Asymptomatic Periapical Lesions Research Articles

Genetic polymorphism of interleukins 6 and 17 correlated with apical periodontitis: A Cross-sectional study.

Interleukins 6 and 17 act in bone resorption in the presence of infections of endodontic origin for host defense. Genetic polymorphisms may be associated with increased bone loss, represented by areas of large periapical lesions. This study aimed to verify the frequency of interleukin 6 and 17 gene polymorphism in patients with asymptomatic apical periodontitis or chronic apical abscess and to verify the existence of correlations between periapical lesion area with age, gender, and presence of the polymorphism, in the studied population, in the state of Pernambuco. A population consisting of thirty diagnosed individuals was included. The area of the lesions was measured in mm². Genomic DNA was extracted and genotyping was performed by Polymerase Chain Reaction Restriction Fragment Length Polymorphism for interleukin 6 (rs 1800795) and interleukin 17 (rs 2275913). Fisher's exact, chi-square, and odds ratio tests were used. A logistic regression analysis was also performed using sex, age, and the presence of polymorphism as covariates, in addition to linear regression to test the relationship between age and lesion area. All tests used a significance level of 0.05% (p ≤0.05%). There was no statistical significance in the occurrence of large areas of periapical lesions correlated with age, sex, and diagnosis, nor in the distribution of alleles in the polymorphism of interleukins 6 and 17 in the studied groups. The frequency of homozygous and heterozygous polymorphism was high. The polymorphism of these interleukins is not correlated with the increase in the areas of asymptomatic periapical inflammatory lesions.

The effect of photodynamic therapy on postoperative pain in teeth with primary endodontic infection

Introduction: The objective of this study was to investigate the action of photodynamic therapy on pain control after endodontic treatment in asymptomatic teeth with a primary infection, within a single visit. Methods: Sixty (60) single-rooted teeth with pulp necrosis and periapical lesions were selected and randomly divided into two (2) groups (n = 30), according to the protocol; a control group (CG) and a group using photodynamic therapy (aPDT). The canals were instrumented with Reciproc files # 25 up to 40 along the entire length of the canal, using 2% chlorhexidine gel as the auxiliary chemical substance, followed by irrigation with sterile saline. aPDT consited of 0.005% methylene blue as photosensitizer, using AsGaAl diode laser, 660 nm wavelength, 100 mW of power and 9 J of energy, using optical fibers with 365 μm in diameter. The canals were filled with Endomethasone N cement. Results: Pain intensity was assessed at 8, 12, 24, 48, 72 h and 1 week after endodontic treatment using a visual analogue scale. The level of pain was classified as none (0), mild (1–3), moderate (4–7) or severe (8–10). The data were at a significance level of 5%. There was a statistically significant difference (p<0.05) in the periods of 8, 12, 24, 48 and 72 h between the control group and the aPDT group. After 1 week, there was no statistically significant difference. Conclusions: It is concluded that photodynamic therapy had a significant effect on decreasing post-endodontic treatment pain in teeth with necrotic pulp and asymptomatic periapical lesions.

Effect of Calcium Hydroxide Alone or in Combination with Ibuprofen and Ciprofloxacin on Nuclear Factor Kappa B Ligand and Osteoprotegerin Level in Periapical Lesions: A Randomized Controlled Clinical Study

IntroductionThe aim of the present study was to evaluate the effects of calcium hydroxide (Ca[OH]2), Ca(OH)2 + ibuprofen, and Ca(OH)2 + ciprofloxacin in terms of receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) levels in asymptomatic periapical lesions. MethodsSixty-six patients were randomly divided into 3 groups using a Web program according to the medication selected: Ca(OH)2, Ca(OH)2 + ibuprofen, and Ca(OH)2 + ciprofloxacin. After removing gutta-percha from the root canals, the RANKL and OPG samples were taken from the interstitial fluid of the apical tissues using 3 paper points. At the second appointment, medicaments were removed, and second sampling was performed using the same method. The RANKL and OPG levels were measured by the enzyme-linked immunosorbent assay, and the RANKL/OPG ratio was calculated. ResultsAccording to the intragroup analysis, there were no statistically significant differences between the preoperative and postoperative levels of the RANKL/OPG ratio in any of the groups. Intergroup analyses showed that there were no statistically significant differences among the Ca(OH)2, Ca(OH)2 + ibuprofen, Ca(OH)2 + ciprofloxacin groups in terms of the percentage change in RANKL/OPG levels before and after treatment. ConclusionsWithin the limitations of the present study, it can be concluded that addition of ibuprofen or ciprofloxacin to Ca(OH)2 paste does not provide any extra benefit in terms of lowering RANKL and OPG levels.

