Biomedical subjects

T Pioch

Publications and source records attributed to T Pioch.

33 records · Page 2Linked to original sources

PubMed1996

A method to monitor dental demineralisation in vitro.

This paper presents an in vitro method for monitoring the progression of dental hard tissue demineralisation using consecutive, standardised radiographs. Reliability and factors affecting the reproducibility of this method were established by replicate measurements and comparison to histological evaluation. Whereas assessment of the extent of the lesions by measuring linear distances was highly reproducible, reproducibility of measurements of the central depth of a lesion is affected by the superficial extension and the surrounding hard tissue. Radiographic imaging underestimates the extent of demineralisation as compared to histological analysis.

Disease Progression↗

PubMed1996

Experimental investigation of the shear strengths of teeth in the region of the dentinoenamel junction.

The shear strengths of human incisors, canines, premolars, and molars and bovine incisors in the region of the dentinoenamel junction were tested. The median shear strength of all human teeth, 38.99 MPa, was not significantly different from that of bovine teeth, 37.40 MPa. Among the groups of human teeth, the highest median shear strength was obtained from mandibular premolars (46.15 MPa), and the lowest from mandibular canines (32.63 MPa). Physical treatments (cooling or drying) led to a significant reduction in shear strengths. A similar effect was found after exposure to amino butyrate (a caries-removing agent) but not after exposure to sodium hypochlorite (used in endodontic treatment). In all investigated groups of teeth, the fracture areas were mainly in dentin and never exactly at the dentinoenamel junction; indicating that the cohesion of dentin, not the adhesion between dentin and enamel, is the limiting factor in the shear strength.

Aminobutyrates↗

PubMed1993

[A comparison of 3 laser systems for dental enamel ablation].

Three different laser systems were compared according to their applicability in dentistry: a Ho:YAG laser (lambda = 2, 12 microns, pulse duration = 250 microseconds and 4 microseconds, pulse energy up to 300 mJ), an Er:YAG laser (lambda = 2,94 microns, pulse duration = 60-100 microseconds, pulse energy up to 100 mJ) and an in dentistry so far unknown picosecond Nd:YLF laser (lambda = 1,053 microns, pulse duration = 30 ps, pulse energy up to 1 mJ). The morphological changes of the enamel due to laser radiation were studied using light and scanning electron microscopy. Possible enamel fractures were visualized with dye penetration tests. Thermally caused, about 3 mm long enamel fractures were only observed using the Ho:YAG laser. Smaller fractures, up to 300 microns, were generated with the Ho:YAG and the Er:YAG laser. The Nd:YLF laser produced well defined square cavities with a high precision. No enamel fractures could be observed. The dye penetration in the cavity walls was less than 20 microns.

Dental Cavity Preparation↗

PubMed1992

An experimental study of the stability of irradiated teeth in the region of the dentinoenamel junction.

In this in vitro study we investigated the influence of ionizing gamma rays on the stability in the region of the dentinoenamel junction. We removed the enamel on the labial surface of 30 incisors of bovines up to the dentinoenamel junction, so that a circular area of enamel with a diameter of 2.0 +/- 0.1 mm was left and an enamel cylinder was created. 15 teeth were irradiated by a cobalt-60-source (energy dose 70 Gy). The other 15 teeth were used as controls. Using a material testing apparatus the shear bond strengths were measured by breaking off the enamel cylinders. Furthermore, the breaking modes were investigated in SEM. Comparing the results of the shear bond strength experiments, it was obvious that the stability in the region of the dentinoenamel junction was significantly less among the irradiated teeth than among the non-irradiated teeth. The median value of the gamma ray treated teeth was x = 19.1 MPa and that of the non-ray-treated teeth was x = 37.4 MPa. The non-irradiated teeth showed fractured surfaces only in dentin in 10 cases and in 5 cases in both dentin and enamel. In contrast to that, the irradiated teeth had fractured surfaces in 12 cases exclusively in dentin and only in 3 cases the enamel was also fractured. These results lead us to conclude that changes of biophysical property of teeth can be caused by the influence of ionizing rays.

