Histochemical study of strain L fibroblasts exposed to endotoxin. The effect on cellular organelles

Fluorosed fibroblast attachment on fluorosed and nonfluorosed teeth after SRP and EDTA root biomodification

BACKGROUND

Fluorosis causes mineralization changes in the tooth and can lead to morphologic alterations of fibroblasts. To understand the effect of fluorosis on periodontal healing, the initial step during healing, such as fibroblast attachment to the root surface, needs to be evaluated. Hence, the objective of the present study was to study the attachment of fluorosed fibroblasts on the fluorosed and nonfluorosed root fragments.

MATERIALS AND METHODS

A total of 56 fluorosed and nonfluorosed, periodontally healthy and diseased tooth roots were obtained and allotted to eight groups: Fluorosed and nonfluorosed healthy controls (FH and NFH, respectively), fluorosed and nonfluorosed diseased controls (FD and NFD, respectively), fluorosed and nonfluorosed roots treated with scaling and root planing (FD + S and NFD + S, respectively), and similar groups treated with scaling and root planing and 24% ethylenediaminetetraacetic acid (EDTA) gel application for 2 min (FD + SE and NFD + SE, respectively). After the respective treatment, the root fragments were incubated in the human periodontal ligament fibroblast cells obtained and cultured from freshly extracted healthy human fluorosed premolar tooth root.

RESULTS

In the nonfluorosed roots category, greater attachment was found in the untreated nonfluorosed diseased (P = 0.036) and SRP-treated nonfluorosed diseased groups (P = 0.008) as compared to the nonfluorosed healthy group. While in the fluorosed roots category, no significant difference was observed in FL-FA (P > 0.05) within the group. However, no attachment was observed in EDTA-treated fluorosed root fragments. When fluorosed groups were compared to nonfluorosed groups, no significant changes were noted between the groups.

CONCLUSION

SRP proves to be a standard requirement for fibroblast attachment to occur both in fluorosed and nonfluorosed roots. Although there was no significant difference in attachment between SRP and SRP + EDTA among fluorosed roots, EDTA does not seem to be a promising agent for root biomodification in fluorosed roots in a given concentration and time of treatment.

In vitro evaluation of the biocompatibility of contaminated implant surfaces treated with an Er : YAG laser and an air powder system

Titanium platelets with a sand-blasted and acid-etched surface were coated with bovine serum albumin and incubated with a suspension of Porphyromonas gingivalis (ATCC 33277). Four groups with a total of 48 specimens were formed. Laser irradiation of the specimens (n = 12) was performed on a computer-controlled XY translation stage at pulse energy 60 mJ and frequency 10 pps. Twelve specimens were treated with an air powder system. After the respective treatment, human gingival fibroblasts were incubated on the specimens. The proliferation rate was determined by means of fluorescence activity of a redox indicator (Alamar Blue Assay) which is reduced by metabolic activity related to cellular growth. Proliferation was determined up to 72 h. Contaminated and non-treated as well as sterile specimens served as positive and negative controls. Proliferation activity was significantly (Mann-Whitney U-test, P < 0.05) reduced on contaminated and non-treated platelets when compared to sterile specimens. Both on laser as well as air powder-treated specimens, cell growth was not significantly different from that on sterile specimens. Air powder treatment led to microscopically visible alterations of the implant surface whereas laser-treated surfaces remained unchanged. Both air powder and Er : YAG laser irradiation have a good potential to remove cytotoxic bacterial components from implant surfaces. At the irradiation parameters investigated, the Er : YAG laser ensures a reliable decontamination of implants in vitro without altering surface morphology.

Effect of diode laser irradiation on the attachment rate of periodontal ligament cells: an in vitro study

BACKGROUND

The present study is part of a basic research program investigating the cellular effects of an 810 nm GaAlAs-diode laser on human periodontal tissues. The aim of the investigation was to evaluate the effects of laser treatment of root surface specimens on the attachment of periodontal ligament (PDL) cells in vitro.

