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Biomedical subjects

J Tiekso

Publications and source records attributed to J Tiekso.

At least 19 recordsLinked to original sources
PubMed1999

Expression of cell-cycle proteins p53, p21 (WAF-1), PCNA and Ki-67 in benign, premalignant and malignant skin lesions with implicated HPV involvement.

A series of 120 biopsies from benign (verruca vulgaris and keratoacanthoma), premalignant (actinic keratosis and extragenital Bowen's disease) and malignant (squamous cell carcinoma) skin lesions were studied immunohistochemically for the expression of cell-cycle proteins p53, p21 (WAF-1), PCNA and Ki-67. The presence of human papillomavirus (HPV) DNA in these samples had been analysed previously using in situ hybridization (ISH) and PCR. Moderate to intense expression of both PCNA and Ki-67 was present in most of the lesions studied. PCNA staining was extensive in the epidermis underneath the layers where abundant HPV DNA staining was shown in HPV DNA-positive verrucas. In keratoacanthomas, p21 and PCNA expression remained low, despite intense p53 expression. In actinic keratosis, only half of the specimens showed overexpression of p53 associated with moderate or intense expression of PCNA. In extragenital Bowen's lesions, all these cell-cycle markers were overexpressed, but in squamous cell carcinomas, they were heterogeneously expressed and showed no correlation with tumour differentiation. Our results suggest a mechanism by which HPV can reactivate the host genes (leading to cell proliferation) to support its own DNA replication. Also p21 might start keratinocyte differentiation in areas where HPV DNA replication starts. Cell proliferation remained active in actinic keratosis and Bowen's lesions, emphasizing the precancer character of these lesions in contrast with the benign nature of keratoacanthoma and verruca vulgaris.

Bowen's Disease↗
PubMed1998

Physical, chemical, and histologic changes in dentin caries lesions of primary teeth induced by regular use of polyol chewing gums.

A previous clinical trial showed that long-term use of saliva-stimulating polyol (xylitol and sorbitol) chewing gums was associated with arrest of dental caries in young subjects. After a 20-22-month intervention (when the subjects were 8 years old), a total of 23 primary teeth with extensive dentin caries lesions whose surface in clinical examination was found to be totally rehardened (remineralized) could be removed because the teeth were near their physiologic exfoliation time. These teeth were subjected to histologic, microhardness, and electron microscopic tests. The majority of the specimens had been remineralized from the surface by a non-cellular-mediated process within the remaining collapsed, organic extracellular matrix associated with the remaining dentinal surface. Many of the underlying dentinal tubules were filled with a matrix that had been subsequently mineralized. Dental microanalyses showed that the topmost (outer) 20-microm-thick rehardened layer of the lesions exhibited the highest Ca:P ratio, which leveled off at a depth of approximately 150 microm. The rehardened surface layer (normally <0.1 mm in thickness) was significantly (P < 0.001) harder than sound dentin and nearly as hard as sound enamel. Although the main source of the mineral present in the rehardened layer was most likely of salivary origin, some extracellular remineralization was probably mediated by odontoblasts. The results complete the dinical diagnoses of the original trial and suggest that regular use of polyol chewing gums may induce changes in dentin caries lesions, which in histologic and physiochemical studies show typical characteristics of rehardening and mineralization.

Calcium↗
PubMed1995

The relation between tooth eruption and alveolar crest height in a human skeletal sample.

It is commonly assumed that alveolar crest height increases with continuing tooth eruption unless affected by marginal inflammation. To test this hypothesis, the relation between eruption and alveolar crest height was examined in skulls from a sample consisting of the remains of 244 individuals from the late medieval period. The mandibular first and second molars and second premolars were analysed. The age of the skulls was determined on the basis of dental development and molar attrition. Radiographs were taken and points representing the levels of the inferior dental canal (IDC), root apices (AP), alveolar crest (AC), cementum-enamel junction (CEJ) and occlusal surface were determined on the radiographs. The level of the IDC was used as a reference not changing with age. The distances between the points were measured with a help of a computer-digitizer system. Variable IDC-AP increased with age, indicating continuous eruption of the teeth. The distance between AC and CEJ also increased while the distance between IDC and AC remained constant, showing that the alveolar crest height did not increase accordingly. The lack of inflammatory changes on the alveolar bone surface suggests that occlusal attrition may be compensated for by continuous eruption without bone growth in the alveolar margin.

