Biomedical subjects

O Fejerskov

Publications and source records attributed to O Fejerskov.

At least 37 records · Page 2Linked to original sources

PubMed1997

Subgingival microbiota in adult Chinese: prevalence and relation to periodontal disease progression.

The "checkerboard" Dna-Dna hybridization technology was used to study the epidemiology of 18 microbial species associated with various states of periodontal health and disease, in a sample of 148 Chinese subjects never exposed to systematic dental therapeutic intervention, aged 30 to 39 and 50 to 59 years. Our aims were to: 1) describe the prevalence of these microorganisms; 2) correlate the microbiological and clinical profiles of the subjects; and 3) examine the association between the microbiological variables and the longitudinal changes of periodontal status that occurred over a preceding 10-year period. A maximum of 14 subgingival samples were obtained from each subject-1,864 in all. The frequency of occurrence of the 18 species examined was high in this Chinese population, on both the subject and the tooth site level. However, all species were not found equally capable of reaching high numbers in the subgingival samples and, as a rule, colonized heavily only limited proportions of tooth sites within each mouth. There was a profound increase of certain species such as Porphyromonas gingivalis, Treponema denticola, and Bacteroides forsythus in deep pockets or progressing sites. Multivariate techniques using the subgingival profile could effectively discriminate between deep/shallow pockets and progressing/ stable tooth sites. The microbiological variables showed an enhanced discriminating potential when classifications were performed on the individual subject level. Colonization by P. gingivalis, B. forsythus, Campylobacter rectus, and T. denticola at levels exceeding certain thresholds entailed a significantly increased probability (odds ratios > 4) for an individual subject to harbor deep pockets or progressing tooth sites.

Adult↗

PubMed1996

Profiles of destructive periodontal disease in different populations.

In this study we evaluated the traditional view that the severity of periodontal disease varies between populations in that African and Asian populations are more severely affected than other populations. Our data on periodontal destruction in two random samples of a Kenyan and a Chinese adult population were recalculated to conform with the methods of examination and data presentation utilized in each of 6 other studies of attachment loss levels in different populations. The adult Kenyan and the adult Chinese group, who had very poor oral hygiene conditions and massive gingival inflammation, had attachment loss levels which were quite similar to those in a Japanese population (31), in a Norwegian population (27) and in a New Mexico group of adults (30). Attachment losses were similar in a population of young US adults (26) aged between 35 and 60 years relative to the corresponding Kenyan and Chinese groups while young US citizens had higher and elderly US citizens had lower mean attachment levels than either Kenyans and Chinese. Higher attachment loss levels beyond the age of 27 years were reported for a population of Sri Lankan Tamil tea workers (27) and across all ages in two South Pacific island populations (29). Overall, the analysis indicates that the periodontal attachment loss profiles may differ between populations, but that these differences do not conform with the traditional generalization that African and Asian populations suffer more severe periodontal breakdown than other populations.

Adolescent↗

PubMed1996

Transmission electron microscopy of cementum crystals correlated with Ca and F distribution in normal and carious human root surfaces.

Root-surface caries, like enamel caries, develops as a subsurface type of mineral loss. Very little is known about the composition of the surface zone covering the body of the lesion, and the ultrastructure and composition of carious cementum are not known. The aim of this study was to correlate the ultrastructure and arrangement of the cementum crystals with the distribution of fluoride and calcium in root cementum from human teeth with sound, unexposed, or exposed root surfaces as well as in early stages of root-surface caries. Microradiographically, unexposed specimens showed a relatively homogeneous mineral distribution contrasting with the formation of an apparently highly mineralized surface layer in exposed and, in particular, in carious cementum. The electron-probe findings showed a substantial fluoride peak corresponding to the surface layers in carious tissues in particular, whereas the calcium profile in the surface did not reflect the apparent increase in mineralization. A substantial increase in size of the cementum crystals was found in specimens with formation of the fluoride-rich, well-mineralized surface zone. The crystal lattice intervals when observed along the (001) plane showed a hydroxyapatite spacing. The findings indicated that a significant crystal growth can be achieved in human cementum concomitant with fluoride accumulation.

