摘要:

Abstract –The aim of the present paper was to identify some chemical and structural factors which may prevent a full remineralization of caries lesions and to study whether it is possible to overcome such obstacles. Samples of powdered enamel apatite were equilibrated with solutions metastably supersaturated with respect to enamel hydroxyapatite and fluorapatite. After 10 min and 60 min of equilibration at 20°C the suspensions were centrifuged and the calcium and phosphate concentrations and the pH were determined in the supernatant. In parallel studies, 50–75‐μm‐thick sections of 27 fluorotic teeth of a severity of 5–7 according to Thylstrup and Fejerskov's classification were examined by microradiography and in polarized light using distilled water, and Thoulett's media or seen dry in air. Five obstacles inhibiting remineralization were identified: 1) Although remineralizing solutions or saliva are supersaturated with respect to enamel apatite the total amount of calcium and phosphate dissolved in it is small, so that after precipitation of the dissolved mineral only 1/20 000‐1/30 000 of the volume of the mineralizing solution is occupied by mineral. 2) The concentration gradients from the mineralizing solution into the enamel is small, which indicates a slow diffusion into and out of the lesion. 3) The uptake of calcium and phosphate by the enamel apatite crystals is so rapid that the aqueous phase within the pores can be presumed to be only marginally supersaturated in the deeper parts of the lesion. 4) The surface layer of the enamel lesions was found to be a serious obstacle to remineralization so that a subsurface area remains hypomineralized after exposure to salivary remineralization even for a lifetime. 5) Nucleation of new apatite crystals to substitute lost crystals is an uns

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01615.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –In this paper the results are presented on the action of glutardialdehyde (GDA) on the in vitro demineralization of human dentin and on the in vivo demineralization of dentin using the Ögaard orthodontic banding system. The results show that a 2 min application of a 2% GDA solution at pH = 3.6 reduces dentin demineralization in vitro and in vivo substantially. Microradiography shows a percentage reduction of lesion depth and mineral loss in vitro of 20 and 36%, respectively. After 2 wk in vivo demineralization the same percentage reductions are 60 and 44%, respectively. The mechanism of action of GDA on dentin is not certain yet. Presumably the in vitro action is due to surface cross‐linking of the dentin matrix causing reduced Ca and phosphate transport out of the dentin. In vivo an additional effect may be a rather short term influence of GDA on plaque or on plaque accumulation. The results of this paper indicate that glutardialdehyde is an interesting agent to consider in the reduction of root ca

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01616.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –This study describes the effects of intravenously given corticosteroids on dentin formation in adult rat molars. Six rats twice a day received corticosteroids 20 mg/kg for 8 days, 10 mg/kg for 13 days, and 5 mg/kg for 19 days. Six rats given a heterotopic heart transplant received 10 mg/kg of corticosteroids twice a day for 40–64 days. Six rats were used as controls. Tetracycline was given at the start of the experiment and after 3 wk of treatment. After 40–46 days the rats were killed. Light microscopic examination of the molars showed no differences in the dentin formation or in the predentin zone between the experimental and control rats. In the ultraviolet light microscope two lines of tetracycline were visible along the root canal walls in both experimental groups. There was an obvious distance between the two lines, which indicated formation of new dentin. In the control group no formation of dentin was vi

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01617.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –During a 2‐yr study period samples from saliva, the tongue, and 276 interdental spaces were obtained from 23 7‐yr‐old children in order to (a) relate the presence of lactobacilli in various oral sites to the occurrence of lactobacilli in saliva, and (b) relate the presence of mutans streptococci and various types of lactobacilli interdentally to the development of proximal carious lesions. The results showed an increased number of interdental samples containing lactobacilli with an increasing number of salivary lactobacilli. Furthermore, lactobacilli were never found interdentally without the presence of mutans streptococci, and lactobacilli proved to be the more suitable microorganism for prediction of proximal carious lesions. Neither the number nor the differentiation into different species of interdental lactobacilli seemed to be of importance, but simply whether they were present. The presence of lactobacilli probably reflects a caries‐inducing environment (etiologic microflora + fermentable carbohydrates), thus explaining their high predictive ability compared to their rather limited etiologic importance in the initiation

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01618.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –A material of 22 primary and 4 permanent teeth from 22 children with amelogenesis imperfecta (AI) were examined by microradiographic techniques. The children were part of a patient material earlier examined in genetical and clinical studies. The results were compared with corresponding data from two non‐affected control groups and correlated with the available clinical and genetical data. Teeth were examined from seven of the eight different variants of AI seen in the clinical study. In most cases both hypoplasias and areas of hypomineralization were observed in the same tooth, indicating that both the secretory and the maturation phases of the amelogenesis are affected in AI. In teeth from children with the same clinical variant but different inheritance patterns, no specific finding could be related to a specific inheritance pattern. The findings in the one boy with AI as an X‐linked trait were unique in this material. In all control teeth except one, no hypoplasias or areas of hypomineralization were found in the enamel. In conclusion, the subclassification of AI into different forms can be questioned. Variations in clinical and histologic characteristics connected with the same inheritance pattern suggest that the genetic defect, in conjunction with a large biological variation, could explain the multiplicity in clinical expressivity that characteriz

