Biomedical subjects

D Gaspersic

Publications and source records attributed to D Gaspersic.

At least 19 recordsLinked to original sources

PubMed2001

Bioconcentration of lipophilic organochlorines in ovine dentine.

The bioconcentration of lipophilic organochlorines in ovine dentine in comparison to adipose tissue was examined. Sheep were given a single dose (0.2-1.4 mg/kg body wt) of individual polychlorobiphenyl (PCB) congeners (tetrachlorobiphenyls IUPAC Nos. 54 and 80, and hexachlorobiphenyls IUPAC Nos. 155 and 169) and organochlorine pesticides 1,1-bis(4-chlorophenyl)-2,2-dichloroethene) (4,4'-DDE) and hexachlorobenzene (HCB). They were killed 2 months after the dose and teeth and adipose tissue were collected. For the extraction of organochlorines, dentine was treated ultrasonically with sulfuric acid and hexane. The concentration of organochlorines in dentine and adipose tissue was determined by high-resolution gas chromatography with electron-capture detection. The bioconcentration of 'planar' compounds (PCB-169, HCB) in dentine, compared to adipose tissue, was lower than that of 'non-planar' (PCB-155, 4,4'-DDE). Ratios of the non-planar to planar compounds PCB-155/-169 and 4,4'-DDE/HCB in dentine were 1.4 and 7.2, and in adipose tissue 0.5 and 2.4, respectively. The dentine:adipose tissue bioconcentration ratios (on a lipid basis) of PCB-54, -80, -155, -169, 4,4'-DDE and HCB were 47, 16, 0.3, 0.1, 3.2 and 1.0, respectively. The results indicate that the bioconcentration of organochlorines in different tissues cannot be based on lipid content only. It is suggested that the physicochemical properties of individual organochlorines, i.e. lipophilicity (K(ow)), diffusivity, metabolism and tissue-specific interactions, play a part in the different bioconcentrations of individual organochlorine pollutants in dentine compared to adipose tissue.

Adipose Tissue↗

PubMed2000

Effect of 10% carbamide peroxide bleaching gel on enamel microhardness, microstructure, and mineral content.

The effect of 10% carbamide peroxide on human enamel subsurface layers was examined. Microhardness, microstructure, and mineral content were studied in such a manner that control and test side were located on the same tooth. Longitudinally sectioned samples were obtained from six teeth and Vickers microhardness of the enamel was measured. Enamel microstructure was analyzed using a scanning electron microscope and subjected to electron probe microanalysis for chemical analysis of calcium (Ca) and phosphorus (P). The concentration of Ca in the bleaching gel was measured spectrophotometrically and the concentration of P was measured photometrically. Results showed that a bleaching gel of 10% carbamide peroxide did not significantly affect the microhardness of the enamel. Scanning electron microscopic analysis showed local changes in enamel microstructure similar to those of initial caries. Electron probe microanalysis showed lowered concentrations of Ca and P; in addition the Ca:P ratio was lowered. There was some Ca and P in the bleaching gel after use. It is concluded that 10% carbamide peroxide causes local microstructural and chemical changes in enamel that are likely not clinically significant.

Adolescent↗

PubMed1999

The effect of pilocarpine and biperiden on salivary secretion during and after radiotherapy in head and neck cancer patients.

PURPOSE: The influence of parasympathicomimetic pilocarpine and anticholinergic biperiden on salivation in patients irradiated for malignant tumors of the head and neck region was assessed in a prospectively designed clinical study. METHODS AND MATERIALS: Sixty-nine patients, irradiated for head and neck cancer with salivary glands included in the irradiation fields, were randomly assigned into three groups (A, B, and C). Group A consisted of patients receiving pilocarpine, group B of those who were receiving biperiden during radiotherapy and pilocarpine for 6 weeks after its completion, while group C comprised patients not receiving any xerostomy prevention therapy during or after radiotherapy. The quantity of secreted unstimulated saliva was measured before the beginning of radiotherapy, after 30 Gy of irradiation, on completed irradiation, and 3, 6, and 12 months after completion of radiotherapy. RESULTS: Saliva secretion has been found to be the least affected by irradiation treatment in the group of patients receiving biperiden throughout the course of radiotherapy. Six months after completed irradiation, the differences in the quantity of secreted saliva between groups C and B as well as between groups A and B were statistically significant (P = 0.002 and 0.05 respectively). In patients receiving pilocarpine during radiotherapy, and those in the control group, further decrease in saliva secretion was observed. One year after completed therapy, the quantity of secreted saliva could only be measured in the patients receiving biperiden during radiotherapy: it amounted to 16% of the average quantity of saliva secreted before the beginning of irradiation. CONCLUSION: It seems that the inhibition of saliva production during irradiation treatment and the stimulation after completed radiotherapy may contribute to the preservation of salivary gland function after therapy.

