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Biomedical subjects

L Tronstad

Publications and source records attributed to L Tronstad.

28 records · Page 2Linked to original sources
PubMed1976

Morphologic and enzyme histochemical observations on the pulp of human primary molars 3 to 5 years after formocresol treatment.

The state of the pulp of twenty-seven primary teeth treated by formocresol pulpotomy (clinically and radiographically successful) was assessed 3 to 5 years after treatment. A wide variation was found in the pulpal condition, from normal pulp tissue to total necrosis. Resorption and apposition of hard tissue were common findings. Five teeth were freeze-sectioned and incubated for histochemical demonstration of oxidative enzymes. The pulps of two teeth were vital; two teeth had necrotic areas subjacent to the amputation paste; and one pulp was totally necrotic. Six teeth were extracted 5 minutes after formocresol pulpotomy and incubated for demonstration of oxidative enzymes. An unstained zone, 1 to 2 mm. deep, was seen in all incubated sections. In conclusion, it seems that the formocresol method should be regarded only as a means to keep primary teeth with pulp exposures functioning for a relativley short period of time.

Dental Pulp↗
PubMed1976

Biological tests on an experimental glass ionomer (silicopolyacrylate) cement.

The biological compatibility of an experimental glass ionomer (silicopolyacrylate) cement has been assessed in in vitro (cell culture) and in vivo (monkey teeth) tests. For comparison a conventional silicate cement (Super Syntrex) was included in the in vivo experiments. In vitro, the glass ionomer cement was toxic when freshly prepared. The toxicity decreased, however, with increasing setting time. In experiments with prolonged cell-material contact time with specimens which had set for 24 h, the material appeared to be non-toxic. The in vivo experiments confirmed previous reports concerning unfavourable pulp reaction caused by silicate cement, while the glass ionomer cement caused mainly a mild pulp reaction after 8 days of observation. Unfortunately no longer-term observations were obtained since the material had been washed out of the cavities within 36 days.

Acrylates↗
PubMed1976

Fluoride in an experimental cavity varnish.

The aim of the present study was to assess the behavior of fluoride in an experimental cavity varnish. The varnish consisted manily of ethanol and the fluoride was added as a 1 M solution of sodium fluoride. When increasing amounts of ethanol were added to fluoride in water the readings (mV) given by a fluoride ion electrode unexpectedly increased. This effect of ethanol on the readings was less marked at the highest fluoride concentrations. At considerable excess of ethanol, as in the varnish, reproducible readings were obtained. Free fluoride ions corresponding to an effective concentrations of 1 M aqueous fluoride seemed to be present in the varnish. When various amounts of hydroxyapatite were added to the varnish, the fluoride content of the varnish was reduced whereas an increased amount of fluoride was recovered from the apatite.

Dental Cavity Lining↗
PubMed1976

Biologic tests of a proposed pulp capping agent (Reocap).

A calcium hydroxide-containing cement (Reocap) was tested with regard to its suitability as a pulp capping agent. The pulp of 34 monkey teeth was exposed and Reocap was applied to the pulp wound and the cavity floor, after which the cavities were filled with amalgam. The observation periods were 8 days (10 teeth) and 80 days (24 teeth). After 8 days a necrotic area was seen in the pulp subjacent to the pulp capping agent and the surrounding tissue was inflamed to varying degree. After 80 days hard tissue formation was observed at the exposure site in 21 teeth. The hard tissue enclosed areas of necrotic and/or vital tissue and a complete bridge had not formed. In 7 teeth the pulp was necrotic whereas 3 teeth presented a pulp free of inflammation. In the remaining teeth the pulp showed a chronic inflammatory reaction. As judged by these results, Reocap does not appear to be as well suited as a pulp capping agent as pure calcium hydroxide.

Animals↗
PubMed1975

Biological tests of a silicophosphate cement.

The biological compatibility of a silicophosphate cement (Fluoro-Thin) and a zinc phosphate cement (de Trey's Improved) has been assessed in in vitro (cell culture) and in vivo (monkey teeth) tests. In the in vitro tests both materials were toxic when freshly prepared. In experiments with prolonged cell-material contact time, with set specimens of the materials, the zinc phosphate cement appeared to be non-toxic, whereas the silicophosphate cement was clearly toxic. The in vivo experiments confirmed that a possible pulp reaction cauded by zinc phosphate cement is of a mild nature. The silicophosphate cement, however, cauded a moderate or severe reaction in the pulp after 8 days of observation, and there was chronic inflammation in most teeth after 36 or 72 days. It was concluded, therefore, that Fluoro-Thin should not be used as a luting agent or for restorative purposes in direct contact with vital dentine.

Animals↗
PubMed1975

The use of dental services among Norwegian adults in 1973.

The dental treatment pattern and its determinants were surveyed in 1973 by interviews with a sample comprising 1,632 persons drawn to cover the total Norwegian population aged 15 and above. In all, 58% of the interviewees stated having visited a dentist during the year prior to the interview. In contrast, 16% had not consulted a dentist for at least 5 years. Fifty-five percent of the sample reported having received fillings at the last dental visit and 15% reported having received some periodontal and/or preventive treatment. Regular (at least annual) treatment attendance was claimed by 52% of the sample. However, some respondents had seemingly embellished their treatment behavior, and a relatively valid estimate for the current proportion of regular treatment attenders was considered to be 40% of the adult population in Norway. Sex and geographic region were found to be the most influential predictors of the recent treatment pattern, whereas school dental treatment had a major influence in youth. Dental conditions including the wearing of dentures was the reason most often given for not seeing a dentist on a regular basis.

Adolescent↗
PubMedDate not supplied

Scanning electron microscopy of cavity margins finished with ultra-speed instruments.

The quality of the margins of the box portions of Class II cavities finished with rotating instruments at ultraspeed was assessed. In a closed row of teeth, an adequate finish was obtained at the embrasure margin where the burs rotated toward the tooth surface and into the cavity. The finish of the opposite embrasure margin and of the gingival margin was imperfect, regardless of the instrument used.

Child↗