Endogenous peripheral pain regulatory systems in orofacial pain patients

IntroductionInitiation of pulpal pain begins with the release of bacterial toxins and inflammatory mediators that either activate or sensitize nociceptors thereby activating the trigeminal pain pathway. In addition, pain perception quickly triggers inhibitory signals that are often mediated by endogenously produced analgesic substances such as opioid peptides. The balance between inflammatory mediators and endogenously released analgesics may contribute to clinical conditions such as symptomatic versus asymptomatic pulpitis. We hypothesized that patients with asymptomatic periradicular pathosis have increased levels of the opioid peptides compared to patients with symptomatic periradicular pathosis. In addition, we also proposed to study the immune cell type that is responsible for the release the opioid peptides in periradicular lesions. Material and methodFifty tissue biopsy samples obtained from patients who have received endodontic microsurgery and assigned to either symptomatic and asymptomatic groups (n = 25/group) based on their pre-operative clinical periradicular testings. Immunohistochemistry, enzyme-linked immunosorbent assay (ELISA) and Fluorescence-Activated Cell Sorting (FACS) were performed to determine the expressions, levels and the cellular sources of opioid peptides, namely; β-endorphin (END), met-enkephalin (ENK) and dynorphin A (DYN), respectively. Radioimmunoassay (RIA) was performed to determine the functional role of conditioned media (CM) from asymptomatic and symptomatic patients on regulation of trigeminal (TG) neuronal activity in vitro. ResultsCompared to symptomatic group, patients with asymptomatic lesions showed 3-fold increase in END levels only. Macrophages showed the highest expression of END, DYN and ENK. This study shows that the application of CM from asymptomatic and symptomatic patients triggered differential regulation of TG neuronal activity. ConclusionEndogenous opioid peptides are present in periapical lesions. The higher level of endogenous opioid peptides in asymptomatic periapical lesions could explain the lack of symptoms in asymptomatic lesions.

Production of immunoregulatory cytokines in clinically asymptomatic periapical lesions depends on the lesions size

Bacground/Aim. Development of periapical lesions (PLs) involves a complex cross-talk between pathogenic microorganisms from the root canal and host immune mechanisms. In these processes proinflammatory cytokines are involved in stimulation of inflammation and osteodestructive mechanisms, whereas anti-inflammatory cytokines, with the immunoregulatory functions, have the opposite effects. How this balance is controlled is still the subject of numerous studies. The aim of this study was to examine whether the local production of interleukin (IL)-10, IL-27 and transforming growth factor (TGF)-? in human asymptomatic PLs depends on the lesion size and how levels of these immunoregulatory cytokines correlate with the cellular composition of PLs. Methods. The study was conducted on 30 PLs which were collected at the Clinic for Stomatology of the Military Medical Academy, Belgrade, Serbia. The PLs were divided according to their size into small- and largesize lesions (n = 12 and n = 18, respectively). The inflammatory cells (PL-ICs) were isolated from PLs and cultivated for 24 hours in culture medium supplemented with phorbol myristate acetate and Ca2+ ionophore. Cytospins were processed for immunocytology by using monoclonal antibodies to cell subsets. The levels of cytokines in culture supernatants were determined by the ELISA method. Statistical analysis was performed using the Student t-test and the Spearman?s correlation test. The values of p &lt; 0.05 were considered to be significant. Results. The levels of IL-10 and TGF-? were significantly higher in the PL-ICs cultures of large-size lesions than in small ones (p &lt; 0.01 and p &lt; 0.05, respectively). In contrast, the levels of IL-27 were higher in the cultures of small-size lesions than in small ones (p &lt; 0.05). Although the total number of PL-ICs and the proportion of mononuclear phagocytes were higher in the large-size PLs (p &lt; 0.01 and p &lt; 0.05, respectively), their main composition was not significantly different between the groups. The proportions of B cells/plasma cells (CD19/CD38+ cells), CD8+ T cells and CD14+ cells were significantly higher in the large-size PLs (p &lt; 0.005; p &lt; 0.05; p &lt; 0.05, respectively). In contrast, the proportion of total T cells (CD3+ cells) was higher in the small-size lesions (p &lt; 0.05). No statistically significant correlation was found between the levels of these cytokines and the composition/ phenotype of PL-ICs. Conclusion. This study suggests that IL-10, IL-27 and TGF-? may play different roles in suppression of unwanted immune/inflammatory reactions in asymptomatic PLs, depending on the extension of pathological process as judged by the size of lesions.

