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This study was designed to evaluate the effect of soaking in either Hank's balanced salt solution (HBSS) or milk on periodontal ligament (PDL) cell viability in avulsed teeth. Dry storage times of 30, 60, and 90 min were evaluated. PDL cell viability was determined after removal of the cells from the root surfaces of extracted teeth using a modification of the procedure described by Nakashima (Arch Oral Biol 1991;36:655-63). After trypsinization and subsequent treatment in collagenase, the cells were stained with trypan blue, and viable and non-viable cells were counted using a hemocytometer and converted to percentages for statistical comparison. The results of this study demonstrated no significant difference in the number of viable cells with or without soaking in HBSS or milk at any of the dry storage times. In addition, there was no significant difference in PDL cell viability between the 30-and the 60-min dry periods. Although the soaking procedure had no obvious negative consequence, no significant improvement in PDL cell viability by the addition of this step was demonstrated under the conditions of this study.

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In this study, the effect of the synthetic glucocorticoid hormone dexamethasone (DXM) on HSV replication was studied in a DXM receptor-positive mouse neuroblastoma (NB) cell line. In cells treated with 10(-7) M DXM and then infected with HSV, there was a statistically significant 9-18-fold increase in the amount of virus produced in these cells compared to untreated controls. Adsorption kinetic studies with HSV were performed in DXM-treated NB cells and untreated controls. It was found that there was a significant increase in the adsorption rate of HSV in the DXM-treated cells as compared with the controls. During the course of these studies, a strain of NB cells was noted to have lost its ability to stimulate HSV replication following DXM treatment. Receptor binding assays were performed on cytosols prepared from NB cells that responded with an increase in HSV titers to DXM treatment and the new strain of NB cells that was DXM refractile. These latter cells were found to have lost their DXM receptors. These results indicate that the modulation of HSV replication of DXM treated cells was regulated by the presence of DXM receptors in these cells. Once lost, the cells do not respond to DXM treatment with increased HSV replication. These observations may lead to a clinical assay to determine patients with high glucocorticoid levels who may be at risk of recurrent herpes infections.

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One of the key factors for obtaining a favourable long-term prognosis in avulsed teeth is maintenance of the vitality of the periodontal ligament (PDL) cells. Most studies which have examined PDL cell vitality have used neutral red or trypan blue as stains. However, these stains have certain inherent disadvantages. The purpose of this paper was to (i) evaluate the use of saline and milk as storage media for PDL cells and (ii) determine the value of using fluorescein diacetate (FDA) as a staining medium for vital PDL cells on the root surface of avulsed teeth. Thirty-two single-rooted premolars were utilized from patients aged 13 to 28 years. Following atraumatic extraction, the teeth in the experimental groups were air dried for 10 min and then placed in either milk or saline for 120 min. Both control and experimental teeth were subjected to trypsinization procedures, staining with FDA, and haemocytometer readings to determine the number of vital cells. There was no statistically significant difference in the number of viable cells on the root surfaces of teeth after 2 h of storage in either milk or in saline. Furthermore, staining with FDA provided an excellent method by which to determine PDL cell vitality.

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The use of latex examination gloves in the dental office has become the standard of care. However, the effectiveness of gloves as a barrier after coming into contact with specific dental materials is still uncertain. To examine the effects of dental materials is still uncertain. To examine the effects of dental materials on latex, 100 latex examination glove finger tips were divided into 10 groups. Each group was manipulated in a different dental material for 15 minutes. Permeability was detected by the passage of herpes virus across the latex membrane, rinsed from the inner glove surface and titrated onto Vero cells. Significant virus leakage was discovered in gloves treated with acrylic monomer, chloroform, and orange solvent. Little virus leakage was noted in bleach, soap, and 30% phosphoric acid etchant treated gloves, and no virus leakage was found with composite resin, ethanol, formocresol, and water treated gloves. These data were supported with scanning electron micrographs taken of the treated glove samples and comparing with the controls. When certain dental materials are manipulated while wearing gloves, irreversible damage to the material occurs and may increase the practitioner's exposure to pathogens.