Adult↗

PubMed1996

Plaque pH and microflora of dental plaque on sound and carious root surfaces.

Given the hypothesis that root caries is the result of acid formation by acidogenic micro-organisms, the present study was performed to relate sucrose-induced pH response of dental plaque on root surfaces to the microbial composition of the overlying plaque. Seventeen caries-active elderly Chinese with poor oral hygiene and with both sound and carious root surfaces were examined. Plaque pH was measured before and up to one hour after a controlled sucrose mouthrinse. Plaque samples for microbiologic analyses were collected from 2 sound and 2 or 3 carious pH-measurement sites in each subject. The prevalence of the following micro-organisms was assessed as % of total viable counts on Brucella agar: Prevotella intermedia, Prevotella melaninogenica, Fusobacterium nucleatum, Campylobacter rectus, Capnocytophaga spp., Actinomyces viscosus, Actinomyces naeslundi, Streptococcus spp., S. sanguis, S. mitis, S. mutans, S. sobrinus, Lactobacillus spp., and Candida spp. There was no difference in plaque pH response on sound and carious root surfaces. The plaque pH response was more pronounced in the maxilla than in the mandible for both sound and carious sites. There was no difference in microbial composition of dental plaque on sound and carious root surfaces. The pH response to sucrose was the same regardless of the presence or absence of mutans streptococci. Our results thus do not readily support the traditional concept of caries formation.

Aged↗

PubMed1996

Structural changes in fluorosed dental enamel of red deer (Cervus elaphus L.) from a region with severe environmental pollution by fluorides.

A macroscopic, microradiographic and scanning electron microscope study was performed on the structure of fluorosed dental enamel in red deer from a fluoride polluted region (North Bohemia, Czech Republic). As was revealed by analysis of mandibular bone fluoride content, the rate of skeletal fluoride accumulation in the fluorotic deer was about 6 times that in controls taken from a region not exposed to excessive fluoride deposition. In all fluorosed mandibles, the 1st molar was consistently less fluorotic than the other permanent teeth. This was related to the fact that crown formation in the M1 takes place prenatally and during the lactation period. Fluorosed teeth exhibited opaque and posteruptively stained enamel, reduction or loss of enamel ridges, moderately to grossly increased wear and, in more severe cases, also enamel surface lesions of partly posteruptive, partly developmental origin. Microradiographically, fluorosed enamel was characterised by subsurface hypomineralisation, interpreted as a result of fluoride interference with the process of enamel maturation. In addition, an accentuation of the incremental pattern due to the occurrence of alternating bands with highly varying mineral content was observed in severely fluorosed teeth, denoting fluoride disturbance during the secretory stage of amelogenesis. A corresponding enhancement of the incremental pattern was also seen in the dentine. The enamel along the more pronounced hypoplasias consisted of stacked, thin layers of crystals arranged in parallel, indicating that the ameloblasts in these locations had lost the distal (prism-forming) portions of their Tomes processes. The findings of the present study indicate that red deer are highly sensitive bioindicators of environmental pollution by fluorides.

Animals↗

PubMed1996

The effects of a mouthrinse containing sodium benzoate and alcohol on the quantity and metabolism of dental plaque.

