Biomedical subjects

Z Tarle

Publications and source records attributed to Z Tarle.

9 recordsLinked to original sources

PubMed2002

Composite conversion and temperature rise using a conventional, plasma arc, and an experimental blue LED curing unit.

The objective of this study was to evaluate the degree of conversion and temperature rise in three different composite materials when illuminated by an experimental light source [blue superbright light emitting diodes (LEDs)] and compared with plasma light and traditional photopolymerization unit. The degree of conversion and temperature rise were measured using Fourier transform infrared (FTIR) spectroscopy and digital multimeter, respectively. The results revealed significantly higher degree of conversion values in case of conventional curing than with other two light sources whereas temperature rise was significantly lower when blue LEDs and plasma light were used. There were great differences in light intensities between blue LEDs of only 9 mW cm-2 compared with plasma light of 1370 mW cm-2 and Elipar II of 560 mW cm-2. Better match of LED spectral distribution peak to camphorquinone absorption distribution peak probably explains much lower intensities used for similar photopolymerization effect like in the case of rapid plasma lamp curing.

Absorption↗

PubMed2002

Photopolymerization of composite resins with plasma light.

Everyday improvements in components and characteristics of composite materials have induced faster development of curing units. Besides standard halogen curing units and soft-start photopolymerization light sources, some experiments with argon and pulsed laser light and low intensity blue superbright light emitting diodes have been made. On the other hand, rapid polymerization with strong plasma light is also clinically applicable. The aim of this study was to measure the degree of conversion and temperature rise for three restorative composite materials: Tetric Ceram (Vivadent, Schaan, Liechtenstein), Pertac II (ESPE, Seefeld, Germany) and Z100 (3M Dental Products, St Paul, MN, USA) during polymerization with plasma light Apollo 95E (DMDS, Dental/Medical Diagnostic Systems, Fleury d'Aude, France) and compare it with the results of polymerization with a halogen curing unit, Elipar Trilight (ESPE, Seefeld, Germany). The results revealed the degree of conversion values in the case of polymerization with plasma light to be almost equal to those obtained by curing with the halogen curing unit, whereas the temperature rise was almost negligible.

Analysis of Variance↗

PubMed2002

Double tooth.

The form of primary and permanent teeth can differ morphologically from that which is considered normal, completely or in some parts. The changes in tooth form can be hereditary or caused by some disease or trauma. Fusion is a union of one or more teeth during development. Gemination means that two separate morphological units were created by division of the tooth germ. The intention of this study was to state the prevalence of double teeth (fusion and gemination) among the persons tested, as to gender, distribution in the maxilla or mandible, and whether the anomaly occurred bilaterally or unilaterally. The results of this investigation have shown that in a total of examined 3,517 plaster models, a prevalence of double teeth was 0.2%. 57.2% of them were fusioned and 42.9% geminated.

Female↗

PubMed2001

Degree of conversion and temperature rise during polymerization of composite resin samples with blue diodes.

To ensure an adequate clinical composite filling light source for photopolymerization is of great importance. In everyday clinical conditions commonly used unit for polymerization of composite material is halogen curing unit. The development of new blue superbright light emitting diodes (LED) of 470 nm wavelengths comes as an alternative to standard halogen curing unit of 450-470 nm wavelengths. The purpose of this study was to compare the degree of conversion (DC) and temperature rise of four hybrid composite materials: Tetric Ceram, Pertac II, Valux Plus and Degufill Mineral during 40 s illumination with standard halogen curing unit Heliolux GTE of 600 mW cm(-2) intensity, Elipar Highlight soft-start curing unit of 100 mW cm(-2) (10 s) and 700 mW cm(-2) (30 s) intensity and 16 blue superbright LED of minimal intensity of 12 mW cm(-2) on the surface and 1 mm depth. The results revealed only a little bit higher DC values in case of polymerization with even 66 times stronger halogen curing units which showed twice higher temperature than blue diodes. Temperature and DC obtained are higher on the surface than on 1 mm depth regardless on the light source used.

Analysis of Variance↗

PubMed2001

The efficiency of dentine adhesives in treating non-caries cervical lesions.

