PubMed Health⌕ Search

Biomedical subjects

M A van't Hof

Publications and source records attributed to M A van't Hof.

At least 19 recordsLinked to original sources
PubMed1992

Fabrication times for indirect composite resin restorations.

Fabrication times for indirect posterior composite resin restorations were recorded in a prospective clinical efficacy study. Four operators completed 132 one-visit inlays and onlays utilizing a new indirect posterior composite resin system (ICS). The mean time needed for the fabrication of one ICS restoration was 90 min, including the 'laboratory time'. When two restorations were provided simultaneously, the overall mean fabrication time was 120 min. The fabrication times were significantly influenced by the operator and the number of restorations. In several clinical phases a 40 per cent difference in mean fabrication time could be identified between operators. The extent of the restoration had no influence on mean fabrication time. The results of this study are considered to provide some indication of the cost-effectiveness of ICS restorations.

Adult↗
PubMed1992

Long-term second-line treatment: a prospective drug survival study.

The long-term use of second-line antirheumatic drugs was prospectively studied in a consecutive sample of 245 patients with recently diagnosed rheumatoid arthritis. A survival analysis was done in which treatment termination due to side-effects and to insufficient therapeutic effect were used as index causes. Cumulative drug 'survival' of aurothioglucose with treatment termination due to toxicity was significantly less compared with hydroxychloroquine. With regard to lack of efficacy as index cause, the administration time of hydroxychloroquine was significantly less than that of either aurothioglucose or sulphasalazine. Treatment termination due to lack of efficacy or combined insufficient therapeutic response and toxicity proved to be influenced by the initial disease activity and by the rank order of prescription.

Arthritis, Rheumatoid↗
PubMed1992

Validity of single variables and composite indices for measuring disease activity in rheumatoid arthritis.

There is no agreement as to which variable best mirrors disease activity in rheumatoid arthritis (RA) and no studies have been performed on the validity of disease activity variables. In this study the validity of 10 commonly used single variables and three composite indices was tested. All patients participated in a large follow up study in two clinics. The patients (n = 233) had classical or definite RA and a disease duration of less than one year at entry. The mean follow up time was 30 months; the follow up frequency was once every four weeks; 6011 records were used in the analysis. The validation criteria included correlations with the other variables (correlational validity), with the physical disability (criterion validity I), and with the radiographically determined damage of hands and feet (construct validity). The judgment of a group of rheumatologists in clinical practice was also used as a model of criterion validity (II). In this comparison the disease activity score and Mallya index showed the best validity. The best single variable was the number of swollen joints. The validity of most single variables was poor and these variables were not suitable as single endpoint measures in clinical trials.

Arthritis, Rheumatoid↗
PubMed1991

[Statistics for dentists. Confidence intervals].

The mean score of a sample deviates most probably from the mean score of the population, in which one is most interested. It is possible to calculate a kind of minimum and maximum value, the so called confidence interval, which indicates the position of the mean score of the population. Some worked examples elucidate the procedure of constructing such confidence intervals for the population mean, using the standard error of the (sample) mean (SEM).

Confidence Intervals↗
PubMed1991

[National dental health survey. 4. Dental visits. 1. Behavior and knowledge].

This paper is part of a series on the national oral health survey in the Netherlands (LEOT-project). Previous articles described the development of the questionnaires and the results concerning oral hygiene and nutrition. This paper presents the results as for the dental attendance behaviour and knowledge concerning it of the dentate Dutch population. As an average the Dutch dentate visited the dentist 2.4 times a year. 89% visited the dentist in the last year of this investigation. The largest part of the visits (68%) concerned 'check-up visits'. 14% did not visit the dentist for a check-up. Knowledge about dental visits is rather limited; especially concerning treatment possibilities.

Dental Care↗
PubMed1990

Relation of axial bone mass to habitual calcium intake and to cortical bone loss in healthy early postmenopausal women.

A group of 60 healthy early postmenopausal women participating in an ongoing study on the effect of habitual calcium intake on the rate of cortical bone loss at the radius, were subjected to additional skeletal measurements at the lumbar spine and femoral neck. The women were between 58 and 64 years of age, and 3 to 10 years postmenopausal. No correlations were found between habitual calcium intake (range 560 to 2580 mg/day) and either bone mineral content of the radius, the lumbar spine and the femoral neck, or spine deformity index. Body mass index was found to be positively correlated with bone mass indices of the radius (decrease of BMD and BMD) and femoral neck (BMC), but not with of the lumbar spine (BMC, BMD and SDI), even after adjustments had been made for confounding factors. Although the rate of cortical bone loss at the radius correlated significantly with bone mineral content of lumbar spine and femoral neck, the error in predicting bone mass of the lumbar spine or the femoral neck from longitudinal measurements of cortical bone at the radius was high. The rate of cortical bone loss did not correlate with the spine deformity index. We conclude that in healthy women in early menopause, the bone mineral content of both the appendicular and the axial skeleton are not influenced by habitual calcium intake. A higher body mass index has a protective effect on the appendicular skeleton but appears to be less protective to the axial skeleton. Longitudinal measurements of cortical bone mass are of limited value to predict bone density of the appendicular and axial skeleton.