Adolescent↗
PubMed1994

Clinician's ability to identify caries risk subjects.

The clinician's ability to identify caries risk children without saliva tests was studied in five health care centers. 77 examiners predicted, after the annual check-up and treatment, whether, during the following 12 months, the child would develop new dentinal caries lesions to be filled. 7917 children aged 5-16 yr were included. Only information routinely available at clinical examinations was used. In general, the overall sensitivity was 44% and specificity 90%. Some clinicians were able to identify the caries risk children with high sensitivity and specificity figures.

Adolescent↗
PubMed1994

Multifactorial modeling for root caries prediction: 3-year follow-up results.

The study was part of a series aiming at the development of caries tests. The initial material (n = 104, age range 47-79 yr, mean 62 yr) was reduced to 96, who were observed for 3 yr. During the follow-up four subjects died, all due to myocardial infarction, and four refused to participate. Thorough oral examinations were conducted at the baseline, 1- and 3-yr registrations; coronal and root surface caries were registered separately according to WHO classification. The tests included salivary mutans streptococci, lactobacilli, candida/yeasts, secretion rate, buffer effect and sucrase activity, and quantitation of visible plaque. The association between prospective root caries increment and several tests was significant. Multifactorial modeling resulted in the combination of Past Root Caries Experience (OR 12.8), Lactobacilli (OR 8.6) and Candida (OR 2.8). At screening, the criterion "two or three positive tests" of these yielded acceptable accuracy (77.1) and a relative risk of 3.3.

Aged↗
PubMed1994

Flow rate and composition of whole saliva in rural and urban Tanzania with special reference to diet, age, and gender.

The association of flow rate and biochemical and microbiological characteristics of saliva with diet was studied in 83 12-year-old children and in 127 adults (84 in the age group 35-44 years, 43 in the age group 65-74 years) living in rural and urban communities in Tanzania. No significant differences were observed between the salivary flow rates of the rural and urban subjects. The mean salivary flow rates were slightly lower in women than in men and significantly lower in the 12-year-old children than in the two older age groups (p < 0.05). The buffer effect was higher in the rural than the urban population. Further, it was lower in women than in men (p < 0.001). Salivary protein, IgG, and sialic acid concentrations were significantly higher in the rural than in the urban population, whereas amylase activity and IgA concentrations were lower. Microbiological studies showed mutans streptococci in 97% of the rural and in 91% of the urban subjects (n.s.). Lactobacilli grew significantly less often in the rural than urban samples (p < 0.01). Analyses of 24-hour dietary recalls showed that the rural and urban diets differed. The proteins in the rural diet were largely of plant origin, while in the urban diet animal proteins dominated. The rural diet contained also less sucrose but more fibre (mainly from grain) than the urban diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A re-analysis of caries rates in a preventive trial using Poisson regression models.

The analysis of caries incidence in clinical trials has several challenging features: (1) The distribution of the number of caries onsets per patient is skewed, with the majority of patients having few or no cavities; (2) the number of surfaces at risk varies (i) over time and (ii) between patients, due to eruption and exfoliation patterns, dental diseases, and treatments; (3) surfaces within a patient differ in their caries susceptibility, and (4) caries onsets within a patient are correlated due to shared host factors. Recent statistical developments in the area of correlated data analyses permit incorporation of some of these characteristics into the analyses. With Poisson regression models, the expected number of caries onsets can be related to the number of surfaces at risk, the time they have been at risk, and surface- and subject-specific explanatory variables. The parameter estimated in these models is an epidemiological measure of disease occurrence: the disease incidence rate (caries rate) or the rate of change from healthy (sound) to diseased (carious). Differences and ratios of these rates provide standard epidemiological measures of excess risk. To illustrate, Poisson regression models were used for exploratory analyses of the Ylivieska xylitol study.

Age Factors↗
PubMed1993

Long-term effect of xylitol chewing gum in the prevention of dental caries: a follow-up 5 years after termination of a prevention program.

