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Biomedical subjects

A Thylstrup

Publications and source records attributed to A Thylstrup.

At least 55 records · Page 3Linked to original sources
PubMed1986

Clinical and scanning electron microscopic study of surface changes of incipient caries lesions after debonding.

The surface features of incipient caries lesions around bonded orthodontic brackets were assessed longitudinally. In standardized periods after debonding and clean-up, color slides were made and silicone impressions were taken of two maxillary incisors on each of six adolescent patients. These teeth were characterized by varying degrees of macroscopically visible demineralized white areas around the bonded brackets. The color slides were studied in a dark room. The positive surface replicas were studied in SEM. At the time of debonding heavy accumulations of dental plaque were observed in all areas corresponding to the white, demineralized areas. During the experimental period there was a reduction in these plaque deposits. The appearance of the lesions changed from chalky-white at the time of debonding to a more diffuse opacity, particularly in the peripheral parts of the lesion. Examination of the surface replicas in the SEM revealed a general tendency toward leveling of the surface of the lesion indicating a loss of porous tissue. At higher magnification the lesions showed signs of wear. Four teeth were presented to illustrate typical examples of the time-related changes at the surface. The present study confirmed that removal of cariogenic challenge results in arrest of further demineralization. The gradual regression of the lesion at the clinical level was believed to be primarily a result of surface abrasion with some redeposition of minerals.

Adolescent↗
PubMed1986

A polarized light and scanning electron microscope study of the effect of Duraphat treatment on in vivo caries.

The present study was carried out to examine the effect of application of a fluoride varnish (Duraphat) on experimentally produced caries in vivo. After a 4-wk period of cariogenic challenge on homologous pairs of premolars, Duraphat was applied on one of the teeth while the other was extracted and saved as a control. The Duraphat treated teeth remained in a cariogenic environment for a new period of 2 wk prior to extraction. All the control teeth displayed the classical characteristics of active incipient subsurface carious lesions. The Duraphat treated lesions showed an increase in surface porosity relative to their controls while the subsurface porosity was dramatically reduced. When examined in the SEM, the corresponding surface appeared smooth with a leveling out of the original surface irregularities. High power microscopy disclosed, however, a distinct network of intercrystalline spaces. Application of Duraphat prior to reestablishment of cariogenic challenge apparently gives rise to a marked redistribution of minerals in active initial carious lesions.

Adolescent↗
PubMed1986

Restorative treatment pattern and longevity of amalgam restorations in Denmark.

A survey has been made of the reasons for placement and replacement of 6052 amalgam restorations in Denmark. In patients more than 16 years of age 48% of all restorations were made because of primary caries, and 52% were replacements of failed restorations. In primary teeth 64% and in permanent teeth of children 83% of the restorations were made because of primary caries. The reasons for replacement of restorations were dependent on dentition, age of the patient, and type of restoration. Secondary caries was the most frequent reason for replacement of failed restorations in permanent teeth, comprising a third of all replacements. Marginal discrepancies and bulk fracture of fillings were the other two major reasons. In primary teeth fracture and loss of fillings were the two major reasons for replacement of amalgam restorations, whereas secondary caries caused less than a quarter of all restorations to be replaced. The age of the restorations replaced ranged from 0 to 38 years, and half of the restorations replaced in permanent teeth of adults were less than 7 years old. A shorter longevity of failed restorations was noted in primary teeth and permanent teeth of children.

Adolescent↗
PubMed1986

Restorative treatment pattern and longevity of resin restorations in Denmark.

A survey has been made of the reasons for placement and replacement of 883 resin restorations in Denmark. In patients more than 16 years of age 39% of all restorations were made because of primary caries, and 61% were replacements of failed restorations. In primary teeth 63% and in permanent teeth of children 65% of the restorations were made because of primary caries. The reasons for replacement of restorations were dependent on dentition, age of the patient, and type of restoration. Secondary caries, loss of fillings, and marginal discrepancies were the most frequently recorded reasons for replacement of failed resin restorations. The age of the restorations replaced ranged from 0 to 15 years, and half of the replaced resin restorations in adults were just over 6 years old. In permanent teeth in children half of the failed restorations were replaced within 2 years, whereas half of those in primary teeth were replaced within 1 year. Information on a selected material of old silicate cement restorations in adults showed that two-thirds of these were replaced owing to marginal discrepancies and lost fillings.

Adolescent↗
PubMed1985

Three-year caries increments after fluoride rinses or topical applications with a fluoride varnish.

251 9-12-yr-old children completed a 3-yr, double-blind, clinical trial of two caries preventive fluoride programs. Caries increments and progression patterns were compared in two groups of children who rinsed every fortnight with a 0.2% NaF solution or received biannual topical applications with a fluoride varnish (Fluor-Protector). Clinically recorded mean DFS increments were 3.3 +/- 0.2 (SE) in the rinse group and 3.5 +/- 0.2 in the varnish group. In both groups nearly half of these increments were recorded in the occlusal surfaces of second molars. The mean incremental DFS recorded radiographically on approximal surfaces of posterior teeth were 1.1 +/- 0.2 and 1.5 +/- 0.2 in the rinse and varnish group, respectively. None of the inter-group differences were statistically significant (P greater than 0.05). Detailed analyses of the radiographic scores revealed a similar and extremely slow caries progression in the two study groups and they strengthened the conclusion of equal clinical efficacy of the two treatments. None of the fluoride programs had been able to change preestablished patterns of caries development among the children.

Child↗
PubMed1985

Two-year assessment of anterior resin restorations inserted with two acid-etch restorative procedures.

Fifty-two pairs of Class III restorations in a microfilled resin Silar were inserted in acid-etched cavities. A bevel preparation was performed along the margin of one cavity (A) whereas the other cavity was treated with the surface-active comonomer NPG-GMA before filling (B). After finishing of the restorations, the surface of the type B filling was re-etched and covered with a layer of non-composite, low-viscous resin. Following a 2-yr observation period 65 restorations were classified as "good", 33 were "adequate" and 4 were "unsatisfactory" or were replaced during the study period. The only significant difference between type A and type B restorations was marginal discolorations which most frequently were observed along the beveled type A restorations. The occurrence of such failures was increased by marginal deficiencies and occlusion/articulation on the restorations.

Acid Etching, Dental↗
PubMed1984

Dental health status and attitudes to dental care in families participating in a Danish fluoride tablet program.

The caries experience and dental fluorosis of 84 Danish children, who had used fluoride tablets for 1-4 yr in the period 1976-80, were compared with those of a group matching in sex, age, place of living, and socioeconomic status. The average age of the children at the time of examination was 5.8 yr. A recording of mothers' attitudes to dental care, knowledge about tooth brushing, attitudes to candy, and number of teeth in the maxilla showed no difference between the fluoride tablet group and the non-users' group. Moreover, there was no significant difference between the two groups with respect to dental caries. The findings are discussed in relation to recent reports on the decline of dental caries resulting from widespread use of local administration of fluorides.

Adult↗