The aim of this study was to investigate the efficacy of a pre-brushing rinse containing sodium benzoate and alcohol, on 2 week old dental plaque. In a double-blind, placebo-controlled crossover study 20 individuals abstained from oral hygiene for periods of 2 weeks. Ten individuals were then assigned to rinse once for 30 seconds with either the test mouthrinse or a placebo mouthrinse. Following this, all individuals had their teeth cleaned and maintained proper oral hygiene for four weeks before the experiment was repeated. This time, the control individuals were assigned to the test rinse and vice versa. Using the Plaque Index on three buccal sites on all teeth, plaque was recorded before and after rinsing, as well as following a subsequent toothbrushing. For metabolic studies plaque from the lingual surfaces on the teeth in one quadrant in the upper and the lower jaw was sampled before rinsing and from the two remaining quadrants following the rinse, and analysed. There was no difference in Plaque Index between the two experimental periods. An oral rinse with the test mouthrinse had no effect on the amount of plaque, nor did it enhance the subsequent plaque removal after brushing. The independent biochemical analysis showed a significant effect of rinsing on the glycolytic potential, but with no effect on the glycolytic profile, which was similar for test and control plaque samples. Thus, a single oral rinse with a mouthrinse containing sodium benzoate and alcohol does not affect removal of plaque nor does it seems to influence the glycolytic potential of the plaque.

Acids↗

PubMed1995

Relationship between CPITN and periodontal attachment loss findings in an adult population.

This study investigates the relationship between CPITN findings and the prevalence and severity of periodontal attachment loss in a rural Kenyan population comprising 1131 persons aged 15-65 years. All persons were examined for calculus, gingival bleeding, pocket depths and attachment loss levels on 4 sites of each tooth present. Recordings of bleeding, calculus and pocket depths were used to compute CPITN scores based on the 10 index teeth originally proposed, and these CPITN scores were subsequently related to the attachment loss findings derived from the full-mouth assessment. In most cases, persons with a CPITN score < or = 1 did not have attachment loss > or = 4 mm. However, among 40+ year-old persons with CPITN score 2 over 90% had attachment loss > or = 4 mm and over 50% of the 50+ year-olds with CPITN score 3 had attachment loss > or = 6 mm. Less than 20% of the 15-29 year-olds with CPITN score 3 had attachment loss > or = 6 mm, and usually the attachment loss levels ranged between 0 and 3 mm. Beyond the age of 35 years over 10% of the sextants with CPITN score 0 had attachment loss > or = 4 mm. Below the age of 35 years more than one third of all sextants with CPITN score 3 had attachment loss levels < or = 3 mm. Thus, the CPITN findings overestimate both prevalence and severity of periodontal attachment loss among the younger age groups and underestimate these parameters among elderly subject.

Adolescent↗

PubMed1995

Periodontopathogens in elderly Chinese with different periodontal disease experience.

If an etiological relationship exists between destructive periodontal disease and putative periodontopathogens, they would be expected to have a very low prevalence in periodontally healthy elderly persons. To test this hypothesis, 2 subgroups of elderly, rural Chinese (a periodontally "best" and a "worst" group, each comprising 15 persons) were identified in 1990 from a cohort aged 55-69 years, examined in 1984. Assessment of changes in periodontal status over the 6-year period were possible by comparing detailed clinical recordings performed by the same examinator. Subgingival microbial samples were taken at the mesial aspects of an upper central incisor and a lower canine and examined for the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia group, Prevotella melaninogenica group, Capnocytophaga, Selenomonas, Campylobacter rectus as well as predominant Streptococcus and Actinomyces species. During the 6 years prior to microbiological sampling, persons in the "best" group had lost an average of 1.21 +/- 0.48 mm attachment, while persons in the "worst" group had lost an average of 1.60 +/- 0.94 mm. The latter group had lost 53.3 teeth, predominantly for periodontal reasons, in contrast to 1.8 teeth lost in the "best" group. "Best" persons did not differ from "worst" persons with respect to the occurrence of the putative periopathogens, total viable count, and total streptococcal and Actinomyces recovery. Similarly, sites which had experienced an attachment loss > or = 2 mm during the 6-year period did not differ microbiologically from sites with less attachment loss. It is concluded that subgingival microbial characterization does not allow for a distinction between elderly individuals with markedly different periodontal disease experiences.

Actinomyces↗

PubMed1995

Strategies in the design of preventive programs.