Herpesviruses viral loads and levels of proinflammatory cytokines in apical periodontitis.

This study aimed to analyse Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) viral loads in symptomatic and asymptomatic apical periodontitis lesions, to determine levels of TNF-α, IL-1β and IL-6 in these lesions and to investigate a possible correlation between herpesviral copy numbers and levels of proinflammatory cytokines. A total of 100 samples of apical periodontitis were subjected to HCMV and EBV copy numbers analysis by nested polymerase chain reaction (PCR) and TaqMan real-time PCR. The concentrations of TNF-α, IL-1β and IL-6 were determined by ELISA method. SPSS software was used for statistical analysis. There were no significant differences in the occurrence of EBV and HCMV between symptomatic and asymptomatic periapical lesions (p=.686, p=.879, respectively). Only 12 of 74 EBV (16.2%) and four of 54 HCMV (13.5%) nested PCR-positive samples showed increased viral copy numbers above the limit of 125 copies/ml. There was no significant correlation between the levels of analysed proinflammatory cytokines and herpesviral copy numbers in our sample. The observed low viral loads point to a relatively rare occurrence of active EBV and HCMV infection in our sample. Latent herpesviral infection does not enhance the production of investigated proinflammatory cytokines.

Expression levels of the receptor activator of NF-κB ligand and osteoprotegerin and the number of gram-negative bacteria in symptomatic and asymptomatic periapical lesions

ObjectiveThe study aimed to verify the potential correlation between the detected amount of gram-negative bacteria and the radiographic sizes of the lesions in patients with symptomatic and asymptomatic apical periodontitis. Furthermore, to evaluate whether the expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) and the RANKL/OPG ratio are differentially regulated in both groups. DesignTwenty patients with periapical lesions were divided into two groups: symptomatic (SYM) n=10 and asymptomatic (ASYM) n=10. After periapical surgery, the lesions were collected and processed for histological examination, and immunohistochemistry. The percentage of RANKL- and OPG-immunopositive areas relative to the total area of the microscopic field was calculated. For gram staining, the number of gram-negative cells per microscopic field was assessed. The radiographs of each patient were processed and measured. The Student’s t-test and the Pearson correlation coefficient were performed. ResultsThe SYM group showed a significantly higher number of gram-negative cells (p=0.007) when compared to the ASYM group. A higher number of gram-negative bacteria occurred more frequently in larger periapical lesions and the SYM group (p=0.03). The expression for RANKL and OPG and the RANKL/OPG ratio were not significantly different between the groups. There was a significant positive correlation between the number of bacteria and OPG levels in the SYM group (p=0.01). ConclusionThe number of bacteria seems to influence the symptoms and the radiographic size of a periapical lesion. Gram-negative bacteria may play an important role in OPG activity in the SYM group.

Use of Cone-beam Computed Tomography during Retreatment of a 2-rooted Maxillary Central Incisor: Case Report of a Complex Diagnosis and Treatment

A double-rooted maxillary incisor is an extremely rare anatomic variation. Only a few case reports describe this abnormal anatomy. In recent decades, cone-beam computed tomographic (CBCT) imaging has become more common for endodontic purposes. This case report describes the retreatment of double-rooted maxillary central incisors using CBCT imaging. In 2012, a 20-year-old man was referred to our department because of asymptomatic periapical lesions in teeth #8, #9, and #10. During the evaluation of a periapical radiograph, a rare anatomic variation, in the form of an additional root of tooth #9, was detected, and it was impossible to decide about the source of the lesion between teeth #9 and #10. During retreatment, after gutta-percha removal, CBCT imaging was performed; this allowed proper treatment of the additional root and a final diagnosis of normal periapical tissue of tooth #10 with no treatment needed. The 18-month follow-up revealed a healing lesion in tooth #9 and normal periapical tissue in tooth #10. During the treatment of teeth with an anatomic variation, CBCT imaging can serve as an auxiliary tool for 3-dimensional evaluation that influences treatment steps and techniques. CBCT scanning can be very useful in assessing the actual location of a periapical lesion, which influences diagnosis and treatment planning.