Absorptiometry, Photon↗
PubMed1990

Treatment times for posterior resin-bonded bridges.

In a longitudinal clinical trial the treatment times needed for the fabrication of Posterior Resin-Bonded Bridges (PRBB's) were recorded and analyzed. From a total of 200 PRBB's with different designs and retention systems, 152 were selected for this analysis. The selected bridges were made by 12 operators: 3 university staff members and 9 general practitioners. The mean treatment time for PRBB's was 80 min. When posterior composite restorations were made in the abutment teeth, the mean treatment time increased by 25% up to 100 min. From the factors which were considered to influence the treatment time, a significant effect was found for "restorations", "operator" and "experience of the operator". The other factors considered, such as "tooth preparation", "retention system", "isolation method", "occlusion", and "location", showed no detectable effect on the treatment time. The results of this study are considered to be useful in further cost-benefit analyses.

Acid Etching, Dental↗
PubMed1990

Prevalence of dental caries in 7-13-yr-old children in Morogoro District, Tanzania, in 1984, 1986, and 1988.

A 4-yr mixed-longitudinal study to determine the prevalence of caries in 7-13-yr-old Tanzanian children was started in 1984. The parameters considered were age, locality, Socio-Economic Status, and sex. Locality was composed of urban (Morogoro town), rural (Morogoro District), and rural areas in the District with an average fluoride level of 0.5 ppm or more in all drinking water present. SES was established based on the occupation of the father or mother and on housing conditions. Overall, the reproducibility of the dental conditions studied (D2MT/S and D3MT/S) was high, with lower scores for the conditions including early enamel lesions (D3MT/S). The reproducibility of the SES scoring system was high (kappa = 0.96 and kappa = 0.90), but the association over the 2 yr of measurement (1984 and 1988) was weak (r = 0.50). There were no restorations found. The percentage of children with caries increased with increasing age from 12-17% at age 7 to 37% at age 13. The statistical tests (ANOVA) revealed an age effect for all conditions studied in 1984, 1986, and 1988 and a locality effect in 1988 only. The mean D3MT-scores varied between 0.15 and 0.24 at age 7 to 0.76 at age 13, while the mean D3MS-scores varied between 0.27 and 0.31 at age 7 to 1.18 at age 13. In general, the caries prevalence observed was low. Children living in naturally fluoridated rural areas had significantly lower caries scores than children in non-fluoridated areas.

Adolescent↗
PubMed1990

Severity of Parkinson's disease is a risk factor for peak-dose dyskinesia.

Fifty four patients with idiopathic Parkinson's disease receiving levodopa therapy were studied. Thirty three of these patients displayed peak-dose dyskinesia. Neither the duration of Parkinson's disease nor the duration of levodopa therapy discriminated between patients with and patients without peak-dose dyskinesia. Consequently, these criteria could not determine whether the first appearance of peak-dose dyskinesia depends on the duration of Parkinson's disease--a factor that is related to the severity of the disease--or on the duration of levodopa therapy. A subgroup of nineteen patients with unilateral or unequivocally asymmetrical peak-dose dyskinesia was examined 12 hours after withdrawal of levodopa. A levodopa testdose provoked unilateral or unilateral preponderant peak-dose dyskinesia which always involved the most severely affected side and which also happened to be the side of onset of the disease. This demonstrates that the severity of Parkinson's disease is the main risk factor for peak-dose dyskinesia.

Aged↗
PubMed1989

Clinical performance of resin-bonded bridges: a 5-year prospective study. I. Design of the study and influence of experimental variables.

A total of 203 resin-bonded bridges were inserted under controlled clinical conditions and evaluated over a period of 5 years. The study included two experiments to test the influences of retainer type, cementation material and operator on the success rate of resin-bonded bridges. The overall survival at 5 years was 75%. Micromechanical retainers were better than macromechanical retainers. For inserting micromechanical retainers, the cementation materials Clearfil F and Panavia Ex were better than Conclude. An operator effect was not found in this study.

Adult↗
PubMed1989

Effect of mucin on the corrosion behaviour of dental casting alloys.

The influence of mucin on the corrosion behaviour of seven typical dental casting alloys was investigated. A commercial saliva substitute (Saliva Orthana) containing mucin, and a control from which the mucin had been removed, were used. The electrochemical behaviour of the test alloys was evaluated around the open circuit potential (OCP) utilizing standard potentiodynamic techniques, as a function of oxygen concentrations and pH. The results of the corrosion measurements were analysed by a four-way ANOVA to detect the influence of alloy, environment and possible interactions. Mucin seems to act as a cathodic inhibitor at pH 6.7 but not at pH 4.6. An unidentified component (e.g. benzoate) of the saliva substitute probably acts as an adsorption inhibitor. Anodic passivation is also correlated with the artificial saliva composition.

Analysis of Variance↗
PubMed1989

[Prevalence of TMJ signs and symptoms in the Dutch adult population].

In 1986 a nationwide dental survey was carried out in The Netherlands. One of the sub-objectives of the study was to assess the prevalence of TMJ signs and symptoms in the Dutch adult population. A stratified sample of 3526 persons, aged 15 to 74 years, participated in the study. Participants in the clinical examinations were asked by questionnaire about subjective signs and symptoms of TMJ. Clinical examination of joint sounds, deviation and pain during mandibular movements were also performed. With regard to the Helkimo classification it can be stated that 78.4% of the participants had no subjective signs and symptoms of TMJ, whereas clinically recorded 55.6% were symptomfree. 4.9% had severe subjective signs and symptoms, and 2.8% had clinically recorded severe signs and symptoms of TMJ. In general a higher percentage of women in comparison to men showed signs and symptoms of mandibular dysfunction. Only 1.4% of the people with severe subjective signs and symptoms had sought for professional help.

Adolescent↗
PubMed1989

[Periodontal disease in Dutch adults].

A nationwide epidemiological survey was carried out on a stratified sample (age, sex, SES and area) of 2784 dentate people in the age of 15-74 years. Prevalence of plaque, gingivitis, calculus and pockets was recorded. About 85% of the individuals had gingivitis. The percentage of individuals with calculus varied from 40% (15-19 years old) to 76% in the oldest age group (65-74 year). More then 50% of the people, aged 30 and over had pockets greater than 3.5 mm.

Adolescent↗
PubMed1989

[Lesions of the oral mucosa].

Representative data were gathered about the prevalence of mucosal lesions in Dutch adults (15-74 years old). The reliability of the observation methods was moderate. Some data were not usable for this reason. Only a low percentage of people without a denture, had a mucosal lesion. About 60% of the people with a denture had hyperaemia of the palatine mucosa. A flabby ridge exists in 34% of the 35-54 year olds and in 51% of the 55-74 year olds with such a prosthesis.

Dental Health Surveys↗
PubMed1989

[Nationwide survey in the Netherlands (Leot-Project). 7. Dental prostheses].

Data are presented about the prevalence of full and partial dentures and dental bridges in the adult population of The Netherlands. Furthermore, the quality of full dentures and the resorption of the jaws were studied. Differences were found between the social classes (a higher percentage of people with dentures in the lower classes) and between the various regions of the country (more denture wearers in the Northern region). Only a low percentage of the full dentures met all the quality requirements. This can be possibly explained by the fact that resorption of the lower jaw was severe in a majority of the cases.

Bone Resorption↗
PubMed1989

[Cosmetic dentistry].

A nationwide dental survey was carried out in The Netherlands. One of the objectives of the study was to assess the objective and subjective need for cosmetic dentistry in the Dutch adult population. A stratified sample of 2784 dentate persons, aged 15 to 74 years, participated in the study. The esthetics of anterior teeth and bicuspids in upper and lower arches were assessed by the dental examiners as well as by the examinees. Analyses of the data showed that 15.8 to 62.6 percent of the people in the age-range form 15 to 74 years was in need for cosmetic dental care, according to the dental examiners. Based on the patient's opinion (subjective need) these percentages varied between 17.5 and 40.4 percent. The discrepancy between the objective and subjective assessment in the percentage of people in need for cosmetic dental care increased with age. The results indicate that there is a need for cosmetic (restorative) dentistry in The Netherlands.

Adolescent↗
PubMed1989

[Dental characteristics and orthodontic treatment need of the Dutch adult population].

In this article the results are presented of a nationwide representative study of dental anomalies in the group of 15-74 years Dutchmen. Also the subjective and objective need of orthodontic treatment in the age group 15-34 years is described. The principal findings are: of the 15-19 years olds, 27% is treated with orthodontic appliance; general practitioners performed 45% of these orthodontic treatments; --unsatisfied with the position of the front teeth is 25% of the 15-34 year old; an objective need for treatment is found in 39% of this age group; in 14% there is both an objective and a subjective need for treatment; both the subjective and objective need of orthodontic treatment is greater in the group of persons who were treated in the past than in the group of persons who never were treated.

Adolescent↗