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At least 1,621 records · Page 90Linked to original sources
PubMed1995

Lateral-access Class II restoration using resin-modified glass-ionomer or silver-cermet cement.

Direct-access preparation of a carious proximal surface is perhaps the most conservative approach to restoration. Physical properties and handling characteristics of silver amalgam and of resin composite and lack of fluoride ion release make these materials unsuitable for direct buccal- or lingual-access proximal restoration. Insufficient strengths and radiolucency of self-hardening glass-ionomer cements preclude their use for Class II restorations. However, glass-ionomer silver-cermet cement and some resin-modified glass-ionomer materials are proving useful for non-stress-bearing Class II restorations and may have applications in preventive dentistry. This article describes lateral-access Class II restoration with modified glass-ionomer cements. Emphasis is placed on careful handling of materials, maintenance of an ideal operative field, and conservation of tooth structure.

Cermet Cements↗
PubMed1995

Bonding of resin composites to resin-modified glass ionomers.

PURPOSE: To evaluate the bonding between resin composites and resin-modified glass ionomer restorative materials. MATERIALS AND METHODS: Bar-shaped specimens of Fuji II LC, Photac-Fil, and Vitremer were fabricated in a mold. After application of unfilled resin, resin composite (either Silux Plus or Restorative Z100) was condensed into the mold against the glass ionomer substrate and was light-cured. These bonded specimens, as well as intact specimens of each material, were placed on a three-point bending apparatus and were loaded until failure using a Zwick testing machine. The transverse strength of each specimen was calculated. RESULTS: Mean transverse strengths of bonded specimens ranged from 50% to 78% of the transverse strength of the intact glass ionomer materials. The lowest transverse strength was 18.1 MPa, for Photac-Fil/Z100, and the highest was 29.6 MPa, for Fuji II LC/Silux. Statistical analysis indicated that the type of composite used had no significant effect on transverse strength. However, the type of resin-modified glass ionomer used was significant. Although there was much overlap between materials, bonded specimens made with Fuji II LC had the highest absolute strength, and those made with Photac-Fil had the lowest absolute strength. Bonded Vitremer specimens had the highest transverse strength relative to the cohesive strength of the material.

Analysis of Variance↗
PubMed1995

[A study of leukocyte chemotaxis in a glass micropipette].

Chemotaxis, the directional locomotion of a cell toward a source of a chemical gradient, is an important phenomenon occurring for mobilizing immune cells at sites of infection and injury. This phenomenon has been simulated in analyzing the movement in vitro of a chemoattracted cell inside a glass micropipette. A microneedle filled with fMLP, N-formyl-methionyl-leucyl-phenylalanine, at a concentration of 9.10(-7) M in 1% gelatin, is inserted in a glass micropipette containing Hanks buffer solution. After diffusion of fMLP in the glass micropipette until a constant gradient is established, the tip of the glass micropipette is moved near a polymorphonuclear neutrophil. Its spontaneous movement inside the micropipette towards the chemotactic source can be observed and quantified. Without any counter-pressure (positive pressure), the cell spontaneously advances with an average velocity of 0.14 +/- 0.04 micron/s. Corresponding to the maximal strength developed by the cell during its motion, the required strength to stop the chemotactic migration has been estimated to be 39 +/- 4 nN. Giving both qualitative and quantitative information on the dynamics of cell motility, this experiment will be helpful in the understanding of some aspects of cell motility in the tissues.

Chemotaxis, Leukocyte↗
PubMed1994

In vivo evaluation of glass-ionomer cement adhesion to dentin.

Class V cavities were prepared in 20 vital teeth and 10 extracted teeth. For all the restorations, glass-ionomer cement was used as a liner at the base of the cavity. The cavity was then restored with a microfilled composite resin. After the extraction of the vital teeth, all specimens were sectioned and tested for marginal microinfiltration of 2% methylene blue dye. The teeth restored in vivo showed no signs of infiltration between the dentin and the glass-ionomer liner. The dye penetrated between the liner and the composite resin in five in vivo restorations. The in vitro restorations dye was present between the dentin and the liner. Examination of replicas under the scanning electron microscope revealed no gaps between the glass-ionomer cement and the dentin in the in vivo specimens, while gaps of various sizes were present in the in vitro replicas. Glass-ionomer cement was able to bond to dentin when used as a liner in vital teeth but not when used in extracted teeth. This can be attributed to the presence of a partially humid environment in vivo that favors the application process. In vitro, specimens are to a large extent dehydrated.