METHODS

Root specimens were prepared from periodontally diseased teeth. PDL cells were obtained from human third molar ligaments. Cells were cultured under simple, standardized, and reproducible experimental conditions. One hundred fifty root specimens were scaled and root planed with curets followed by air-powder abrasive treatment; 75 were then lased and 75 served as controls. The irradiation time was 20 seconds at a power output of 1 W. The root segments were placed into culture dishes, covered with a solution of PDL cells, and incubated for 72 hours. The specimens were then washed with phosphate buffer to remove cells not attached to the surface, and the adherent cells were stained with methylene blue. Cells were counted using a reflected light microscope and the cell density per mm2 was calculated.

RESULTS

The analysis of 150 specimens revealed no significant differences between the groups (P = 0.347, Wilcoxon test). The cell numbers, however, were slightly higher on laser specimens. The mean was 66 cells/mm2 in the laser group and 63.7 cells/mm2 in the control group.

CONCLUSIONS

The application of the diode laser at the parameters used did not have a substantially positive effect on the new attachment of PDL cells on the tooth specimens. It remains to be investigated whether the difference detected is really clinically relevant.

Scanning electron microscopic study of the effects of Er:YAG laser on root cementum

Use of Er:YAG laser has been proposed for the removal of microbial deposits and calculus present on teeth affected by periodontal disease. However, the influence of Er:YAG laser irradiation on root surfaces has not yet been fully investigated. The aim of the present study was to evaluate the effects of Er:YAG laser irradiation on root cementum by scanning electron microscopy (SEM). Specimens were obtained from extracted human periodontally-diseased teeth using a water-cooled high-speed bur. An Er:YAG laser beam was then applied at various powers ranging from 25 to 100 mJ/ pulse/sec. The laser irradiation was performed under water irrigation, with the tip held perpendicular to the root surface in the contact mode. Following laser exposure, specimens were fixed, dehydrated, and dried at critical-point in liquid CO2. After mounting on SEM plates and sputter-coating with gold, the cementum surface was examined by SEM. Observations of the root surface showed a relatively flat surface in control specimens. In Er:YAG exposed specimens, the laser beam created a circular, notched-edge, crater-like defect on the root. The bottom of the lesion showed an irregular and sharp-pointed surface. Subsequently, the specimens were fractured with a sharp scalpel perpendicularly to the surface. SEM observations of these specimens showed a 15 microm layer of damaged tissue within the laser-irradiated cementum. The tissue presented an amorphous appearance and the Sharpey's and matrix fiber bundles were not clearly distinguishable. These observations indicate that cementum tissue could be damaged by Er:YAG laser irradiation.

Cytokine-inducing components of periodontopathogenic bacteria

Pro-inflammatory cytokines such as interleukin (IL)-1, IL-6, IL-8 and tumour necrosis factor (TNF) are believed to be the major pathological mediators of inflammatory diseases ranging from arthritis to the periodontal diseases. The stimuli inducing proinflammatory cytokine induction in the former disease is unclear but in the periodontal diseases it is obvious that the stimulus is the accumulation of bacteria in the subgingival region. As these bacteria do not invade the lesional tissues in large numbers, it is believed that their soluble components or products interact with host tissues to induce cytokine gene transcription. The paradigm is that lipopolysaccharide is the key bacterial component inducing pro-inflammatory cytokine gene expression. However, over the past decade a growing number of reports on non-oral bacteria have established that many other bacterial components, as well as secretory products, have the capacity to induce cytokine synthesis. Some of these, such as the protein pneumolysin from Streptococcus pneumoniae, are incredibly potent (in this case inducing cytokine synthesis at femtomolar concentrations). This review surveys the range of bacterial components and products which have been shown to stimulate cytokine synthesis with particular emphasis on the hypothesis that these components play a role in the pathology of the periodontal diseases.

The effects of the Nd:YAG laser on in vitro fibroblast attachment to endotoxin-treated root surfaces

