Data were analyzed by Kruskal-Wallis, ANOVA and Tukey's post-hoc tests (?=0.05). There was no significant difference (p>0.05) among the materials with respect to collagen fiber formation or GRT thickness. However, Calen/ZO produced the least severe inflammatory infiltrate (p<0.05). The area of the GRT was significantly smaller (p<0.05) for Calen/ZO and Sealapex. In conclusion, Calen/ZO presented the best tissue reaction, followed by Sealapex and ZOE.

Histopathological evaluation of root canal filling materials for primary teeth

This study aimed to assess the response of apical and periapical tissues of dogs' teeth after root canal filling with different materials. Forty roots from dogs' premolars were prepared biomechanically and assigned to 4 groups filled with: Group I: commercial calcium hydroxide and polyethylene glycol-based paste (Calen®) thickened with zinc oxide; Group II: paste composed of iodoform, Rifocort® and camphorated paramonochlorophenol; Group III: zinc oxide-eugenol cement; Group IV: sterile saline. After 30 days, the samples were subjected to histological processing. The histopathological findings revealed that in Groups I and IV the apical and periapical regions exhibited normal appearance, with large number of fibers and cells and no resorption of mineralized tissues. In Group II, mild inflammatory infiltrate and mild edema were observed, with discrete fibrogenesis and bone resorption. Group III showed altered periapical region and thickened periodontal ligament with presence of inflammatory cells and edema. It may be concluded that the Calen paste thickened with zinc oxide yielded the best tissue response, being the most indicated material for root canal filling of primary teeth with pulp vitality.

Biocompatibility of different intracanal medications in rat bucal submucosa tissue

The aim of this study was to analyze the buccal tissue responses of Wistar rats to 2% chlorhexidine solution, calcium hydroxide and the association of both products. For this purpose, 30 specimens were randomly implanted in the filtrum of the four upper and lower hemiarches with a polyethylene tube containing one of the following substances: 2% chlorhexidine solution, calcium hydroxide and 2% chlorhexidine solution (test groups); calcium hydroxide and distilled water and distilled water (control groups). Ten rats each were distributed according to time interval of evaluation at 7, 15 and 30 days. The histological sections were stained with Harris hematoxylin and eosin. Analysis was performed with an optical microscope at x100, x200 and x400 magnifications by an expert examiner blinded to the materials. The sections were classified by scores attributed to inflammatory events and by a ranking determined according to the severity of the inflammation. The results of the inflammatory events and severity ranking were submitted to the Kruskal-Wallis test at a 0.05 level of significance. No statistically significant difference occurred among the tested materials; however, all materials showed a decreased of severity with respect to longer time intervals.

Subcutaneous tissue response of isogenic mice to calcium hydroxide-based pastes with chlorhexidine

This study was evaluated the response of subcutaneous connective tissue of isogenic mice to calcium hydroxide-based pastes with chlorhexidine digluconate (CHX). Seventy isogenic male BALB/c mice aged 6-8 weeks and weighing 15-20 g were randomly assigned to 8 groups. The animals received polyethylene tube implants as follows: Groups I, II, and III (n=10) - Calen® paste mixed with 0.4% CHX (experimental paste; Calen/CHX) for 7, 21, and 63 days, respectively; Groups IV, V, and VI (n=10) - UltraCal™ paste mixed with 2% CHX (experimental paste supplied by Ultradent Products Inc.; Ultracal/CHX) for 7, 21, and 63 days, respectively; and Groups VII and VIII (n=5): empty tube for 7 and 21 days, respectively. At the end of the experimental periods, the implants were removed together with the surrounding tissues (skin and subcutaneous connective tissue). The biopsied tissues were subjected to routine processing for histological analysis. Using a descriptive analysis and a four-point (0-3) scoring system, the following criteria were considered for qualitative and quantitative analysis of the tissue around the implanted materials: collagen fiber formation, tissue thickness and inflammatory infiltrate. A quantitative analysis was performed by measuring the thickness (µm), area (µm²) and perimeter (µm) of the reactionary granulomatous tissue formed at the tube ends. Data were analyzed statistically by the Kruskal-Wallis test and Dunn's post-test (α=0.05). Calen/CHX showed biocompatibility with the subcutaneous and reactionary tissues, with areas of discrete fibrosis and normal conjunctive fibrous tissue, though without statistically significant difference (p>0.05) from the control groups. In Groups I to III, there was a predominance of score 1, while in Groups IV to VI scores 2 and 3 predominated for all analyzed parameters. UltraCal/CHX, on the other hand, induced the formation of an inflammatory infiltrate and abundant exudate, suggesting a persistent residual aggression from the material, even 63 days after implant placement. In conclusion, the Calen paste mixed with 0.4% CHX allowed an adequate tissue response, whereas the UltraCal paste mixed with 2% CHX showed unsatisfactory results.

