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PubMed2005

Fibroblastic cells from human periapical granulation tissue preferentially form calcified matrices in decalcified boiled rat bone.

We have been studying the potential of human fibroblastic cells (HFC) from periapical granulation tissue to form a calcified matrix. Recently, we reported that inflamed periapical granulation tissue contains osteogenic cells. In the present study, we tested the hypothesis that HFC, cultured with decalcified bone (DB) of rat, might form much greater calcified matrices than with rat decalcified boiled bone (DBB), which was originally prepared as a negative control. HFC were cultured with DB or DBB in the presence or absence of 2 mM beta-glycerophosphate (beta-GP) and 50 microg/ml ascorbic acid. After six weeks of culture, a number of von Kossa-positive globular structures were unexpectedly observed inside DBB, but not DB. Without HFC, such structures were never seen in DBB incubated with 2 mM beta-GP and 50 microg/ml ascorbic acid. DB cultured with HFC under the same conditions did not show these structures. Electron-microscopic observation revealed that matrix vesicles aggregated on collagen fibrils around globular structures in DBB. Energy dispersive X-ray microanalysis confirmed that these structures were calcified matrices composed of calcium and phosphate. These results suggest that human periapical granulation tissue contains cells responsible for the formation of calcified matrices in DBB, and that DBB could serve as an excellent scaffold for the calcification of HFC, rather than DB.

Animals↗
PubMed2001

Presence of IFN-gamma and IL-4 in human periapical granulation tissues and regeneration tissues.

To study mediators associated with the progression of disease and the process of bone regeneration in human apical periodontitis, we examined samples of periapical granulation tissues and regeneration tissues obtained from five patients by use of immunohistochemical methods. Periapical granulation tissues were found to contain a large number of CD4-positive T cells and CD68-positive monocytes/macrophages (CD4: 35.2%, CD68: 32.7%). The CD4-positive T cells and CD68-positive monocytes/macrophages were predominantly present in regeneration tissues (CD4: 62.1%, CD68: 16.0%). In these the percentages of CD4-positive T cells were higher as compared with periapical granulation tissues (from 35.2% to 62.1%). In periapical granulation tissues, CD4-positive T cells stained positively for interferon-gamma (IFN-gamma) and negatively for interleukin-4 (IL-4). In regeneration tissues, IL-4-producing cells could be detected. However, IFN-gamma-producing cells could not be detected. These results suggest that IFN-gamma and IL-4 may modulate the pathogenesis of infectious disease and the process of bone regeneration in local inflammation sites such as human apical periodontitis.

Adolescent↗
PubMed1990

Differential localization of type I and type III procollagen messenger ribonucleic acids in inflamed periodontal and periapical connective tissues by in situ hybridization.

Inflammatory lesions of periodontal and periapical connective tissue were studied by in situ hybridization to detect cells responsible for type I and type III collagen production. Formalin-fixed and paraffin-embedded tissue specimens from patients with oral lesions of various stages of inflammation were hybridized with cDNA probes specific for human pro alpha 1(I) and pro alpha 1(III) collagen mRNAs, and with bacteriophage lambda DNA as a control probe. This technique permitted us to localize fibroblasts active in type I collagen synthesis in the vicinity of inflammatory infiltrates in all the samples studied. Cells containing high levels of type III collagen mRNA were seen in early abscess formation and they were particularly abundant in pyogenic granuloma and irritation fibroma. Type I collagen mRNA was prominent in gingival fibrosis. In the infrabony lesions with active inflammatory infiltrations the production of collagen was confined mostly to the periphery of the lesions. These findings give indirect evidence that cytokines liberated during the early stages of the inflammatory process stimulate expression of the type III collagen gene by fibroblasts. In chronic lesions a gradual switch from type III to type I collagen gene expression occurs. The change in collagen types appears to underlie the observed isolation of the inflammation by a collagenous capsule. In all the samples studied fibroblasts exhibited marked variation in their levels of procollagen mRNAs, supporting previous views about their heterogeneity in connective tissues. The approach presented here offers new possibilities to study cellular interactions and metabolic activities in inflammatory lesions.

Adolescent↗
PubMed2004

Pathogenesis of apical periodontitis and the causes of endodontic failures.

Apical periodontitis is a sequel to endodontic infection and manifests itself as the host defense response to microbial challenge emanating from the root canal system. It is viewed as a dynamic encounter between microbial factors and host defenses at the interface between infected radicular pulp and periodontal ligament that results in local inflammation, resorption of hard tissues, destruction of other periapical tissues, and eventual formation of various histopathological categories of apical periodontitis, commonly referred to as periapical lesions. The treatment of apical periodontitis, as a disease of root canal infection, consists of eradicating microbes or substantially reducing the microbial load from the root canal and preventing re-infection by orthograde root filling. The treatment has a remarkably high degree of success. Nevertheless, endodontic treatment can fail. Most failures occur when treatment procedures, mostly of a technical nature, have not reached a satisfactory standard for the control and elimination of infection. Even when the highest standards and the most careful procedures are followed, failures still occur. This is because there are root canal regions that cannot be cleaned and obturated with existing equipments, materials, and techniques, and thus, infection can persist. In very rare cases, there are also factors located within the inflamed periapical tissue that can interfere with post-treatment healing of the lesion. The data on the biological causes of endodontic failures are recent and scattered in various journals. This communication is meant to provide a comprehensive overview of the etio-pathogenesis of apical periodontitis and the causes of failed endodontic treatments that can be visualized in radiographs as asymptomatic post-treatment periapical radiolucencies.

Animals↗
PubMed1992

Endotoxin and gram-negative bacteria in the rat periapical lesions.

The purpose of this study was to measure the amount of endotoxin as well as to identify Gram-negative bacteria in experimental periapical lesions in rats. Molar pulps were exposed and infected and the amount of endotoxin in the periapical tissue of the right mandibular first molar was measured by Endospecy, while the colony number of Gram-negative bacteria was determined in the same region of the left mandibular first molar. In the control animals, the amount of endotoxin in the periapical tissues did not change at all during the experimental period, and no Gram-negative bacteria were isolated. In the experimental animals, the amount of endotoxin in the periapical tissues increased gradually from 1 to 70 days, and its level was significantly greater than that of control animals after 7 days. Gram-negative bacteria were isolated from the periapical tissues and their number gradually increased from 1 to 14 days (26 to 82%), but decreased at 21 days. It was approximately 60% from 28 to 70 days. The results of this study showed that the amount of endotoxin in the periapical tissues gradually increased with increasing time and that Gram-negative bacteria were isolated from the same region but did not increase in number concurrently with the increase in the amount of endotoxin.

Animals↗
PubMed1991

Healing assessment of osseous defects of periapical lesions associated with failed endodontically treated teeth with use of freeze-dried bone allograft.

Freeze-dried bone allograft (FDBA) has been used extensively in periodontal surgery and in the treatment of pocket osseous defects resulting from inflammatory periodontal disease. No other endodontic investigation has used this type of graft material in the treatment of bony resorptive defects of the periapical lesions associated with failed endodontic therapy. Therefore this study was conducted with the use of FDBA, to assess healing ability of osseous defects after removal of periapical lesions associated with failed endodontically treated teeth. In all patients periapical lesions were surgically removed with retrograde amalgam seal and the graft material was then carefully packed without pressure into the bony defect. The lesions were fixed in 10% neutral buffered formalin and prepared for histologic examination. Long-term recall demonstrated bone regeneration and good tolerance of allograft material by the periapical tissues. The periapical lesions were either periapical granulomas or apical periodontal cysts. We conclude that FDBA is a biocompatible material of osteogenic potential and can be used effectively in treating osseous defects of periapical lesions associated with failed endodontically treated teeth.

Adolescent↗
PubMed2000

Cytokine expression in periapical granulation tissue as assessed by immunohistochemistry.

