Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “GLASSES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,477 records · Page 82Linked to original sources
PubMed2006

Biocompatibility of glass-ionomer cements using mouse lymphoma cells in vitro.

Glass-ionomer cements are widely used in dentistry as restorative materials and adhesives for composite restorations. A number of genotoxicity studies have been conducted using these materials with results conflicting so far. Thus, the approach was aimed to look at the genotoxic and cytotoxic potential of three different glass-ionomer cements available commercially (Ketac Cem, Ketac Molar and Vitrebond) by the single cell gel (comet) assay and trypan blue exclusion test, respectively. For this, such materials were exposed to mouse lymphoma cells in vitro for 1 h at 37 degrees C. Data were assessed by Kruskall-Wallis non-parametric test. The results showed that all powders assayed did not show genotoxic effects. On the other hand, the liquid from Vitrebond at 0.1% dilution caused an increase of DNA injury. Significant statistically differences (P < 0.05) in cytotoxicity provoked by all powders tested were observed for exposure at 1,000 micro g mL(-1) concentration and 100 micro g mL(-1) for Ketac Molar. With respect to liquids of glass-ionomer cements evaluated, the major toxic effect on cell viability was produced at 1%, beginning at the dilution of 0.5% for Vitrebond. Taken together, these results support the notion that some components of glass-ionomer cements show both genotoxic and cytotoxic effects in higher concentrations.

Animals↗
PubMed1996

Comparison of the in vitro fatigue resistance of an acrylic resin removable partial denture reinforced with continuous glass fibers or metal wires.

PURPOSE: The fatigue resistance of heat-polymerized acrylic resin test specimens reinforced with continuous glass fibers or metal wire was investigated. MATERIALS AND METHODS: Test specimens in the shape of maxillary removable partial dentures were reinforced with one of the following: (1) circular steel wire (cross-sectional diameter, 1.0 mm); (2) semicircular steel wire (cross-sectional diameter, 1.0 x 2.0 mm); or (3) continuous unidirectional E-glass fibers. Ten specimens were fabricated for each test group. The specimens were tested by a constant force flexural fatigue test at a force of 180 N while immersed in 37 degrees C water. The number of loading cycles required to generate a fatigue fracture and the position of the fracture were measured. RESULTS: Results showed that the test specimens, which were either unreinforced or reinforced with metal wires, fractured after 13,197 to 39,237 loading cycles. For the glass fiber-reinforced test specimens, the fracture did not coincide with the region of the strengthener but with the opposite side of the test specimen after 1,239,298 loading cycles. The position of the fracture showed a statistically significant variation between the test groups (P < .001). CONCLUSIONS: This study suggests that the fatigue resistance of acrylic resin removable partial dentures reinforced with glass fibers are superior to those removable partial dentures reinforced with conventional metal wire.

Analysis of Variance↗
PubMed2001

Laboratory strength of glass ionomer and zinc phosphate cements.

PURPOSE: The present in vitro study examined 3 mechanical properties, namely compressive, flexural, and diametral tensile strength, of various commercially available cements and core materials as a function of time after mixing. MATERIALS AND METHODS: The examined materials were 2 cermet cements (Ketac Silver [ESPE, Seefeld, Germany] and Chelon Silver [ESPE]), 1 metal-reinforced glass ionomer cement (Miracle Mix [GC Dental Industrial Corp, Tokyo, Japan]), 2 conventional glass ionomer cements (Ketac Bond [ESPE] and Ketac Cem [ESPE]), 1 standard cure zinc phosphate cement (Harvard Cement [Richter and Hoffmann, Berlin, Germany]), and 1 zinc phosphate cement with the addition of 30% silver amalgam alloy powder (Harvard Cement 70% with Dispersalloy 30% [Richter and Hoffmann/Johnson and Johnson, East Windsor, NJ]). Properties were measured using a universal testing machine at 15 minutes, 1 hour, and 24 hours after first mixing. RESULTS: Compressive strengths varied widely between the 3 times of measurement from 5.8 +/- 6.6 MPa for Ketac Cem to 144.3 +/- 10.2 MPa for Ketac Silver. Twenty-four hours after mixing, the Bonferroni test showed significant (p <or= .01) differences between Ketac Silver and all other materials tested. Diametral tensile strengths ranged widely from 4.4 +/- 0.9 MPa for Ketac Cem to 11.5 +/- 2.2 MPa for Chelon Silver. At 15 minutes, 1 hour, and 24 hours after first mixing, the analysis of variance did not show any significant differences between Ketac Silver, Chelon Silver, and Miracle Mix. The 3-point flexural strength of Ketac Silver showed, at 15 minutes with 13.5 +/- 3.9 MPa and at 24 hours with 27.2 +/- 7.4 MPa, the highest values. CONCLUSIONS: Setting time influences the mechanical properties of the materials tested in this study. Ketac Silver, a glass ionomer cement reinforced with sintered glass-silver particles, showed the highest mechanical properties of the examined materials.