Mesenchymal Stem Cells from Periapical Lesions Upregulate the Production of Immunoregulatory Cytokines by Inflammatory Cells in Culture / Mezenhimske matične ćelije iz periapeksnih lezija stimulišu produkciju imunoregulacijskih citokina od strane inflamacijskih ćelija u kulturi

Abstract The pathophysiology of periapical lesions (PLs) is under control of pro-inflammatory and anti-inflammatory (mainly immunoregulatory) cytokines. We have recently established mesenchymal stem cells (MSCs) from PLs and showed their suppressive effects on the production of proinflammatory cytokines from PLs inflammatory cells (ICs). In this work we studied the production of interleukin (IL)-10, IL-27 and transforming growth factor (TGF)-β, by PL-ICs in direct or indirect contacts with PL-MSCs. PL-ICs, which were isolated from four different asymptomatic PLs, predominantly composed of lymphocytes, followed by neutrophil granulocytes, macrophages and plasma cells. PLMSCs, expressing typical MSC markers, were co-cultivated with PL-ICs at 1:10 ratio, either in direct contact or in a transwell-system, for 24 hours. The levels of cytokines in cell-culture supernatants were tested by ELISA. The results showed that PL-MSCs up-regulated the production of all three immunoregulatory cytokines by PL-ICs. PL-MSCs stimulated the production of IL-10 and IL-27 via soluble factors, whereas the up-regulation of TGF-β required direct cell-to-cell contacts. In conclusion, our results showed for the first time the involvement of PL-MSCs in restriction of inflammation in PLs by up-regulation of immunoregulatory cytokines.

The odontogenic-related microinflammation in patients with chronic kidney disease

Objectives: This study estimated plasma levels of interleukin IL-1β, IL-6, tumour necrosis factor-α (TNF-α), interferon-γ (INF-γ) in chronic kidney disease (CKD) patients with a single odontogenic pathology. Material and methods: Forty-nine selected adult CKD patients with single odontogenic pathology based on clinical and X-ray examination: patients after proper root canal treatment, without periapical lesions (n = 12), with pulp necrosis (n = 7), with asymptomatic periapical lesions (n = 22), with periodontal disease (n = 8), and 14 with healthy teeth were enrolled. Patients with coexisting different dental pathologies and the evidence of other infection were excluded. In all patients plasma concentrations of CRP, IL-1β, IL-6, TNF-α, and INF-γ were measured. Results: Patients with periodontitis were characterized by increased concentrations of IL-6 and TNF-α. Those with pulp necrosis had significantly more frequently serum CRP level over 2 mg/L and presented significantly elevated IL-6, but decreased TNF-α concentration than in the subjects with healthy teeth. In patients with periapical lesions and patients after root canal therapy, the concentrations of cytokines did not indicate for the systemic inflammation. Conclusions: Periodontitis and pulp necrosis are important sources of systemic microinflammation in CKD patients. Plasma concentrations of IL-6 and TNF-α appear to be more sensitive markers of odontogenic inflammation in CKD patients than CRP.

Expression Levels of Matrix Metalloproteinase-9 and Gram-negative Bacteria in Symptomatic and Asymptomatic Periapical Lesions

IntroductionThe aim of this study was to test the hypothesis that the expression of matrix metalloproteinase (MMP)-9 is significantly elevated in patients with symptomatic apical periodontitis and to correlate this with the detected amount of gram-negative bacteria. MethodsTwenty-six patients with periapical lesions involving at least 2 teeth were included in this study. The patients were divided into 2 groups: the symptomatic (SYM) group included 13 patients expressing pain with periapical lesions, and the asymptomatic (ASYM) group included 13 patients expressing no pain. Root canal treatment was performed followed by endodontic surgery and periapical lesion collection. Periapical lesions were serially cut into 4-μ sections. Some sections were processed for histologic examination using hematoxylin-eosin stain. Other sections were processed for immunohistochemical examination. For MMP-9, the area fraction of the positive cells was measured, and the percentage of the MMP-9–immunopositive area to the total area of the microscopic field was calculated. For gram-negative stain cells, the number of cells showing the pink-red color was counted per microscopic field. The Student's t test was used to compare the SYM and ASYM groups. The Pearson correlation coefficient was used to determine a significant correlation between the number of cells and the MMP-9 level. The significance level was set at P ≤ .05. ResultsThe SYM group showed a statistically significantly higher mean number of gram-negative cells (P = .001) and MMP-9 area percent (P < .001) than the ASYM group. There was a statistically significant positive (r = .927) correlation between the number of gram-negative cells and the MMP-9 area percent (P < .001). ConclusionsThere is good evidence to suspect a significant role of gram-negative bacteria and MMP-9 in symptomatic periapical lesions.