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01619.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –The caries preventive effect of topical application of fluoride varnish (Duraphat), ferric‐aluminum‐fluoride solution (FeAlF) and chlorhexidine gel was compared in a 2‐yr clinical study. Children with more than 106mutans streptococci per ml saliva were selected and a total of 189 13‐yr‐old children participated in the study. The children in the fluoride groups were treated every third month with either Duraphat or FeAlF‐solution. In the chlorhexidine group children with more than 2.5 × 105mutans streptococci per ml of saliva were treated every third month. The mean number of new decayed and filled tooth surfaces was 3.06 in the chlorhexidine group, 5.88 in the Duraphat group, 5.33 in the FeAlF group, and 6.34 in the control group. Thus supervised antimicrobial treatment can significantly reduce the incidence of dental (caries) in children with high numbers of mutan

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01620.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –Current‐induced effects on the growth and adhesion ofStreptococcus mutanswere studied. The spontaneous currents formed between gold‐amalgam pairs showed starting current peaks of approximately 200 μA followed by constant currents of approximately 15 μA. The presence of the gold‐amalgam pair had no effect on the growth ofS. mutans, which was unaffected even when constant potentials of 1000 mV and 2000 mV were used to produce extreme experimental conditions. Three volts or more was needed to inhibit the growth ofS. mutans. Organic acids produced byS. mutansduring growth had also little or no effect on the magnitudes of the spontaneous currents formed between the gold‐amalgam pairs. Adhesion ofS. mutans, grown with or without added sucrose, appeared unaffected by spontaneous currents induced by the metal c

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01621.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –The existing forms of neutral proteases present in inflamed human gingiva were examined. Neutral 2 M KCl extracts of inflamed human gingival tissue were fractionated by gel filtration on Sephacryl S‐200 and the fractions were assayed for collagenase, trypsin‐, chymotrypsin‐, and elastase‐like proteases. Apparent molecular weights of 80–85 kDa were obtained for trypsin‐, chymotrypsin‐, and elastase‐like proteases, and 70–75 kDa for latent collagenase. Further fractionation of high molecular weight proteases on Con A‐Sepharose revealed that, unlike collagenase, chymotrypsin‐, and elastase‐like proteases, the trypsin‐like protease was bound by the affinity column. Native human placental type IV (basement membrane) collagen was degraded by chymotrypsin‐like and elastase‐like proteases but not by the trypsin‐like protease. This degradation was inhibited by phenylmethyl sulfonyl fluoride and EDTA. The serine proteases also degraded efficiently denatured type I collagen. No correlation of the activities of trypsin‐like protease and the other proteolytic enzymes was found in extracts of 18 individual gingival specimens. Significant correlation, however, was noted between collagenase and gelatinase. The gingival culture studies showed that, while the highest activity of the trypsin‐, chymotrypsin‐, and elastase‐like enzymes were measured in medium during first days of the culture, collagenase and gelatinase activities increased up to the fourth day of culture and stayed high until the end of the culture. These results suggest that the neutral proteases that may participate in the periodontal tissue destruction are pr

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01622.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –Cell surface ultrastructure and other surface properties ofPorphyromonas gingivalisstrain W50 and pleiotropic mutants W50/BP1 (black), W50/BR1 (brown), and W50/BE1 (beige) were studied. The percentage hydrophobicity of strains W50, W50/BP1, W50/BR1, and W50/ BE1 gradually decreased from 24 to 9. Ruthenium red stained cells studied by transmission electron microscopy revealed a layer of extracellular polymeric material of varying thickness depending on the strain. The layer was thickest in W50/BP1 (15–20 nm), strains W50 and W50/ BR1 both had a layer of 12–15 nm, while strain W50/BE1 completely lacked this layer. The results clearly showed that the hydrophobicity ofP. gingivaliswas related not only to the thickness of the layer but also to other factors like the composition of the capsular material, such that only strain W50/BE1, for example, showed no haemagglutinating activity. The surface properties of the pleiotropic mutants appeared to be stable characteristics as cells grown on either solid or in liquid media gave comparable results. The loss of virulence of the beige strain (W50/BE1) is probably partly due to the alteration of these surface properties. Both virulent and avirulent strains, however, possessed extracellular ves

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01623.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract –Monoclonal anti‐CD4, anti‐CD8, and anti‐GD18 antibodies were applied in avidinbiotin‐peroxidase complex staining using a pre‐embedding immunoelectron microscopy technique. Although most of the local T cells in situ were of CD4+subtype, local CD8+cells generally had a lower nucleus/cytoplasm ratio and contained more cell organelles than CD4+cells. This suggests a local activation of CD8+subpopulation, rather than activation of the numerically predominant CD4+cells. Topographical analysis disclosed that all lymphocytes, regardless of location, were CD18+and that most of the CD8+cells were located subbasally and intraepithelially, whereas CD4+cells often occurred in small clusters deeper down in the subepithelial lymphocyte‐rich band. Furthermore, CD8+cells were often in close contact with macrophages, whereas CD4+cells were in some instances in direct contact with plasma cells. This indicates that CD4+cells may be involved in T cell‐dependent B cell‐mediated immunoglobulin synthesis, whereas CD8+cytotoxic lymphocytes and tissue macrophages may be involved in the local pathogenetic process leading to basement mem

ISSN:0909-8836    

DOI:10.1111/j.1600-0722.1989.tb01624.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY