Effect of CO2 laser on pulpal temperature and surface morphology: an in vitro study.

OBJECTIVES: The objective of this study was to evaluate the potential effects on underlying dental hard tissues of a high pulse rate carbon dioxide (CO2) laser that was designed for soft tissue surgery. METHODS: Eighteen extracted human teeth were sectioned longitudinally, cleaned, and varnished, leaving nine exposed windows on each: six on the coronal surface (enamel) and three on the root surface (cementum, dentin). The CO2 irradiation conditions used were: wave length 10.6 microm; 1.2-2.6J/cm(2) fluence per pulse; repetition rate 120-1000Hz; 100-200ms pulse duration; and cumulative fluences ranging from 14 to 2200J/cm(2). Each window was irradiated with a 0.3mm beam diameter at one of nine power settings for 0.1, 0.5, or 1.0s. The pulp chamber temperature was measured with a microthermocouple. The irradiated teeth were evaluated by Polarized Light Microscopy (PLM) and Scanning Electron Microscopy (SEM). RESULTS: The pulp chamber temperature rise ranged from 0.5 to 19 degrees C depending on the location of the window and distance to pulp chamber. SEM revealed crystal fusion in both enamel and dentin at all cumulative fluences. At cumulative fluences of 40J/cm(2), 200 pulses/second and higher, measurable tissue loss was observed with PLM both in dentin and enamel. CONCLUSIONS: These results indicate there are threshold conditions above which pulsed CO2 laser light used for soft tissue surgery may cause detrimental changes to underlying oral hard tissue and to the pulp.

Immunological markers of frequently recurrent genital herpes simplex virus and their response to hypnotherapy: a pilot study.

Patients were recruited for hypnotherapy from a clinic for patients with frequently recurrent genital herpes simplex virus (rgHSV). Psychological and immunological parameters were measured 6 weeks prior to hypnotherapy and 6 weeks afterwards, during which time each patient kept a diary of symptoms of rgHSV. Following hypnotherapy there was a significant overall reduction in the number of reported episodes of rgHSV, accompanied by an increase in the numbers of CD3 and CD8 lymphocytes, which may represent a non specific effect of hypnosis. The improvers showed significant rises in natural killer (NK) cell counts, HSV specific lymphokine activated killer (LAK) activity, and reduced levels of anxiety when compared to non-improvers. NK cell numbers and HSV specific LAK activity may therefore be important in the reduction in rgHSV following hypnotherapy.

Trends in female sexual behaviour and sexually transmitted diseases in London, 1982-1992.

OBJECTIVE: To measure changes in female sexual behaviour, including condom use, and their relationship with the incidence of sexually transmitted and other genital diseases in women during the decade 1982-92. DESIGN: A prospective series of cross-sectional surveys of sexual behaviour reported by a standardised self-administered questionnaire in new patients who presented for screening and diagnosis. SETTING: A genitourinary medicine clinic in West London. SUBJECTS: 4089 consecutive newly attending patients who completed sexual behaviour questionnaires during 1982, 1987, 1989 and 1992. MAIN OUTCOME MEASURES: Trends in socio-demographic status, sexual behaviour, condom-use, sexually transmitted diseases and other genital infections diagnosed by routine clinical and laboratory methods. RESULTS: Women reported significantly increasing condom use (from 3.6% to 20.7%) and decreasing oral contraception (from 51.2% to 40.1%), but the proportion who used no contraception (23.6% to 24.7%) and the proportion who had never been pregnant (58.3% to 59.9%) remained similar. Numbers of sexual partners in the preceding year decreased (p < 0.001) and an increasing proportion of women practised oral intercourse (p < 0.001). During the same period, there was a progressive decline (p < 0.001) in the incidence of gonorrhoea, chlamydial infection and trichomoniasis by approximately two-thirds. However, the incidence of vaginal candidosis (p < 0.001), bacterial vaginosis (p < 0.001) and genital warts (p < 0.01) increased. CONCLUSIONS: Increasing use of condoms for vaginal intercourse with both regular and non-regular partners has been associated with a decrease in the incidence of gonorrhoea, chlamydial infection and trichomoniasis. There was also an increase in the practice of fellatio and a change in the spectrum of STD and other genital infections with little net reduction in morbidity. HIV infection showed no evidence of heterosexual spread.

Scanning electron microscope observations of CO2 laser effects on dental enamel.