Detection of human cytomegalovirus and Epstein-Barr Virus in symptomatic and asymptomatic apical periodontitis lesions by real-time PCR

Objectives: Recent studies have investigated the occurrence of human cytomegalovirus and Epstein-Barr Virus in samples from apical periodontitis lesions and a role in the pathogenesis of this disease has been suggested. Because genotype distribution and seroprevalence of EBV and HCMV differ among populations, it is important to determine the presence of these viruses in endodontic periapical lesions of different populations. The aims of this study were to determine the presence of HCMV and EBV DNAs in samples from Turkish patients with symptomatic and asymptomatic apical periodontitis lesions using real-time polymerase chain reaction method and to evaluate their presence in both symptomatic and asymptomatic apical periodontitis lesions. Study Design: Periapical samples were collected from 12 asymptomatic and 16 symptomatic periapical lesions in conjunction with apicectomy. HCMV and EBV DNAs were identified in the samples by real-time PCR. The chi-squared test with Yates’s correction or the Fisher’s exact test was used to analyse the significance of differences. Results: HCMV DNA was detected in 10 of the 16 (62.5%) symptomatic and in five of the 12 (41.7 %) asymptomatic periapical study lesions. The EBV DNA was identified in seven of the 16 (43.7 %) symptomatic and three of the 12 (25 %) asymptomatic periapical lesions. The difference in occurrence of HCMV and EBV DNA between symptomatic and asymptomatic periapical lesions was not statistically significant. (All comparisons have p > 0.05). Conclusions: Our findings suggest that HCMV and EBV is a frequent inhabitant of both symptomatic and asymptomatic apical periodontitis lesions of endodontic origin in Turkish population. Key words:Human cytomegalovirus, Epstein-Barr Virus, apical periodontitis, Polymerase chain reaction method.

Significance of Human Cytomegalovirus and Epstein-Barr Virus in Inducing Cytokine Expression in Periapical Lesions

Introduction Because herpesviruses might be etiologically involved in periapical pathosis of endodontic origin, this study aimed to determine the occurrence of human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), and the expression of mRNA transcripts of tumor necrosis factor (TNF)-α, γ-interferon (IFN), interleukin (IL)-1β, IL-6, IL-12, and IL-10 in periapical granulomatous lesions collected in conjunction with apicoectomy. Methods A total of 9 symptomatic and 6 asymptomatic teeth with periapical lesions were studied. Periapical samples were collected in conjunction with apicoectomy, which was being performed because of radiographic evidence of incomplete periapical healing after conventional root canal therapy. By using established polymerase chain reaction primers and procedures, polymerase chain reaction assays were used to identify herpesvirus and cytokine gene expression. Results The difference in occurrence of HCMV, EBV, and cytokines between symptomatic and asymptomatic periapical lesions was statistically significant: HCMV ( P = .048), EBV ( P = .002), IFN ( P = .001), IL-1 ( P = .012), IL-6 ( P = .026), IL-10 ( P = .026), IL-12 ( P = .012), and TNF ( P < .001) (Mann-Whitney U test). There was a significant correlation between EBV, HCMV, and TNF, γ-IFN, IL-1, and IL-12 in symptomatic periapical lesions (Spearman test). Conclusions The present findings provide evidence of a putative role of HCMV and EBV in the pathogenesis of symptomatic periapical pathosis. The release of tissue-destructive cytokines might be of pathogenetic significance.

