摘要:

Abstract—Using nine serially sectioned germectomized mandibular third molars it was possible to examine light microscopical (LM) and transmission‐electron microscopical (TEM) features of maturing human enamel organ cells. The degree of enamel mineralization was estimated by quantitative imbibition studies in polarized light. It was possible to distinguish between three progressive stages of enamel mineralization. The most advanced stage was characterized by external enamel porosity. In the least advanced stages the enamel porosity appeared more extensive beneath a less porous surface layer. Ruffle‐ and smooth‐ended ameloblasts were identified corresponding to the maturing enamel. Smooth‐ended ameloblasts were the most frequently observed. However, no preferences for one of the two cell types could be observed in relation to the different stages of enamel mineralization. The maturing human enamel organ cells broadly revealed the same characteristics with respect to morphology features, intracellular organization, and junctional complexes as described in the maturation zone of the rat incisor enamel organ. Our findings therefore add to the view that the basic pattern of amelogenesis is identical in human and rat incis

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01053.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Experimental erosion in human dentin was investigated with scanning electron microscopy. Erosion was caused by solutions containing either 0.030 mekV/g malic acid (pH 3.4), 0.034 mekV/g phosphoric acid (pH 2.6), or 0.038 mekV/g citric acid (pH 2.8). Test specimens prepared from the coronal parts of erupted third molars were immersed in the solutions from 30 s to 60 min. When compared with controls, exposure of dentin tubules was observed in all the specimens already after 30 s immersion, irrespective of the acid used. Mineral loss was seen to progress at the interface between peritubular and intertubular dentin in specimens immersed for 60 s in the acidic solutions. Longer times of immersion resulted in hollowing of the tubular openings by complete destruction of the peritubular dentin. Surface roughness and porosities were seen also at the intertubular areas. Although based on a simplified study model, our results may explain why so many patients with erosions suffer from painful sensitivity of their teeth: the acids causing erosion can expose inner dentin structures to outer stimuli by significant enlargement of the dentinal tubule

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01054.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—The adsorption of salivary proteins to dental enamel during pellicle formation has been shown to be a specific process and dependent on the chemical composition of the surfaces. Most studies on the amino acid composition of the acquired enamel pellicle have, however, been performed on the “2‐h‐pellicle”under controlled experimental conditions. This may have eliminated some natural factors involved in pellicle formation. The aim of the present study was to investigate the effect of extended time of formation and diet on the pellicle formation. Pellicle material was collected from the same subject after 2 and after 24 h when food and beverages were avoided, and after 24 h with the intake of a normal diet. The collected pellicle materials were hydrolyzed and amino acid analyzed. The results showed that pellicle material collected after 24 h and fasting had a chemical composition similar to the “2‐h‐pellicle”, whereas pellicle material collected after 24 h and a normal diet was different, indicating a dietary contribution to pellicle formation or a bacterial degradatio

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01055.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Extracted third molars were used to study the effect of Nd:YAG laser irradiation combined with CO2laser beam on dental hard tissues. The specimens were studied with SEM after lasing and the size of the impact areas and beam penetration into enamel and dentin were planimetrically analyzed. High‐energy CO2laser (e.g. 10 s irradiation with 10 W output energy) penetrated all enamel and dentin. The simultaneous addition of Nd:YAG irradiation to the CO2beam was found to increase the effect of CO2laser, while Nd:YAG irradiation alone, used with equivalent energy densities, did not cause any effect on enamel surface. Thus, Nd:YAG laser was found to potentiate statistically significantly the effect of CO2irradiation, but the morphologic alterations on dental hard tissues, such as crater formation at the beam focus site, appeared to be due to CO2irradiation al

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01056.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Biomedical determinants of dental caries have been more extensively investigated than psychosocial factors and their impact on caries prevalence and incidence seems to be greater. However, a majority of these investigations relate to children and adolescents. An implementation of social and psychologic variables may be more relevant regarding dental caries in adults. In addition, a multidisciplinary approach might improve our understanding of dental caries as a multifactorial disease and bridge the gap between a biomedical concept and a more holistic approach to dental healt

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01057.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—The viscosity of mixtures ofStreptococcus mutanswater‐soluble glucan and stimulated whole saliva or buffer was measured at pH 5, 6, 7, and 8. The viscosity was measured as a function of shear rate in the range 15 s‐1‐230 s‐1. Though the centrifuged saliva had a viscosity close to that of water it increased the viscosity of the glucan up to 65% at pH 6 and 55% at pH 7 and at a shear rate of 20 s‐1, indicating an interaction between saliva components and glucan that could be an important part of the cohesive forces of plaque matrix. The interaction between saliva and glucan was less pronounced at pH 5 and 8, which indicates a charge‐dependent interaction. The viscosity increase at pH 6 and 7 was higher at low than at high shear rates, suggesting a higher contribution to plaque stability when weak as opposed to high mechanical forces are exerted