The purpose of this study was to evaluate the effects of the Nd:YAG laser on in vitro fibroblast attachment to endotoxin-treated root surfaces and to describe any laser-induced cementum surface alterations. Thirty 4 mm x 4 mm cementum segments were obtained from unerupted third molars. The treatment groups were as follows: 1) control, healthy root segment; 2) non-lased, endotoxin treated; and 3) lased, endotoxin treated. The endotoxin treated roots were soaked in E. coli 055:B5 lipopolysaccharide (556 EU/ml) for 72 hours. The lased, endotoxin-treated root segments were treated with a Nd:YAG laser using a 320 microns contact optic fiber handpiece with an energy setting of 80 mJ at 10 pulses per second for one minute. The root segments were subsequently placed in fibroblast culture dishes for 40 hours and then prepared for scanning electron microscopy (SEM) observation. SEM examination revealed two different types of attachment: flat and round. Flat cells represented firmly attached cells due to well-defined points of attachment and numerous lamellapodia. Round cells possessed few attachment processes and were, therefore, considered poorly attached. The lased, endotoxin-treated root segments had significantly decreased numbers of flat fibroblasts versus the control and non-lased, endotoxin-treated root segments. The absence of flat fibroblasts in the laser treated root segments was a consistent finding. The non-lased, endotoxin-treated root segments had significantly increased numbers of round fibroblasts versus the control and lased, endotoxin treated groups. The lased root segments exhibited surface alterations which included charring, crater formation, cementum meltdown, and tracking.(ABSTRACT TRUNCATED AT 250 WORDS)

A quantitative analysis of the migration, attachment, and orientation of human gingival fibroblasts to human dental root surfaces in vitro

The purpose of this study was to assess the migration, attachment, and orientation of human gingival fibroblasts to human dental roots over a period of 21 days in vitro. The fibroblasts were incubated with a total of 120 periodontally diseased and non-diseased root slices (200 microns thickness) which had been treated in the following manner: 1) Root planed diseased root (DT); 2) Root planed and citric acid demineralized diseased root (DTD); 3) Non-treated diseased root (DNT); 4) Citric acid demineralized diseased root (DNTD); 5) Non-diseased control (ND); 6) Citric acid demineralized non-diseased root (CA); 7) Citric acid and collagenase digested non-diseased root (CAC); 8) EDTA demineralized non-diseased root (E); and 9) EDTA-demineralized and collagenase-digested non-diseased root (EC). The results showed that that most active phase of cell attachment and orientation occurred during the first 10 days of the experiment. Statistical differences were observed between the variables, and, in terms of cell attachment and orientation to the root slices, it was concluded that: 1) Root planing improves diseased roots; 2) Acid demineralization subsequent to root planing improved diseased roots to such an extent as to render them comparable to non-diseased roots; 3) Citric acid demineralization alone improved diseased roots to the same extent as root planed diseased roots; 4) The exposure of collagen fibrils resulting from acid demineralization of the tools is not the sole reason for the improvement of the root surface, but rather a combination of the exposed collagen fibrils with the creation of a more hospitable environment was found to be responsible.

Hand versus ultrasonic instrumentation in the removal of endotoxins from root surfaces in vitro

The goal of this study was to determine whether ultrasonic scalers are as effective as curettes in providing fibroblast attachment to the scaled root surfaces. Extracted, peridontally involved teeth were cut along the sagittal plane; then one half of the root was curetted, the other half ultrasonically scaled. In addition, monkey kidney fibroblasts were suspended in a petri dish containing root fragments of the tooth halves. At the same time, control dishes without fragments were mounted. All dishes were treated with radioisotopic techniques. There was no significant difference in fibroblast growth between peridontally involved root surfaces treated using curettes or ultrasonic scalers. Both treatments caused the roots to lose their toxicity. The limitations of ultrasonic scalers in terms of shape, size and awkward handling need to be considered when choosing the approach that best suits each case.

Blastogenetic responsiveness of peripheral blood lymphocytes from patients with adult periodontitis, evaluated by a reverse hemolytic plaque assay

Peripheral blood lymphocytes were obtained from 10 patients with advanced periodontitis and from 5 normal control subjects. The lymphocytes were cultured with dental plaque, supernatant of homologous fibroblast cytoplasm and Pokeweed-mitogen (PWM). The number of immunoglobulin-secreting cells (ISC) was assessed after 7 days using a reverse hemolytic plaque assay (RHPA). The stimulation levels of lymphocytes from periodontitis patients and control subjects stimulated with dental plaque and PWM were not statistically different (p greater than 0.05). In contrast, the number of ISC produced after stimulation with fibroblast cytoplasm was increased significantly in the patients group (p less than 0.05). These data support the hypothesis that autologous substances play an important rôle in the cellular immune responses of patients with severe chronic inflammatory periodontal disease (CIPD).