Relationship between human cytomegalovirus transcription and symptomatic apical periodontitis in Iran

Apical periodontitis of endodontic origin may develop as a result of cooperative interactions among herpesviruses, specific pathogenic bacteria and tissue-destructive inflammatory mediators. This study sought to identify the presence of Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) transcripts in symptomatic and asymptomatic periapical lesions of individuals living in Iran. Fifty endodontic patients (28 with symptomatic periapical lesions and 22 with asymptomatic periapical lesions) were included in the study. In each study subject, a microbiological periapical sample was collected using a curette in conjunction with periapical surgery. A reverse transcription-polymerase chain reaction assay was used to identify transcripts of EBV and HCMV. Human cytomegalovirus transcript was detected in 15 of the 28 (53.6%) symptomatic and in six of the 22 (27.3%) asymptomatic periapical study lesions (significant difference between symptomatic and asymptomatic lesions; P = 0.03, chi-square test). Epstein-Barr virus transcript was identified in one symptomatic and in two asymptomatic periapical lesions. This study establishes that HCMV transcription is common in apical periodontitis and is most frequent in symptomatic lesions. The high frequency of active herpesvirus infections in severe apical periodontitis changes the pathogenic paradigm of the disease and may also have preventive and therapeutic implications.

Cytomegalovirus infection in symptomatic periapical pathosis.

To compare the presence of human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) infections in samples from 25 symptomatic and 19 asymptomatic periapical lesions. Periapical samples were collected by sterile curettes in conjunction with apicectomy. cDNA-based HCMV and EBV identification was performed on total mRNAs extracted from peripapical tissues, using primers for genes transcribed during the productive phase of the herpesvirus infection. Statistical analysis was performed using chi-squared test. HCMV was detected in 100% of the symptomatic and in 37% of the asymptomatic study lesions. EBV was identified only in HCMV-infected periapical lesions. The difference in occurrence of HCMV and EBV between symptomatic and asymptomatic periapical lesions was statistically significant (P < 0.0001). The noteworthy finding of this study was the ubiquitous occurrence of HCMV active infection in symptomatic periapical pathosis. EBV may contribute to periapical pathogenesis in a subset of symptomatic lesions. HCMV and EBV infections may cause periapical pathosis by inducing cytokine and chemokine release from inflammatory or connective tissue cells, or by impairing local host defences resulting in heightened virulence of resident bacterial pathogens. Knowledge about the role of herpesviruses in periapical pathosis seems important to fully delineate the pathogenesis of endodontic infectious diseases. HCMV and probably EBV should be added to the list of putative pathogenic agents in symptomatic periapical disease.

Herpesviral-bacterial Coinfection in Periapical Pathosis

Two members of the herpesvirus family, human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV), seem to be important putative pathogens of human periodontitis and symptomatic periapical lesions, causing pathosis either by inducing immunosuppression with a subsequent risk of aggressive bacterial infections or by infecting of periodontal cells directly. This study aimed to relate periapical occurrence of HCMV, EBV, and herpes simplex virus active infections to clinical characteristics of periapical lesions and periapical bacterial flora. Microbial samples were collected from 34 periapical lesions in conjunction with periapical surgery. Part of the periapical specimen was frozen for virologic examination, and another part was transferred to anaerobic transport medium for bacteriologic examination. RNA was isolated by means of a guanidinium isothiocyanate-acid phenol procedure, and cDNA was produced using herpesvirus-specific primers and reverse-transcription polymerase chain reaction amplification. Bacteriologic examination was performed according to established anaerobic culture methods. Of the 34 periapical lesions studied, 20 showed both HCMV and EBV, seven showed only HCMV, one showed only EBV, and six showed neither HCMV nor EBV. Herpes simplex virus was detected in two lesions. Higher occurrence of herpesvirus was detected in large versus small periapical lesions (p < 0.001) and in symptomatic versus asymptomatic periapical lesions (p < 0.001). A total of 18 microbial groups and an average of 2.1 to 3.0 bacterial groups were isolated from various categories of periapical lesions. The important finding of this study was that most teeth with necrotic pulp and periapical lesions harbored herpesviruses in periapical granulomatous tissue. Herpesvirus species in cooperation with endodontopathic bacteria may play major roles in the etiopathogenesis of aggressive types of periapical pathosis in humans.

