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Biomedical subjects

E Kvam

Publications and source records attributed to E Kvam.

At least 37 records · Page 2Linked to original sources
PubMed1990

Secondary dentin in replanted teeth--a histometric study.

To quantify the secondary dentin formation in replanted teeth, 16 human premolars with a postoperative observation period of 6, 12 and 24 weeks were studied histometrically. In spite of marked intra- and interindividual variations, a regression analysis revealed a significant correlation (r = 0.70) between observation time and the quantity of secondary dentin in the coronal pulp registered by histometry. A comparison with a previous semiquantitative interpretation of the same material showed that the histometric method was more accurate.

Dentin, Secondary↗
PubMed1990

A comparison of three photosensitizers with respect to efficiency of cell inactivation, fluorescence quantum yield and DNA strand breaks.

Intracellular properties of three photosensitizers relevant to photodynamic cancer therapy were compared using cultured human NHIK 3025 cells. When taken up in the cells, the hydrophilic photosensitizer aluminum phthalocyanine tetra sulfonate required about 10 times more quanta of light absorbed per cell to kill 90% of the cells than did the hydrophobic dyes Photofrin II and tetra(3-hydroxyphenyl)porphyrin. In spite of this, the phthalocyanine molecule was the most efficient dye per quantum of excitation light, since the extinction coefficient of the phthalocyanine is more than 10 times higher than that of the two hydrophobic photosensitizers at therapeutic wavelengths. The two hydrophobic dyes had significantly higher fluorescence quantum yields when taken up by cells than when bound to human plasma or human serum albumin, whereas the opposite was true for the hydrophilic phthalocyanine dye--suggesting intracellular aggregation. Finally, the potential genetic toxicities of the drugs in the form of DNA strand breaks were compared. The aluminum phthalocyanine tetra sulfonate photosensitized more DNA strand breaks than did Photofrin II and tetra(3-hydroxyphenyl)porphyrin when compared at the same level of cell survival.

Cell Survival↗
PubMed1990

[Who needs orthodontic treatment?].

Most people have a dentition with individual morphologic characteristics and exhibit dental arches deviating from strict ideal norms. Such deviations may be small rotations only or slightly tipped teeth. In other cases the deviations are so marked that it is justified to term the dentition a malocclusion. Not all these deviations and malocclusions need to be corrected. Hence it is important to be able to decide when it is beneficial for the patient to receive orthodontic treatment. A decisive factor in the evaluation of the treatment need is patients' perception of malocclusions. Investigations have shown that most patients initiate orthodontic treatment after consulting their regular dentist. It is important that the latter are updated about treatment indications and potential. In the present paper the recent documentation on orthodontic treatment need is described and discussed.

Health Services Needs and Demand↗
PubMed1989

Intracellular localization of photosensitizers.

The intracellular localization of photosensitizers can be studied by different methods. One method involves homogenization of the cells followed by differential ultracentrifugation which leads to fractions enriched in nuclear, mitochondrial, and microsomal material as well as a supernatant fraction. More detailed information can be obtained by electron microscopy of cells exposed to light in the presence of photosensitizers. This method is based on the assumption that damage is primarily induced at intracellular sites where the concentration of photosensitizer is high. By irradiating the cells at 6 degrees C, where biochemical reactions are slow, and then incubating them for different times at 37 degrees C, it is possible to follow the development of damage. The amount of photosensitized damage to enzymes or cell functions whose localization in the cells is known gives information about the intracellular localization of the sensitizer. Fluorescence microscopy is the most direct method and is widely applicable because most photosensitizers fluoresce. Lipophilic dyes generally localize in membrane structures. In future more attention should be paid to the localization of dyes in lysosomes, as suggested by early reports. Mitochondria, the endoplasmic reticulum and nuclear membrane are other important loci for intracellular localization of sensitizers.

Animals↗
PubMed1989

Dentofacial morphology in children playing musical wind instruments: a longitudinal study.

Playing wind instruments requires increased ventilation and increased orofacial muscle activity. The aim of the present investigation was to study the longitudinal effects on the dentofacial morphology of increased ventilation and orofacial muscle activity associated with playing wind instruments. Lateral cephalograms and dental casts obtained from wind instrument players at the ages of 6, 9, 12, and 15 years were studied and compared to control groups. In addition information was obtained as to how many hours per day they practised their instruments. Significant differences between the musicians and controls were found. The musicians had a decreased anterior facial height and wider dental arches. The findings are interpreted as being due to increased orofacial muscle activity and increased intra-oral pressure resulting from wind instrument playing.

Cephalometry↗
PubMed1989

Traumatic ulcers and pain in adults during orthodontic treatment.

In the present investigation the frequency of oral ulcers and pain in 79 adults orthodontic patients was recorded. Only four of all patients had never had oral ulceration during treatment, but 83% of the patients characterized the trouble as minor. About 47% of the patients said that ulcers caused by the fixed appliance were the most annoying part of the treatment, and 38% said that activation of the appliance caused the most discomfort. In about 63% of the patients there was less pain when the treatment had lasted for some months, and in 24% there was no significant change in the discomfort. The pain following activation lasted for only 2-3 days (71%), but 20% had pain for more than 3 days, and five individuals felt pain constantly. The recurrence of aphthous ulceration (RAU) was not significantly affected during the orthodontic treatment, and in only one case was there an increase in the occurrence of herpes labialis.