Initial attachment of fibroblast-like cells to periodontally-diseased root surfaces in vitro

The precise factors mediating both initial cell attachment and longer term connective tissue reattachment after tissue destruction due to periodontal disease are not known. An in vitro model was used to assess initial attachment of fibroblast-like cells to periodontally-diseased root surfaces. Root fragments were obtained from freshly extracted teeth from 6 different patients. Individual roots were prepared such that a comparison could be made of initial attachment to non-instrumented diseased root surface, curetted diseased root surface and the non-diseased, non-instrumented portion of the same root. The amount of hard tissue removed by instrumentation was quantitated and kept constant between 0.9-1.0 mm. The unsterilized fragments were incubated with human gingival fibroblasts (HGF) for 1 h at 37 degrees, after which the roots were first washed to remove non-adherent cells and then photographed. The number of attached cells per unit area was quantitated from the photographs using a grid system. No significant differences could be detected between the numbers of cells attached to the 3 types of root surfaces studied on the individual roots or between any of the roots studied. Thus, initial attachment of HGF to diseased root surfaces is not inhibited by the presence of plaque or endotoxins.

Inhibitory effect of periodontally diseased root extracts on the growth of human gingival fibroblasts

Cementum shavings obtained from periodontally diseased and nondiseased areas of 100 removed, single-rooted teeth were extracted with either pyrogen-free water (PFW) for 5 minutes, 1 M citric acid for 5 minutes or 45% phenol-PFW for 90 minutes at 65 degrees C. The extracts were membrane-filtered, dialyzed exhaustively versus PFW, lyophilized, weighed and then dissolved in complete growth medium. The phenol-water or citric acid extracts of cementum shavings from periodontally diseased roots were positive for endotoxin by the limulus lysate assay (LLA). Pyrogen-free water extracts of diseased or phenol-water extracts of nondiseased cementum shavings were negative, or only slightly positive, respectively, for endotoxin by LLA. Media containing the various extracts were added to logarithmically growing cultures of human gingival fibroblasts (HGF). Separate cultures of HGF were exposed to Escherichia coli endotoxin at concentrations of 50, 100, 250 and 500 micrograms/ml to determine the growth-inhibitory effects of a known endotoxin. Cell growth was analyzed by measuring the incorporation of tritiated thymidine into cells. Suppression of HGF growth from 30 to 49% by E. coli endotoxin was concentration-dependent and linear over the concentration range of endotoxin tested. Pyrogen-free water extracts of diseased (endotoxin negative) or phenol-water extracts of nondiseased cementum shavings (slightly endotoxin positive) did not effect HGF growth. However, citric acid or phenol-water extracts of diseased cementum shavings (highly endotoxin positive) significantly suppressed HGF growth 58% and 61%, respectively. These results indicate that citric acid is effective in removing cytotoxic substances, presumably endotoxin, from cementum shavings and suggest that citric acid treatment is effective clinically in detoxifying periodontally diseased root surfaces.

Intracellular localization of bacterial lipopolysaccharide using the avidin biotin complex method at the electron microscopic level

The intracellular localization in 3T6 fibroblasts of Escherichia coli lipopolysaccharide (LPS) using the rapid avidin-biotin-immunoperoxidase technique at the electron microscopic level was studied. The role of bacterial endotoxin in the etiology of periodontal disease has been well documented previously. The purpose of the present study was to localize LPS within the cell, thereby determining which organelles concentrate the material and relate this to the cytologic pathophysiology. An increased concentration of LPS was found in the cell nuclei and, specifically, in association with nuclear chromatin and nucleoli. The concentration of LPS in the nucleus was directly related to the time of incubation, with some product appearing in that site within 2 minutes. There was no specific localization of endotoxin in mitochondria, lysosomes, Golgi, endoplasmic reticulum or ribosomes. These results imply that bacterial endotoxin may have a direct effect on nuclear components of fibroblasts. The relationship of these results to the etiologic mechanisms of periodontal disease is discussed.

