Local and systemic immune response to orally administered liposome-associated soluble S. mutans cell wall antigens

The aim of the present study was to develop an immunization procedure which preferentially stimulated the IgA system of rats, with release of IgA in secretions. Rats immunized by intragastric route with liposome-associated soluble antigen extracted from Streptococcus mutans cell wall, showed a significantly higher IgA (and IgG) response than did rats injected with the soluble antigen alone. In saliva, maximal antibody titres were obtained 11 days after the beginning of intubations for IgA, and 16 days for IgG. After a booster immunization, the secondary response occurred very quickly in saliva and, like the primary response, it was almost exclusively of the IgA class. This demonstrates, on one hand the existence of immunological memory in the IgA system and, on the other, the efficiency of liposomes as insoluble adjuvants in eliciting an immunological response.

Transmission electron microscopy of plaque accumulations in denture stomatitis

Denture pellicle in denture stomatitis has been studied with transmission electron microscopy after embedding the denture base in a water-miscible resin in seven patients with heavy plaque deposits on their dentures and in five patients with no apparent plaque accumulation. In the first group, the denture surface was covered by a well differentiated granular pellicle. A cell-free zone was interposed between the pellicle and the plaque, which consisted predominantly of rounded, rod-shaped, and filamentous microorganisms with a loose distribution, separated by an electron-lucent amorphous and gel-like matrix. C. albicans were scattered among the bacteria and often presented with degenerated cytoplasm. In the second group, a structurally heterogeneous pellicle was seen adjacent to the denture surface. A thin plaque that consisted mainly of dense accumulations of C. albicans, a narrow dense matrix, and few bacteria was found. Calculus accumulations on the dentures consisted of amicrobial calcifications in the deeper layers, whereas the superficial parts showed bacterial calcifications.

Identification and preliminary characterization of saliva-interacting surface antigens of Streptococcus mutans by immunoblotting, ligand blotting, and immunoprecipitation

The ability of surface protein antigens of Streptococcus mutans to interact with salivary components was examined by Western blot and immunoprecipitation methods. Immunoblotting of S. mutans OMZ175 wall-associated antigens revealed 10 major antigens, designated according to their estimated molecular weights. Four of them, with molecular weights of 135,000, 125,000, 120,000, and 115,000 in their denaturated form, bound salivary components. This property was further investigated by immunoprecipitation experiments: the reactivity with saliva was confirmed for antigens with molecular weights of 135,000, 125,000, and 120,000 in their native form, and their locations on the bacterial cell surface were established. These three antigens were characterized as glycoproteins; they directly bound concanavalin A, and pronase abolished their antigenicity, which was partly retained after treatment with NaIO4. Because of their distribution in several other stains of S. mutans, it will be of interest to study their possible implication in the mechanism of attachment of streptococcal strains to saliva-coated tooth surfaces.

[Low caries activity and salivary pH in youngsters dialyzed for chronic renal failure]

Caries experience was studied in 18 young patients dialyzed for chronic renal failure and aged 7 to 17 years. The mean plaque index (Silness and Löe, 1964) was 1.89 +/- 0.15. Beside abundant plaque, these patients presented with poor oral hygiene and a food intake rich in sugars. Despite these unfavourable factors, caries experience was low. Of a total of 18 patients, ten (56%) had a DMF of 0. In addition, 11 subjects presented dental hypoplasias on more than two teeth. In these patients, the pH of whole saliva was determined at the beginning of the dialysis at time T and at the end of the dialysis at time To. The values at time T were always higher than those of time To. The mean pH at time T was 8.58 +/- 0.01 and the mean pH at time To was 8.09 +/- 0.01. These high salivary pH values are related to the low caries experience noted in these patients.