Analysis of Variance↗
PubMed1991

The effect of glass ionomer cement and composite resin fillings on marginal gingiva.

Glass ionomer cement and composite resin are the most popular restorative materials in operative dentistry today. Earlier studies have shown more crevicular exudate around different types of composite resins than around intact enamel surfaces. The aim of this study was (1) to investigate plaque, retention on and the condition of the gingiva around, 1-year-old, subgingivally located, glass ionomer cement and composite resin fillings, and (2) to compare the initiation of gingival inflammation around these materials with that around enamel during a 14-day period of experimental gingivitis. Plaque index, gingival index, bleeding on probing and crevicular fluid were recorded and compared intra-individually. The amount of plaque and the degree of gingivitis adjacent to the composite fillings were not significantly higher than those for the glass ionomer cement and enamel surfaces in both the cross sectional and the experimental gingivitis study. Composite resin surfaces showed significantly higher crevicular fluid levels than did enamel at all days in the experimental gingivitis study. Glass ionomer cement showed significantly higher values at day-0 and day-7.

Adult↗
PubMed1998

ART restorations and glass ionomer sealants in Zimbabwe: survival after 3 years.

Atraumatic restorative treatment (ART) consists of removing demineralised tooth tissues with hand instruments only, restoring the prepared cavity and sealing the adjacent pits and fissures with an adhesive filling material. This relatively painless, no-handpiece, minimal intervention approach to controlling dental caries is described. ART was applied in an oral health care programme in Zimbabwe that was carried out amongst secondary school students from 1994 to 1997. A new glass ionomer (Fuji IX) was used as the restorative and sealant material. Sealants were placed in high caries risk students using the 'press-finger' technique. A total of 297 one-surface ART restorations and 95 glass ionomer sealants were placed in 142 and 66 students, respectively. After 3 years, the lost-to-follow-up percentages for one-surface ART restorations and glass ionomer sealants were 30.6% and 30.5%, respectively. Actuarial (life table) analysis resulted in 3-year survival rates of one-surface ART restorations of 88.3% (95% CI: 92.4%-84.2%), ranging from 94.3% to 65.4% per operator. A total of 28 ART restorations placed in 25 students failed. Reasons for failure related to the material and the operator (11 restorations or 5.3% each), and to caries adjacent to the restoration (one restoration or 0.5%). Reasons for failure were not recorded for five restorations (2.3%). Sealants were placed on surfaces diagnosed as early enamel lesions. After 3 years, 71.4% (95% CI: 81.7%-61.1%) of the fully and partially retained sealants survived with a range of 100% to 55.6% per operator. Of the sealed surfaces 96.3% (95% CI: 100%-92.2%) survived 3 years without developing caries. Experienced operators placed better ART restorations than inexperienced operators. This study has demonstrated that ART with a glass ionomer restorative material and sealants provided high quality preventive and restorative dental care to this student population. ART has become one of the treatment modalities available to oral health workers in managing dental caries.

Adolescent↗
PubMed2006

Caries-preventive effect of resin-based and glass ionomer sealants over time: a systematic review.