Composite Resins↗
PubMed1994

Marginal contraction gap formation of light-cured glass ionomers.

The capability of dental restorative materials to effectively seal the margins of tooth preparations is critical. The adhesive properties of the conventional chemically-cured glass ionomer cements have provided a potential for sealing cavity margins, but recently light-cured versions of the glass ionomer cements have been introduced. This study examined the adhesion to dentin of two new light-cured glass ionomer cement restorative materials, Fuji II LC and VariGlass VLC. Gap formation at the tooth/restoration interface in dentin cavities was recorded as a measure of the sealing ability of the materials. Cylindrical cavities were prepared in dentin of extracted teeth and randomly assigned to three equal groups. The control group of specimens was restored with a chemically-cured glass ionomer, Fuji Cap II, while the experimental groups were restored with one of the two light-cured materials. All specimens were subjected to thermocycling. The sealing of each material to dentin was evaluated by measuring the gap between the restoration and tooth structure. The control group registered mean gaps of 26 microns while the experimental groups registered mean gaps of 8 microns (Fuji II LC) and 10 microns (VariGlass VLC). The light-cured materials displayed substantially better adaptation to the cavity preparations than the conventional materials (P < 0.005), with no significant difference between the two experimental groups.

Acrylic Resins↗
PubMed1993

Glass-ionomer-resin restoration of primary molars with adjacent Class II carious lesions.

Glass-ionomer-resin cements carry the advantages of both traditional glass-ionomer cements (such as esthetics and fluoride ion leaching) and light-curing resins (such as adhesive bonding to tooth structure and rapid material hardening by visible light exposure). In addition, their physical properties are improved over those of self-hardening glass-ionomer cements. The glass-ionomer-resin cements can be used to restore primary teeth quickly and successfully. The technique for simultaneously restoring adjacent Class II lesions in primary teeth is presented.

Composite Resins↗
PubMed1994

The co-cured, light-activated glass-ionomer cement-composite resin restoration.

The simultaneous curing of unpolymerized composite resin and inactivated light-curing glass-ionomer cement appears to offer a number of clinical improvements to the laminated glass-ionomer cement-composite resin restoration. The observation that composite resin cures before the glass-ionomer cement suggests that the polymerization shrinkage of the resin may be taken up by the uncured glass-ionomer cement, reducing the internal stress of the restoration. A procedure is described for the placement of this type of laminate restoration that reduces both technique sensitivity and placement time, by eliminating a number of the steps required for a conventional "sandwich" restoration. The apparent clinical success of this technique indicates the need for laboratory testing to evaluate the potential of this procedure.

Composite Resins↗
PubMedDate not supplied

A restorative dentistry renaissance for children: light-hardened glass ionomer/resin cement.

The light-hardened glass ionomer/resin dental restorative material was introduced in 1992. Its formula includes 80 percent glass ionomer material combined with a 20 percent visible light polymerized resin component. The authors have completed over 1300 class I, class III, and class V restorations in primary teeth, using the new material. The new material is considered by the authors to be a great improvement over the self-hardening glass ionomers. The addition of the 20 percent light-hardened resin component to the glass ionomer formula gives the material an initial setting time under sixty seconds, and improves resistance to wear and fracture.

Child↗
PubMedDate not supplied

Total quality in tubing glass manufacturing.

Today's demand for higher quality products can be satisfied through a comprehensive quality assurance system (Total Quality System, "Worldwide Quality Standard") using the latest state of the art measuring technologies. Totally automated state of the art glass vial manufacturing begins once the glass tubes are loaded into the machine and ends with the finished product in the packaging machine, all without human contact. This standard is achieved by measuring dimensions with SPC (statistical process control) and 100% inspection of the products. These systems complement each other and give the machine operator instant data in an overview format. To achieve the visual requirements forma vitrum developed the FVC90 control line. This optical surface inspection device controls online and without contact 100% of the products for cosmetic defects as small as 50 microns. It can detect and eject defects such as dirt, scratches, chips, air-lines, loose glass particles, cracks, etc. The sensitivity of the system can be adjusted and is fixed based on client needs. An important quality assurance technique is the checking of dimensions at the production machine with a Vision System. With this system deviations are instantly recognized and corrections can be made immediately, thus assuring that glass products can be run on the high-speed filling machines for which they are designed. These computer assisted inspection systems are key in producing the highest quality pharmaceutical glassware in the 90's.

