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Biomedical subjects

C Bruun

Publications and source records attributed to C Bruun.

At least 19 recordsLinked to original sources
PubMed1991

Formation of CaF2 on sound enamel and in caries-like enamel lesions after different forms of fluoride applications in vitro.

The formation of calcium fluoride (CaF2) was measured on sound enamel (SE) and in caries-like enamel lesions (CL) after treatment in vitro with 2% neutral NaF or Duraphat. The caries-like lesions were created by exposure to acidified gel at pH 4.5 within a 0.07-cm2 window punched in water-repellant tape. The same window area was used in series (n = 10) of SE or CL during the application of NaF for 1 or 5 min or for 18 h or Duraphat for 6 or 18 h. CaF2 was extracted with 1 M KOH for 24 h, and fluoride was determined by gas chromatography. The short-term applications of NaF produced only negligible amounts of CaF2 on SE. The amounts of CaF2 in CL after 5 min application of NaF corresponded to (mean +/- SEM) 27 +/- 2.0 micrograms F/cm2. More than half of this amount was observed after only 1 min exposure to the NaF solution. The quantities of CaF2 in CL were similar after 6 and 18 h application of Duraphat, amounting to 26 +/- 2.2 and 31 +/- 2.2 micrograms F/cm2, respectively, suggesting that the reaction was essentially terminated after 6 h. These amounts were only about one fourth of the quantity obtained after 18 h exposure to the NaF solution. Thus, the conventional 5-min treatment with NaF produced the same amount of CaF2 in CL as 6 or 18 h exposure to Duraphat.

Calcium Fluoride↗
PubMed1989

Temperatures measured during reaming of the femoral neck and head. A preliminary report.

Thermal injury is a well-known complication during mechanical manipulation of cortical bone. In order to investigate the magnitude of the problem in relation to cancellous bone, the temperature elevation in the head of the femur during reaming for a sliding screw osteosynthesis was measured in ten patients. Temperatures in excess of 50 degrees for a duration of more than one minute were found within approximately 2 mm from the periphery of the reamer. This finding implies that the thread of the screw will be placed in an osteonecrotic zone.

Aged↗
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↗
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↗
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↗
PubMed1983

Study on the dissolution behaviour of calcium fluoride.

The dissolution of two analytical calcium fluoride preparations was studied in aqueous solution. Dissolved calcium fluoride was determined from analysis of Ca and F in solution. Original samples of the two preparations and the residue after partial dissolution were studied by X-ray diffractometry in comparison with natural fluorite. The dissolution of calcium fluoride was found to be extremely slow. After a period of 1-15 weeks, depending on the experimental conditions, a state was reached where apparently no further dissolution occurred, although the solution was far from saturation. The dissolution rate was obviously closely related to the crystal size. On partial dissolution the mean crystal size increased, probably due to the disappearance of the finest fractions. Placing the salt in a dialysis bag before immersion in the water lowered the dissolution rate and increased the undissolved fraction considerably. The results seem to support the assertion that calcium fluoride accumulated in early carious lesions after topical applications of fluoride may persist for considerable periods of time.

Calcium Fluoride↗
PubMed1982

Fluoride in mixed human saliva after different topical fluoride treatments and possible relation to caries inhibition.

Fluoride concentrations in mixed saliva were measured at different intervals following topical treatments with various fluoride preparations and procedures such as dentifrice, tablets, mouthrinse and topical solution. The results were related to available caries reduction data from corresponding clinical trials previously published. Salivary fluoride levels varied widely reflecting the different dosages applied, whereas the caries reduction data irrespective of type of treatment appear very similar, with a magnitude of about 30%. When combining salivary fluoride data with recent understanding of enamel-fluoride kinetics it was possible to explain the clinical caries reductions.

Adolescent↗
PubMed1979

Fluoride concentrations in saliva in relation to chewing of various supplementary fluoride preparations.

Fluoride concentrations were measured in whole saliva samples collected from 16 subjects at different intervals up to 60 min after chewing of various supplementary F preparations: chewable F tablets (0.21 mg F), plain F tablets (0.25 mg F) or F-containing chewing gum (0.25 mg F). Each of the F preparations was administered in a low dose (0.21--0.25 mg F) or in a high dose (0.42--0.50 mg F). Mean resting levels of fluoride in saliva ranged from 0.03 to 0.05 parts/10(6). Peak values averaging 15--25 parts F/10(6) in the low-dose group and 25--40 parts F/10(6) in the high-dose group were recorded within 5 min after intake. After 30 min, the salivary fluoride concentrations in both groups had decreased to levels below 1 part/10(6) and approached resting levels 60 min after intake. The availability of fluoride in saliva, as estimated from AUC values (areas under curves, relating fluoride concentrations to the time from 0 to 60 min), was similar with each of the preparations applied in the low dose. When used in the high dose, the chewing gum and also the plain tablets provided significantly more fluoride in saliva than the chewable tablets. The data may suggest that unflavored plain F tablets are equally suitable as a vehicle for fluoride aiming at a topical cariostatic effect as specially designed chewable tablets or chewing gum.

Chewing Gum↗