Studies of the effects of carbon dioxide (CO2) lasers on dental enamel have demonstrated that surface changes can be produced at low fluences (< 10 J/cm2) if wavelengths are used which are efficiently absorbed by the hard tissues. In this study, scanning electron microscopy (SEM) was used to characterize the wavelength dependence of surface changes in dental enamel after exposure to an extensive range of CO2 laser conditions. Bovine and human enamel were irradiated by a tunable, pulsed CO2 laser (9.3, 9.6, 10.3, 10.6 microns), with 5, 25, or 100 pulses, at absorbed fluences of 2, 5, 10, or 20 J/cm2, and pulse widths of 50, 100, 200, 500 microseconds. SEM micrographs revealed evidence of melting, crystal fusion, and exfoliation in a wavelength-dependent manner. Crystal fusion occurred at absorbed fluences as low as 5 J/cm2 per pulse at 9.3, 9.6, and 10.3 microns, in contrast to no crystal fusion at 10.6 microns (< or = 20 J/cm2). Longer pulses at constant fluence conditions decreased the extent of surface melting and crystal fusion. The total number of laser pulses delivered to the tissue did not significantly affect surface changes as long as a minimum of 5 to 10 pulses was used. Within the four easily accessible wavelengths of the CO2 laser, there are dramatic differences in the observed surface changes of dental hard tissue.

Comparison of cell sediment and surface grown "test plaque" using scanning electron microscopy.

Scanning electron microscopy was used to compare the morphology, integrity and distribution of bacterial cells in a test plaque grown on the surface of enamel with that of the cell sediment plaque routinely used in a short-term intraoral caries model. Cultures of S. mutans IB-1600 or S. sobrinus 6715-13 were grown in complex media supplemented with either 2.0% sucrose (glucan plaque) or 0.2% glucose (non-glucan plaque). Cell sediment (CS) plaque was prepared by centrifuging the cultures after incubation, recovering the cell sediment, and spreading it on Metricel membrane filter paper. Surface grown (SG) plaque was prepared by suspending saliva-coated bovine enamel in the culture medium, incubating, and recovering the enamel assembly with bacterial accumulations. Cell morphology and integrity, as well as the appearance of glucan-like material produced by the cells, was similar in both CS and SG test plaques. The cell distribution however, varied in the SG plaque from extremes of all cells to all glucan, whereas the cell sediment plaque was more uniform in cell distribution. A highly standardized test plaque minimizes variability in the intraoral caries model. These findings support the contention that the bacterial cells in a cell sediment plaque are similar in morphology, integrity and glucan production to surface grown plaque, and have the added advantage of uniform distribution, which makes the cell sediment plaque more appropriate for intraoral caries model studies.

Calcium fluoride formation on sound enamel using fluoride solutions with and without lactate.

The formation of calcium (Ca) fluoride (CaF2) on bovine enamel blocks during clinically relevant treatment times using neutral fluoride (F) solutions (0.26 mol/l F) with and without 0.1 mol/l lactate was investigated. Uncoated and pellicle-coated blocks were evaluated for alkali-soluble (1 mol/l KOH, three consecutive 24-hour treatments) Ca, PO4, and F after treatment by the F solutions for 0, 5, 15, 30, and 60 min. There was an overall time-related increase in F recovery, while Ca tended to remain at baseline levels. Less F was recovered from the pellicle-coated blocks. The addition of lactate to the F treatment solution did not result in an overall increase in alkali-soluble F recovery, but did result in the formation of cuboidal shaped crystals which closely approached the morphology of pure CaF2. A 1:2 stoichiometric ratio Ca:2F (mol:mol) was not established based on chemical analyses. The ultrastructural and elemental composition of surface deposits on the samples, as determined using scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy, established the presence of CaF2 after 24-hour F treatments; however, it was not possible to directly demonstrate the formation of CaF2 after clinically relevant treatment times.

Binding of murine osteoblastic cells to titanium disks and collagen I gels: implications for alternative interpretations of osseointegration.

Using 3H-thymidine-labeled MC3T3-El osteoblastic cells, the number of osteoblasts bound to titanium surfaces after various surface treatments and incubation periods was directly measured. MC3T3-El cell binding to titanium surfaces was saturable at a low level (approximately 10,000 cells/cm2). Although treatment of these surfaces with fibronectin, keratin sulfate, and the fibronectin-derived peptide GRGDS (glycine-arginine-glycine-glutamate-serine) increases cellular binding by 29% to 31%, the relative binding to titanium was 5 to 10 times lower than binding to collagen I gels. A collagen I matrix competed with the commercially pure titanium surfaces for cell binding from solution, suggesting that direct binding of osteoblasts to titanium surfaces present within an organic matrix may not be favored. The significance of immediate and direct bone cell attachment to titanium surfaces for osseointegration should be reevaluated.