Tooth ultrastructure of late triassic Haramiyidae

Six molars of Haramiyidae from the French lower Rhaetic were examined by scanning and transmission electron microscopy, and by electron diffraction. Typical polished wear facets were located on the tops and on the occlusal bases of cuspids. Enamel was found to have had a structural pattern defined as "pre-prismatic", consisting of a repetitive pinnate orientation of the c-axes of apatite crystallites but without interprismatic material. Peritubular dentin was not found, but hydroxyapatite deposition in the dentinal tubular lumens was observed, whereas typical denticles with dentinal tubules and hydroxyapatite deposits were located in the pulp chambers. Taken together, these different features are strongly indicative of mastication, and hence enforce the suspected mammalian status of the Haramiyidae.

Cementogenesis and soft tissue attachment after citric acid treatment in a human. An electron microscopic study

The four maxillary incisors and two maxillary premolars of a 25-year-old male patient were used to study epithelial and connective tissue attachment 67 days and 164 days after flap surgery and cutting of an horizontal intradentinal groove near the buccal cervical region. Three teeth were topically conditioned for 3 minutes with citric acid pH = 1. The three other teeth were used as controls. The histologic examination was carried out in double-blind conditions; the examiners did not know which specimens were acid treated until the end of the study. Two of the three cases treated with citric acid showed improved healing conditions, when compared to the controls; a more coronal position of the epithelial attachment in the dentin nick as well as a relatively important gain in connective tissue attachment. Two types of connective tissue attachment were observed. The first consisted of an attachment to dentin, without cementum formation and was characterized by a mineralization of decalcified dentin collagen spliced with collagen, newly secreted by fibroblasts. The second type involved cementum formation. Topical citric acid treatment, however, can not be considered as a completely reliable clinical procedure since in one experimental case the type of attachment observed was not better than that seen in the control.

Comparative unsupervised clinical trial on caries inhibition effect of monofluorophosphate and amine fluoride dentifrices after 3 years in Strasbourg, France

A randomized, double blind clinical trial of the caries inhibition effects of dentifrices containing respectively monofluorophosphate and amine fluoride was performed. A third control group used a toothpaste without fluoride. A total number of 2008 schoolchildren ranging in age from 6 to 8 years and living in Strasbourg (France) participated in this study. After a baseline examination three groups were constructed with the block randomization technic. The caries inhibition effects of the three dental pastes were compared after 3 years of unsupervised use. The monofluorophosphate dentifrice showed a reduction of 7.02% for DMFT, 5.17% for DMFS and 25.26% for the df rate. The reduction of amine fluoride dentifrice caries was respectively 21.62% for DMFT, 20.94% for DMFS and 48.66% for the df rate.

Electron microscopy of avian osteopetrosis induced by retrovirus MAV.2-O

Diaphyseal tibial bone of 12.5-13-day and 19-day-old embryos and 20-day-old hatched chicks infected with retrovirus MAV.2-O were examined by transmission electron microscopy. The viruses were associated with lining osteoblasts and osteocytes. Whereas the infection of the osteoblast layer seemed to be a transient stage, virus association with osteocytes was a constant and main ultrastructural feature. The viruses were found either in the osteoid or in the periosteocytic space of the bone lacunae. They arose from dense cytoplasmic areas located near the cell plasmalemma via a budding process. The newly budded virus particles often had a large tail or a fine stalk-like process lost in the extracellular space. The viruses underwent calcification by deposition of inorganic material and were incorporated in the bone trabeculae. No production of virus was observed in typical osteoclasts with well-differentiated ruffled borders. The viral-induced avian osteopetrosis seemed to result from increased bone deposition through stimulation of osteoblast and osteocyte activities, whereas osteoclastic bone resorption seemed to be undisturbed.

[Scanning electron microscopy of the normal and carious aprismatic enamel surface of human temporary teeth]

The study of human primary teeth surfaces by scanning electron microscopy has shown that the localization and the extent of the aprismatic surface layer although present in all teeth studied was quite variable from one tooth to an other. Such an aprismatic layer could be found along the molar fissures. However each tooth studied possessed an important surface layer consisting of prismatic enamel. The respective distribution of prismatic and aprismatic enamel layers was highly variable and can hardly by systematized. The study of apparently intact layers of incipient carious white spot lesions has shown that the irregular type of surface destruction was related to the presence of an aprismatic enamel surface layer.

