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Biomedical subjects

K Bjorvatn

Publications and source records attributed to K Bjorvatn.

At least 37 records · Page 2Linked to original sources
PubMed1995

Prevalence of dental fluorosis in Sudanese children from two villages with 0.25 and 2.56 ppm fluoride in the drinking water.

Dental fluorosis is endemic in Eastern Africa and a high prevalence has been found even in low-fluoride (approximately 0.5 ppm) areas. Substantial seasonal changes in the fluoride content of water have also been reported. The aim of the present study was to ascertain, through one year, the fluoride concentration in water from two underground reservoirs in Sudan, in Treit el Biga (TeB) and Abu Groon (AG), and to assess dental fluorosis in children aged 7-16 years who had been lifelong residents. The water in one of the reservoirs (TeB) was shown to have a low, very stable fluoride concentration (0.25 ppm SD 0.04) whereas the other (AG) had a tenfold higher, and slightly varying, fluoride concentration (2.56 ppm SD 0.26). Dental fluorosis was recorded on maxillary central incisors according to Dean's index. In TeB 91% of the children showed signs of dental fluorosis whereas in AG all children had fluorotic teeth. The Community Fluorosis Index in TeB and AG was 1.40 and 2.44, respectively. There was a significantly higher degree of fluorosis in boys than in girls in the low-fluoride area. In TeB, older boys tended to have more fluorosis than younger boys; the difference, however, was not statistically significant. No significant sex or age differences in fluorosis were found in AG. In both villages great inter-individual variations in dental fluorosis were recorded. The prevalence and severity of dental fluorosis in TeB was higher than that previously reported in areas with similar fluoride concentrations in the drinking water.

Adolescent↗
PubMed1994

Defluoridation of drinking water with pottery: effect of firing temperature.

Excessive fluoride (F) in drinking water should be removed, but simple, inexpensive methods of fluoride removal are not readily available. This study examines the F(-)-binding capacity of clay and clayware, especially the effect of the firing temperature on the F(-)-binding process. A series of pots were made from ordinary potter's clay and fired at 500-1000 degrees C. Likewise, small clay bricks were fired and then crushed and sieved. NaF solutions containing 10 mg/l F- (10 ppm F-) were prepared. Suitable aliquots of the solutions were poured into clay pots or exposed to powdered clayware. Samples were taken at storage periods of 30 min to 20 days and analyzed for F- by ion-selective electrodes. The rate and capacity of F(-)-binding in the clayware varied with the firing temperature. Clay fired at approximately 600 degrees C was most effective. Temperatures over 700 degrees C caused a decline in F(-)-binding, and pottery fired at 900 degrees C and above seemed unable to remove F- from water. Pots fired at 500 degrees C or less cracked in water. The findings indicate that clayware, fired at an optimal temperature, may be of practical value for partial defluoridation of drinking water.

Aluminum Silicates↗
PubMed1992

Effect of stannous fluoride and tetracycline on periodontal repair after delayed tooth replantation in dogs.

Previous studies have indicated that inflammatory resorption and ankylosis, which are frequent sequela after delayed tooth replantation, can be greatly reduced by treating the root surface with 1% solutions of stannous fluoride and tetracycline. However, the SnF2 conditioning leaves a long-standing inflammatory reaction in the periodontal ligament. To examine whether a more dilute SnF2 solution would reduce postoperative inflammation without jeopardizing any beneficial effects, anterior teeth in three young adult beagles were extracted and allowed to air-dry for 45 min. They were then immersed in 0.1% SnF2 for 5 min, rinsed in saline, immersed in 1% doxycycline HCl for 5 min, rinsed, and replanted. Control teeth were air-dried and replanted without further treatment. Block biopsies were harvested after 4 wk of healing and processed for histometric analysis. In experimental teeth, 85% of the root surface area showed normal healing, compared to 33% in control teeth. Conversely, resorption and ankylosis were more frequent in controls than in experimental teeth. A persisting inflammatory reaction either adjacent to or at a distance from the root surface was seen in limited areas in both experimental and control teeth. Compared to preceding studies, the findings indicate that reducing the strength of the SnF2 solution from 1% to 0.1% may result in less persistent inflammation, at the cost, however, of less complete prevention of inflammatory resorption and ankylosis.

Alveolar Process↗
PubMed1991

[Allogeneic transplantation--two case reports].

After a brief discussion on the transplantation of teeth, two cases of allogeneic transplantation, respectively from brother to sister, and from daughter to mother, are presented. Based on the two cases and a limited number of case histories found in dental literature, it is suggested that immunological screening of donor and recipient may help improve the prognosis of allogeneic transplantation of teeth.