Computer-Aided Design↗
PubMed1994

Assessment of glass polyalkenoate restorations in primary molar teeth.

This study assess the suitability of glass polyalkenoate cement as a restorative material in primary molars, when placed by community dental officers in their own clinics. Nine officers placed the restorations and two assessors examined the restorations after one and three years, recording details of the success or failure of each restoration. A total of 635 glass polyalkenoate restorations were placed and, after one year, 149 (23.4%) of these had failed. Of the 359 available for examination after three years, a further 142 (22.4%) had failed, leaving 217 (42.7%) intact. This study shows that the major factor in the successful use of glass polyalkenoate cements as a restorative material in deciduous molars is the classification type of cavity. A significant number of Class II restorations failed within the first year. The study confirms that glass polyalkenoate cements provide a satisfactory means of restoring Class I cavities in primary teeth.

Chi-Square Distribution↗
PubMedDate not supplied

In vitro comparative fluoride release, and weight and volume change in light-curing and self-curing glass ionomer materials.

The purpose of this study was to evaluate and compare in vitro fluoride release from and weight and volume changes of Photac-Fil, a light-curing polymaleinate restorative glass ionomer, with Ketac-Fil, a self-curing glass ionomer, and Ketac-Silver, a metal reinforced glass ionomer. Five discs of each material, measuring 2 mm height and 5 mm diameter, were suspended in separate vials of distilled water and laboratory artificial saliva. Fluoride release into the solutions was measured using a calibrated fluoride-sensitive ion meter initially at 24 hr and then weekly from 1 to 9 weeks. These results were evaluated statistically using repeated measures analysis of variance. Volumes and weights were recorded at the start and end of the experiment and analyzed using the paired t-test. Photac-Fil released similar amounts of fluoride to Ketac-Silver, but significantly less than Ketac-Fil in distilled water (P < or = 0.05). In artificial saliva, Photac-Fil released similar amounts to Ketac-Fil, but significantly more than Ketac-Silver (P < or = 0.05). Photac-Fil volume increased in distilled water and artificial saliva (P < or = 0.05) as did Ketac-Fil and Ketac-Silver in artificial saliva (P < or = 0.05). The only material that demonstrated significant net weight increase was Ketac-Silver in artificial saliva (P < or = 0.05). In summary, differences in fluoride release between these three glass ionomer materials varied as a function of the media in which they were stored. Whereas Ketac-Fil exhibited significantly greater fluoride release than the other materials in distilled water, in artificial saliva Ketac-Fil and Photac-Fil exhibited comparable fluoride release. Dimensional change, as evaluated by volume and weight differences, was also affected by storage media.

Analysis of Variance↗
PubMedDate not supplied

Adsorption of recombinant human granulocyte colony stimulating factor (rhG-CSF) to polyvinyl chloride, polypropylene, and glass: effect of solvent additives.

The adsorption of recombinant-derived proteins to glass and polymeric materials used in their packaging and delivery remains a problem. Loss of these very expensive proteins to surface adsorption not only results in reduced yields during purification and scale-up, but also to decreased therapeutic efficacy. The purpose of the present investigation was to inhibit/minimize adsorption of a model protein, namely, recombinant human granulocyte colony stimulating factor (rhG-CSF) to glass, polyvinyl chloride (PVC), and polypropylene by inclusion of select solvent additives. Solvent additives used to inhibit/minimize surface adsorption included glycerin, U.S.P. (0.5%, 1%, 5%, and 25% v/v), Pluronic F-127 (0.005%, 0.05%, and 0.5% w/w), Pluronic F-68 (0.005%, 0.05%, and 0.5% w/w), Tween 80 (0.005% and 0.05% w/w) and Tween 20 (0.005%, 0.05%, and 0.5% w/w). Over the rhG-CSF concentration range of 0.0 ng/ml to 300 ng/ml, the amount of rhG-CSF bound per cm2 of PVC increased with an increase in the rhG-CSF concentration tested. At rhG-CSF equilibrium concentrations of 262 +/- 3.7 ng/ml and 136 +/- 1.9 ng/ml, the rhG-CSF bound/cm2 of PVC at 22 degrees C and 45 degrees C reached a maximum of 37.6 +/- 9.8 ng/cm2 and 165.2 +/- 11.7 ng/cm2, respectively. The adsorption isotherms determined at each temperature were described by the classic Freundlich equation. Moreover, the rate of adsorption of rhG-CSF to PVC was extremely rapid. The mean values of the percent of rhG-CSF bound to PVC after only 10 minutes of equilibration at 22 degrees C and 45 degrees C were 92.8 +/- 9.2 percent and 97.3 +/- 17.9 percent, respectively. The mean values of the percent of rhG-CSF bound to PVC at 22 degrees C and 45 degrees C after 24 hours were 52.4 +/- 10.9% and 70.0 +/- 9.7%, respectively, indicating that some desorption of rhG-CSF does occur during 24 hr. However, surface adsorption of rhG-CSF to PVC was shown to be irreversible over a 1 hr time period. Using viscometry, an estimate of the thickness of the adsorbed layer of rhG-CSF to glass was determined to be approximately 1 micron. The overall rank order of the solvent additives for minimizing adsorption of rhG-CSF to PVC was Tween 20 > Tween 80 > Pluronic F-127 > Pluronic F-68. Tween 20 was the most effective solvent additive for inhibiting surface adsorption of rhG-CSF to parenteral vials made of either glass or polypropylene.

Adsorption↗
PubMedDate not supplied

Bond strength of light-cured glass ionomers to carious primary dentin.

The pre-cooperative or handicapped child with decay presents a special challenge to the practitioner and may require sedation or general anesthesia. Treatment with an interim restoration may delay treatment until the child is more mature and can accept dental treatment and is a more conservative approach than sedation, extractions or general anesthesia. Glass ionomer materials have been utilized for this application, but little is known about their retention to carious dentin. The purpose of this study was to determine whether the presence of artificial dentin decay will affect the shear bond strength of two light-cured glass ionomer materials. VariGlass and Vitrebond glass ionomer materials were attached to carious and non-carious primary dentin surfaces and bond strengths determined. There were no significant differences in shear bond strengths between the decayed and non-decayed surfaces [p < or = .001]. VariGlass had higher shear bond strengths than Vitrebond only after a pre-treatment with the PAA containing liquid. Pre-treatment with the liquid provided with each light-cured glass ionomer was beneficial in all instances except for Vitrebond on non-decayed surfaces.

Acid Etching, Dental↗
PubMed1997

Bioactive glass particles of narrow size range for the treatment of oral bone defects: a 1-24 month experiment with several materials and particle sizes and size ranges.

The aim of this study was to evaluate bone growth around bioactive glass particles in bone defects in comparison to hydroxylapatite particles. The bioactive glass particles were implanted in the partial edentulous jaws of Beagle dogs in two different compositions and several sizes and size ranges. After 1, 2, 3, 6, 12 and 24 months the samples were harvested and processed for undecalcified sectioning. Histological analysis showed a superior response of the bioactive glass particles of composition A and narrow size range (300-355 microns). Besides extensive osteoconductive properties, the bone repair was also stimulated by bone growth in the internally eroded particles. The data demonstrate conclusively that the well known corrosion reactions of the bioactive glass lead to the formation of protective pouches. In these protective pouches formation of new bone is detected without this bone being connected to the bone tissue outside the particles. These islands of newly formed bone tissue function as nuclei for further bone growth and enhance the repair of the defect.

Animals↗
PubMed1996

Class II composite resin restorations using glass-ionomer liners: microleakage studies.

Microleakage studies were undertaken for Class II composite resin restorations that had been lined with glass-ionomer cement using the 'sandwich' technique. Thirty freshly extracted permanent molars and premolars were mounted in polymethylmethacrylate blocks. Class II cavities were prepared using carbide burs No. 245 in a water cooled dental handpiece, (cavity box 5 x 3 x 2 mm). Specimens were divided into three groups of 10 each. Group A was restored with hybrid composite resin only, Group B with hybrid composite using a light-cured glass-ionomer liner applied to dentin only, and Group C with hybrid composite using light-cured glass-ionomer liner carried out to the cavosurface margin, (beyond the DEJ). All the specimens were thermocycled between 5 degrees C and 55 degrees C for 250 cycles for 3 hours, followed by placement in 0.5% aqueous basic fuchsin dye for 24 hours at 37 degrees C. Specimens were sectioned mesio-distally through the restorations using an Isomet apparatus. The extent of dye penetration was scored under a stereomicroscope with reference to the DEJ, (0 = no penetration, 1 = penetration to the enamel, 2 = penetration beyond the DEJ). Statistical analysis of the data showed significant differences among the means of the groups at p < 0.001. The results of this study indicate that the application of a light-cured glass-ionomer up to the cavosurface margin inhibits the microleakage of Class II restorations in vitro.