INTRODUCTION: The difference in preventing dentine lesion development between resin-based and glass ionomer sealant materials is unclear. Two recently published reviews were unable to conclude on the difference because the comparison was an exclusion criterion in one review and there were statistical shortcomings in the relevant papers in the other (Cochrane) review. OBJECTIVES: The aim of the present investigation was to carry out a systematic review on the caries-preventive effect of these two types of sealant materials under more liberal exclusion criteria concerning the statistical presentations in the publications. METHODS: Based on five exclusion criteria, the literature search in the electronic libraries PubMed and MEDLINE and the publications retrieved in the Cochrane review, revealed 12 eligible publications for analyses. A variety of glass ionomers and resin-based sealant materials had been applied in the included studies. Attributable risk (AR) was chosen rather than relative risk (RR), as used in the Cochrane review, because RR is very instable in a low caries population. RESULTS: There was no consistent pattern observed with respect to the caries-preventive effect of either resin-based or glass ionomer sealants. Therefore, it was impossible to calculate an overall AR. CONCLUSIONS: There is no evidence that either resin-based or glass ionomer sealant material is superior to the other in preventing dentine lesion development in pits and fissures over time.

Dental Caries↗
PubMed1979

Does occupational exposure to glass-fibres increase the general skin reactivity to irritants?

A total of 33 workers at a glass-wool factory were tested (patch tests with glass-fibres and chemical irritants, epicutaneous tests with Trafuril and intracutaneous tests with histamine) before starting to work at the factory and then re-tested after at least 4 weeks of exposure to glass-fibres. No statistically significant differences in the intensity of the skin reactions before and after exposure were found. Thus no general increased irritancy of the normal skin was induced by the continuous exposure to glass-fibres.

Adolescent↗
PubMed1990

Glass ionomer and resin-based fissure sealants: a clinical study.

The aim of this study was to compare the retention rate of a glass ionomer cement formulated for fissure sealing with two resin-based sealants, 208 occlusal fissures of permanent molars and premolars were sealed with either Fuji III, Delton or Concise WS by four dentists. Clinical assessments and a replica scoring technique were used to register the performance of the sealants at baseline, after 6-12 months, and then yearly up to 5 yr. As judged clinically, 61% of the glass ionomer sealants were lost within 6-12 months and 84% after 30-36 months. Although total loss was recorded clinically for the majority of the glass ionomer sealants, some retained sealant was observed in the tooth replicas in 93% of them. The clinical evaluation of the resin-based sealants showed an average complete retention rate of 90% after 4.5-5 yr. The corresponding figure with the replica technique was 58%. Caries was recorded in 5% of the resin-based and in none of the glass ionomer sealed surfaces.

Acrylates↗
PubMed1990

Release of fluoride from conventional and metal-reinforced glass-ionomer cements.

Fluoride was extracted by 1 or 50 ml deionized water from 0.3 ml samples of two conventional and three metal-reinforced glass-ionomer cements. The fluoride concentration was determined by electrode. It was found that the fluoride concentration around the glass-ionomer cements ranged 2-3 ppm after 15 min and 3-5 ppm after 45 min. The maximum fluoride concentration attained within 24 h varied from 15-21 ppm, while the total amount of fluoride released during 100 days varied from about 2 mg fluoride to 12 mg fluoride per ml glass-ionomer cement. An alloy reinforced cement and its conventional counterpart released the highest amount of fluoride whereas a glass-cermet type released the lowest amount. Within the premises of this study it was concluded that composition and handling of the cements are of importance for the release of fluoride, and that a caries inhibitory fluoride concentration can be established in the surroundings of all of the cements.

Cermet Cements↗
PubMed1991

Fluoride release and uptake by glass ionomers.

The aim was to study the fluoride release 1) from 7 and 15-month-old glass ionomer specimens after treating them with fluoride; 2) from fresh compared with matured material; and 3) from specimens stored for 29 months in running water. Glass ionomer test specimens which had been in running water for first 7 then 15 months were treated with a 50 ppm fluoride solution after which the specimens were again exposed to running water for first 24 h and then 1 wk. The fluoride release was measured after each of the two periods of time. The fluoride treated specimens released more fluoride than the nontreated ones. This effect was not observed with composite resin specimens which were studied for comparison. Fluoride release from fresh glass ionomer specimens was observed to be 3-10 fold compared to specimens that had matured for 3 days. The release of fluoride from specimens that had been in running water for 29 months was measured and the results were compared with those of earlier measurements. It was found that the release reached a constant level for all tested glass ionomers during the second year.

Absorption↗
PubMed1996

Comparison of two- and three-body wear of glass-ionomers and composites.