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Dentin bonding agents reduce microleakage and enhance marginal adaption of composite resin restorations. These characteristics are advantages for their use as an endodontic retrofilling material. Because these materials will be in direct contact with vital tissues, their cytotoxic potential must be evaluated before clinical use. It was the purpose of this study to evaluate the cell cytotoxicity of amalgam, Caulk Universal Bond, Gluma, 35% HEMA, Morita Clearfil, Scotchbond 2, Super EBA, Tenure, and Tenure 5-4. VERO cells were grown in RPMI-1640 medium and cell monolayers were prepared by incubating 15 ml of the cell suspension in 60-mm culture dishes at 37 degrees C in 5% CO2. Twelve milliliters of a medium-agarose mixture containing 1% neutral red vital stain were overlayed onto the cell layer and allowed to solidify. The materials were directly exposed to the agarose overlays by inverting 6.0-mm diameter polypropylene capsules containing the cured and liquid sample materials either immediately (0 time) or after placement in phosphate-buffered saline with 1% gentamicin for 7, 15, or 30 days. Cytotoxicity was determined by measuring the zone of killed cells around the sample 24 h after placement on the agarose. Cytotoxicity was determined by measuring the zones of cell inhibition at 24 h and at 7, 15, and 30 days. Initially, all of the materials were found to be cytotoxic, except amalgam and the Tenure components. The dentin bonding primers showed a mean zone of inhibition of 13.2 mm and the cleansers a 40.0-mm zone. Amalgam demonstrated increasing cytotoxicity: 0.0 mm at 24 h to 12.0 mm at 30 days.(ABSTRACT TRUNCATED AT 250 WORDS)

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The purpose of this study was to assess the potential cytotoxicity of impression materials. The impression material brands tested included Impregum, Reprosil, Surgident, Permlastic, Jeltrate Regular and Jeltrate Fast Set. These impression materials and their components were tested for their possible cytotoxic effects by three different methods. The results showed that all impression materials were cytotoxic to some degree by all three assay methods and some of the components were also cytotoxic. These results support the literature showing in vivo adverse effects of certain impression materials and/or their components in patients and practitioners.

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Sponges are routinely used as a storage medium for endodontic files during clinical practice; however, very little research has been done to determine the effectiveness of sterilization procedures for these contaminated sponges. The purpose of this in vitro study was to determine the efficacy of chemical vapor sterilizers (chemiclaves), steam pressure sterilizers (autoclaves), and dry heat sterilizers on laboratory contaminated sponges. Four different types of sponges were used in this study: a black, relatively nonporous sponge; a red, semiporous stationary sponge; a blue, endodontic sponge, and a yellow, common household sponge. Natural sponges were eliminated from the study, because their large pore size made them unsuitable as a storage medium for endodontic instruments. The sponges were divided into three groups: chemiclave, autoclave, and dry heat. Five samples of each sponge type were impregnated with biological indicating strips containing spores of Bacillus stearothermophilus. Each sponge was subjected to 25 cycles of sterilization. The spore strip indicator was inserted into the sponges at 1, 5, 10, 15, 20, and 25 cycles. The spore strip was cultivated in trypticase soy broth medium solution at 55 +/- 1 degree C for 7 days. At 7 days the culture vials were read for turbidity; its presence indicating a positive culture. The samples that were subjected to chemiclaving demonstrated positive cultures of 0.00%, 0.00%, and 30.00% and those to autoclaving 3.33%, 0.00%, and 0.00% positive cultures for the black, red, and blue sponge types, respectively. None of the sponges survived dry heat sterilization. The O-Cell-O sponges become unusable when subjected to all of the sterilization methods used in this study.

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To determine the extent of antiviral activity present in a number of plant extracts, hot glycerin extracts were prepared from Rheum officinale, Aloe barbadensis, Rhamnus frangula, Rhamnus purshianus, and Cassia angustifolia and their virucidal effects were tested against herpes simplex virus type 1. All the plant extracts inactivated the virus. The active components in these plants were separated by thin-layer chromatography and identified as anthraquinones. A purified sample of aloe emodin was prepared from aloin, and its effects on the infectivity of herpes simplex virus type 1 and type 2, varicella-zoster virus, pseudorabies virus, influenza virus, adenovirus, and rhinovirus were tested by mixing virus with dilutions of aloe emodin for 15 min at 37 degrees C, immediately diluting the sample, and assaying the amount of infectious virus remaining in the sample. The results showed that aloe emodin inactivated all of the viruses tested except adenovirus and rhinovirus. Electron microscopic examination of anthraquinone-treated herpes simplex virus demonstrated that the envelopes were partially disrupted. These results show that anthraquinones extracted from a variety of plants are directly virucidal to enveloped viruses.

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Results of this study indicate that impression materials vary in their ability to absorb and retain virus. Disinfection procedures specific for each material or groups of materials should be developed.

