摘要:

Abstract –20 reference strains and 72 isolated strains from dental plaque of streptococci‐, actinomyces, and lactobacilli species were examined for sucrase and maltase activities. The type of sucrase in the different strains was determined by use of the α‐glucosidase inhibitor, acarbose. The enzyme activities were determined as formation of monosaccharide, and quantitated spectrophotometrically. Although variations occurred in enzyme activities between reference and isolated strains, the same general pattern was noticed. Strains of Streptococcus mutans and S. salivarius showed regularly the highest sucrase activities, followed by strains of Actinomyces viscosus and A. naeslundii. Most lactobacilli belonged to the bacteria with low sucrase activity like S. sanguis and S. mitior. In some lactobacilli strains, however, a high sucrase activity was observed. The level of sucrase activity in S. mutans strains was dependent on biotype/serotype, as strains of biotype V/serotype e showed high activities, biotypes I and IV corresponding to serotypes c, f, and d showed intermediate activity, and biotype III/serotype a always showed low activity. In most of the strains the sucrases were composed of enzymes with specificity against both α‐glucosidic linkage and β‐fructosidic linkage of the sucrose molecule, but in varying ratios. In all species, except S. sanguis and S. mitior, lower maltase than sucrase activity was observed, but even in the two species mentioned the maltase activities were relatively low. On the basis of observations of selected reference strains in every species examined both sucrases and maltases are to some exte

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00865.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –Human lysozyme in physiologic concentrations (17–50 μg/ml) had apparently no effects on growth rate and viability of exponentially growing Fusobacterium nucleatum Fevl cells, but cells in the stationary phase were affected. When grown in the presence of active lysozyme about 70% of the cells in late exponential phase (24‐h culture) were able to form colonies, compared to about 100% in the control culture. About 24 h later the colony forming abilities were about 5% and 20%, respectively. Addition of lysozyme to suspensions of cells taken from any growth phase did not lead to any significant decrease in turbidity, that is, no more than 10% decrease at 650 nm. Control cells treated with acridine orange fluoresced with a uniform bright orange color, while the lysozyme treated stationary phase cells fluoresced more faintly. Intracellular granules were more preponderant in the latter cells. When incubated with the hydrophobic probe 8‐anilinonaphthalene‐l‐sulfonic acid (ANS), lysozyme exposed cells gave approximately 20% higher fluorescence intensity than the control cells. Changes in the ultrastructure of the lysozyme treated cells were best studied in the transmission electron microscope using ultrathin sectioned preparations. The peptidoglycan layer became disorganized and apparently dissolved and the ordered structure of the cell wall had disappeared in zones. The cells, however, still retained their form, and only a few per cent had lost their cellular content. This explains why the turbidity of the solution did not change s

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00866.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –In order to find out whether microbes can be detected in the incipient rat caries lesions underneath the visibly intact enamel surface, the maxilla of OM‐rats, fed a cariogenic diet, were fixed and partially bisected sagittally with a thin saw. The individual teeth were finally split with a knife to get a crack surface from the fissure region. Selected tooth halves showing slight carious changes at the dentin‐enamel junction were prepared for SEM and examined. In many preparations, colonies of organisms were found firmly attached to the crack surface. Single, predominantly coccus‐like organisms and a few rods could be seen mostly located in the interprismatic furrows at varying depth throughout the enamel. Somc lacuna‐like hollows, with or without the occupant organisms, could be seen carved in the prism structure. The enamel side of the DEJ in the lesion area could be completely covered by the microbes. In samples representing arrested caries, amorphous precipitates were found at the interprismatic substance of the D

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00867.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –A method was developed to facilitate the estimation of S. mutans levels in saliva. Paraffin‐stimulated saliva was poured on a special slide coated with mitis‐salivarius‐sucrose agar. Two discs containing bacitracin (5 μg) were placed on the inoculated slide and the growth density of S. mutans around the bacitracin discs was scored after incubation in candle jars at 37°C for 48h. The obtained score values correlated well with the numbers of CFU of S. mutans per 1 ml of saliva estimated by a conventional method using mitis‐salivarius‐bacitracin agar. The experimental method was further tested by incubating the slides in an atmosphere created by CO2generating tables that were placed into the cover tubes of the slides. These score values were similar to those after conventional incubation. The method is suggested for epidemiologic studies and in selecting persons at high risk for caries and in controlling the effectiveness of prophylactic measures of t