Dental caries is mostly recorded at the cavity level only. A reduced mean number of cavities in new age cohorts is often thought of as a result of prevention of the disease, dental caries. However, what is measured is rather our success in controlling the disease in such a way that prevalence of its more severe manifestations (cavities) can be reduced in children. Caries lesions and periodontal breakdown are cumulative with age and progress steadily in all populations. Thus, caries is the predominant reason for tooth loss in almost all age groups. The low prevalence and skewed distribution of dental caries make several fluoride programs less (if at all) cost-effective. Rather than considering a "whole population strategy" as opposed to a "high-risk strategy", it is argued that they should go hand in hand. However, the high-risk strategy may appear to have an unfavorable ratio of benefits to costs. So far the available literature shows no evidence that we have tests which, with sufficient predictive power, can identify groups or individuals of "high risk". It is therefore concluded that a population strategy should be maintained and further developed with emphasis on oral hygiene, because it influences norms and behavior. More knowledge about the pathogenesis of oral disease is needed before we can develop truly cost-effective strategies for the prevention of caries and periodontal breakdown.

Adolescent↗

PubMed1994

Approximal plaque pH following topical applications of standard buffers in vivo.

In this study, the null hypothesis was tested that topical application of standard buffer solutions, pH 7.00 and pH 4.01, to 4-day-old plaque deposits accumulated in situ causes the plaque to attain the pH values of the buffer solutions applied. Following a 4-day abstention from all oral hygiene procedures, the plaque pH of four interdental sites in each of 5 volunteers was measured at resting state and following topical applications of buffers pH 7 and pH 4. Later the same day plaque pH was measured following rinses with the buffers. Topical application of buffer pH 7 caused a plaque pH increased from a mean value of 6.40 to 6.59 within 30 s, while buffer pH 4 caused plaque pH to drop to a mean value of 5.11. Rinsing with buffers caused plaque pH to increase to 6.50 (buffer pH 7) and to drop to 4.92 (buffer pH 4). Statistical analysis of the results led to rejection of the null hypothesis. The results thus indicated that the validity of the in situ approach of calibration of plaque-covered indwelling electrodes may be questioned.

Administration, Topical↗

PubMed1994

Dental tissue effects of fluoride.

It is now well-established that a linear relationship exists between fluoride dose and enamel fluorosis in human populations. With increasing severity, the subsurface enamel all along the tooth becomes increasingly porous (hypomineralized), and the lesion extends toward the inner enamel. In dentin, hypomineralization results in an enhancement of the incremental lines. After eruption, the more severe forms are subject to extensive mechanical breakdown of the surface. The continuum of fluoride-induced changes can best be classified by the TF index, which reflects, on an ordinal scale, the histopathological features and increases in enamel fluoride concentrations. Human and animal studies have shown that it is possible to develop dental fluorosis by exposure during enamel maturation alone. It is less apparent whether an effect of fluoride on the stage of enamel matrix secretion, alone, is able to produce changes in enamel similar to those described as dental fluorosis in man. The clinical concept of post-eruptive maturation of erupting sound human enamel, resulting in fluoride uptake, most likely reflects subclinical caries. Incorporation of fluoride into enamel is principally possible only as a result of concomitant enamel dissolution (caries lesion development). At higher fluoride concentrations, calcium-fluoride-like material may form, although the formation, identification, and dissolution of this compound are far from resolved. It is concluded that dental fluorosis is a sensitive way of recording past fluoride exposure because, so far, no other agent or condition in man is known to create changes within the dentition similar to those induced by fluoride. Since the predominant cariostatic effect of fluoride is not due to its uptake by the enamel during tooth development, it is possible to obtain extensive caries reductions without a concomitant risk of dental fluorosis.

Amelogenesis↗

PubMed1994

Human experimental caries models: intra-oral environmental variability.