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Monolayers of NB41A3 (MNB) cells were exposed to pharmacologic doses of dexamethasone (DXM). After 24-h, the cells were infected with herpes simplex virus type 1 (HSV-1) at a multiplicity of infection (m.o.i.) = 0.1. After every 24-h period, extracellular and intracellular virus aliquots were collected and frozen. The aliquots were titered in a standard plaque-forming assay. It was shown that the hormone led to a statistically significant increase of extra- and intracellular virus titers above the titers exhibited by these cells without added hormone. The same experiment was repeated in Vero cells, but the hormone did not elevate the resultant HSV-1 titers. A binding assay was performed on these two cell lines by use of 3H-DXM to determine if a DXM receptor was present. Specific binding was seen, but only in the MNB cell line. The Bmax of this receptor was 480 fmol/mg protein and it had a Kd of 2.3 nM. The S value of the receptor ligand complex equalled 8.0. These results indicate that cells possessing hormone receptors allow for a more efficient replication of the virus and suggest that these hormones may play an important role in the exacerbation of herpes simplex virus infection in vivo.

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The purpose of this study was to examine the potential toxic effects of several orthodontic adhesives immediately after polymerization and at various time intervals up to 2 years postopolymerization by means of an in vitro overlay assay. Adhesive samples were incubated on tissue cultures containing an agar overlay with a vital dye (neutral red). Viable cells were stained red; nonviable cells were unstained. The circular pattern of nonviable cells demonstrated a zone of inhibition that was measured and compared. All materials tested showed cytotoxic effects immediately after polymerization and the toxic effect decreased with time postpolymerization. However, 2 years after initial polymerization, significant zones of inhibition indicating continued in vitro toxicity were still evident in all but one of the adhesives.

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The cytotoxicity of orthodontic bonding agents (OBAs) has been demonstrated in both animal and in vitro studies. Many practitioners and their assistants have experienced contact dermatitis of the fingers following contact with OBA. Latex gloves have also been reported to cause similar symptoms in several reports. The purpose of this study was to evaluate and quantify the toxic effects of latex and vinyl gloves, several OBAs, and combinations of these in vitro to determine the kind of glove that should by worn by practitioners when manipulating an OBA. It was determined that when OBAs are applied to washed latex, the combined toxic effect on cultured cells exceeded that of the washed gloves alone. However, when vinyl glove material instead of latex was tested, the toxic effects decreased more than 50%. Therefore, we suggest that practitioners who experience contact dermatitis in orthodontic practices wear vinyl gloves instead of latex, especially when manipulating OBAs. We also acknowledge the need for further research on the subject.

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This study compared conventional viral isolation (VI) in cell cultures with a commercial product--Virgo antigen detection system--for the identification and typing of herpes simplex virus (HSV). The system is designed to identify and type HSV from direct lesion smears (DS) and from cell culture smears (CS) infected with a swab from the patient's lesion by means of an indirect fluorescence assay (IFA) using HSV type-common and HSV-2 type-specific monoclonal antibodies. A total of 71 coded specimens manifesting clinical characteristics consistent with HSV were included in this evaluation from which DS, CS, and VI were performed. Specimens were taken from a variety of intraoral and extraoral sites, from both recurrent and primary lesions, and at various stages of lesion progression. The results showed that HSV was not detected in 22 of the 71 specimens by either DS, CS, or VI. Forty-nine specimens were positive by both CS and VI; 47 of these were typed as HSV-1 and 2 were typed as HSV-2. Thirty-eight of the 49 positive CS and VI specimens also were positive by DS. The remaining 11 DS slides did not have sufficient cells for analysis. It was concluded that the success of a valid DS test depended on the stage of the lesion and the sampling technique. The sensitivity and specificity of CS and DS were 100% and 82%, respectively, for detection of virus when compared with VI. When done properly with an adequate number of cells from the lesion, the DS proved to be an accurate and rapid (2 hours) procedure.

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This study indicated that when inoculated onto dental charts, both viruses and bacteria were capable of survival allowing the potential for transmission of infection within the dental office. The conscientious dental practitioner can take steps to reduce this possible mode of infection by removing contaminated surgical gloves or washing hands before handling the chart. An additional method of reducing this potential would be to wipe the chart with an antiseptic solution. Although this study has shown that there is a potential for the spread of infection with the organisms tested, the actual extent of dental chart contamination and resultant illnesses contracted are the basis for further study. Additional studies are needed to follow the pattern of chart distribution from person to person within the dental office, determine the types and quantities of pathogens present in the mouth that would contaminate the charts, and sample the charts under actual clinical conditions to determine the types and viability of the organisms present.