Effects of the association between a calcium hydroxide paste and 0.4% chlorhexidine on the development of the osteogenic phenotype in vitro

The present study aimed to evaluate whether the association between a calcium hydroxide paste (Calen paste) and 0.4% chlorhexidine (CHX) affects the development of the osteogenic phenotype in vitro. With rat calvarial osteogenic cell cultures, the following parameters were assayed: cell morphology and viability, alkaline phosphatase activity, total protein content, bone sialoprotein immunolocalization, and mineralized nodule formation. Comparisons were carried out by using the nonparametric Kruskal-Wallis test (level of significance, 5%). The results showed that the association between Calen paste and 0.4% CHX did not affect the development of the osteogenic phenotype. No significant changes were observed in terms of cell shape, cell viability, alkaline phosphatase activity, and the total amount of bone-like nodule formation among control, Calen, or Calen + CHX groups. The strategy to combine Ca(OH)(2) and CHX to promote a desirable synergistic antibacterial effect during endodontic treatment in vivo might not significantly affect osteoblastic cell biology.

MTA and calcium hydroxide for pulp capping

This study evaluated the biocompatibility of mineral trioxide aggregate (MTA) after direct capping of exposed pulp tissue in dog's teeth. Class I cavities were prepared in 26 teeth from 3 adult dogs. MTA was applied over the exposed pulp in 13 teeth and paste of calcium hydroxide plus distilled water (control) was applied in the remaining 13 teeth. After 90 days, the animals were killed; the maxilla and mandible were dissected and sectioned to obtain individual roots. The samples were processed histologically. The pulp and periapical response observed with the use of MTA was similar to that of calcium hydroxide paste. In all specimens, there was a dentin bridge obliterating the exposure, an intact odontoblastic layer, no inflammatory cells, normal connective pulp tissue, normal apical and periapical regions and no bone tissue changes. Similar to calcium hydroxide, MTA presented excellent response when used for direct pulp capping.

Importance of bacterial endotoxin (LPS) in endodontics

New knowledge of the structure and biological activity of endotoxins (LPS) has revolutionized concepts concerning their mechanisms of action and forms of inactivation. Since the 1980's, technological advances in microbiological culture and identification have shown that anaerobic microorganisms, especially Gram-negative, predominate in root canals of teeth with pulp necrosis and radiographically visible chronic periapical lesions. Gram-negative bacteria not only have different factors of virulence and generate sub-products that are toxic to apical and periapical tissues, as also contain endotoxin (LPS) on their cell wall. This is especially important because endotoxin is released during multiplication or bacterial death, causing a series of biological effects that lead to an inflammatory reaction and resorption of mineralized tissues. Thus, due to the role of endotoxin in the pathogenesis of periapical lesions, we reviewed the literature concerning the biological activity of endotoxin and the relevance of its inactivation during treatment of teeth with pulp necrosis and chronic periapical lesion.