An improved intra-oral enamel demineralization test model for the study of dental caries.

The intra-oral enamel demineralization test (IEDT) was introduced by Brudevold et al. (1984). This caries model involves human subjects wearing palatal appliances each holding eight bovine enamel blocks covered by a bacterial cell layer prepared by the harvesting of cultures of Streptococcus mutants (test plaque). The original model used the iodide permeability test for assessment of the extent of demineralization of bovine enamel blocks resulting from acid production by the test plaque after dietary substrate challenge. The IEDT model has been expanded and improved by us in the following ways: (1) Based on encouraging findings from an in vitro study (Zero et al., 1990), the surface microhardness test has been adopted to measure the extent of demineralization occurring at three sites on the enamel blocks corresponding to an area over which the effective plaque thickness is 0.5, 1.5, and 2.5 mm; (2) intra-oral pH of the test plaque is measured by means of a Beetrode miniature pH electrode at baseline, then at five, 10, 15, 30, and 45 min after the start of a test; (3) plaque samples are collected at the end of a test and analyzed for organic acid content by means of HPLC; (4) the bacterial test challenge has been expanded to include different cariogenic bacteria which are grown under various growth conditions. The improved model has the capability of studying fundamental aspects of the caries process, namely, the relationships among dietary substrate challenge, plaque pH change, plaque organic acid profiles, microbial virulence properties, and enamel demineralization. Furthermore, the model has the potential for use in more applied research on caries-preventive agents such as fluoride.

Trends in sexual behaviour and HIV testing among women presenting at a genitourinary medicine clinic during the advent of AIDS.

Changes in female sexual behaviour with the advent of AIDS and safer sex campaigns were studied. Subjects were drawn from a wide social spectrum of women attending an STD clinic in West London where there is a high prevalence of HIV infection among homosexual men. Between 1982 and 1989, 4224 women answered a self-administered questionnaire: women who reported more than one sexual partner in the previous year fell from 56.9% in 1982 to 51.8% in 1989 (p = 0.003). Anal intercourse showed no change and was reported by 8.8% in 1982 and 9.4% in 1989 (p = 0.8). Oral intercourse increased from 36.9% in 1982 to 44.7% in 1989 (p = 0.001). Condom use for contraception increased from 3.6% in 1982 to 16.2% in 1989 (p less than 0.001). Between 1987 and 1989, 35.6% of 3199 women reported having non-regular partners with no significant trend over this period; these women had earlier coitarche (17.0 years cf 17.9 years), many more partners (p less than 0.0001) and more practised anal (p = 0.007) and oral (p less than 0.0001) intercourse. However, frequent use of condoms doubled from 23.6% in 1987 to 47.6% in 1989. During this period, the prevalence of antibody to HIV (anti-HIV) remained unchanged (0.27-0.37%), but more women declined to be tested. Anonymised testing showed that none of those who refused consent for named testing was anti-HIV positive. It is concluded that significant changes in female sexual behaviour have taken place with the advent of AIDS but there has been no evidence of heterosexual spread beyond the confines of well defined risk behaviours. Risks of the magnitude reported in homosexual men were not found in heterosexual women.

Comparison of vaginal flora after treatment with a clotrimazole 500 mg vaginal pessary or a fluconazole 150 mg capsule for vaginal candidosis.

The effect of antifungal therapy on the vaginal microbial flora was studied in 23 patients suffering from culture-positive, symptomatic vaginal candidosis. They were randomly allocated to receive either a 500 mg clotrimazole vaginal pessary or a 150 mg fluconazole capsule. Quantitative microbiological examination was carried out on samples of vaginal secretions obtained prior, and at intervals up to 10 days after, treatment. No significant difference was found in the vaginal flora before or after therapy in individual patients or between the treatment groups. In patients with C glabrata or C krusei, the yeasts persisted longer in the vagina with poorer response to either of the medications.

A straightforward scanning electron microscopy technique for examining non-metal coated dental hard tissues.

Modifications to the standard operating settings for accelerating voltage, condenser lens current, scan rate, working distance and tilt on the conventional scanning electron microscope (SEM) enabled non-metal coated dental hard tissues and synthetic apatite pellets to be viewed free of charging effects. Well-resolved images at magnifications as high as 35,000x were achieved using accelerating voltages less than 5 kV. The methodology detailed here allowed for serial SEM examination of the same sample at various points during an experimental procedure, and may be applied to other sample types. The procedure is non-destructive to the sample and requires no physical modification to the microscope.