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The cytotoxicity of a newly developed dentin bonding system was examined in African green monkey kidney cells and human embryonic lung cells. A tissue culture agar overlay procedure, a longitudinal study, and a cell replication assay were employed to evaluate cytotoxicity. Several of the components were discovered to be cytotoxic when tested individually in vitro. However, when used in the prescribed manner, little or no cytotoxic effect was elicited. The results of this study support further testing of these materials in vivo.

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Previous studies have shown that toxic reactions to direct-bonding adhesives can be demonstrated both in animals and in cell culture tests. These effects have also been shown with other related dental materials. The purpose of this study was to compare the relative toxicity of a number of common orthodontic adhesives and to determine, by means of a rapid, sensitive in vitro cell culture agar overlay test, how their toxicity changed with time subsequent to polymerization. Various othordontic bonding materials were tested either immediately or at various times up to 30 days after polymerization. The cells were stained with a vital dye (neutral red), the diameter of the area of unstained, nonviable cells was measured, and the results of three tests per sample were averaged and analyzed by means of Duncan's Multiple Range Tests. All materials were found to have some cytotoxic effect immediately after mixing, with the activator components of two "no-mix" materials exhibiting significantly higher toxicity (p less than 0.05) than other materials tested. The sealant materials showed a significantly greater toxicity than paste resins, both initially after mixing and after 30 days postpolymerization. If applicable to the clinical situation, these data indicate that care is needed particularly in handling liquid activators. Excess "polymerized" sealant, which may contain many nonreacted groups, should be carefully removed by scaling peripheral to the bracket bases, particularly in subgingival and interproximal areas.

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Supernatant fluids from cultures of a mouse mammary tumor (MT) cell line were found to produce a specific cell detachment effect when inoculated into HeLa cells. The cell detachment factor (CDG) responsible for this effect was examined. Repeated attempts to cultivate this CDF in bacteriologic, fungal, and mycoplasma media were unsuccessful. However, using the DNA fluorochrome staining technique and specific immunofluorescent staining procedures, the CDF was identified positively as a noncultivable strain of Mycoplasma hyorhinis. It was also noted that this CDF could be labeled with [3H]uridine in MT cell cultures, concentrated, and banded at a density of 1.18 g/cm3 when centrifuged to equilibrium in a 20 to 60% sucrose gradient. Using a multiple antibiotic treatment regimen, the MT cells were "cured" of the M. hyorhinis contaminant. Re-infection of these cells with an exogenous strain of M. hyorhinis resulted in the same cell detachment effect, and this strain when labeled with [3H]uridine also sedimented at a density of 1.18 g/cm3. The salient feature of these studies is that M. hyorhinis sediments at the same density of mouse mammary tumor virus (MMTV) in sucrose density gradients. This was demonstrated by sucrose density gradient analyses of a purified sample of MMTV, assaying for reverse transcriptase activity, and a [3H]uridine labeled sample of the M. hyorhinis present in the MT cell cultures.

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A large number of particles resembling oncornaviruses were observed in the ventral lobe of a normal rat prostate. The particles were seen budding into the intercellular spaces of the epithelial lumen cells. They exhibited features morphologically similar to immature C-type particles, with an electron-lucent center and a diameter of approximately 100 nm. Neither intracellular A-type particles nor mature C-type particles were observed. This is the first report of particles resembling oncornaviruses in normal rat prostatic tissue.

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Antibody levels in sera and respiratory secretions and resistance to respiratory infections were examined in mice given live infuenza virus in small-particle (2 mum) aerosols, large-particle (10 mum) aerosols, intraperitoneally, and subcutaneously. After parenteral administration antibody was found primarily in the serum, but small amounts were recovered in bronchoalveolar washings after 2 to 3 weeks. Specific antibody was present in both sera and bronchoalveolar washings from mice given virus in small-particle aerosols to achieve virus dissemination throughout the respiratory tract. Immunoglobulin A, immunoglobulin G, and trace amounts of immunoglobulin M, all specific for the infecting virus, were detected in bronchoalveolar washings of small-particle aerosol-infected mice. Virus administration in large-particle aerosols (for primary virus localization in upper respiratory tract) at doses greater than those required to initiate infection with small-particle aerosols failed to stimulate production of antibody in sera or bronchoalveolar washings. Small-particle aerosol-immunized mice were resistant to subsequent challenge with 10(2.0) respiratory median lethal doses of virulent virus, whereas large-particle aerosol-immunized mice were not protected. Parenteral immunization modified the course of the disease in challenged mice and reduce mortality rates but did not prevent reinfection of the respiratory tract.

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