The two-body and three-body wear of glass-ionomers (GIC), visible light cured glass-ionomers (VLC-GIC), and composites were compared. The wear simulations were performed for the two-body wear in an artificial mouth and for the three-body wear with the so-called ACTA machine. The tested materials were different conventional glass-ionomers, light cured glass-ionomers, composites, and amalgam. The wear rates of 8 specimens of each material for the two-body and 16 for the three-body wear test were compared. After 10(5) cycles with each testing device, the wear shapes were measured. All measurements were related to the wear rate of amalgam. For the two-body wear method, the worn materials were qualitatively judged by scanning electron microscopy. The two different wear testing methods lead to similar results with slight differences in ranking. Amalgam showed the lowest wear rates with both methods. Photac Fil, a newly developed VLC-GIC, showed dramatically lower wear resistance than composites and conventional GIC with both methods. Further investigations are necessary to identify the material-specific parameters influencing the wear behaviour of a material in relation to different wear testing methods.

Acrylic Resins↗
PubMedDate not supplied

Effect of surface coatings on flexural properties of glass ionomers.

The purpose of this study was to investigate the change in flexural strength and fracture toughness of light-cured glass ionomer cements after long-term immersion in water, and to investigate the effect of surface coatings on their properties. 2 resin-modified and 1 conventional glass ionomer cements were employed. For the flexural strength, a 25 x 2 x 2 mm stainless steel mold was used. For the fracture toughness (KtC), single edge notch specimens with dimensions 25 x 2.5 x 5 mm and a 0.5 mm notch (a/W = 0.5) were prepared in a stainless steel mold. Specimens were subjected to the 3 point bending at 0.5 mm/min after storage in 37 degrees C water for the periods of 1 h, 24 h, 1 wk, 1 month, and 6 months. The glass ionomer cements tended to exhibit an increase in mechanical properties over the 24-h period and then to maintain a constant strength. The surface protection of the resin-modified glass ionomer cement has some effect on the mechanical properties during early setting reactions, and it is desirable that the cement should be protected from direct water contact for at least 1 h after cement mixing.

Analysis of Variance↗
PubMed1996

Glass ionomer as fissure sealant--a critical review.

This paper presents a review of the literature on glass ionomer cements used as fissure sealants. An objective assessment of the presently available scientific literature on the use of glass ionomer materials as pit and fissure sealants is not encouraging in terms of retention, but appears somewhat more positive for caries prevention. At the time of this writing, the published literature indicates that retention for resin-based sealants is better than for glass ionomer sealants, but differences in caries prevention remain equivocal. Future research should concentrate on assessing the effects of fluoride-releasing, resin-modified, glass ionomer materials.

Dental Bonding↗
PubMed1996

Dental caries under glass ionomer restorations.

The Atraumatic Restorative Treatment (ART) technique has two potential limitations. Because only hand instruments are used, dental caries can be left during cavity preparation. Beyond this limitation, the glass ionomer filling material currently used has some unfavorable mechanical properties with respect to its strength, wear resistance, and shrinkage during setting. The purpose of this paper is to provide an overview of changes that can be expected in carious dentin when a glass ionomer restoration is placed. Restriction of the substrate supply and the release of different components from the glass ionomer have an inhibiting effect on cariogenic microorganisms. Whether this influence is sufficient to completely arrest the caries process is doubtful. The influence of glass ionomers on the remineralization of carious dentin needs further research.

Bacteria↗
PubMed1991

Cariostatic effect of glass ionomer cement: a five-year clinical study.

Composite resin and glass ionomer cement were used to restore 67 and 65 Class V carious lesions, respectively. The restorations were assessed each year for recurrent caries and marginal staining. After five years, 1 per cent of glass ionomer and 6 per cent of composite restorations had become carious, and there was approximately twice as much marginal staining around the composite as around the glass ionomers. There appear to be significant benefits in using glass ionomer to restore Class V carious lesions.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1999

The use of glass ionomer in special needs patients.