ABO Blood-Group System↗
PubMed1990

Effect of stannous fluoride and tetracycline on repair after delayed replantation of root-planed teeth in dogs.

Mandibular incisors were extracted and allowed to dry in air for 45 min. They were then root-planed extensively, leaving a cervical collar and the apical region uninstrumented, to prevent direct contact between root surface and alveolar bone after replantation while, at the same time, enabling precise and stable reseating of the tooth. Control teeth were replanted either without further treatment or after treatment with citric acid for 3 min. Experimental teeth were treated before replantation with 1% SnF2 for 5 min, 1% tetracycline HCl for 5 min, or 1% SnF2 followed by 1% tetracycline. Histometric analysis of healing in the root-planed areas showed minimal amounts of inflammatory resorption and ankylosis after 21 days in experimental teeth as compared with the control teeth. A persisting inflammatory reaction in the periodontal ligament without root resorption was, however, frequently seen. The observations confirm that the frequency of adverse healing reactions after delayed replantation of teeth from which nonvital soft tissue remnants have been removed can be reduced by demineralizing the root surface and preventing mechanical trauma to the root surface in the postoperative period. Root surface treatment with SnF2 followed by tetracycline resulted in complete absence of inflammatory resorption and ankylosis in this short-term experiment.

Animals↗
PubMed1990

[Oral health in Sudan--a challenge to Norwegian dentistry?].

The paper gives an overview over the oral health situation in the Sudan. Available epidemiologic data indicate that the caries prevalence is low, but increasing. Recent information on periodontal disease is scarce. Dental fluorosis is of growing concern. Oral cancer, especially squamous cell carcinoma, is prevalent. Sudan has approximately 300 dentists to meet the treatment needs of the country's 25 million inhabitants. The great majority of the dentists live in the Khartoum area. The University of Khartoum, School of Dentistry has a capacity of 20 candidates a year. A close cooperation has been established between the dental school in Khartoum and its counterpart at the University of Bergen.

Adolescent↗
PubMed1989

Effect of tetracycline and SnF2 on root resorption in replanted incisors in dogs.

The present study was made to assess the effect of applying SnF2, tetracycline, or both, to root surfaces of extracted teeth prior to replantation. In five young adult beagles, a total of 18 mandibular incisors were extracted, bench dried for 45 min, and reimplanted in their respective sockets either after no further treatment or following treatment with 1% doxycycline HCl for 5 min, 1% SnF2 for 5 min, or 1% SnF2 followed by 1% doxycycline HCl. After 4 wk of healing, the relative frequency of root resorption (surface resorption, inflammatory resorption and replacement resorption) was approximately 27% of the root surface in bench-dried as well as in doxycycline-treated specimens. By contrast, SnF2-treated and SnF2 + doxycycline-treated teeth showed less than 1% resorption. In the latter two specimen groups an inflammatory reaction in the periodontal ligament without resorption occurred with a frequency of 38.3% and 11.1%, respectively. The results indicate that application of SnF2 to the root surface prior to replantation effectively reduces resorptive processes during the first postoperative weeks. By subsequently treating the root surface with tetracycline, the adverse effect of SnF2 on periodontal connective tissue repair may be reduced.

Animals↗
PubMed1987

Topical application of tetracycline in regenerative periodontal surgery in beagles.

This study was designed to test the effect of tetracycline on healing subsequent to periodontal surgery. Aqueous solutions of tetracyclines are highly acidic and may therefore represent a suitable substitute for citric acid. Furthermore, tetracyclines react with dental hard tissues to from long-lasting antimicrobial compounds, and they have a retarding effect on pellicle and plaque formation and an antienzymatic effect. The alveolar bone around mandibular premolars was surgically reduced up to 6 mm from the cementoenamel junction in two beagles. The denuded root surfaces were exposed to the oral environment during 3 months without plaque control. Regenerative surgery was then carried out, using root surface conditioning with 1% tetracycline and coronally repositioned flaps. Six months later, histologic evaluation showed connective tissue attachment extending to the cementoenamel junction in most of the specimens. Superficial root resorption was prevalent in the cervical region, below which a collar of replacement resorption partly surrounded the roots in a characteristic manner. Morphometric analysis showed that attachment gain was similar to that obtained with citric acid in a preceding series of seven dogs. These preliminary results indicate that connective tissue attachment gain after topical use of tetracycline is similar to that obtained with citric acid. In addition, the antibacterial capacity and biological effects of tetracycline warrant further study of its possible clinical use in periodontal reconstructive surgery.