Adult↗

PubMed1997

Identification of protostylid.

The presence of the protostylid was determined on 942 extracted lower molars of recent Slovenians. Dental casts of 32 extracted molars exhibiting a protostylid pit were obtained from alginate as well as from silicone impressions. The quality of the reproduction of protostylid pits was determined and the identification of these on dental casts was compared with their identification on the extracted teeth. The presence of the protostylid pit was confirmed histologically. Compared with previous studies the results show a higher frequency of protostylid on the third molars (51.2%); 70.3% of these protostylids relate to surface irregularities and are as such much readily observable by the protostylid pit. Determination of protostylid pits from the casts made from silicone impressions is more reliable compared to the same determination from the casts obtained from alginate impressions. The former method may be even more reliable than determination on the extracted teeth. Owing to common local enamel hypoplasias on the third molars, there is a considerable possibility of misjudging the presence of a protostylid if the determination is not confirmed histologically. Though the identification of the protostylid is difficult because of its poor expressivity, the accuracy of investigations would significantly increase if protostylids on lower third molars were given more attention. By doing so the data on frequency and expressivity of this dental trait would be of more value.

Adult↗

PubMed1996

Morphometry, scanning electron microscopy and X-ray spectral microanalysis of protostylid pits on human lower third molars.

Protostylid pits on 50 lower third molars were studied. The depth and width of the pits, the thickness of the enamel at the pit bottom and the concavity of the dentino-enamel junction under the pit were measured by light microscopy. The pit content was examined by scanning electron microscopy and X-ray spectral microanalysis. The results show that the morphometric variables of protostylid pits are similar to those of occlusal fissures and pits. The protostylid pits were seen to contain globular formations, belonging mainly to dental calculus; organic rod-shaped bodies, which could represent remnants of the enamel organ--or more probably--foreign bodies, were frequently observed. The study suggests that the development of the most common form of protostylid is basically similar to that of an occlusal cusp, with variations attributable to the low expression of the protostylid and particularities of cusp development in the lateral tooth wall.

Calcium↗

PubMed1995

Micromorphometric analysis of cervical enamel structure of human upper third molars.

Fifty-two teeth were sectioned and embedded such that the structural characteristics of the palatal enamel could be examined by scanning electron microscopy. Measurements were made of the height of aprismatic cervical enamel, of cervical enamel with atypically shaped prisms, and of cervical enamel without Hunter-Schreger bands. Enamel thickness 80, 1000 and 2500 microns occlusally from the cervical enamel border, the maximum thickness of cervical enamel with atypical prism shape and that of aprismatic cervical enamel, and the thickness of occlusal enamel were also measured. The height of cervical enamel with atypical prism shape ranged between 103 and 756 microns, and was inversely related to the thickness of typically structured enamel, suggesting that atypical enamel formation follows some order. Atypical enamel in the cervical area may affect caries susceptibility as well as the efficacy of acid-etching in this region.

Adult↗

PubMed1995

Enamel microhardness and histological features of composite enamel pearls of different size.