Placement of restorations for patients who are physically or intellectually disabled or mentally ill can pose considerable difficulties for the general practitioner. Access to the oral environment is often limited and patient tolerance and concentration may be reduced to rather brief periods of time. Oral hygiene routines may be less than ideal leading to a high caries rate. Enamel surfaces which do not normally become carious can develop broad but shallow lesions with a poorly defined outline. Selection of the most suitable restorative material will be important, with longevity of the restoration as the prime consideration. Other factors such as access, isolation of the lesion and patient co-operation must also be taken into account. Also, forces acting on restorative materials may be less than usual due to poor occlusion, teeth opposing dentures or being completely unopposed. Restoration by indirect techniques will often not be possible so the choice will be limited to the three plastic restorative materials normally used in restorative dentistry: amalgam, resin composite and glass ionomer. As a result of clinical experience it is suggested that glass ionomer will often be the material of choice. This paper describes five years experience with the resin-modified glass ionomers in an institutional practice which is limited to patients with special needs. Clinical significance Placement of restorations, with a reasonable expectation of longevity, can pose considerable problems for the patient with special needs. Resin-modified glass ionomer is a useful alternative material and has been placed with a high degree of success over a period of five years.

Dental Care for Persons with Disabilities↗
PubMed2006

The effect of silver fluoride and potassium iodide on the bond strength of auto cure glass ionomer cement to dentine.

BACKGROUND: Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been shown to reduce the incidence of caries in primary dentitions. The clinical application of this material has been limited by staining associated with both teeth and restorative materials. The application of potassium iodide (KI) after AgF eliminates stain formation. There is a lack of information as to how the addition of AgF followed by KI may affect the bond strength to dentine. The purpose of this study was to compare the bond strengths of auto cure glass ionomer cement to dentine surfaces that had been treated with AgF and KI and without treatment. METHODS: Ten recently extracted human third molars were embedded into methyl methacrylate resin and sliced to form a square block of exposed dentine surfaces. Each of the four surfaces were treated by one of the following procedures: (a) etching with 37 per cent phosphoric acid; (b) applying GC dentine conditioner; (c) etching, followed by application of AgF/KI then washing off the precipitate and air drying; and (d) etching, applying AgF/KI and air drying the reaction products on the surface. Fuji VII auto cure glass ionomer cement was bonded onto each sample and fracture tested. RESULTS: The dentine samples treated with AgF/KI followed by washing away the precipitate and air drying had bond strengths (2.83 MPa) not significantly different from samples that had been conditioned (2.40 MPa). Samples where the AgF/KI precipitate had been air dried onto the dentine surface had significantly lower bond strengths (1.49 MPa) than the washed samples. Samples that were etched had significantly lower bond strengths (1.91MPa) than the conditioned samples. CONCLUSIONS: This study found that the application of AgF/KI to etched dentine samples followed by washing off the precipitate, created bond strengths that were not significantly different to conditioned samples. Leaving the AgF/KI precipitate on the dentine surface significantly reduced the bond strength of auto cured glass ionomer cement to dentine. Washing away the reaction products and air drying is recommended as the clinical protocol for using AgF and KI on dentine surfaces prior to application of an auto cure glass ionomer cement.

Acid Etching, Dental↗
PubMed2006

Flexural properties of glass fibre reinforced acrylic resin polymers.

BACKGROUND: In recent years, glass fibres have been used to strengthen denture base resins. A major difficulty in using reinforcing fibres with multiphase acrylic resins, such as powder liquid resins, is inadequate impregnation of the fibres with the resin. METHODS: This investigation examined the reinforcing effect of glass fibres on the fracture resistance and flexural strength of acrylic denture base resins. Eighty identical specimens were formed in specially designed moulds in accordance with the manufacturer's recommendations. The four experimental groups were prepared and these consisted of conventional acrylic resin and the same resin reinforced with glass fibres. Ten specimens were fabricated in a standardized fashion for each experimental group. Flexural strength was tested using a 3-point universal testing machine. RESULTS: In this study, statistically significant differences were found in the flexural strength of the specimens (P < 0.05). The injection-moulded, fibre-reinforced group had significantly lower flexural strength than the injection-moulded group (P < 0.001), strength than the microwave-moulded, fibre-reinforced group (P < 0.001), and the microwave-moulded, fibre-reinforced group had lower flexural strength than the microwave-moulded group. The fracture resistance was significantly higher in the injection-moulded, fibre-reinforced group than in the injection-moulded group (P < 0.05), and the fracture resistance was significantly higher in the microwave-moulded, fibre-reinforced group than in the microwave-moulded group. CONCLUSION: Within the limitations of this study, the flexural strength of heat-polymerized PMMA denture resin was improved after reinforcement with glass fibres. It may be possible to apply these results to distal extension partial and complete denture bases.

Acrylic Resins↗