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Biomedical subjects

A Thylstrup

Publications and source records attributed to A Thylstrup.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Indications and use of fissure sealants in public dental health care in Denmark. A questionnaire-investigation].

During the past decade usage of the fissure sealant technique for occlusal caries prevention has been increasingly recommended. This study explores variations in indications and usage of this technique in Denmark. A questionnaire was sent to 205 chief dental officers in the Danish Public Child Dental Health Service (PDHS) covering 90% of Danish children and to municipalities, where dental health to children is provided by private practitioners. More than half of the respondents did not use firmly defined criteria for fissure sealant application. Oral hygiene and previous caries experience were most often stated as indications. Actual usage of the sealant technique differed significantly from the PDHS and private clinics. Thus, 33% of the chief dental officers in the PDHS said that sealants were routinely applied to 8- and 13-year-olds, 43% to 30-80% of the children, and 15% used sealants to less than 10% of 8- and 13-year-olds. In contrast, only 5% of the private clinics reported routinely use of sealing technique, 22% used application to 30-80% of the children, while more than one third of the private practitioners used sealants to less than 10% of the 8- and 13-year-olds. In spite of the significant difference in sealant usage between PDHS and private practitioners, it was not possible to see a corresponding difference neither in caries prevalence nor in occlusal filling incidence. Moreover, analysis of PDHS caries prevalence data revealed that PDHS variations could not be explained by variations of risk in terms of social classes and caries incidence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

A light and scanning electron microscopic study of enamel decalcification in children living in a water-fluoridated area.

Eleven children, each having one or two pairs of premolars to be extracted for orthodontic purposes, participated in the study. The model involved placement of a special orthodontic band that allowed the accumulation of plaque in a defined area between the band and the buccal enamel. Examination of enamel changes was carried out in experimental teeth that had been exposed to local plaque accumulation for one, two, four, eight or 14 days. The specimens were examined under the light (LM) and the scanning electron microscope (SEM). All teeth had signs of very mild dental fluorosis. No indications of demineralization were noted after one day. SEM examination showed signs of crystal dissolution in some of the two-day specimens. Six of eight four-day specimens exhibited surface dissolution. All eight- and 14-day specimens showed signs of surface demineralization in the LM as well as in the SEM. These observations documented that undisturbed bacterial deposits are capable of initiating enamel demineralization within short time periods, even in children living in a water-fluoridated area.

Adolescent↗
PubMed1990

Clinical evidence of the role of pre-eruptive fluoride in caries prevention.

Recent clinical and laboratory evidence has suggested that systemic fluoride plays a more minor role in caries inhibition than was previously believed. This paper reviews clinical data on water fluoridation, the topical administration of fluorides, and fluoride supplements in the light of more recent understanding of the disease dental caries. Due to reduced functional usage, erupting teeth tend to accumulate plaque which has cariogenic potential. For this reason, the period from tooth emergence to the establishment of interproximal contact and full occlusion is the most critical for caries initiation. Analyses of clinical data indicate that maximum protection against caries is obtained when teeth erupt into an environment with low concentrations of ionic fluoride. The similarity in caries reductions obtained in water fluoridation studies and long-term studies with topically administered fluoride regimens, including fluoride-containing dentifrices, indicates that the pre-eruptive effect of fluoride is of borderline significance relative to the more significant post-eruptive effect. Water fluoridation and topical fluoride programs are thus important measures for the control of caries at the community level. For the individual, topical application of fluoride is seen as an integral part of caries treatment aimed at arresting progressive caries. Fluoride application is thus considered a supportive therapy, in conjunction with cariogenic plaque control. Daily use of fluoridated dentifrices from tooth eruption is more efficacious than daily use of fluoride supplements from birth.

Dental Caries↗
PubMed1989

A 3-year clinical and SEM study of surface changes of carious enamel lesions after inactivation.

The surface features of incipient carious lesions around bonded orthodontic brackets were assessed during a 3-year period after appliance removal. At standardized intervals color slides and silicone impressions for replication were made of two maxillary incisors on each of six adolescent patients. The labial surfaces of the teeth had demineralized white areas around the bonded brackets. The color slides were projected and studied in a darkroom. The positive surface replicas were studied by scanning electron microscopy (SEM). At the time of debonding, large accumulations of dental plaque were observed in those areas with white, demineralized surfaces. During the posttreatment or experimental period, there was a reduction in the amount of plaque. The appearance of the lesions changed from chalky-white at time of debonding to a more diffuse opacity, particularly in the peripheral parts. Under SEM the surfaces of the lesions were less irregular 3 years after debonding. At higher magnification the labial surfaces showed signs of wear. The present study confirms that removal of cariogenic challenge results in arrest of further demineralization. The gradual regression of the lesion at the clinical level is believed to be primarily a result of surface abrasion.