The aims of this study were to investigate the expression of pro-inflammatory, anti-inflammatory and immune-related cytokines present in periapical lesions. We investigated the expression of cytokines: namely interleukins IL-2, IL-4, IL-6, IL-10 and interferon-gamma (IFN-gamma) in formalin-fixed, paraffin-embedded sections of periapical granulation tissue. The study samples were biopsies from 24 patients with periapical lesions: 12 with periapical granulomas and 12 patients with radicular cysts. Immunohistochemistry was also performed on tonsillar tissue which served as a control. We utilised a set of specific monoclonal antibodies and polyclonal monospecific antibodies to detect cells that expressed the different cytokines within the tissues. We also considered the nature of the periapical immune response by investigation of the T-helper 1 (Th-1) and T-helper 2 (Th-2) lymphocyte subsets using their cytokine profile, i.e., Th-1: IL-2 and IFN-gamma and Th-2: IL-4, IL-5 and IL-6. Only a few cells were weakly positive for the IL-2 protein in each of the tissue sections. Cells that expressed IL-4 or IL-6 were far more numerous than cells that expressed either IL-2 or IFN-gamma. Thus, we demonstrated a greater number of Th-2 cells in periapical lesions. This relative ratio of the T-cell subsets underlines the importance of the anti-inflammatory mechanisms taking place in the diseased tissue manifested by the wide array of IL-10-expressing cells: B cells, T suppressor cells (CD8 (+)) and tissue macrophages. The numbers of inflammatory cells expressing the anti-inflammatory molecules far outnumbered the cells that expressed pro-inflammatory cytokines. Thus, the downregulation of the inflammatory response and the predominant Th-2 or humoral immune response in periapical periodontitis may be important features that dictate the outcome of the disease process in the periapical lesion.

Adult↗
PubMed1992

Apical closure of an immature root subsequent to apical curettage.

A 7-year-old female presented with a history of trauma to the mandibular central incisor resulting in pulpal necrosis and soft tissue swelling. During apexification treatment, an ultrasonic file was separated and lodged in the periapical tissues. Surgical retrieval of the broken instrument resulted in complete curettage of the periapical tissues. Apical closure occurred following intracanal calcium hydroxide therapy. The findings suggested that hard tissue barrier formation occurred despite the absence of Hertwig's epithelial root sheath and local periapical tissues.

Calcium Hydroxide↗
PubMed1992

A bacteriological and histological evaluation of 58 periapical lesions.

Periapical tissue from 58 cases requiring periapical surgery was examined histologically and cultured for the presence of microbes. Twenty-nine had a possible oral cavity communication and 29 did not. Approximately one-half of each biopsy was submitted for culture while the other portion was examined histologically. Cultures were positive for the presence of bacteria in 51 of 58 cases while bacteria were seen histologically in only 8 of 58 cases. A total of 50 different species of bacteria were isolated from the 58 cultures of periapical tissue. Of 133 isolates, 87 were strict anaerobes, 37 were facultative anaerobes, and 9 were aerobes. Bacteroides species were found in 17 cultures, always with additional bacteria. Seventeen of 58 biopsies contained foreign particulate matter thought to be root canal sealer. Bacteria were found in periapical granulomas, radicular cysts, and a periapical abscess. According to our data, bacteria, foreign material, missed canals, vertical root fractures, and periodontal disease may all contribute to the chronic, non-healing periradicular lesion.

Bacteria, Anaerobic↗
PubMed2001

Is herpes simplex virus associated with pulp/periapical inflammation?

OBJECTIVES: This study focuses on the detection of herpes simplex virus (HSV) DNA in dental pulp and inflamed periapical tissue. STUDY DESIGN: Dental pulp tissue (vital and necrotic) and periapical tissue samples were collected under strictly sterile conditions and examined for the presence of HSV DNA. Saliva samples were also examined for the presence of the viral DNA. The polymerase chain reaction assay was used to detect viral DNA. Blood samples were collected, and the enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies against HSV was carried out. RESULTS: According to the ELISA test, 19 of the 23 blood samples were IgG-positive and IgM-negative to HSV, whereas 4 were IgG-negative and IgM-negative. HSV DNA was not detected in the tissue and the saliva samples tested. CONCLUSION: HSV is not present and therefore is probably not involved in the pathology of tooth neural tissue.

Adolescent↗
PubMed1990

[Histopathological studies on tissue reactions to experimental root canal sealer in cats].

This study was designed to elucidate whether or not the root canal sealers, newly prepared here, show high affinities and promote the osteo-cicatric healing for the remaining dental pulp and periapical regions. For these purposes, I used two types of sealers, newly devised here and mainly composed of powdered corals mixed with propyreneglycol for the experiment 1 and powdered human dentins mixed with atelocollagen implant for the experiment 2. Guttapercha points with these sealers were applied in the premolar and molar tooth mesial or distal canals of 24 adult cats, whereas in controls guttapercha points with Canals, made commercially, were used instead of these sealers. After treatment, the periapical tissues and accessory root canal regions were histopathologically observed at different intervals throughout 30 to 130 days. The results obtained were as follows: 1. When guttapercha points were penetrated beyond the apical foramen and reached periapical tissues, prolonged inflammatory reactions of a slight or medium degree were observed in all three types of sealers. 2. When Canals were applied, prolonged inflammatory reactions were persistent if the sealer flooded out. In contrast, if they were in just-filling (Type-I, as termed in text), inflammatory reactions were often detectable at the accessory root regions. Many exudative inflammatory cells around the over-tip of guttapercha points were seen, as compared around the apicals of the dental root. 3. When powdered coral was used, strong inflammatory reactions was little found. Adjunction of the new bone was usually observed in the alveolar bone. The tendency of scar formations was seen in the periapical tissues where the inflammatory reaction was assumed to have occurred. 4. When powdered human dentin was used, in any experiments, inflammatory reaction were not seen with a few exceptions. However, if inflammatory responses were existed in a few cases, their degrees were relatively strong. 5. If the debris of dentin was blocked within the root canal apex, fine examples were seen regardless of the three types of the sealers. 6. Calcium in the powdered coral showed a conspicuous peak by energy X-ray analysis. The ratio of Ca and P of powdered human dentin was 1:1. From the above findings, both powdered coral and powdered human dentin could be useful as composites of sealers.

Animals↗
PubMed1998

Apical limit of root canal instrumentation and obturation, part 2. A histological study.

The results of an in vivo histological study involving apical and periapical tissues following root canal therapy after different observation periods demonstrated the most favourable histological conditions when the instrumentation and obturation remained at or short of the apical constriction. This was the case in the presence of vital or necrotic pulps, also when bacteria had penetrated the foramen and were present in the periapical tissues. When the sealer and/or the gutta-percha was extruded into the periapical tissue, the lateral canals and the apical ramifications, there was always a severe inflammatory reaction including a foreign body reaction despite a clinical absence of pain.

Adolescent↗
PubMed2005

Histological observations of periradicular healing following root canal treatment.

The purpose of this study was to observe histologically the sequence of events leading to resolution of periradicular tissues, with a view to advancing the perception of periapical healing. Our material consisted of periapical specimens obtained from 15 single-rooted, endodontically treated teeth of patients aged 25-40 years. All the teeth required extraction because of complicated crown-root fracture following trauma, iatrogenic aetiology (cervical root resorption following bleaching) or extensive carious lesions. The patients were informed that, based on their clinical condition, surgical procedures should be performed under flap reflection in order to extract the fractured root. Informed consent, which was necessary for the surgery, was obtained in all cases. A small block section containing the apical root tip and surrounding periapical tissues was removed prior to root extraction. The results of histological examination revealed osteoblastic activty and osteoid bone formation six days after the root canal instrumentation. Periapical tissue healing was observed despite the presence of overfilled material. The lining epithelium was infiltrated with chronic inflammatory cells and surrounded by collagen bundles and newly formed bone.

Adult↗
PubMed1994

Distribution of Ia antigen-expressing nonlymphoid cells in various stages of induced periapical lesions in rat molars.

Periapical lesions were experimentally produced in rat lower first molars by exposing the pulp to the oral environment for 1 to 56 days. Temporal changes in the number and distribution of la antigen-expressing nonlymphoid cells in the periapical tissue were examined immunohistochemically on decalcified cryostat sections using OX6, a monoclonal antibody against rat la antigen. Influx of la-positive exudative cells into the periapical tissue was observed from 1 day postoperatively. Between 14 and 28 days when expansion of the periapical lesion was most evident, numerous la-positive macrophage-like and dendritic cell-like cells of diverse morphologies were found in the periapical tissue. The number of these cells showed further increase at 56 days postoperatively, when the lesion expansion had ceased. These results suggest the involvement of la antigen-expressing nonlymphoid cells in the development and perpetuation of periapical pathosis. They may act primarily as antigen-presenting cells, which are essential for the initiation of antigen-specific immune defense.