The aim of this study was to investigate the enamel microhardness and the histological features of eight enamel pearls of various size. The microhardness of the pearl enamel ranged from 272.4 to 407.2 Vickers microhardness values (VMV) and resembled that of the enamel of the carrier teeth (277.1-424.3). A histological resemblance between the tissues of the enamel pearls and those of the carrier teeth was also found. The resemblance was more pronounced in larger pearls, which showed a variability of the enamel microhardness and structure in the occlusal-cervical direction typical of the tooth crown. Large pearls also exhibited a root and a pulp. Some histological features of the enamel pearls were probably caused by pressures exerted on the developing pearl by its surroundings. It is suggested that the histogenesis of small and large pearls is based on the ability of the developing root of the carrier tooth to behave in part as a new tooth germ.

Dental Enamel↗

PubMed1994

Some principles in the dental crown construction in permanent maxillary centrals of Slovenians.

To increase the understanding of the incisors crown form, the lingual fossa depth, crown width and crown thickness between lingual marginal ridges of the permanent maxillary centrals were measured on 257 stone casts of Slovene children. The right-left, male-female differences, as well as the correlations between the variables themselves were analysed. Male centrals exhibited wider and thicker crown compared to female centrals, while the lingual fossa depth showed no sex differences. A positive correlation in terms of positive allometry between lingual fossa depth and crown width was established. A negative lingual fossa depth-crown thickness correlation was found with female left centrals. High right-left symmetry was established, except for the directional asymmetry of all three measured variables on female centrals. The results indicate that the positive correlation in terms of positive allometry between the thickness of the lingual marginal ridges and the crown width is one of the basic principles of the crown formation for the permanent maxillary centrals. Usually we have to work with absolute thickening of the lingual marginal ridges because relative thickening on the account of the crown thickness is less usual. The latter possibility is less favourable for the firmness of the dental crown.

Analysis of Variance↗

PubMed1993

Morphology of the most common form of protostylid on human lower molars.

Scanning electron microscopy of the enamel surface and enamel structure in the protostylid area classified as a surface irregularity was performed on 26 human lower third molars. This protostylid class can be regarded as the onset of a cusp formation, while the protostylid pits should be considered to be fissures between a protoconid and a poorly expressed protostylid.

Dental Enamel↗

PubMed1992

Histogenetic aspects of the composition and structure of human ectopic enamel, studied by scanning electron microscopy.

This study was made on 12 enamel projections and 12 enamel pearls on human permanent molars to compare their structure and composition, which might elucidate possible histogenetic differences between these two forms of ectopic enamel. The enamel projections contained approx. 2 (weight)% less Ca and P than control occlusal and mid-coronal enamel. Their mineralization was less homogeneous and probably defective. Their enamel structure was markedly irregular in the prismatic as well as the aprismatic layer, but the composition and structure were very similar to those of the control enamel close to cervical border. The enamel of the pearls largely corresponded in composition and structure to the control occlusal and mid-coronal enamel. The enamel of large pearls also resembled coronal enamel in its compositional and structural variability in the occlusal-cervical direction. These findings suggest that amelogenesis in enamel projections is a continuation of amelogenesis in the cervical region. In contrast, amelogenesis in enamel pearls follows the same pattern as that in a dental crown, from the occlusal region to the cervical enamel border. Therefore, the enamel pearl may well be regarded as an attempt at new tooth formation.

Amelogenesis↗

PubMed1992

Relationship between the lingual fossa depth, mesiodistal and bucolingual diameter of dental crown in permanent maxillary incisors with the living Slovenians.

On 311 dental stone casts of living children aged from 8 to 12 years, were measured the lingual fossa depth, MD diameter, and the BL diameter of the permanent maxillary incisors. The correlations and the differences of measured variables between left and right incisors, centrals and laterals, male and female incisors as well as the correlations between measured variables themselves were analysed. High left-right symmetry was established, except for directional asymmetry in female centrals. A significant positive correlation in terms of positive allometry between the lingual fossa depth and MD diameter was found. In the light of these results, the significance of the lingual fossa depth as a factor of strength is discussed.

Child↗

PubMed1989

[Dental and pulpal pain].

Sensory capacity of pulpo-dentinal complex depends on the site, different density and functional diversity of nerve fibers in the dental pulp. In the dentin and dental pulp only the pain is provoked regardless of the kind of irritant. But the pain can be expressed by several forms of appearance.

Dental Pulp↗

PubMed1986