Administration, Topical↗
PubMed1986

Scanning electron-microscopic study of pellicle and plaque formation on tetracycline-impregnated dentin.

Previous experiments have shown that tetracyclines may react with hydroxyapatite, e.g. in enamel and dentin, without losing their antimicrobial capacity. The present paper examines the pattern of pellicle and plaque formation on doxycycline-treated dentin by the use of scanning electron microscopy (SEM). From newly extracted human teeth were prepared standardized dentin slabs, half of which were soaked in aqueous solutions of doxycycline HCl, 10 mg/ml (pH 2.5) for 10 min. Seven volunteers carried doxycycline-impregnated specimens ligated to the buccal surface of a maxillary molar for 2 h, 8 h, 24 h and 120 h, respectively. Untreated control specimens were ligated to the contralateral teeth. After removal from the oral cavity, the dentin slabs were briefly rinsed in water, allowed to air dry and processed for SEM. SEM assessment of the specimens showed that doxycycline-impregnation resulted in a superficial etching of the dentin, a reduced rate of pellicle formation as well as an impairment of pellicle adhesion, and a retarded bacterial plaque formation on the dentin surfaces.

Bacteria↗
PubMed1986

Intraoral bacterial growth on tetracycline-impregnated dentin.

Previous studies have shown that tetracyclines react with enamel and dentin in vitro to form slightly soluble compounds with a pronounced and long-lasting antimicrobial capacity. The purpose of the present project was to study the effect of doxycycline-impregnation of dentin on the growth of oral microorganisms in vivo. Slabs of native human dentin were immersed in aqueous solutions of doxycycline HCl, 10 mg/ml, for 10 min, and were subsequently ligated to orthodontic brackets placed bucally on maxillary molars in seven individuals. Untreated native dentin specimens were similarly placed on contralateral teeth. Test and control specimens were removed from the oral cavity after 2 h, 24 or 120 h, respectively. The individual specimens were then placed in 0.5-ml saline and agitated mechanically for 30 s. The resulting bacterial suspensions were plated onto blood agar and various selective growth media. Based on CFU-counts obtained after incubation of the plates, doxycycline-treated dentin specimens showed a significantly lower number of viable microorganisms after 2 h and 24 h in the oral cavity than did the control specimens. The bacterial growth was also less pronounced in the test specimens after 120 h. The effect of doxycycline was similar for all the cultivable bacteria. No significant difference in yeast growth was seen between test and control specimens.

Bacteria↗
PubMed1985

Tetracycline-impregnated enamel and dentin: duration of antimicrobial capacity.

The present study was done in order to examine the durability of the tetracycline-induced antimicrobial capacity, and also to assess the reproducibility of the bacterial growth-inhibitory assay used. Standardized enamel and dentin specimens were impregnated in aqueous solutions of tetracycline HCl, oxytetracycline HCl or doxycycline HCl, rinsed in water, and stored dry for 200 days. Another series of specimens was impregnated in solutions of doxycycline HCl and then rinsed in tap water for varying periods up to 35 days. In addition, drug-impregnated specimens were used for reproducibility tests without storage or prolonged rinsing. Impregnated specimens were tested for antimicrobial capacity on agar plates seeded with S. sanguis. After 24 h aerobic incubation in 10% CO2 atmosphere, the plates were inspected and the diameter of the bacterial growth inhibition zones measured. The drug-impregnated enamel and dentin specimens consistently demonstrated growth-inhibitory capacity. The results of the reproducibility tests showed moderate intrasample and day-to-day variation. Two hundred days of dry storage or 35 days soaking in water reduced, but did not eliminate, the bacterial growth-inhibitory capacity of the impregnated dental specimens. The results show that a short-term exposure of dental hard tissues to tetracyclines may result in a long-lasting antibacterial capacity.

Bacteria↗
PubMed1984

Inhibition of bacterial growth by tetracycline-impregnated enamel and dentin.

Tetracyclines can react with enamel and dentin to form relatively insoluble fluorescent compounds. The purpose of this study was to evaluate the possible antimicrobial effect of these reaction products on various microorganisms associated with human dental plaque and periodontal disease. Slabs of native dentin and enamel as well as demineralized dentin were immersed in aqueous solutions of tetracycline HCl, oxytetracycline HCl and doxycycline HCl for periods of 1 h or 24 h. Unimpregnated enamel and dentin slabs sterilized by gamma irradiation and specimens impregnated with phenoxymethylpenicillin calcium were used as controls. Test and control specimens were placed on agar plates seeded with B. cereus, C. ochraceus, S. sanguis, F. nucleatum, B. melaninogenicus or A. viscosus and were subsequently incubated aerobically or anaerobically at 37 degrees C. With the exception of enamel impregnated for 1 h in a 0.01 mg/ml tetracycline solution, all test specimens caused growth inhibition zones, varying in size according to concentration of the drug, immersion period and bacterial species. The results indicate that tetracyclines react with enamel and dentin to form slightly soluble compounds with a pronounced antibacterial effect. In comparison, the antimicrobial effect of dentin treated with penicillin was small.