Human immunodeficiency virus infection, hepatitis B virus infection, and sexual behaviour of women attending a genitourinary medicine clinic.

During the six months immediately after a public information campaign about the acquired immune deficiency syndrome 1115 women who attended a genitourinary medicine clinic in west London were tested for antibodies to the human immunodeficiency virus (HIV). Three women (0.27%) were positive, and all three were regular sexual partners of men with high risk lifestyles--two intravenous drug users and one bisexual. A consecutive series of 647 women from the cohort was tested for antibodies for hepatitis B core antigen: 27 were positive, of whom six had been born in the United Kingdom and were not known to have been at risk. The two women who were seropositive for HIV who completed a questionnaire on their sexual behaviour before they were tested reported both anal and oral receipt of semen and were in the upper fifth percentile for lifetime sexual partners. More than half (53%) of 424 women who reported that they had non-regular sexual partners never used a condom. It is concluded that heterosexual women in London are at a low risk of becoming infected with HIV.

PIP: A cohort of women were screened for sexual behavior and for antibodies to HIV and hepatitis B. These women attended a clinic for sexually transmitted diseases in an area of London where homosexual men have a high prevalence of both infections. The spread of AIDS among heterosexuals is likely to appear 1st in women who are partners of bisexual men and in localities where the prevalence of HIV infection in homosexual men is the highest. Of 115 women who were tested, 3 women (0.27%) were positive, and all 3 were regular sexual partners of men with high risk lifestyles--2 intravenous drug users and 1 bisexual. A consecutive series of 647 women from the cohort was tested for antibodies for hepatitis B core antigen: 27 were positive, of whom 6 had been born in the U.K. and were not known to have been at risk. The 2 who were seropositive for HIV and who had completed a questionaire on their sexual behavior before testing reported both anal and oral receipt of semen and were in the upper 5th percentile for lifetime sexual partners. More than 1/2 (53%) of 424 women who reported that they had nonregular sexual partners never used a condom. Patients at risk for HIV infection are also at greater risk of hepatitis B infection. Prevalence of hepatitis B infection among patients in genito-urinary medicine clinics has been reported at 4% to 8% for women compared with 4% to 18% for heterosexual men and 19% to 76% for homosexual men. Women in west London showed a low prevalence of hepatitis B, and most of those women were born outside the U.K. and may have been infected since childhood. The advice of a recent national campaign to use condoms seems to have had little effect. However, it appears from this group of women that there is no evidence of HIV infection being spread from casual vaginal intercourse. The risk of becoming infected with HIV for heterosexual women in London is very low and is likely to remain so if the epidemiological parallel with hepatitis B is valid.

The effect of relaxin on cyclic adenosine 3',5'-monophosphate concentrations in rat myometrial cells in culture.

Relaxin, a uterine relaxant secreted by the corpus luteum, was able to elevate cAMP concentrations in the presence of 1-methyl-3-isobutyl xanthine (MIX) (0.1 mM) or forskolin (0.4 microM) in a time- and dose-dependent manner in rat myometrial cells in culture but not in stromal cells. The optimal culture conditions for the cAMP response were determined to be an initial plating density of 1-1.5 X 10(6) cells/ml (3 ml/35-mm dish) and a 2-day culture period. In the presence of MIX, the time course of cAMP elevation in response to relaxin exhibited a lag phase of more than 5 min before cAMP concentrations rose significantly. However, in the presence of forskolin, relaxin elevated cAMP within 1 min. The concentration-response relationships were almost identical in the presence of MIX or forskolin. Isoproterenol was able to increase cAMP concentrations in myometrial cultures in both the absence and presence of MIX and to elevate cAMP levels rapidly within 1 min. These data suggest that cAMP could play some role in the initiation of uterine relaxation mediated by relaxin.

Symbolic play and early communication development in hearing-impaired children.

This study investigated the relationship between symbolic play and language performance for young hearing-impaired children. Subjects included 20 hearing-impaired youngsters ranging in age from 38 months to 69 months. The children were placed in two ordinal communication groups. Placement in one of the communication levels was dependent upon information concerning the number of spontaneous expressive communication units the child produced. The experimental task consisted of three predetermined play themes in which the child previously displayed functional play. A nonconventional item was then included, and the play behaviors were observed for the occurrence of symbolic play under a spontaneous or modeled condition. The results indicate a significant difference in symbolic play between the two ordinal communication levels. Additionally, there was a strong positive relationship observed between the variables of symbolic play and early communication development.