Adolescent↗
PubMed1989

Dental plaque and caries on occlusal surfaces of first permanent molars in relation to stage of eruption.

The occlusal surfaces of partly and fully erupted first right permanent molars were examined with respect to the occurrence and distribution of plaque and dental caries in a group of 57 six- to eight-year-old children. The children were classified into four groups ranging from one tooth partially erupted to full occlusion. Occlusal plaque was recorded at two levels of examination: (1) visible plaque and (2) detailed mapping by means of a plaque detector system. Dental caries was recorded after professional cleaning. The recording of plaque was repeated after 48 hr without oral hygiene. The findings showed a significant reduction in the easily detectable plaque in fully erupted teeth, compared with the three groups representing partly erupted teeth. The detailed mapping of plaque showed a clear pattern of preferential locations related to the macromorphology of the occlusal surfaces, and revealed reduction in the frequency of thick plaque accumulation in the fully erupted teeth. The proportion of active lesions was reduced in fully erupted teeth, and arrested lesions were mainly observed in the same group. This indicated that erupting teeth are more likely to develop dental caries, due to favorable conditions for plaque accumulation. Functional usage of teeth in addition to improved access for toothbrushing promoted arrestment of lesions initiated during eruption.

Child↗
PubMed1989

The microflora associated with the development of initial enamel decalcification below orthodontic bands in vivo in children living in a fluoridated-water area.

Thirty-four caries-free teeth destined for orthodontic extraction were banded to provide a protected area for the accumulation of plaque. The teeth were extracted at one, two, four, eight, and 14 days after being banded, and samples of the flora below the band were analyzed for the presence of Streptococcus sanguis, Streptococcus 'mitior', 'mutans streptococci', Actinomyces viscosus, Actinomyces naeslundii, Actinomyces odontolyticus, Lactobacillus species, and Veillonella. After plaque sampling, the teeth were sent to the Royal Dental College (Copenhagen) for histological analysis. The results showed that S. mutans could colonize the area below the band after one day, but that colonization was only 100% at 14 days. Lactobacillus was only isolated from 2/8 samples at four days and from 4/8 samples at 14 days. S. sanguis and 'S. mitior' were regularly isolated at all banding times, and Veillonella was isolated from all samples. A. viscosus was the most commonly isolated Actinomyces. The numbers of Streptococcus and Veillonella were significantly higher at day 1 than at day 14 (p less than 0.05). S. mutans and A. viscosus were isolated more frequently at day 14 than at day 1 (p less than 0.01). Histological examination revealed that dissolution of the enamel below a band could occur after two days, but that even after 14 days dissolution could be questionable. Dissolution was detected in areas where S. mutans was not isolated (8/34), but S. mutans was also present in samples showing dissolution (12/34). There was no relationship between dissolution and the numbers of S. mutans; however, the isolation frequency of S. mutans was associated with dissolution (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces↗
PubMed1988

Caries experience in urban Tanzanian children 1973-84.

In 1973 and 1984 the caries status of 624 and 394 children, respectively, was recorded in an urban area of northern Tanzania where the water fluoride content was 2.0-3.5 ppm. Although slightly different scoring criteria were used, the data showed very low levels of caries, and little evidence of increases in caries experience over the 10-yr period. The distribution of caries lesions was markedly skewed, such that a minority of individuals account for most of the caries. The levels of caries were low by international standards and equivalent to those found in children from low fluoride areas of Tanzania.

Adolescent↗
PubMed1988

The effect of regular professional plaque removal on dental caries in vivo. A polarized light and scanning electron microscope study.

This study aims to describe the histological and ultrastructural enamel reactions to regular disturbance/removal of dental plaque, using an in vivo caries model. Fourteen young volunteers undergoing orthodontic treatment participated in the study. To create local protected areas, orthodontic bands with a buccal space were placed in homologous pairs of premolars. One tooth in each pair served as control and had the band cemented for the entire test period of 5 weeks. The other band was removed weekly and the buccal surface cleaned, either by careful pumicing with a nonfluoride toothpaste, or by simple cleaning with a cotton pellet. Results indicated that 5 weeks with completely undisturbed plaque accumulation resulted in visible enamel demineralization in all 14 individuals, whilst a weekly performed professional plaque removal was able to prevent lesion progress independent of the cleaning procedure. It is therefore concluded that regular mechanical disturbance of dental plaque is able to suppress bacterial activity and hence caries development.

Bicuspid↗
PubMed1988

Dentifrice usage among Danish children.

The usage of dentifrice was studied in 179 Danish children of approximate ages 3, 7, 9, and 16 years. The usage was assessed by measurement of the aggregated quantities used at home during a two-week period. Information was also obtained on toothbrushing habits. The mean daily usage with the same brand of dentifrice increased from 1.1 g among 3-year-olds to 1.5, 2.3, and 3.4 g among 7-, 9-, and 16-year-olds, respectively. The amount used showed a significant, positive relationship to the orifice diameter of the tube. However, the lengths of ribbon of paste squeezed out per brushing were quite similar, regardless of tube orifice diameter. When the usage data were considered in light of the fact that young children swallow an average of 15 to 30% of the dentifrice used for brushing, it became obvious that a notable number of the 3- and 7-year-olds can be expected to ingest fluoride from 1000- and 1500-ppm-F dentifrices in quantities exceeding recommended daily doses.

Adolescent↗
PubMed1988

The effect of controlled oral hygiene in overdenture wearers.

The effect of controlled oral hygiene was studied in 40 patients treated with immediate complete overdentures in one or both jaws. Before prosthetic treatment conservative periodontal treatment was conducted with intensive instruction and motivation in oral hygiene care. Caries and periodontal status were recorded before and 2-4 weeks (day 0), 6 months, and 12 months after prosthetic treatment. However, the patients were seen more frequently for motivation and professional tooth cleaning. The material included 44 overdentures with a total of 92 abutments, with 1-4 abutments in each jaw. Before treatment the overall mean plaque index score was 1.43 +/- 0.68 and the overall mean gingival index score 1.57 +/- 0.53, and on day 0 and after 6 and 12 months the overall mean PlI score was 0.33-0.65 and the overall mean GI score 0.67-0.97. Adjacent to the abutments there was a significant reduction of the PlI and the GI scores from before treatment to day 0 and from day 0 to 6 months after prosthetic treatment (P less than 0.001). There was a significant reduction of pocket depth from day 0 to 6 months and from 6 to 12 months (P less than 0.01). The results of this study have shown that it is possible to maintain teeth as abutments for overdentures in patients with an initial poor dental status.

Aged↗
PubMed1987

Intraoral hydrolysis of monofluorophosphate.

The intraoral hydrolysis of monofluorophosphate (MFP) was compared in nine subjects with natural teeth and in nine edentulous subjects after a 1-min mouthrinse with a 100 ppm MFP solution. Analyses of total F and F- in whole saliva samples collected up to 15 min after the rinse suggested that apatite catalyzed breakdown of MFP mediated by dental enamel contributes significantly to the intraoral hydrolysis of MFP.

Adult↗
PubMed1987

Surface changes during the arrest of active enamel carious lesions in vivo. A scanning electron microscope study.

The present study examines early enamel surface alterations taking place when active carious lesions enter an arrested stage. Orthodontic bands with a standardized space for plaque accumulation were used to produce incipient carious lesions on the buccal surface of all four first premolars of four young adolescents. The premolars were to be extracted for orthodontic reasons. After 4 weeks of local cariogenic challenge, all teeth were debanded. In each patient one tooth was extracted at the time of debanding. The remaining premolars were extracted 1, 2, and 3 weeks after re-exposure to the oral environment. No fluoride was added during the entire test period, and the patients were told to maintain usual oral hygiene. Scanning electron microscope examination of the experimental surface areas disclosed a gradual wearing away of the outermost crystals during the 3 weeks of observation. This was associated with a leveling off of surface irregularities and the development of a multitude of scratches. The observed attrition of the porous surface in the lesion area indicates that functional wear and toothbrushing were responsible for the arrestment by disturbance and removal of bacterial deposits.

Bacteria↗