About 65% of the original 258 children who participated in 1982-1984 in a caries prevention program involving the use of xylitol chewing gum were retrieved in 1989 for a follow-up study. Ninety-five subjects from the original xylitol (X) group and 70 subjects from the original control (no-gum, C) group were available. In 1984, when the children completed the program at the age of 13-14 years, the caries scores were significantly lower in children who had used xylitol gums daily, compared with the C group. In 1989, 5 years after the discontinuation of the gum program, the difference between the X and C groups had continued to increase in favor of the X group. These effects were explained by assuming that the X gum program had facilitated the establishment of a low-virulent bacterial flora on the surfaces of the teeth, and especially on those teeth that erupted during the trial proper. This type of results are possibly helpful when evaluating cost-benefit ratios of caries prevention.

Chewing Gum↗
PubMed1993

Missing teeth and ischaemic heart disease in men aged 45-64 years.

The aim of the present study was to investigate the associations between number of missing teeth (expressing sustained oral infections) and diagnosed ischaemic heart disease using cross-sectional data from 1384 men aged 45-64 years. The study population was derived from a representative sample of adult Finns. Ischaemic heart disease was considered to be present in those with angina pectoris or previous myocardial infarction, whether definite or possible. A tooth was recorded as missing if none of it was visible or could be felt with an instrument. According to multiple linear analyses, the variation in ischaemic heart disease was independently explained by age, clinical diagnosis of arterial hypertension, geographical area, educational level and number of missing teeth. Smoking and cholesterol were not significant explanatory factors. The explanation for the observed association between missing teeth and ischaemic heart disease is that they may share a common behavioural background factor. There may also be a more direct causal relationship between the phenomena.

Age Factors↗
PubMed1993

Trigeminal foraminal patterns in "skeletal" Class II and Class III adults--a radiocephalometric study.

Radiocephalometric analysis, based mainly on the foramina of the trigeminal nerve branches, was applied to three samples of adults, two representing fairly extreme profile types, the third representing "normal" dentofacial build. The aim of the study was to find out whether the analytical method could be used to differentiate between facial types. It appeared that some elements of the method had diagnostic powers, and could substitute for traditional methods. Many dimensions inspected, however, were fairly similar in all facial types, thus suggesting a general basic role of the trigeminal nerve in relation to craniofacial structure. Generally speaking, the foraminal pattern was relatively stable in "normal" faces, but more variable in deviant faces.

Adult↗
PubMed1992

Multifactorial modeling for root caries prediction.

The study was part of a series of investigations aiming at the development of diagnostic caries tests for screening of risk subjects. The material consisted of 100 adult subjects (mean 62 yr, range 47-79 yr), 50 of these under chronic medication. The series of tests included two chairside registrations, i.e. incipient demineralization of exposed root surfaces without cavitation (RD 1) and quantitation of visible plaque (VPT%), three microbiological tests for mutans streptococci, lactobacilli, and candida/yeasts and three tests on stimulated saliva, i.e. secretion rate, buffering capacity and sucrase activity. A thorough clinical examination was conducted at the baseline and 1-yr registration phases, caries being registered at a tooth surface level according to WHO recommendations separately for coronal and root caries. Considerably more root caries than coronal caries developed during the observation period. For coronal caries increment, the predictive value of any of the tests was not significant. For root caries, however, the association between several tests and prospective caries increment was significant. Subsequent multifactorial modeling yielded the highest predictive value to the combination of Past Root Caries Experience (OR 25.0, Visible Plaque (OR 4.2), Candida (OR 8.0) and Lactobacilli (OR 5.8). A positive finding of Past Root Caries (RDFS) or the combination of the other three tests (Can, LB, VPT%) as criteria for selection in screening for root caries produced good accuracy (84.0) and a relative risk of 5.5.

Aged↗
PubMed1992

[The assessment of the caries risk in young adults].

Several factors for caries prediction have been proved in a one-year follow-up study on 73 patients. The white-spot lesions have proved to be a good criteria for caries prediction in this population. These lesions could be combined with the microbiological tests Dentocult SM and Oricult N or with the determination of the buffer capacity (Dentobuff), which did not much improve the prediction.