Possible role of calcium in periodontal disease

The uptake of Ca2+ by endotoxin-challenged 3T6 fibroblasts, in vitro, was studied. In recent years, the role of calcium in cell injury ultimately leading to cell death has attracted a fair amount of interest. The purpose of the study was to determine whether the direct toxic action of endotoxin is related to a disturbance in Ca2+ homeostasis. Increased calcium uptake in endotoxin-challenged cells was found to be directly related to the bacterial source and method of extraction of endotoxin, the cell density of the culture and the pH of the medium. The effect of endotoxin on calcium uptake was completely reversed by polymyxin B which is known to neutralize the endotoxicity of lipopolysaccharides. These results imply that the increased calcium uptake may be one of the mechanisms by which endotoxin causes direct tissue damage. The potential significance of these data to periodontal disease is discussed.

Effect of various root surface treatments on the viability and attachment of human gingival fibroblasts

Periodontally involved extracted human teeth were either untreated or were treated with root planing, citric acid, or root planing followed by citric acid. Following incubation of the roots, in the presence of normal human gingival fibroblasts for varying periods of time, cells were assayed for viability by radioactive label (51Cr). In addition, the ability to promote attachment and growth of gingival fibroblasts, by root treatment as above, was observed. The results of multiple experiments in each category indicated strongly that none of the roots, regardless of treatment or nontreatment, had any significant adverse affect on the viability of the cells. However, only root-planed roots, whether or not citric acid was used, promoted cell attachment and growth.

Diabetes and periodontal diseases. Possible role of vitamin c deficiency: an hypothesis

An hypothesis is proposed relating the possible role of vitamin deficiency as an etiologic factor contributing to periodontal disease in diabetes. The hypothesis is based upon the following: (1) transport of ascorbate across cell membranes may be impaired by glucose, but facilitated by insulin; (2) glucose utilization is significantly accelerated by sublethal concentrations of endotoxin; (3) endotoxin-induced histamine sensitivity of tissue is enhanced by ascorbic deficiency; and (4) ascorbic acid deficiency alters mucosal barrier function. The interrelationship of these factors is discussed.

In vitro cytotoxicity of periodontally diseased root surfaces

The purpose of this experiment was to develop a model system for controlled in vitro testing of root surface toxicity. Human gingival fibroblasts were placed into a depression created in the root surfaces of ten heat sterilized periodontally involved teeth, one half of which were root planed to remove all irritants. The teeth and fibroblasts were incubated in culture medium for 5 days, after which the cells were fixed and stained. Each tooth was examined for migration of cells onto the root planed and non-root planed areas of the tooth, and for evidence of any cytotoxic reaction. No difference in pattern of cell growth, cell migration, or cytotoxic reaction was discernible between root planed and non-root planed areas. Normal fibroblasts could be detected on the surfaces of dentin, calculus, periodontally involved cementum, and enamel. It appears that heat-sterilized periodontally-involved root surfaces, as well as calculus and calculus-laden enamel, were not toxic to human gingival fibroblasts in cell culture.

Stimulation of macromolecular synthesis by endotoxin-treated 3T6 fibroblasts

The interaction of endotoxin with cultured fibroblasts resulted in a depression of cellular proliferation and an increased synthesis of macromolecules, namely collagenous and non-collagenous proteins. The collagen salt-soluble fraction was increased at the expense of the insoluble fraction, and both the salt-soluble fraction and collagen secreted into the medium was underhydroxylated.

Biologic preparation of diseased root surfaces

Untreated periodontally-involved teeth contain cementum-bound endotoxin, that may prevent periodontal new attachment during healing after pocket therapy. The purpose of this study was to restore biocompatibility to diseased root surfaces by a non-invasive treatment. Untreated human teeth removed for severe chronic periodontal disease were split buccolingually, the level of connective tissue was scribed on the roots, the specimens cleaned of plaque and visible calculus, and autoclaved. Cementum removal was not attempted. One member of each pair was treated with phosphate-buffered saline as a control. Sodium desoxycholate (2%), Cohn plasma fraction IV1 (5%), or deoxycholate followed by plasma fraction were applied for one minute. Roots were incubated in a suspension of gingival fibroblasts for 48 hours, then rinsed, fixed, and stained. Counts were made of the number of attached cells at 40 x magnification using an ocular grid. There was a significant increase (p less than 0.01) of the combination treatment over controls. All treatments provided a biological surface for attachment of fibroblasts, in vitro, compared to untreated roots.