Microbial flora of root canal–treated teeth associated with asymptomatic periapical radiolucent lesions

This study aimed to investigate the composition of microflora in endodontically treated teeth associated with asymptomatic periapical lesions in southern Chinese patients. Twenty-four teeth which had received nonsurgical root canal treatment more than 4 years previously, and which presents an acceptable coronal restoration with a periapical radiolucent area, were re-treated nonsurgically. Bacteriological samples were obtained after removal of the old root canal filling. The samples were inoculated on enriched trypticase soy agar and four selective media for incubation at 37 degrees C in both a carbon dioxide-enriched atmosphere and anaerobically. Eighteen teeth that had received gutta-percha root canal fillings were grouped for analysis, 12 (66.7%) of which contained cultivable microorganisms. The total colony forming units per ml of transport medium ranged from 0 to 2.3 x 10(5). The number of bacterial genera recovered ranged between 0 and 6, with facultative gram-positive cocci being the most prevalent group of bacteria isolated. Facultative anaerobic bacteria were present in all, whereas strict anaerobic bacteria were found in 3 out of the 12 teeth with positive growth. The size of the periapical rarefaction did not show any relationship with the quantity of microorganisms recovered. Coagulase-negative staphylococci, streptococci and Pseudomonas aeruginosa were most frequently isolated in this group of patients. The possible origin of these organisms is discussed.

Concentrations of leukotriene B 4 in symptomatic and asymptomatic periapical lesions

Twelve periapical lesions from symptomatic and asymptomatic patients (six each) were obtained and immediately frozen in liquid nitrogen. Six pulps from unerupted third molars as well as chronically inflamed gingival tissues were also obtained, frozen, and used as negative and positive controls, respectively. The concentration of leukotriene (LT) B4 was determined by reverse phase high pressure liquid chromatography. Representative samples from each group were fixed in formalin, sectioned, and stained with hematoxylin and eosin. Extremely low levels of LTB4 were detected in the uninflamed pulpal samples in comparison to those found in chronically inflamed gingival tissues and periradicular lesions. A significant statistical difference was noted between concentrations of LTB4 in periapical lesions of symptomatic patients and those found in asymptomatic patients and samples of chronically inflamed gingival tissues (p < 0.05). In addition, a positive correlation was found between the presence of symptoms, the concentration of LTB4, and presence of polymorphonuclear leukocytes in symptomatic periapical lesions. The results show presence of high concentrations of LTB4 in symptomatic human periapical lesions.

Therapy-resistant foreign body giant cell granuloma at the periapex of a root-filled human tooth

Although the primary etiological factor of periapical lesions is microbial, there are other independent factors that can adversely affect the outcome of endodontic treatment. In this communication, we present morphological evidence in support of the role of a foreign body reaction of periapical tissue to root-filling materials. The specimen consisted of a surgical biopsy of an asymptomatic periapical lesion which persisted after a decade of postendodontic follow-up. The biopsy was processed for correlated light and electron microscopy and was analyzed by various microtechniques. The unique feature of the lesion was the presence of vast numbers of large multinucleated cells and their cytoplasmic inclusion bodies. Morphologically, these multinucleated cells resembled foreign body giant cells. They contained characteristic birefringent cytoplasmic inclusions which on electron-probe X-ray microanalysis consistently revealed the presence of magnesium and silicon. The magnesium and silicon are presumably the remnants of a root-filling excess which protruded into the periapex and had been resorbed during the follow-up period. These observations strongly suggest that in the absence of microbial factors, root-filling materials which contain irritating substances can evoke a foreign body reaction at the periapex, leading to the development of asymptomatic periapical lesions that may remain refractory to endodontic therapy for long periods of time.

Extraradicular endodontic infections.

Abstract Eight asymptomatic periapical inflammatory lesions which were refractory to conventional endodontic therapy were examined for the presence of bacteria. Access to the periapical lesions was gained using an aseptic surgical technique. Sterile currettes were used to take microbiological samples from the soft tissue lesions and scrapings from the surface of the root tips. Möller's VMGA III transport medium was utilized and the bacteriological samples were processed using a continuous anaerobic technique. Bacterial growth was evident in the samples from all 8 lesions. Two lesions exclusively yielded anaerobic bacteria and 5 lesions were heavily dominated by anaerobes. Black‐pigmented Bacteroides species as well as anaerobic gram–positive rods and cocci were isolated. Staphylococcus epidermidis was recovered from 3 lesions and 2 Actinomyces species were isolated from 1 lesion. Facultative Streptococcus species were rare periapical isolates. Our study clearly showed that anaerobic bacteria are able to survive and maintain an infectious disease process in periapical tissues.