Adult↗
PubMed1991

Gingival crevicular fluid plasmin activity in different clinical conditions and after periodontal treatment.

Plasmin is an important enzyme in the process of wound healing and it has been suggested that it plays a role in the pathogenesis and healing of periodontal diseases. In this study, plasmin activity in crevicular fluid (CF) was measured in different clinical conditions and after periodontal treatment. 152 CF samples were collected with paper strips from 12 subjects. Five other subjects received a single periodontal treatment after the first sample collection and the post-treatment samples were collected 2, 5, 10, 20 and 40 days thereafter. The individual strips were placed immediately on plasminogen-free fibrin plates or in plastic vials containing sterile saline. The vials were agitated and 20 microliters of each solution was pipetted onto fibrin plates. The remaining solution was used in protein analysis. The plates were incubated for 24 hrs at 37 degrees C and the activity of plasmin determined by weighing the fibrin liquified by the samples. The variation of CF plasmin activity in different pockets within individuals was larger than between the subjects. There was a weak positive correlation between CF plasmin activity and the amount of plaque, bleeding tendency, pocket depth and bone loss by x-ray. However, plasmin concentration (units of plasmin activity per CF volume) did not correlate with clinical parameters. A weak negative correlation between plasmin activity per volume and the amount of CF was seen. Neither did CF protein concentration correlate with the clinical parameters. Periodontal treatment resulted in a dramatic decrease in plasmin activity. In 20 days the activity returned to pre-operative levels in four subjects out of five.

Adult↗
PubMed1989

Long-term effect of xylitol chewing gum on dental caries.

About 85% (n = 269) of the subjects who participated in the Ylivieska follow-up studies on the effect of xylitol chewing gum on dental caries during 1982-84 or 1982-85 were re-examined in 1987 for the analysis of possible long-term preventive effects. Further caries reduction was found 2 or 3 yr after the discontinuation of the use of xylitol. The effect was especially marked in girls; the reduction in caries increment in the post-use years was 60% for the 2-yr users, suggesting that more pronounced caries reduction was associated with the most regular use of xylitol. In teeth erupting during the first year of the use of xylitol gum the long-term preventive effect was greater than in other teeth. Several explanations are suggested: lasting effect of the microbiological changes in the mouth, bacterial colonization on newly erupted teeth by organisms other than S. mutans, and/or thorough maturation of the teeth under favorable physico-chemical circumstances. The results suggest that the value of xylitol in caries prevention depends on the timing of the treatment in relation to the development of the dentition.

Adolescent↗
PubMed1989

Oral biochemical status and depression of Streptococcus mutans in children during 24- to 36-month use of xylitol chewing gum.

Plaque and whole saliva samples were collected from initially 11- to 12-year-old children randomly chosen from two groups which participated in a 2- to 3-year field trial designed to test the efficacy of xylitol chewing gums in caries prevention. No initial differences were observed between the groups with regard to the plaque levels of Streptococcus mutans, but at the end of the 2-year xylitol gum regimen, the levels were smaller (p less than 0.05) in children using xylitol gum than in control children. In a similar follow-up study on children who were considered to be at high risk with regard to dental caries and who continued the study over a 3rd year, the xylitol-consuming subjects showed at the end of the study significantly smaller (p less than 0.004) salivary S. mutans counts than the control children. These effects were achieved after using up to 3 xylitol gums/day (daily xylitol dose per child was 7-10 g). Salivary flow rate and several salivary chemical parameters did not change.

Amino Acids↗
PubMed1988

Xylitol chewing gum in caries prevention: a field study in children.

As the prevalence of dental caries decreases in industrialized nations like the United States, it simultaneously increases in developing nations and Third World countries. The decrease in the West is attributed to increased use of fluorides, but the increase in developing countries has been explained by an increase in the consumption of sugar. As this information continues to propel researchers to find sucrose substitutes, xylitol has been singled out as a proposed sucrose replacement. The question tackled by this study was: Can the daily use of chewing gum containing xylitol increase the efficacy of the existing caries-preventive measures now regularly used for 11- to 15-year-old children in most industrialized western countries?

Adolescent↗