Displaced calcium hydroxide paste causing inferior alveolar nerve paraesthesia: report of a case

A patient presented with an intraoral red, painful, and hard swelling in the lower right jaw. Radiographs showed a 2 x 1 cm area of radiopaque material surrounding the apex of the second premolar. The material, according to the patient's dentist, was calcium hydroxide paste used as a temporary dressing material in the root canal. The patient developed paraesthesia in her lower lip probably due to a neurotoxic effect caused by calcium hydroxide. The foreign material was surgically excavated from the spongious bone, directly adjacent to the nerve, and the patient later regained her sensation in the lip. A histopathological analysis revealed necrosis, deposits of foreign bodies, and inflammatory cells and foreign-body giant cells. This report illustrates the toxicity and adjacent clinical symptoms of calcium hydroxide paste when displaced into bone tissue close to the alveolar inferior nerve. It also demonstrates the benefits of removing such displaced material before symptoms progress.

Mast cells in tissue response to dentistry materials: an adhesive resin, a calcium hydroxide and a glass ionomer cement

Synthetic materials used in dentistry may trigger various inflammatory responses. In order to evaluate biocompatibility, standardized implants of Calcium Hydroxide (CH), Glass Ionomer Cement (GIC) and Light-activated Dental Adhesive (LDA) were surgically introduced into Wistar rats' back bone. Six (experimental) animal groups, five each, and two Sham (S) groups were studied after 15 and 30 days from surgery. In each animal, the density of mast cells and interstitial fibrosis volume was evaluated by quantitative light microscopy. In addition, the interaction between the disk material and its fibrous capsule was evaluated by scanning electron microscopy. The density of mast cells per area (N(A)[mast cells]) was lower in CH group than in LDA group. GIC group displayed N(A)[mast cells] results intermediate between CH and LDA groups (p<0.05). The smallest interstitial fibrosis volume density (Vv[f]) was observed in CH group, then in GIC group, while the greatest in LDA group. After 30 days, the fibrosis in LDA group was 30% higher than in CH group (p<0.05). In S group, discreet fibrosis restricted to surgical area was present, with few mast cells near the vessels. Significant interaction between fibrous capsule and the surrounding disk material was most evident in CH group. The implanted materials induced mast cell migration, distinct fibrosis development, suggesting that CH is the most biocompatible material among those tested.

Inflammatory response to different endodontic irrigating solutions

AIM

The aim of this study was to evaluate the inflammatory response to irrigating solutions injected into the peritoneal cavity of mice.

METHODOLOGY

Sixty mice received intra-peritoneal injections of 0.3 mL of 0.5% sodium hypochlorite, 2.0% chlorhexidine digluconate or phosphate buffered saline (PBS, control). Five animals of each group were sacrificed at 4, 24, 48 h and 7 days after the injection. Liquid from the peritoneal cavity of each animal was collected for the total and differential counting of inflammatory cells and protein leakage.

RESULTS

The 0.5% sodium hypochlorite solution group had greater migration of neutrophils and mononuclear cells to the peritoneal cavity from 48 to 168 h (P < 0.05). There was a significant increase in protein leakage to the peritoneal cavity after 4 up to 48 h in the 0.5% sodium hypochlorite group compared to the control group. Protein leakage was similar in all groups at 168 h. The 2.0% chlorhexidine group had similar results to the control group at all time periods.

CONCLUSIONS

The 0.5% sodium hypochlorite solution induced an inflammatory response, however, the 2.0% chlorhexidine digluconate solution did not induce a significant inflammatory response.

Root canal sealers cause cytotoxicity and oxidative damage in hepatocytes

Elutable substances and degradation products from root canal sealers may gain access to periodontal tissue in many ways. The aim of this study was to investigate damage and oxidative stress caused by treatment with root canal sealers in primary cultured rat hepatocytes. Four root canal sealers were used: Canals, Sealapex, AH 26, and AH Plus. Toxicity was detected by assessing lactate dehydrogenase (LDH) leakage, and oxidative stress was determined by analysis of glutathione (GSH) levels. One-way analysis of variance was performed on the data. As the concentrations of sealer were increased, LDH leakage increased (p < 0.01). Increased GSH depletion accompanied LDH leakage increase. GSH levels were reduced to zero at a concentration of 0.05% for Canals and 0.10% for AH 26. These results confirmed the hypothesis that root canal sealers can cause cytotoxicity in hepatocytes. The Canals and AH 26 sealers can also cause oxidative stress in hepatocytes.