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00868.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –Selection of caries‐risk groups is difficult and unreliable. In this study we analyzed the known correlates of caries and their interrelations. The subjects (n= 153) were seventh graders (13 yr old) from a school in Kuopio. Data were collected by mail survey (n= 150), from the clinical registers of the local health center (n= 135), and from a saliva test. In the first stage we computed the bivariate correlates between the D‐index and its traditionally defined determinants. In the second stage the predictors of caries risk were ranked using discriminant and multiple regression analyses. The bivariate correlates of caries were: DMF‐index of the previous year (r = 0.69), D‐index of the previous year (r = 0.59), lactobacillus count (r = 0.26), buffer capacity (r = 0.20), and toothbrushing frequency (r = 0.07). In discriminant analyses the DMF‐index among girls and the frequency of consumption of sweets among boys were the only significant discriminators. In the multiple regression analyses, however, the final model (P<0.001) for girls included: DMF‐index of the previous year (β= 0.64) and lactobacillus count (β= 0.31). The corresponding model for boys (P<0.001) included: DMF‐index of the previous year (β= 0.55) and frequency of consumption of sweets (β= 0.24). Using these variables, it is difficult to develop a reliable method for determining the caries susceptible groups, but of them, the DMF‐index seems the most reliable for predicting carie

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00869.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –The effect of Scotchbond on the wall‐to‐wall polymerization contraction of a visible light activated microfilled resin was investigated in cavities prepared in extracted human teeth. The cavities were cleaned either with water spray or a saturated acidic solution of EDTA, the latter giving significantly better results. The cavities were prepared with cavosurface angles between 90° and 160°. A highly significant improvement of marginal adaptation was found with increasing cavosurfac

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00870.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –The marginal porosity of four light activated restoratives (Command, Durafill, Prismafill and Silux) was investigated in extracted human teeth It was found that the use of a lowviscous resin prior to application of the restorative materials significantly reduced the marginal porosity in both acid etched enamel cavities and EDTA‐cleaned dentin cavit

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00871.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –The acidity in aqueous solutions following release of acid components from glass ionomer, silicate, zinc phosphate and zinc polycarboxylate cements has been registered by pH measurements. One brand of each type was studied. Initial setting was accomplished at two different temperatures; 23°C and in the interval from 23°C to about 60°C. In the latter case external heat was transferred to the samples by infrared radiation for a period of 2 min. The highest acidity was associated with the silicate specimen, while the lowest acidity was recorded for the zinc polycarboxylate specimen. Exposure to infrared radiation resulted in a reduced acidity for all types of cements. The effect of infrared exposure was most pronounced for the silicate specimens, resulting in a reduction of acid release by a factor of about 10 compared to the nontreated samples. The resistance to acid release was found to be improved by a factor of about 5 for the glass ionomer and about 3 for the zinc phosphate cement treated in a similar way. Clinically, it seems possible considerably to reduce the risk of pulpal injuries associated with the insertion of silicate restorations by using a moderate infrared radiation treatment. Furthermore, the susceptibility of glass ionomer cements to a high initial erosion should be reduced by the use of such a technique. After exposure of the glass ionomer and silicate specimens to infrared radiation at the temperature interval applied, the samples had a more glossy, tooth‐like appearance compared to the nonexposed samples, improving the aesthetic prop

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00872.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –The antibacterial effect of oral rinses with stannous fluoride and stannous chloride solutions, and of the use of a toothpaste containing stannous fluoride and stannous pyrophosphate was tested by recording the bacterial viable counts on the oral mucous membrane. Stannous chloride had no antibacterial effect, while stannous fluoride drastically reduced the viable counts up to 4 h. Calculations demonstrated that 25% of the tin content in 10 ml rinsing solutions was retained in the mouth, and analyses showed a raised tin level in saliva up to 4 h after rinsing or toothbrushing. It is suggested that most of the retained tin is bound to the oral mucos

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00873.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract –The amounts of copper, mercury, silver or zinc released from two brands of freshly prepared, lathe cut amalgams and from one brand of dispersed phase type amalgam into artificial saliva have been measured. Samples were immersed in the solution a few minutes after the end of trituration and exposed statically for periods of up to about 4 days. The initial mercury release from such specimens could exceed the long term mercury release from old amalgams by more than two orders of magnitude. The measurements indicate that during the first day after insertion of two amalgam fillings, each with an assumed surface area of 1 cm2and under presumably static conditions, mercury at the level of more than twice the mercury food and drink intake could be released in the oral cavity. This is, however, a situation which appears infrequently, e.g. following dental treatment once a year. The amounts of copper and zinc released initially were considerably lower than the corresponding food and drink intake values, while silver might be on the same level. The measurements were conducted using nuclear tracer technique

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1984.tb00874.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY