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Biomedical subjects

M Breier

Publications and source records attributed to M Breier.

12 recordsLinked to original sources
PubMed1999

Bond strength of a fluoride-releasing bracket adhesive. Experimental study.

The aim of the study was to examine a new fluoride-releasing light-cured filling composite for its bonding and debonding qualities when used as a bracket adhesive. The material investigated was a hybrid composite containing a chemically modified fluoride apatite, which is claimed to provide the enamel with phosphate, calcium, and fluoride ions in the presence of an acid pH, recharging its resources of these ions through fluoride-containing toothpastes used in daily oral hygiene. Concurrently suitability as an enamel conditioner was tested in a new self-etching primer, which does not require water rinsing but is gently air dried instead. For comparison a conventional light-cure single-component adhesive was used together with 37% orthophosphoric acid. After application of the respective conditioners, mesh-backed metal brackets were bonded to 20 human premolars in each of the 2 adhesive groups and subjected to a shear test. Bond failure location was evaluated using the Adhesive Remnant Index (ARI). Average bond strength of the experimental bracket adhesive and the conventional etchant was 8.96 MPa. Conditioning with the self-etching primer led to a decrease of mean shear bond strength values to 6.55 MPa. Highest bond strength was determined in the control group (12.19 MPa). The bond strength results obtained in the shear test recommend the new material as a bracket adhesive to be used with orthophosphoric acid for etching.

Analysis of Variance↗
PubMed1995

[The effect of molar position on the distalization behavior of indirect headgear].

The asymmetric indirect headgear is a frequently used method to achieve an unilateral distalization of a molar. Cases have been observed, however, in which the distalization does not proceed in the way or to the degree predicated by the geometry of the outer bow. Among other factors, this discrepancy can be attributed to the geometry of the inner bow. This study demonstrates quantitatively and qualitatively the influence unilateral mesial movement and/or molar rotation exerts on the force system of the indirect headgear. The study makes evident that a neutralization of the molar's sagittal asymmetrical position by means of adjusting the length of the inner bow cannot be omitted. The study recommends the use of special headgear tubes extended in an oro-vestibular direction to eliminate the asymmetrical dynamics which arise in cause of the mesial rotation of a molar.

Biomechanical Phenomena↗
PubMed1995

[Cervical headgear with angled outer arms. A biomechanically comprehensible system?].

When applying the angulated face bow, it doesn't seem possible to avoid vertical and transversal forces which occur in addition to the distalization force as moments. By varying the length and angulation of the outer bow, it is possible to influence the force components and the moments in the sagittal plane. In the clinical analysis of the force system it is assumed that the face bow is an ideal rigid system. Only under this presupposition is the assumption valid, that the product of the force and the perpendicular distance to the molar tube is responsible for the size of the moment. Under this assumption, however, all forces and moments created by the deflection of the headgear are not taken into consideration. An experimental analysis of the forces and turning moments which occur indicates that this simplifying geometric point of view does not always correspond to reality. It was evident, e.g., that there is no linear correlation between the force and moment in mesio-distal direction due to the deflection of the outer bow. This effect becomes the more obvious the longer the outer bow of the headgear is.

Biomechanical Phenomena↗
PubMed1993

[The lateral and transverse forces with indirect headgear and its modifications].

The use of the various variants of indirect headgear engenders transversal and lateral forces as an inevitable side effect. Direct clinical assessment of these forces, however, is not possible. To deal with this problem the study presented here employed 3D force sensors to measure in vitro the sagittal and transversal forces generated by diverse headgear modification. The results show that the transversal and lateral forces reach magnitudes which have direct clinical relevance. A common symmetrical indirect headgear, for instance, generates an expansive force that amounts to 20% of the distal. Transversal forces generated by expansion and compression headgear rapidly exceed therapeutically desirable magnitudes. All asymmetric headgear included in the study produced lateral forces which may lead to unwanted scissor or cross bites. The study presents a method whereby these inevitable lateral forces engendered by asymmetric headgear can potentially be minimized.

Biomechanical Phenomena↗
PubMed1991

[Oral health condition of kindergartners in Budapest].

A survey on caries prevalence and dental care was conducted on 441 children 3-6 years old, from 9 kindergartens in Budapest. Only 36.3% of the examined children showed naturally healthy teeth. The four examined age groups demonstrated an increase in caries incidence from 45.4% at the age of 3 y to 83.6% at the age of 6 y. The average dmf-s for the four age groups (3, 4, 5, 6 y) was: 1.77, 3.97, 5.76, 6.77, respectively. Maximal caries-assault has been recorded at the age of 4. Only 11.5% of the detected carious surfaces were restored. Moreover, 30% of these treated surfaces showed signs of recurrent caries. In general out of 280 children with caries defects only 5 received a complete restoration.

Child↗
PubMedDate not supplied

Cellular immunomodulation and safety of standardized aqueous mistletoe extract PS76A2 in tumor patients treated for 48 weeks.

Non-selected tumor patients (n=12) with various solid carcinomas were treated continuously twice weekly over 48 weeks with the aqueous mistletoe extract PS76A2, standardized to active mistletoe lectin. The preparation was applied subcutaneously at a concentration of 15 ng mistletoe lectin per 0.5 ml. Cellular immune response and safety were determined at various times during and after the therapy. In the course of treatment, virtually all the investigated immunoparameters were raised compared to the baseline values at the start of treatment. The statistically significant rises in the cell count of total lymphocytes, monocytes and natural killer (NK) cells was noteworthy. The differences in comparison with the baseline values at the various measuring times during treatment were up to 35%. In the first weeks of treatment at least, the raised cell count of NK cells correlated with the significantly increased cytotoxic activity versus tumor cells ex vivo. The NK factor (product of NK cells and ex vivo activity) was determined to assess the total NK activity more accurately, which rose up to 50% compared to the baseline value. Other lymphatic subpopulations, for instance CD3+, CD8+, CD3+CD4+ and CD3+CD8+ cells, also revealed distinct rises in cell count in the course of treatment. Within 6 weeks after completion of treatment, the overall values dropped again; but for a series of immunoparameters--in particular for the NK cells--they were still raised in comparison to the baseline values. The extensive laboratory diagnostics (haematology, clinical chemistry) showed that treatment with the standardized mistletoe extract PS76A2 was well tolerated by all patients. In single cases, local reactions at the injection sites were of a minor nature and reversible within two days. Summarizing, it can be stated that the standardized mistletoe extract PS76A2 significantly improved the immune status of tumor patients and was administered safely over a long period.

Adjuvants, Immunologic↗