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Biomedical subjects

C Bruun

Publications and source records attributed to C Bruun.

At least 19 recordsLinked to original sources
PubMed1998

A new in vitro method for testing the interproximal cleaning potential of toothbrushing.

A new laboratory method was developed and used to evaluate the approximal penetration of different toothbrushing techniques. Before brushing, the approximal surfaces on teeth numbers 33 to 38 were covered by a colored coating. After brushing from both the buccal and lingual sides, the teeth were removed and the remaining coatings on the approximal surfaces were photographed and magnified, and their areas were determined by computerization. Two conventional toothbrushing techniques and two toothbrushing techniques specially designed to enhance interproximal access were used. It was found that considerable areas on the approximal surfaces were left untouched by the toothbrush bristles, regardless of the toothbrushing technique employed. The findings suggest that improvements in toothbrush design will be a more important contribution to the attainment of effective interproximal brushing than the development of new brushing techniques. This test method shares many similarities with in vivo conditions and seems also well suited for evaluating interproximal cleaning potential of new toothbrushes.

Analysis of Variance↗
PubMed1997

Are backward words special for older adults?

Two experiments comparing older and young adults confirmed that Stroop interference from lists of incongruent color words was greater for older adults. Similar age effects were observed when the lists of words were presented in 2 unusual print orientations (upside-down; backward and upside-down). In contrast, no age effect was observed, when participants named colors on backward-word lists, as measured with a percentage interference score that corrected for individual differences in baseline (color patches) naming times. Reading speed failed to account for all the interference effects in these data.

Adolescent↗
PubMed1994

In vivo caries models--mechanisms for caries initiation and arrestment.

The effects of intra-oral mechanical forces on caries initiation, progression, and arrestment are evaluated by examination of different in vivo caries models. The models are grouped in four categories: (1) a population study, (2) short-term clinical trials, (3) clinical experiments, and (4) controlled clinical observations. Taken together, these in vivo studies convincingly demonstrate that partial or total elimination of the intra-oral mechanical forces operating during mastication or toothbrushing leads to evolution of cariogenic plaque, resulting in localized carious enamel dissolution. In addition, they show that re-exposure to the partly or totally eliminated mechanical forces not only arrests further lesion progression, but also results in partial lesion regression. The data from in vivo caries studies also show that the clinical and structural changes associated with lesion arrestment or partial regression are not related to any salivary repair mechanism, but are solely the result of mechanical removal of the cariogenic biomass which is physically interrelated with the eroded surface of the active, dull-whitish enamel lesion. No indications of superficial mineral deposition or "blocking" of the external intercrystalline spaces are seen in the surface layer of lesions arrested in vivo. For this reason, the conventional usage of the terminology 'remineralization' is considered absolutely misleading when used to describe the mechanisms responsible for the arrest of lesion progression in vivo.

Clinical Trials as Topic↗
PubMed1993

Calcium fluoride formation in enamel from semi- or low-concentrated F agents in vitro.

The formation of CaF2 was measured on sound enamel and in artificial, standardized (acidified gelatin, pH 4.5) caries-like enamel lesions after exposure to: (a) dentifrice/saliva slurries adjusted to relevant F-concentrations of approximately 100 or 8 ppm by appropriate addition of 1,000 ppm F NaF or Na monofluorophosphate (MFP) dentifrice, respectively, or (b) a mixture of saliva with a 0.2% NaF solution obtained by a usual 1-min rinse procedure or an aqueous solution of 0.2% NaF. CaF2 was determined after extraction with KOH and fluoride analysis by gas chromatography. Only negligible amounts of CaF2 were produced on sound enamel ranging from (mean +/- SEM) 0.76 +/- 0.14 micrograms F/cm2 with the 0.2% NaF solution to as little as 0.04 +/- 0.06 with the MFP dentifrice slurry. In caries-like enamel lesions, the CaF2 production with the 0.2% NaF solution/saliva mixture corresponded to 3.7 +/- 0.4 micrograms F/cm2 and corresponding amounts obtained with the dentifrice/saliva slurries were 1.5 +/- 0.19 micrograms F/cm2 with NaF, but only 0.19 +/- 0.04 with MFP. It was suggested that the deposition of CaF2 in the micropores of early lesions can be expected to be an important mechanism with F rinses, probably to some extent with NaF dentifrices, but barely with MFP dentifrices. The formation of CaF2 on sound enamel is unlikely to play a significant role in the caries-reducing effect of F rinses and F dentifrices.

Calcium Fluoride↗
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↗