Bacteria↗
PubMed1983

In vitro study by fluorescence microscopy and microradiography of tetracycline-tooth interaction.

The administration of tetracycline to the growing child may cause discoloration and hypoplasia in developing teeth. Whether tetracycline may also cause changes in fully mineralized enamel and dentin, is still a matter of discussion. The present investigation examines the in vitro reaction between tetracycline chloride and enamel and dentin of extracted human teeth. Specimens were immersed in 0.5 mg/ml to 20 mg/ml aqueous tetracycline solutions. After 24 hr the specimens were sectioned and studied by fluorescence microscopy and microradiography. The tetracycline solutions, which were all very acidic, were found to cause 1) demineralization of enamel and dentin, 2) incorporation of fluorescent material in enamel and, notably, dentin; and 3) formation of yellow, rhombohedral crystals on dental surfaces, especially in the more concentrated solutions. No fluorescence was seen in totally demineralized dentin. The findings indicate that the incorporation of tetracycline into enamel and dentin is caused by physiochemical processes that may take place regardless of the developmental stage of the mineralized tissues.

Dental Enamel↗
PubMed1982

The effect of penicillin- and tetracycline-containing medicaments on the microhardness of human dental enamel. An in vitro study.

While the sugar content of various medicaments has been accepted as a hazard to dental health, the possible detrimental effect of the medicaments per se has been largely overlooked. In the present study the microhardness of dental enamel was examined before and after the exposure to various salts of penicillin, to tetracycline chloride, and to human saliva. The Vickers hardness index was found to 1. remain stable or increase slightly in enamel exposed to saliva, nonaqueous penicillin suspensions and certain watery solutions of phenoxymethylpenicillin calcium. 2. decrease to a moderate degree in most aqueous penicillin solutions, and 3. decrease drastically in tetracycline solutions and in phenoxymethylpenicillin calcium solutions containing citrate. The results indicate that a direct reaction may take place between the dental enamel and the medicament and/or its degradation products when antibiotic compounds are taken per os.

Dental Enamel↗
PubMed1982

Antibiotic compounds and enamel demineralization. An in vitro study.

Discoloration, pigmentation and even caries-like lesions have been reported in teeth subsequent to per oral administration of antibiotics. The present in vitro study examines the possible medicament/tooth reaction by exposing plane, polished enamel surfaces to aqueous solutions or oily suspensions of various commonly used penicillin compounds, or to solutions of tetracycline sodium. The teeth were examined by visual inspection, microhardness tests, scanning electron microscopy and microradiography. pH and [Ca2+] of the test solutions were analyzed by potentiometry. Surface or subsurface lesions and a decline in microhardness were found in (most) enamel specimens exposed to aqueous solutions of the medicaments. Similar changes were found in test specimens immersed in deionized water, while saliva, oily suspensions of the medicaments and aqueous solutions made from ordinary Ca-penicillin had no adverse affect on the enamel. The most serious destruction was seen in enamel specimens submerged in watery solutions made from effervescent (citrate-containing) Ca-penicillin, or from tetracycline. A slight decline in pH was observed in the aqueous solutions during the experiment. The calcium ion concentration did not increase parallel to enamel destruction.

Dental Enamel↗
PubMed1981

Laboratory study of fluoride impregnated toothpicks.

The uptake of NaF in wooden toothpicks as well as the release of F- from toothpicks impregnated with either sodium fluoride or amine fluoride was studied. The initial rate of fluoride uptake was found to be high, and an amount of NaF suitable for clinical use was obtained after immersing toothpicks in a 4% NaF solution for about 5 min. When immersed in water or saliva, fluoride was rapidly released from the impregnated toothpicks. The F- concentration registered in saliva collected during use of fluoride impregnated toothpicks varied from about 0.1 part/10(6) F (amine fluoride impregnated toothpicks) to more than 50 parts/10(6) F (extended impregnation with NaF). The results indicate that the clinical potential of fluoride impregnated toothpicks should be explored.

Amines↗