In situ caries models serve purposes other than just being a simpler way to obtain data than running a clinical trial. However, variation in information obtained not only among individuals but also, in particular, depending on different locations of the models within the oral cavity have so far been given little attention. In the present review, the aim has been to characterize the different designs of in situ caries models and to describe some important factors which may vary within the oral cavity and thus influence the outcome of the way the different in situ models are used. Advantages and disadvantages of in vivo models vs. in situ models are discussed. In the latter case, the distinction is made between dental appliance models and so-called "single tooth" models. The review concludes that in situ models differ distinctly with regard to their "biological potential". Because of regional differences in salivary film velocity, pH, and composition of the microflora, results obtained by the various models are not likely to be immediately comparable. Moreover, local factors in relation to specimen environment, such as degree of "protection" and plaque thickness, may further add to the differences. It is suggested that these observations are important in considerations of the relevance of substituting clinical trials with in situ studies. Because of the pronounced intra-oral variation in certain parameters thought to be important for caries lesion development, we conclude that no in situ model can, by itself, fulfill the role as the "model of choice". Finally, although in situ models are useful adjuncts in attempts to estimate the relative effects of new anticaries methods or compounds on caries initiation, the selection of in situ study model design will strongly depend on the aim and purpose of the study.

Dental Caries↗

PubMed1994

Caries prevalence in Africa and the People's Republic of China.

Problems arise when attempting to compare caries data collected in both Africa and the People's Republic of China. These difficulties are not only the result of differences in the criteria used for the diagnosis of caries but are also due to the diversity of cultural and social conditions existing within each of the geographical areas. However, interpreted with caution, the data seem to suggest that caries experience among children is still fairly stable and at a low level, in contrast to the predictions of a decade ago. When comparing data from adult and elderly cohorts, however, caries is seen to be a widespread disease with continuing slow progression throughout life.

Adolescent↗

PubMed1994

Degradation of the dental basement membrane during mouse tooth development in vitro.

During tooth development, the basement membrane is degraded at the late bell stage, but the developmental significance of this event is not known. Organ culture offers a method where developmental processes can be manipulated in controlled conditions. We cultured bell-stage tooth germs either in a chemically defined or a serum-containing medium and analyzed the degradation of the basement membrane by different methods. Type IV collagen was present throughout the dental basement membranes at the epithelial-mesenchymal interface at the onset of culture. After 10 days of culture, irrespective of the medium used, type IV collagen and laminin had disappeared from the cuspal areas but were present at the cervical loop. As was the case in vivo, the expression of 72 kDa type IV collagenase gene was intense in the differentiating preodontoblasts and in the odontoblasts during secretion of the first predentin matrix near the cuspal tips. Ultrastructural observations showed that the basal lamina had been removed in all cultured tooth organs. Also, the breakdown of the basement membrane occurred irrespective of the presence of mineral in the dentin matrix. Our observations suggest in contrast to earlier observations, that there are no major differences in basic events leading to dentino- and amelogenesis, when tooth organs are cultured in the presence or absence of serum.

Ameloblasts↗

PubMed1994

Recent advancements in the treatment of root surface caries.

The aim of the paper is to present a review focusing on the magnitude of the problem of root caries. In addition, consideration of the aetiology and characteristics of root surface caries pathology is given as a guide to the appropriate use of operative or non-operative treatment alternatives.

Dental Restoration, Permanent↗

PubMed1993

Scanning electron microscopy of final enamel formation in rat mandibular incisors following single injections of 1-hydroxyethylidene-1,1-bisphosphonate.