Scanning electron microscopy of unused and used manual toothbrushes

A scanning electron microscopic study of the brushing surface of 17 different types of commercial toothbrushes with natural and nylon bristles was conducted on new unused brushes as well as on 65 brushes used from 1 month up to 1 year, once, twice or three times a day, with various brushing techniques. Natural swine or wild boar toothbrushes, even when new, had filaments of irregular length and diameter with deficient and irregular ends. These defective surface conditions became worse with used. Unused soft and hard nylon toothbrushes were made of tufts with bristles of the same length and diameter with cut or rounded ends. The surface of the bristle ends was generally flat but various surface defects were observed. The contours of the bristle ends of both types of nylon toothbrushes improved with use, becoming smooth and rounded. Deteriorations of the brushing surfaces of both soft and hard nylon brushes were observed at time intervals varying from one subject to another, but hard nylon bristles wore best. Soft nylon brushes wore out more rapidly.

Soluble and insoluble proteins of normal human mature enamel

Human mature enamel proteins were prepared by a combination of three extraction procedures in the presence or absence of de-aggregating agents before and after EDTA demineralization. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed the presence of a single low mol. wt protein in the water extract and multicomponent proteins with high mol. wt in the urea and urea-EDTA extracts. Polyacrylamide gel electrophoresis of the proteins contained in the three fractions after reduction and alkylation showed the existence of the two last fractions of different constitutive monomers linked by covalent and non-covalent bonds. Immunological comparison of the proteins showed at least one common protein in the E2 and E3 fractions. It is suggested that the high mol. wt proteins observed in mature enamel matrix were formed by combination of different monomers.

Ultrastructural location of Streptococcus mutans and Streptococcus sanguis antigens in carious human dentine

The ultrastructural localization of bacterial antigens of Streptococcus sanguis and of the various serotypes a,b,c,d,e,f and g of Streptococcus mutans was studied in human carious dentine using the indirect peroxidase-antiperoxidase method with appropriate controls. No positive staining was seen in adjacent normal dentine. In the inner dentine underlying the cytoplasm of fibroblasts and Schwann cells of unmyelinated nerve fibrils. In sclerosed tubules, or on the plasmalemma of the odontoblast process or on both structures. Only in the odontoblast, facing the carious cone, were dense stainings noted in vacuoles of various sizes located in the Golgi apparatus in juxta-nuclear position and in their odontoblast processes. In pulpal regions, underlying the carious cone, dense vacuoles were also observed in the cytoplasm of fibroblasts and Schwann cells of unmyelinated nerve fibrils. In sclerosed tubules, electron dense deposits were noted in the lumen and the walls of the calcified tubules. In the outer carious dentine, invaded by micro-organisms, positive antigenic stainings were observed in the cell wall and capsular material of a great number of micro-organisms as well as in the interbacterial matrix.

High resolution electron microscopic technique applied to the detection of distortions in apatite crystallites during amelogenesis

Distortions in the crystal structure of developing tooth enamel from human fetuses and newborn cats were studied by high resolution electron microscopy. Undecalcified sections were observed in a JEOL 100B transmission electron microscope. Two kinds of crystal sections were observed. In one, the diffraction images corresponded to the (10.0) and (00.2) lattice planes, and in the other they corresponded to the (01.0) and (10.1) planes. The unit cell distortion in naturally bent crystals showed a linear correlation with the inverse of the radius of curvature for both the [00.2] and the [10.1] axes. along the [00.2] axis of crystallites from both cat and human enamel, the distortion per unit cell was linearly correlated with the inverse of the length of the crystallite segment under consideration.