Animals↗
PubMed1994

Irritating effect of formocresol after pulpectomy in vivo.

A study was carried out to investigate the effect of formocresol (formalin-creosote) on the periapical tissue after pulpectomy in rats. A pulpectomy was performed on the mesial root of the right mandibular first molar, and, in group A, a paper point containing saline was inserted into the root canal. In group B, a paper point containing formocresol was inserted, and in group C, a drop of formocresol was applied and a paper point containing formocresol was inserted into the root canal. The periapical tissue was examined histologically and histometrically at 3, 7, 14, and 28 days after insertion, and the inflammatory cells and fibroblasts in the apical granulation tissue were also counted. Histologically, in group A, the inflammation observed was slight at 14 and 28 days, while in groups B and C, a moderate inflammation remained. Histometrically, the area of the apical periodontal ligament in groups B and C was increased significantly compared with that in group A at 14 and 28 days. The inflammatory cell count in groups B and C increased significantly compared with that in group A at 7, 14, and 28 days, whereas the fibroblast count in Groups B and C decreased compared with that in Group A at 7, 14, and 28 days. These results demonstrate that formocresol delayed the healing of periapical tissue after pulpectomy.

Animals↗
PubMed2002

Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment.

OBJECTIVE: The objective of this study was to evaluate the histopathologic response of periapical tissues after root canal treatment of necrotic dog teeth with chronic apical periodontitis by using 2 calcium hydroxide-based root canal dressings and 2 root canal sealers. STUDY DESIGN: Seventy-eight root canals were instrumented by using 5.25% sodium hypochlorite as the irrigating solution, after which a calcium hydroxide paste (Calen/PMCC or Calasept) was placed for 30 days as a dressing. The root canals were then filled by using cold lateral gutta-percha condensation and an endodontic sealer (Sealapex or AH Plus). After 360 days, the animals were killed by anesthetic overdose; then, the teeth were histologically prepared, sectioned, and stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical tissue repair. RESULTS: Statistical analysis showed that the poorest histopathologic results were observed in the Calasept/AH Plus group and that the Sealapex sealer overall resulted in better apical repair than the AH Plus sealer. The histopathologic results of Calen/PMCC paste with both AH Plus and Sealapex and Calasept paste with only Sealapex were statistically similar but were different from the results of Calasept with AH Plus. CONCLUSIONS: The results of this study in the dog showed differences in apical and periapical tissue repair of teeth with chronic apical periodontitis by using 2 calcium hydroxide root canal dressings and 2 sealers. More research is necessary to determine the best combination of dressings and sealers.

Animals↗
PubMed1983

Application of statistical decision theory to radiographic diagnosis of endodontically treated teeth.

The presence or absence of periapical radiolucencies, after a predetermined healing period, have been used as a criteria for therapeutic success or failure in endodontic treatment. However, in radiologic diagnosis it has been shown that variations within and between examiners are substantial. In the present study six endodontists evaluated the periapical tissues in radiographs of 119 endodontically treated roots using a five-graded rating scale. An earlier study on the same radiograph material served as reference and "true" states of the periapical tissues were established. True positive and false positive reports on the presence of periapical lesions could then be calculated. For each observer it was noticed that a higher true positive percentage always was coupled with a higher false positive percentage and vice versa. If pairs of true positive and false positive percentages were plotted on a two-dimensional graph they corresponded well to a Receiver Operating Characteristic (ROC) curve. Variations between the observers could be explained by their adoption of different criteria of periapical disease resulting in different positions on the ROC curve. Influence of observer variation on reported frequencies of periapical lesions was greater, the lower the prevalence of the disease. The best opportunities for revealing relative differences in disease prevalences was created when the examiner defined a strict criterion for disease and reported a positive finding only when absolutely certain.

Decision Theory↗