A single, high dose of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) results in three different types of lesions along the enamel surface of the rat incisor, one of which is seen as a "bright band" crossing the final enamel surface in the scanning electron microscope (SEM). The present study presents the structural surface features of final enamel formation and its subsequent maturation in normal and HEBP-exposed rats. The position of the bright band is examined in relation to where the Tomes processes pits disappear (DTPP), where the boundary between "light" and "dark" enamel (LDB) as seen by SEM is located, and in particular, where the so-called opaque boundary (OB) is positioned. Groups of rats were given a subcutaneous dose of 0, 5, or 10 mg P/kg body wt of HEBP and killed at intervals of either 12 hours or 2 or 9 days. The mandibular incisors were processed for SEM after enzymatic digestion of enamel organ remains. Enamel surface nodules, 100-300 nm in diameter and composed of smaller units, were evident at the start of final enamel formation which was defined as the area from DTPP to LDB. With increasing maturation, the nodules merged to form a smooth surface. In HEBP-treated animals, growth and merging of these surface nodules became arrested at the time of injection resulting in an irreversible "porous" stage corresponding to that part of the surface enamel. This area--the bright band--developed corresponding to the start of the area of final enamel formation and was subsequently carried incisally during the eruption of the incisor.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Fluoride-induced developmental changes in enamel and dentine of European roe deer (Capreolus capreolus L.) as a result of environmental pollution.

Using macroscopic, microradiographic and scanning electron-microscopic methods, the effects of increased fluoride exposure on enamel and dentine formation were studied in fluorosed mandibular premolars and molars of roe deer from the heavily industrialized Ruhr area, Germany. Macroscopically, fluorosed teeth were characterized by opaque and stained enamel and in more severe cases also by enamel surface lesions, reduction or loss of enamel ridges on their occlusal surfaces and increased wear. Microradiographically, fluorosed enamel exhibited different degrees of subsurface hypomineralization, in part apparently indicating a fluoride effect during enamel maturation. In some specimens, a pronounced but varying enhancement of the pattern of Retzius lines was observed throughout the enamel, denoting strongly intermittent fluoride exposure during enamel matrix secretion. This variation in exposure was also reflected histologically in dentine, by bands of interglobular dentine and marked accentuation of incremental lines. Microradiography of sections through enamel surface hypoplastic lesions showed the enamel forming the bottom and partly also the walls of the lesions to be highly mineralized. Scanning electron microscopy showed that the outer enamel along the more pronounced hypoplastic lesions consisted of stacked, thin layers of 'aprismatic' enamel, indicating that the ameloblasts in these areas had lost the distal (rod-forming) regions of their Tomes' processes. These observations demonstrate that the origin of enamel hypoplasias in deer clearly differs from that in rodents, where fluoride induces the formation of subameloblastic cysts. The differences in the degree of fluorotic alteration between the teeth of a single tooth row could be related to the developmental sequence of the dentition in roe deer. The roe deer is thus considered to be a very sensitive and useful bioindicator of environmental pollution by fluorides.

Animals↗

PubMed1993

Serum immunoglobulin G antibodies to Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Streptococcus sanguis during experimental gingivitis in young adults.

Twenty-eight young, healthy adults completed an experimental gingivitis study in which blood and clinical recordings were obtained at baseline; after a 4-week period of thorough oral hygiene; after a subsequent 3-week period of plaque accumulation; and after another 2 weeks of thorough oral hygiene. Serum immunoglobulin G antibodies against whole cells of Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Streptococcus sanguis were determined using enzyme-linked immunosorbent assay. Mean serum immunoglobulin G antibody levels to P. intermedia, F. nucleatum and S. sanguis remained essentially constant during the experiment, whereas the immunoglobulin G antibodies to P. gingivalis declined during the initial period of oral hygiene and the subsequent period of plaque accumulation to an average of 84.5% of the baseline value. This reduction could be attributed to the people who developed marked gingival inflammation during the period of plaque accumulation, indicating that the systemic host response may be associated with local tissue responses to variations in oral hygiene. These people were, however, also characterized by higher initial serum immunoglobulin G responses to P. gingivalis than people who developed less pronounced gingival inflammation during the experiment. The variability and individuality noted in the host response to potential pathogens have important implications for attempts to use such measures for establishing a diagnosis or prognosis for the individual patient.

Adult↗