The aim of this study was to prove the hypothesis that dentine adhesives can be used as therapeutic material in treating dentine hypersensitivity, regardless of aetiology. The research was conducted on 492 students of Zagreb University School of Dental Medicine (154 male, 338 female), 20-25-years-old. The defects of the tooth neck were found in 38 patients, on 133 teeth (38 of male patients, 95 of female) and dentine hypersensitivity was recorded according to the subjective sensations of patients. Therapeutic characteristics of three adhesive materials were examined simultaneously: All Bond 2, fourth generation adhesive, Syntac Single Component and One Step, fifth generation adhesives. Teeth treated with dentine lacquer Cervitec were used as a control group. Tooth necks were treated with selected materials according to instructions of a manufacturer. A completed statistical survey of the results has clearly shown that dentine adhesives can be used in symptomatic therapy of dentine hypersensitivity of the non-caries cervical lesions (NCCL). The survey has also shown that dentine adhesives of the fifth generation (Syntac Single Component and One Step) have much higher efficiency rate than dentine adhesives of the fourth generation (All Bond 2) and dentine lacquer (Cervitec). According to data complied through this study the conclusion can be brought forward that dentine adhesives are not a final solution to the problem of dentine hypersensitivity, because their efficiency decreases with time.

Adult↗

PubMed1998

The effect of the photopolymerization method on the quality of composite resin samples.

An optimal degree of conversion and minimal polymerization shrinkage are generally antagonistic goals, as increased monomer conversion invariably leads to elevated polymerization shrinkage values. However, both parameters are indispensable for an optimal resin composite restoration. A number of approaches have been used to reduce the stress on the restoration cavity wall interface, such as dentine bonding agents to counteract polymerization shrinkage, stress-absorbing lining materials and low-intensity curing lights to control the flow capacity of the material during polymerization. However, the configuration of the cavity and cohesive fractures of the material and surrounding tooth tissues are still a problem in day-to-day clinical practice. A new photopolymerization light source, pulsed laser, ensures a higher degree of conversion and lower polymerization shrinkage, and differentiates this technique from standard polymerization methods and continuous-wave argon laser polymerization. The coherence and monochromacity of pulsed laser light set at 468 nm and the far greater intensity of laser nanopulses produce a saturation effect in the depths of the composite, thus resulting in higher monomer conversion. The total amount of energy illuminating the sample surface, which is only one-fifth of that of conventional methods, and the cooling and relaxation of the material between nanopulses may be responsible for the reduced net polymerization shrinkage.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1998

"C"-shaped canal configuration of mandibular second permanent molar.

Roots of the second mandibular molar often fuse so the purpose of this investigation was to examine the appearance of "C"-shaped root canals and to classify different root canal types. A hundred and twelve randomly chosen second lower permanent molars-after extraction due to periodontal disease-were prepared and then analysed. Contrast liquid (methylene blue) was injected into prepared teeth. Each tooth was cut into slices to view the root canal morphology. Results of the analysis revealed fusion, either total or partial in 14 cases (12.5%). As a conclusion various appearances were classified into 5 types according to the fused canal shapes and the frequency of different types varied from 0.89%-6.25%.

Dental Pulp Cavity↗

PubMed1997

Pulsed blue laser curing of hybrid composite resins.

Clinical performance of light-curing composite restorations is greatly influenced by the quality of the curing-light. Currently used photopolymerization units have some important drawbacks, such as decreasing light output with time and distance, which results in a relatively low degree of conversion and shallow depth of cure, particularly of darker shades. Experiments with continuous argon laser polymerization showed overheating of the composite sample, as well as increased shrinkage of the material. In this study a pulsed laser, set at 468 nm (the maximum of the camphorquinone absorption coefficient), with 20-ns pulse duration, repetition rate of 10 Hz and energy of 10 mJ per pulse, was used as a light source. The aim of the study was to evaluate the effect of polymerization of light and dark shades of three different hybrid composites cured by pulsed laser at the surface and at 3.0 mm depth. The degree of conversion was measured by Fourier transform infrared spectroscopy (FTIR). Applying pulsed blue laser, significantly better results were obtained for both shades compared to standard polymerization values. Very weak dependence of the degree of conversion, between the surface measurements and those at 3.0 mm, were observed in the case of pulsed laser polymerization due to the piercing nanopulses and the monochromatic light at 468 nm.

Dental Cements↗

PubMed1995

Polymerization of composites using pulsed laser.

The quality of visible-light-cured composites depends on the capability of the light source to properly polymerize the material within a specified exposure time. In this study, the degree of conversion of different composite materials (hybrid and microfilled) of light and dark shades was compared after illumination by a standard curing unit and pulsed laser (lambda=468) respectively. The degree of conversion was measured by Fourier transform infrared spectroscopy. Results obtained by the analysis of the pulsed laser-induced polymerization were significantly higher for all the materials and shades observed. All values of the degree of conversion were lower for dark shades of all types of composites, regardless of the photopolymerization technique used. Besides the surface, better polymerization was recorded also at depths of 1.0, 2.0 and 3.0 mm, respectively. These values varied from 59.7%+/-2.14 to 84.5%+/-0.33 for pulsed laser (including all depths) caused by the saturation effect induced by high power laser pulses and from 42.7%+/-1.48 to 74.7%+/-0.99 for standard polymerization.

Acrylic Resins↗