Animals↗

PubMed1991

[Solubility of enamel and synthetic hydroxylapatite on irradiation].

The effect of Co 60-irradiation (70 Gy) on pulverized human enamel and synthetic hydroxyapatite was studied in vitro. Irradiated and non-irradiated samples were experimentally demineralized (pH 5.1) during a period of 28 days. In terms of solubility, defined as the equilibrium of saturation, there was no statistically significant difference between irradiated and non-irradiated enamel. However, in terms of solubility rates, defined as the amount of dissolved substance during the demineralization period, irradiated enamel showed a statistically significantly higher solubility rate than non-irradiated enamel. There was no effect of Co 60-irradiation on synthetic hydroxyapatite.

Dental Enamel Solubility↗

PubMed1991

[Study of properties of electrical root canal length measuring instruments].

Six electrical instruments for locating the apex during endodontic treatment were tested in a laboratory investigation about currency, frequency and scale. Further we looked, whether all instruments show coincidence in the apex point. There are great differences in currency, frequency and scale (apex point). The reproducibility and the precision of an apex locator--at the time--depends an many factors and thus indication seems to be very limited.

Dental Pulp Cavity↗

PubMed1989

The alkalizing properties of calcium hydroxide compounds.

Calcium hydroxide compounds are available in various forms, such as in aqueous suspensions or as cements, liners, pastes or filled resins. When such compounds are exposed to water, the calcium hydroxide dissociates and the pH value shifts to the basic. In this study the compounds Pulpdent, Dycal, Hydroxyline, Gangraena Merz and Prisma VLC-Dycal were subjected to analysis, including quantitative measurement of the amount and the chronological course of ion release following exposure to water, qualitative analysis of the alkalizing effects at the dentin surface and examination of antimicrobial properties. The results showed that calcium hydroxide compounds differed greatly. The strongest degree of ion release, combined with definite antimicrobial properties, was found for the aqueous calcium hydroxide suspension (Pulpdent). The cement (Dycal) demonstrated significantly weaker activity. The liner and the paste (Hydroxyline and Gangraena Merz), as well as the calcium hydroxide filled resin (Prisma VLC-Dycal), were largely lacking in both ion release and antimicrobial properties under the experimental conditions.

Calcium Hydroxide↗

PubMed1989

[Antimicrobial efficacy and alkalizing effect of different calcium hydroxide compounds].

This publication compares the alkalizing effect of various calciumhydroxide compounds and their antimicrobial efficacy. In these experiments aqueous calciumhydroxide suspensions demonstrate the comparably highest alkalization combined with a profound longacting antimicrobial action. At relatively minor alkalization the examined calciumhydroxide cement caused a less profound, but also consistent inhibition of bacterial growth. Samples of calciumhydroxide-containing liners, fillers, and synthetic compounds, although showing a marked alkaline reaction themselves, did, however, not or almost not cause an alkalization of the environment or an inhibition of bacterial growth.

Bacteria↗

PubMed1989

[Bonding of glass-ionomer cements to tooth hard tissues under various experimental conditions].

In this study the enamel- and dentin-bonding properties of two glass-ionomer cements (ChemFil-II and Ketac-Bond) were evaluated under various test conditions in vitro. The tests showed the following results: 1. ChemFil-II exhibits a significantly stronger bond to the hard tooth substances than Ketac-Bond in the short term test (the samples were stored 2 days in synthetic saliva). The stability of the bond made with ChemFil-II, however, proves in the long term test (the samples were stored 150 days in synthetic saliva) to be less than that made with Ketac-Bond. 2. Acid-conditioning of the enamel does not statistically effect a change in the stability of the bond to any significant degree. Corresponding conditioning of the dentin, on the other hand, causes a definite reduction of the bond to be obtained. 3. Deviations from the powder-liquid mixing ratio recommended by the manufacturer result in a statistically significant reduction in the bond stability, whether these involve an increase in the amount of powder or rather a decrease.

Aluminum Silicates↗

PubMed1988