Adult↗
PubMed1988

Facial skeletal dimensions in patients with nasal septal deviation.

The anatomy and the concomitant function of the face seem to be reciprocal issues. Previous studies have shown that stenosis in the posterior part of the nose, hampering nasal air flow, is associated with a retrognathic face and a posterior rotation of the lower jaw, i.e. components of the adenoid syndrome. The present study examines facial cephalometric morphology in adults with a deviated nasal septal cartilage, i.e. an anteriorly positioned nasal stenosis. Compared to a group of unafflicted individuals, also with regard to rhinomanometric resistance, a significantly smaller posterior facial height, smaller height of the anterior nasal aperture, a posterior rotation of the lower jaw and a shorter nasal floor and ceiling were found. This may mean that growth of the nasal septal cartilage and growth of the surrounding skeletal areas are out of step. A relatively undersized skeletal frame, in the sagittal plane, may have led to the buckled non-fitting septal cartilage, with increased air flow resistance as a secondary effect. If this interpretation is correct, an early cautious surgical correction of the septal deviation, also balancing this growth incongruence, might be worth serious consideration.

Adult↗
PubMed1987

Traumatic ulcers and pain during orthodontic treatment.

In the present investigation the frequency of oral ulcers and pain in 161 orthodontic patients was recorded. Of all patients, 95% had experienced pain, but 84.5% said that the pain lasted a few days only. About 11% maintained that the treatment was constantly painful. Significantly more patients coming from private clinics complained of pain than those attending treatment at the Department of Orthodontics. About 50% said that activating or changing archwire was most annoying, whereas 28.7% said ulceration and 21% said headgear was the most annoying part of the treatment. According to 75% of the patients, sleeping habits were not influenced. Only eight patients reported truancy, and seven of these had done this only once. Of all patients, 6.2% had requested interim visits. Small wounds caused by the fixed appliance were reported by 75.8% of the patients, and 2.5% had suffered badly from ulceration caused by the fixed appliances. More girls than boys reported ulceration. There was a significant sex difference as regards recurrent aphthous ulceration (RAU). Increase in the frequency of RAU was reported by 23.1% of the girls and 9.6% of the boys while they had fixed appliances.

Activator Appliances↗
PubMed1987

Histometric study of root resorption on human premolars following experimental replantation.

A histometric method was applied for evaluation of root resorption in 57 experimentally replanted teeth and 22 controls. Representative axiobuccolingual sections were selected for measurement of resorptions at a magnification of x 40. The frequency of root resorption in the control teeth was low. In replanted teeth marked resorptive activity elicited by the trauma appeared after 2 wk. The extent of active resorptions increased until the third postoperative week. On an average 14% of the root periphery was affected at this stage. After the sixth postoperative week progressive cement deposition took place in the resorption lacunae. Incidental ankylosis of the periodontal membrane also occurred from this observation time but there was no increase among the long-term groups.

Adolescent↗
PubMed1977

Evaluation of histologic criteria applied for description of pulp reactions in replanted human premolars.

To test the reproducibility of a scoring system prepared for the study of the tissue changes in replanted teeth, 30 teeth were allocated at random from a material comprising 70 replanted and control teeth. The scoring system elaborated was applied for description of the odontoblast layer, predentin, secondary dentin, circulatory alterations, resorption, Weil's zone, cellular infiltration and calcification. The registrations were performed twice with a time interval of approximately 2 months. The scores were subsequently compared. Generally speaking, the double determinations were in good agreement as only 4.7% of the pairs of registrations failed to correspond. The agreement was particularly good for secondary dentin, cellular infiltration, resorption, Weil's zone and calcification scores. These criteria are accessible for group comparisons when differences in pulp tissue characteristics are small. The remaining three criteria may prove not to be useful unless the tissue response is substantial.

Bicuspid↗
PubMed1976

[Mixed teeth--a case report and an alternative treatment].

A case of "double" lower incisor is described. The patient also had a supernumerary lower incisor and was treated by removal of the abnormal incisor and transplantation of the supernumerary incisor. The transplanted tooth has normal mobility and healthy gingival tissue 6 1/2 months after the transplantation.

Child↗
PubMed1975

Growth in width of the frontal bones after fusion of the metopic suture.

Rat frontal bones reportedly exhibit lateral surface growth many weeks after fusion of the frontal suture. This is histologically confirmed in the present study. The mean width of the cranial vault at the postorbital constriction increased by 10% between the age of 30 and 58 days. The increase must be ascribed to periosteal growth, as the lateral, external surfaces exhibited active growth. External apposition without concomittant internal resorption causes an increase in bone thickness. The cells on the internal surfaces were in a state of rest. The study was based on a limited material; therefore, definite conclusions cannot be drawn.

Animals↗