Bicuspid↗
PubMedDate not supplied

Initial tensile bond strength of resin-modified glass ionomers and polyacid-modified resins on perfused primary dentin.

The objective of this study was to evaluate the initial tensile bond strength of a resin-modified glass ionomer (Photac-Fil) and two polyacid-modified composite resins (Compoglass, Dyract) to primary dentin. A hybrid composite resin (Tetric) and two chemical cured glass ionomers (BaseLine, Hi-Dense) served as controls. Ninety caries-free dentinal discs were ground flat and perfused with Ringer's solution. Dentinal surfaces were conditioned (except for Base Line). From each material, fifteen standardized specimens were attached to the dentin. Light-curing of the respective materials followed (1 min), and adhesion was tested with a universal testing machine 15 min after application. The highest initial bond strength was observed with Tetric (5.17 MPa). Closed test procedure (Kruskal-Wallis) showed significant differences between all materials (P < 0.05), except for Compoglass (1.82 MPa) vs. Dyract (2.35 MPa), and BaseLine (0.37 MPa) vs. Photac-Fil (0.42 MPa). The condensable glass ionomer Hi-Dense revealed a mean tensile bond strength of 0.79 MPa. Adhesion of (polyacid-modified) composite resins is superior to the other tested glass ionomer materials, when applied to perfused primary dentin.

Child↗
PubMed1997

Cariostatic effect of glass ionomer retained orthodontic appliances. An in vivo study.

The cariostatic effect of a fluoride releasing bonding agent was investigated and compared with a conventional composite based material in connection with bonding of orthodontic brackets in 22 homologous pairs of premolars. All subjects had malocclusions requiring orthodontic treatment with fixed appliances and extraction of at least two premolars. 6-13 weeks prior to extraction, orthodontic brackets were bonded to the labial surfaces of the extraction teeth with either a glass ionomer cement or a bis-GMA resin. Initially, the children were instructed in tooth brushing and the regular use of fluoride. After extraction, the bonded teeth were stained and evaluated in a stereo-microscope regarding the incidence and extension of initial enamel demineralisation. The zone of intact enamel adjacent to the bracket base and bonding material was measured in a stereo-microscope at four predetermined locations with the aid of an electronic ruler and scored according to four categories. The incidence of enamel demineralisation adjacent to glass ionomer bonded and composite bonded brackets was 68% and 77% respectively. In 12 pairs of premolars however, the demineralisation appeared to a lesser extent on the enamel around the brackets was generally wider when glass ionomer cement was used compared to the composite resin. These differences were statistically significant (p < 0.05) mesially and distally, but non-significant cervically and incisally. The results indicate that bonding with glass ionomer cement may have a local cariostatic effect in children requiring fixed orthodontic appliances.

Adolescent↗
PubMed1997

In vitro evaluation of sealing pits and fissures with newer glass-ionomer cements developed for the ART technique.

Four conventional glass-ionomer cements specifically developed for use with the atraumatic restorative treatment (ART) technique were compared with a resin-based sealant for marginal and surface dye penetration, material voids, and completeness of enamel fissure penetration. Thirty sound permanent mandibular molar teeth were randomly divided into five groups. After delayed placement of the glass-ionomer cement sealants using standardized finger pressure, and conventional placement of the resin-based sealant using a dental probe, the teeth were first thermocycled then the crowns immersed in methylene blue dye before being sectioned. There were no statistically significant differences found between any of the five materials, apart from less marginal dye leakage being present for the resin-based sealant than for one of the glass-ionomer cements. The cements, however, showed better fissure penetration than did the sealant. Despite the delayed placement and higher viscosity, all of the glass-ionomer cements showed satisfactory penetration of the enamel fissures and minimal marginal and surface dye penetration, and material voids, when placed using firm finger pressure. The cements could prove to be useful in the dental treatment of apprehensive children.

Analysis of Variance↗