Common antigens of streptococcal and non-streptococcal oral bacteria: immunochemical studies of extracellular and cell-wall-associated antigens from Streptococcus sanguis, Streptococcus mutans, Lactobacillus salivarius, and Actinomyces viscosus

Soluble extracellular antigens (ESA) were prepared from the culture supernatant of exponential growing cells of Streptococcus sanguis OMZ 9 by a combination of ammonium sulfate precipitation and chromatography on a Bio-Gel P6 column. Soluble cell wall antigens (WEA) were obtained from the bacterial pellet by extraction with 1 M phosphate buffer (pH 6). Antisera against whole cells of S. sanguis and S. mutans of different serotypes, 10% trichloroacetic extracts of bacterial cell walls, dextran, ESA, and WEA were prepared by injecting the different antigens several times in rabbits. ESA and WEA were prepared from a representative strain of Bratthall's seven serological groups, Lactobacillus salivarius, and Actinomyces viscosus. All sera showed various agglutinin titers against heat-killed cells, and titers were generally higher with homologous cells. The comparison of the different antigens using agar gel diffusion and immunoelectrophoresis showed the presence of extracellular common antigens in both ESA and WEA between the different strains. Absorption of anti-ESA sera with WEA, and anti-WEA sera with ESA, showed the existence of a specific antigen common to all bacteria in each fraction. Enzymatic treatment of the antigen before immunodiffusion demonstrated the protein nature of the two antigens present in ESA and WEA.

[Scanning electron microscopy of dental plaque and tartar on the surface of human cementum]

Supragingival plaque covering cementum, exposed through withdrawal of the epithelial attachment, presented the same bacterial polymorphism as nature dental plaque. Rounded, filamentous and rod-shaped organisms were observed. In some areas, the presence of extracellular material corresponded to plaque matrix. Corn cob configurations consisting of central filamentous bacteria associated with peripheral cocci were often seen in the supragingival plaque overlaying the cementum. The observation of cementum calculus allowed the differentiation of supragingival and subgingival calculus. The first consisted mostly of calcified dental plaque. The calcification started more often in the interbacterial matrix, but sometimes an initial calcification of the bacterial bodies was noted. Beside this calcified bacterial plaque, crystalline inorganic deposits devoid of micro-organisms were observed. The same differences were noted in subgingival calculus but the proportion was clearly reversed. Amicrobial crystalline deposits were more frequent and calcified bacteria were more uncommon.

[Scanning electron microscopy of the surface of human cementum in various physiological and pathological conditions]

In scanning electron microscopy (SEM) of the dental root surfaces human cementum resorption by giant multinucleated cells appeared similar in temporary and permanent teeth. Thus the resorbed zones were formed by associated Howship lacunae. On the lacunae walls, the openings of numerous tubules of the cementocytic lacunae were seen. Such aspects were noted during the physiological resorption of temporary teeth. The cementum surface of permanent teeth without pathology, presented frequently such resorption aspects around their apical regions as well as on other regions, the resorbed areas being more often not widespread. Similar resorption zones were observed in contact with paradental granulomas and along granulation tissue in cases of chronic periodontitis. Orally exposed cementum, after gingival recession, was mainly characterized by the disappearance of the typical dappled aspect of the cellular cementum and by the presence on the smoothed surface of numerous striate. The cementum wall of the periodontal pockets showed always the dappled aspect with the occasional presence of incipient calculus formation as well as calcified fibrillar elements. These calcified fibrils were either short covering the whole surface or were longer being disposed parallel to the surface in interwoven networks or in tufts. Cementum curetage followed by root planning removed the calculus completely. Before root planning, the presence of numerous striae were noted. They disappeared following the action of a rubber cup and an abrasive polishing paste. Ultrasonic scaling gave a relatively clean root surface. However, the cementum surface, apparently devoid fo calculus under visual examination, showed in places the presence of thin calculus layers under the SEM.