M. Sabeti

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.

Herpesviruses in periapical pathosis: an etiopathogenic relationship?

BACKGROUND Much remains to be learned about the etiopathogenesis of periapical pathosis, especially about the molecular events preceding and causing disease onset. Human cytomegalovirus and Epstein-Barr virus, 2 herpesviruses, are discussed in this review as they relate to apical periodontitis in humans. RESULTS Cytomegalovirus or Epstein-Barr virus active infections are detected in more than 90% of granulomas of symptomatic and large periapical lesions. Dual infection with cytomegalovirus and Epstein-Barr virus is closely associated with symptomatic lesions. Herpes simplex virus active infection has no apparent relationship to periapical disease. DISCUSSION The available evidence suggests the involvement of active cytomegalovirus and Epstein-Barr infections in the etiopathogenesis of apical periodontitis. In periapical pathosis, herpesviruses may cause the release of tissue-destructive cytokines, the overgrowth of pathogenic bacteria, and the initiation of cytotoxic or immunopathologic events. Immune impairment resulting from herpesvirus infection may aid bacteria at several stages of the pathogenesis of periapical lesions, including growth in the periapical environment, possible invasion of tissue, and direct damage to tissue. Unraveling the etiology and pathogenesis of periapical pathosis may require a broadening of our experimental approaches to include studies on interactions among herpesviruses, bacteria, and host immune reactions. Understanding the significance of herpesviruses in the development of periapical lesions may aid in the diagnosis, prevention, and treatment of the diseases.

Cytomegalovirus and Epstein-Barr Virus Active Infection in Periapical Lesions of Teeth with Intact Crowns

Herpesviruses seem to play an important role in the pathogenesis of aggressive periodontitis and may also contribute to periapical pathosis. This study determined the presence of human cytomegalovirus, Epstein-Barr virus, and herpes simplex virus productive infection in five symptomatic periapical lesions of teeth having intact crowns and calcified necrotic pulps. Periapical samples were collected in conjunction with periapical surgery and kept frozen until virological examination. Reverse transcription-polymerase chain reaction was used in herpesviral identification. RNA was isolated from periapical tissue by a guanidinium isothiocyanate-acid phenol procedure. cDNAs were generated from highly conserved regions of the test viruses using a preamplification kit. Sensitivity and validity of the PCR-primers were determined according to established methods. Amplification products were identified using gel electrophoresis. Human cytomegalovirus and Epstein-Barr virus dual transcription was detected in all five periapical lesions studied. Herpes simplex virus transcript was not identified in any lesion. The present data suggest that human cytomegalovirus or Epstein-Barr virus activation participate in the pathogenesis of symptomatic periapical lesions. We hypothesize that periapical active herpesvirus infection impairs local defenses, thereby inducing overgrowth of endodontopathic bacteria and the clinical flare-up of inflammation.

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.

Detection of Receptor Activator of NF-κ β Ligand in Apical Periodontitis

A novel protein known as receptor activator of NF-κ β ligand (RANK-L) has been identified as a potential osteoclast differentiation factor. However, comparatively little is known about the expression of RANK-L in the pathogenesis of periradicular lesions. In this study, RANK-L expression was evaluated in biopsy specimens from apical periodontitis. Tissue samples from 21 periapical lesions were collected. RANK-L mRNA was isolated by using the guanidinium isothiocyanate acid phenol method. This was followed by generation of cDNA using specific primer for RANK-L by reverse transcription polymerase chain reaction amplification. RANK-L expression in each periapical sample was assessed by agarose gel electrophoresis. Gel electrophoresis analysis showed a single band of 385 bp corresponding to RANK-L in every periapical lesion. By contrast, normal control tissue showed no detectable RANK-L mRNA expression. In conclusion, RANK-L may play a role in apical periodontitis–induced bone resorption.

Penetration of Epiphany, Epiphany self-etch, and AH Plus into dentinal tubules: a scanning electron microscopy study.

INTRODUCTION The purpose of this study was to measure the average depth of dentinal tubule sealer penetration in the middle third of teeth obturated with gutta-percha/AH Plus (Dentsply, DeTrey, Konstanz, Germany), Resilon/Epiphany (Pentron Clinical Technologies, Wallingford, CT), and Resilon/Epiphany self-etch (SE) using scanning electron microscopy (SEM). METHODS The root canals of 36 extracted single-rooted human teeth were prepared and randomly divided into three groups. Obturations were performed with the following filling materials using the lateral compaction technique: group 1, gutta-percha/AH Plus; group 2, Resilon/Epiphany; and group 3, Resilon/Epiphany SE. The specimens were prepared for SEM examination. The average depth of sealer penetration into the dentinal tubules was measured. Data were analyzed by one-way analysis of variance and a post hoc Tukey test. RESULTS The mean (± standard deviation) values for the average depth of sealer penetration in the middle third of the roots were 22.07 ± 6.92 μm, 31.56 ± 6.80 μm, and 21.50 ± 9.25 μm for AH Plus, Epiphany, and Epiphany SE, respectively. The average penetration depth of Epiphany was significantly higher than that of Epiphany SE and AH Plus (P < .05). There was no significant difference between the penetration depth of Epiphany SE and AH Plus (P > .05). CONCLUSIONS It could be concluded that the average penetration for Epiphany into dentinal tubules within the middle third of the roots was significantly deeper than that of Epiphany SE and AH Plus.

Push-out Bond Strength of Resilon/Epiphany Self-etch to Intraradicular Dentin after Retreatment: A Preliminary Study

INTRODUCTION Retreatment procedures might affect the adhesion capability of refilling materials to dentinal walls. The purpose of this study was to compare the effect of different retreatment techniques on bond strength of Resilon (Resilon Research LLC, Madison, CT)/Epiphany (Pentron Clinical Technologies, LLC, Wallingford, CT) self-etch (SE) with radicular dentin after canal reobturation. METHODS Sixty extracted single-rooted human teeth were prepared using Mtwo rotary files (VDW, Munich, Germany) and obturated with Resilon/Epiphany SE. The roots were randomly divided into four groups; in group 1, no retreatment procedure was done; group 2 was retreated using Mtwo R/Mtwo files; group 3 was retreated using Mtwo R/Mtwo combined with chloroform; and group 4 was retreated using Mtwo R/Mtwo combined with Endosolv R (Septodont, Paris, France). The root canals were then reobturated with Resilon/Epiphany SE. One-millimeter slices of midroot dentin were prepared for the push-out test (n=30 slices per group). Failure modes after the push-out test were examined under microscopy. The data were analyzed by using a one-way analysis of variance and the Dunnett post hoc test. RESULTS Group 3 showed significantly the lowest mean bond strength (p<0.02). No significant difference was found between the values of groups 1, 2, and 4 (p>0.26). The mode of bond failure was predominantly adhesive for all groups. CONCLUSIONS This study showed that the bond strength of Resilon/Epiphany SE after root canal retreatment using Mtwo files, either alone or combined with Endosolv R, was not significantly different from that of nonretreated specimens. Chloroform used for retreatment had an adverse effect on the bond strength of Resilon/Epiphany SE after root canal reobturation.

Push-out bond strength of Resilon/Epiphany self-etch and gutta-percha/AH26 after different irrigation protocols.

OBJECTIVE The purpose of this study was to compare the bond strength of Resilon/Epiphany self-etch (SE) and gutta-percha/AH26 after different irrigation protocols. STUDY DESIGN Extracted single-rooted human teeth were divided into 4 groups and prepared. According to irrigation protocols, groups were: 5.25% NaOCl followed by 17% ethylenediaminetetraacetic acid (EDTA) (groups 1 and 2); and 1.3% NaOCl followed by MTAD (a mixture of tetracycline isomer, an acid, and a detergent) (groups 3 and 4). The root canals were obturated with either gutta-percha/AH26 (groups 1 and 3) or Resilon/Epiphany SE (groups 2 and 4). Push-out bond strength and failure modes were determined. RESULTS Gutta-percha/AH26 showed significantly higher bond strength than Resilon/Epiphany SE. The group with 5.25% NaOCl + EDTA and gutta-percha had a significantly higher bond strength than all of the other groups (P < .05); 1.3% NaOCl + MTAD with gutta-percha showed significantly higher bond strength than 5.25% NaOCl + EDTA with Resilon and 1.3% NaOCl + MTAD with Resilon. There was no significant difference between the bond strengths of the Resilon groups (P > .05). The failure mode for all of the experimental groups was mainly adhesive. CONCLUSIONS Irrigation with 5.25% NaOCl + EDTA can be a better conditioner before using gutta-percha/AH26. The bond strength of Resilon/Epiphany SE was not different after irrigation with 5.25% NaOCl + EDTA or 1.3% NaOCl + MTAD.

Relationship between human cytomegalovirus transcription and symptomatic apical periodontitis in Iran

BACKGROUND/AIMS 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. MATERIAL AND METHODS 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. RESULTS 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. CONCLUSION 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‐infected inflammatory cells in dental periapical lesions

INTRODUCTION As cytomegalovirus may be etiologically involved in periapical pathosis of endodontic origin, this study aimed to determine the cellular source of periapical cytomegalovirus. METHODS Periapical granulomatous tissue was collected from 15 extracted teeth with symptomatic periapical lesions. Multi-color flow cytometry was used to identify cytomegalovirus-infected cells. RESULTS Cytomegalovirus infection was identified in 10 of the 15 (67%) study lesions, and in periapical monocytes/macrophages (40% of lesions) and T lymphocytes (54% of lesions), but not in periapical B lymphocytes. CONCLUSION This study and previous polymerase chain reaction-based investigations show that cytomegalovirus is a frequent inhabitant of symptomatic periapical lesions.