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01058.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Oral implantations of and salivary IgA activity against a freshly isolatedStreptococcus mutansstrain and a repeatedly subcultured variant strain were studied in 20 subjects. The variant strain was eliminated at a higher rate than the parent strain. Both strains were eliminated at a lower rate in subjects with high oral levels of indigenous mutans streptococci than in subjects with low levels of these microorganisms. Subjects with high respectively low IgA activity against the parent strain also had high respectively low IgA activity against the variant strain (P<0.01). The correlation between IgA activity and clearance rate of implanted bacteria was not statistically significant. However, following both implantations, median values of IgA activity were consistently higher in subjects who had eliminated the implanted strain than in subjects who had no

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01059.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—The prevalence ofStreptococcus mutansandStreptococcus sobrinuswas examined in plaque samples from small discrete areas of the buccal tooth surfaces of seven subjects. Strains ofS. mutansandS. sobrinuswere isolated and tested for bacteriocin‐mediated interactions between and within the two species, using the stab inoculation technique.S. mutansandS. sobrinusdid not colonize each tooth surface uniformly and, in plaque from small discrete sites,S. mutansandS. sobrinuswere either undetected or present in different interspecies proportions. Within the same subject, there were no bacteriocin‐mediated interactions between strains of the same mutans species and no difference in bacteriocin activity was found between the strains ofS. mutansandS. sobrinusfrom different sites. When bacteriocin interactions were tested between isolated strains from all seven subjects a somewhat higher inhibition ability was found for producer strains isolated from plaque compared with those isolated from saliva.S. mutansappeared to be more bacteriocinogenic thanS. sobrinus. Replacing the glucose in the medium with sucrose enhanced the bacteriocin activity ofS. mutanstowards otherS. mutansstrains but reduced the inhibitory interaction towards strains ofS. sob

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01060.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Great variations reported in the frequency distribution of buffer capacity values may partly be due to methodological differences in saliva sampling. In this study we wanted to see to what extent these variations are due to repetition and prestimulation. 9‐yr‐old schoolchildren (n: 41, 23 girls and 18 boys), who had never had saliva samples taken before, participated in the present study. The repetition tests were carried out between 9 and 11 a.m. on three subsequent days. The effect of prestimulation was tested 4 days later with the same subjects. The buffer capacity of the samples was determined electrometrically immediately after sampling using the commercial Dentobuff‐test. The intraindividual analysis revealed a significant increase in flow rate but not in buffer capacity along with repetition of the sampling. The analysis further showed that the buffer capacity of children accustomed to saliva sampling increased significantly through prestimulation of 1 min. The use of prestimulation resulted in substantial changes also in the frequency distribution of the buffer capacity values. Our results emphasize the importance of proper sampling conditions in saliva collection when screening children for high cari

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01061.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Abstract—Tissue lesions from eight patients with recurrent oral ulcers (ROU) were subjected to detailed immunohistopathologic studies. In five patients, a specimen of an unaffected area from the opposite site was obtained. The main inflammatory cells in situ were CD3 positive T lymphocytes, with CD4 cells forming approximately half (range 30‐60%) and CD8 cells 20% (range 10‐30%) of all cells. CD19 positive B lymphocytes formed 5‐12% of all cells. Furthermore, 45% (range 15‐65%) of all lymphoid cells had signs of previous antigenous contact and had helper/inducer CDw29 type. Suppressor/inducer CD45R cells formed only about 20% (range 7‐50%) of all cells. Although this observation suggests involvement of antigen as a causative and/or triggering stimulus, elements of a non‐specific inflammatory response were observed as well. Endogenous peroxidase‐positive neutrophils were present at the ulcer site, and were occasionally observed intravascularly and in th extracellular matrix in areas characterized by inflammatory mononuclear cell infiltrates. Although the proportion of endogenous peroxidase‐positive, recently recruited monocytes was low, CD11b and nonspecific esterase‐positive mature tissue macrophages formed about 14% (range 5‐35%) of all inflammatory cells in situ, particularly at the periphery of the lymphoid cell infiltrates. Mast cells were also observed in all samples studied, forming 2‐5% of inflammatory cells in the richly vascularized connective tissue beneath the basement membrane. In the specimens from clinically unaffected areas, inflammatory cells were rare. Our observations stress the multifaceted nature and participation of multiple effector systems in the local tis

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1991.tb01062.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY