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PubMed2006

In vitro evaluation of the retention of zirconia-based ceramic posts luted with glass ionomer and resin cements.

The retention of zirconia-based ceramic posts (CosmoPost system) luted with glass ionomer and resin cements was evaluated. Thirty-two extracted, caries-free, unrestored teeth were selected and stored in chlorhexidine and water solution. The teeth were endodontically treated and randomly assigned to two groups (n=16). Each tooth was decoronated and prepared to a depth of 10.0 mm from root surface to receive a 1.4 mm diameter zirconium dioxide post. Each group had posts cemented with either glass ionomer cement (Fuji I) or resin cement (Variolink II). The post/teeth specimens were embedded in resin blocks and subjected to tensile testing. The tensile force required to dislodge the cemented posts in a tensile testing machine was recorded. The mean stress values of both groups were analyzed for statistical differences using ANOVA and Student's t-test. Significance level was set at 5%. Mean peak forces at failure (N) and standard deviation for the tested cements were the following: Fuji I = 121.8 (+/-17.4) and Variolink II = 228.1 (+/-36.8). Posts luted with the resin cement presented statistically significant higher tensile bond strength than those retained with glass ionomer (p<0.05). It may be concluded that zirconia posts cemented with resin-based cement (Variolink II) failed at statistically significant higher values compared to those cemented with glass ionomer cement (Fuji I). Regardless of the cement type, the posts failed adhesively at the cement/post interface when subjected to a tensile force.

Acid Etching, Dental↗
PubMed2005

Glass ionomer cements: a review of composition, chemistry, and biocompatibility as a dental and medical implant material.

Glass ionomer cements are a group of materials based on the acid/base reaction between poly(alkenoic) acid and an ion-leachable silicate glass. The material was developed in dentistry as a tooth restorative material that released fluoride ions over an extended time, bonded to tooth structure, and was very biocompatible. Its use in dentistry was initially limited by its slow setting time and lack of strength; however, modern formulations of the material have yielded materials with properties that are clinically useful in dentistry. Its biocompatibility, osteoconductive behavior, and ability to bond to bone and metals have generated interest in the material for medical applications. Glass ionomer cements in medicine have been used as bone cements, implants to replace ossicular bones of the inner ear, as well as other craniofacial implants. The early release of fluoride and aluminum ions and release of polyacids have been implicated in tissue biocompatibility in medical use. Additional material development is necessary to optimize its properties for use in medicine. This article reviews the literature written on the composition, chemistry, fluoride release, biocompatibility, and medical uses of glass ionomer cements.

Biocompatible Materials↗
PubMed2000

Occlusal caries formation in vitro: comparison of resin-modified glass ionomer with fluoride-releasing sealant.

The purpose of this laboratory study was to evaluate caries-like lesion formation in occlusal enamel adjacent to a light-cured resin-modified glass ionomer utilized as a pit and fissure sealant and a conventional light-cured, fluoride-releasing sealant. Fluoride-free prophylaxis was done on occlusal surfaces of 12 caries-free mandibular molar teeth that had not been exposed to the oral cavity. Occlusal surface morphology was examined by SEM on the uncoated specimens. Each tooth was then sectioned into 2 portions buccolingually, producing mesial and distal tooth halve. Occlusal surfaces of mesial tooth halves were prepared for an experimental light-cured resin-modified glass ionomer (RMG) sealant (PH-SE II, ESPE), and for comparison, a light-cured fluoride-releasing pit and fissure (PFS) sealant (Helioseal F, Ivoclar) was placed on occlusal surfaces of the corresponding distal tooth halves. The sealed occlusal surfaces were examined uncoated by SEM to compare RMG and PFS adaptation. After thermocycling in artificial saliva, caries-like lesions were formed in the occlusal surfaces adjacent to RMG and PFS. Longitudinal sections were taken for comparison of lesion formation adjacent to RMG and PFS. Mean lesion depths in occlusal surfaces were 64 +/- 17 mm for RMG, and 116 +/- 27 mm for PFS (p < 0.05, paired t-test). Occlusal lesions terminated at the point where bonding occurred between the occlusal enamel and RMG or PFS. SEM surface topography demonstrated adequate adaptation of the materials with obliteration of the typical pit and fissure surface morphology by both RMG and PFS. While both the resin-modified glass ionomer and fluoride-releasing sealant materials protected the pit and fissure enamel from caries development, the resin-modified glass ionomer reduced the extent of caries involvement in the adjacent unsealed occlusal incline enamel, when compared with the resin sealant.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1993

Thermal properties of glass ionomer cement.

Five currently available glass ionomer cements (BASE CEMENT, DENTIN CEMENT, HY-BOND GLAS IONOMER-F, KETAC CEM, TOKUSO IONOMER) were studied with regard to the relationship between thermal properties and powder-liquid ratio (P/L ratio). The experiments were performed using five different P/L ratio of 0.8, 0.9, 1.0, 1.1 and 1.2 (P/L = 1.0: manufacturer's instruction) and measured with a xenon flash thermal-constant measuring device. Thermal diffusivity of the glass ionomer cements ranged from 0.212 to 0.303 x 10(-2) cm2 s-1; it increased according to the increase in the P/L ratio. The specific thermal capacity of the glass ionomer cements ranged from 1.011 to 1.369 Jg-1 K-1; it decreased with the increase in the P/L ratio. Thermal conductivity of the glass ionomer cements ranged from 0.505 to 0.712 Wm-1 K-1; it increased according to the increase in the P/L ratio.

Chemical Phenomena↗
PubMedDate not supplied

5-year clinical performance of resin composite versus resin modified glass ionomer restorative system in non-carious cervical lesions.

AIM: To comparatively assess the 5-year clinical performance of a 1-bottle adhesive and resin composite system with a resin-modified glass ionomer restorative in non-carious cervical lesions. METHOD AND MATERIALS: One operator placed 70 restorations (35 resin modified glass ionomer restorations and 35 resin composite restorations) in 30 patients under rubber dam isolation without mechanical preparation. The restorations were directly assessed by 2 independent examiners, using modified USPHS criteria at baseline and 6, 12, 24 and 60 months. RESULTS: Twenty-two patients were available for recall after 5 years (73.3% recall rate) and 55 out of 70 restorations were evaluated. Excellent agreement was registered for all criteria between examiners (kappa > or = 0.85). Sixteen composite restorations were dislodged (51.5% retention) and 1 ionomer restoration was lost (96.4% retention). The McNemar test detected significant differences in resin composite restorations between baseline and 5-year recall for marginal integrity (p<0.001) and retention (p=0.004). For resin modified glass ionomer restorations, no significant differences were identified for all criteria (p>0.05). When comparing both materials, the Fisher exact test pointed out significant differences in retention (p=0.002) after 5 years of clinical service. CONCLUSIONS: After 5 years of evaluation, the clinical performance of resin modified glass ionomer restorations was superior to resin composite restorations.

Acid Etching, Dental↗
PubMed2001

Effects of a bioactive glass on healing of closed skin wounds in dogs.

OBJECTIVE: To determine effects of intraincisional bioactive glass on healing of sutured skin wounds in dogs. ANIMALS: 9 purpose-bred mature female Beagles. PROCEDURE: 3 small matched bilateral (treated vs control) full-thickness truncal skin incisions were made and sutured. Treated wounds received intraincisional particulate bioactive glass prior to closure. Laser Doppler perfusion imaging was used to assess percentage change in tissue perfusion 3 and 5 days after incision on 1 set of 2 matched wounds, and skin and subcutaneous tissue-cutaneous trunci breaking strength were assessed at 5 days. The other 2 sets of wounds were used for histologic evaluation at 5 and 21 days, respectively. RESULTS: Subjective signs of gross inflammatory reaction were not detected in treated or control wounds. At 5 days, median subcutaneous tissue-cutaneous trunci breaking strength was significantly higher in treated wounds than in control wounds-(188.75 vs 75.00 g). At 5 days, median scores were significantly higher for neutrophils (1 vs 0), macrophages (2 vs 1), and necrosis (1 vs 0) for treated wounds than for control wounds. At 21 days, median macrophage scores were significantly higher for treated wounds than for control wounds (2 vs 1). CONCLUSIONS AND CLINICAL RELEVANCE: Bioactive glass in soft tissues does not cause a gross inflammatory reaction but causes an increase in histologic signs of inflammation, which decreases with time. Bioactive glass has potential for increasing tissue strength. Increased subcutaneous breaking strength could be beneficial in treating wounds in which early healing strength is needed.

Animals↗
PubMed1983

Opacity of glass-ionomer cements.

The translucency of the first generation of glass-ionomer cements to appear on the market was too low to be cosmetically satisfactory. In the present study the opacity of newer editions of glass-ionomer cements was evaluated and compared with that of a well-known composite resin. Disc-shaped specimens were placed on black and on white backings, the luminous reflectances measured and corrected to a specimen thickness of exactly 1 mm, whereafter the contrast ratio was calculated. The newer glass-ionomer cements were found to be more translucent than the first generation of glass-ionomer cements on the market. However, the opacity still needs to be reduced to reach the level of a composite resin. It was further established that early water contact results in a considerable increase in opacity.

Composite Resins↗
PubMed1989

Bonding and gap formation of glass-ionomer cement used in conjunction with composite resin.

Glass-ionomer cement has been suggested as liner in cavities restored with composite resin. The purpose of the present investigation was to measure 1) tensile bond strength between etched glass-ionomer cement and composite resin, and 2) gap formation as assessed by wall-to-wall polymerization contraction and by microleakage with a silver nitrate technique. The influence of the following variables was examined: type of glass-ionomer cement and composite resin, duration of acid etching, irradiation time of unfilled and composite resin, preparation of bevel, conditioning with polyacrylic acid, and storing time in water before gap measurement. Bond strengths varied from 0 MPa when etching was omitted to 3.9 MPa after etching. Glass-ionomer cement lining reduced wall-to-wall contraction and penetration of silver nitrate. A positive correlation was found between wall-to-wall contraction and silver nitrate penetration.

Composite Resins↗
PubMed1994

Three-year comparison of fired ceramic inlays cemented with composite resin or glass ionomer cement.

Ceramic inlays offer a good alternative to posterior composites, which still show a high polymerization shrinkage. The thin cement layer will reduce the total amount of shrinkage and probably result in a better marginal adaptation and decreased marginal leakage. Fired feldspathic ceramic inlays cemented with either a glass ionomer cement or a dual-cured composite resin luting cement were compared intraindividually. During a 3-year period 118 inlays, 59 in each group, were examined. Eleven inlays were evaluated as non-acceptable during the period: two (3.4%) in the composite resin group and nine (15.3%) in the glass ionomer cement group. In the composite group one inlay fractured partially and one inlay was replaced because of postoperative sensitivity. In the glass ionomer group four inlays were totally lost, and partial fractures occurred in five inlays. In the fractured glass ionomer cemented inlays the cement was still in place in the cavities. Eight patients reported post-operative sensitivity. No secondary caries was detected around the inlays even though 46% of the patients were considered high caries risk patients.

Adult↗
PubMed1988

Identical 24-hour gastric pH profiles when using intragastric antimony or glass electrodes or aspirated gastric juice.

Intragastric pH was continuously measured over 24 h with a monocrystalline antimony electrode system and was compared with pH measured in simultaneously aspirated gastric juice and with pH measured by using a conventional intragastric glass electrode. There was a marked correlation between the pH readings obtained with the monocrystalline antimony electrode and the pH values measured in aspirated gastric juice (r = 0.92, p less than 0.001) and with the pH readings obtained with the intragastric glass electrode (r = 0.92, p less than 0.001). Both readings of pH with glass electrode and of pH after aspiration can be predicted by readings of pH with antimony electrode by using linear regression lines with slopes close to 1. Intragastric pH measurement is an alternative to aspiration of gastric juice, and the result obtained with an electrode of monocrystalline antimony is comparable to that obtained with a conventional glass electrode.

Antimony↗
PubMed1996

Deformation of erythrocytes in microvessels and glass capillaries: effects of erythrocyte deformability.

OBJECTIVE: The deformation of erythrocytes in microvessels less than 15 microns in inner diameter was analyzed using a microvascular bed isolated from rabbit mesentery. The deformation was compared with that found in glass capillaries. METHODS: Human erythrocytes were perfused through two media: first, a microvascular-bed section isolated from rabbit mesentery; and second, a set of glass capillaries. Images of deformed erythrocytes were recorded on videotape under strobe light and analyzed with an image processor. The flow velocity of the erythrocytes was determined from the difference of their positions between video frames or by a dual-spot cross-correlation technique. Erythrocyte deformability was modified with diamide, diazene dicarboxylic acid bis[N,N-dimethylamide], by crosslinking spectrins. RESULTS: Symmetrical (parachute-like or slipper-like) deformation of erythrocytes was observed only in microvessels smaller than 13 microns in inner diameter. Erythrocytes in microvessels were less deformed than those in glass capillaries with corresponding diameters, and the marginal cell-free layer was narrower. The deformation increased by increasing the flow velocity of erythrocytes, and the cell-free layer became wider. Diamide-treated cells in microvessels were less deformed than normal cells and showed slightly narrower cell-free layers. Stronger stress in narrower microvessels induced further deformation of cells. CONCLUSIONS: Erythrocyte deformation in microvessels was essentially different from that in glass capillaries, and the effect of erythrocyte deformability on the flow dynamics of erythrocytes in microvessels was properly evaluated using an isolated microvascular bed.

Animals↗
PubMed1993

Cementless total hip replacement. Bio-active glass ceramic coating studied in dogs.

We studied 2 types of a cementless total hip prosthesis in dogs. Both were coated with titanium plasma-spray. In both components, the pores in the deep layer of 1 group were further coated with apatite and wollastonite containing glass-ceramic (AW glass-ceramic). 50 dogs underwent unilateral total hip replacements, and were killed at 1, 3, or 6 months postoperatively. We evaluated the femoral and the acetabular components mechanically and histologically. At 1 month, the detaching load and bone ingrowth of the AW glass-ceramic-coated femoral and acetabular components were higher than those of the control implants. At 3 and 6 months there were no differences between the 2 types of components. Thus, AW glass-ceramic enhanced the early phase of cementless implant fixation.

Animals↗
PubMedDate not supplied

Fabrication of glass micropipettes: a semi-automatic approach for trimming the pipette tip.

Micropipettes as research instruments are well established in cell biology, including blood rheology. However, the experimental results are, to some extent, dependent on the quality of the pipette itself; it is usually critical to have the desired pipette internal diameter and a perpendicular tip. Pipette fabrication is a two-step procedure involving: a) the pulling of the pipette from a glass capillary; b) the trimming of the pipette tip. A common method to trim and fracture the pipette tip is the use of a melted glass bead on a heated tungsten wire. Previous devices using this method were often associated with problems because the heated wire varied in length with temperature. As a result, the bead together with the attached pipette tip moved markedly and thus hampered the possibility to obtain a perpendicularly cut pipette tip. An improved design, based on the same principle with a melted glass bead, is thus suggested; it eliminates the problem with a moving glass bead and, in addition, allows semi-automatic pipette trimming by utilizing the heat-induced elongation/retraction of the heated wire to fracture the tip without requiring manual assistance. Furthermore, a simple pipette storing technique is suggested, based on standard laboratory utensils, in order to more easily handle fragile pipettes without risk of breakage.

Blood Physiological Phenomena↗
PubMed1997

Erosion process of light-cured and conventional glass ionomer cements in citrate buffer solution.

The aim of this study was to clarify the erosion behavior of light-cured glass ionomer cement. One light-cured glass ionomer cement and two conventional chemically-cured glass ionomer cements were immersed in citric acid buffer solutions of pH 4 and pH 6. Fluoride release was almost the same in both types of cements, irrespective of pH. The amounts of other species eluted, such as Al, Sr, Si and P2O5 were smaller in the light-cured glass ionomer cement than in the conventional ones at pH 4. The amounts of species eluted at pH 6 were almost the same in both types of cement. Dissolution of the light-cured cement in pH 4 solution was controlled by the diffusion of the eluted species in the cement matrix. On the other hand, dissolution of the conventional cements was controlled by both diffusion and surface reaction. The surface features of the cements after erosion corresponded well to the dissolution mechanism. In pH 6 solution, dissolution of the cements was mainly controlled by diffusion of the species in the cement.

Buffers↗
PubMed2005

Rare earth oxide-containing fluorescent glass filler for composite resin.

In recent dental care, esthetic restorative materials such as composite resin and porcelain have been widely used and studied. However, their good esthetics makes the visual inspection of restored teeth difficult. In this study, a fluorescent glass filler containing rare earth oxides - which are well-known fluorescent materials - was prepared and used in composite resin to enhance visual inspection capability with small change in color. For example, when irradiated with near ultraviolet light, an Eu2O3-containing filler fluoresced clearly and visibly. The fluorescence intensity of the prepared composite resin increased with increase of Eu2O3 content in the glass filler and with filler/resin ratio in the resin. Despite the clear fluorescence, the effect of Eu2O3 on the color change of composite resin was quite small - even when up to 10 wt% Eu2O3 was added to the glass filler. Tb4O(7-) and Dy2O3-added fillers also showed clear fluorescence, just like Eu2O3-added filler. Therefore, fluorescent glass fillers for composite resins, resulting in small color change in the latter, were successfully prepared in this study.

Composite Resins↗
PubMed1996

Diabetes mellitus among Swedish art glass workers--an effect of arsenic exposure?

OBJECTIVES: The purpose of this study was to search for evidence of an association between occupational arsenic exposure and diabetes mellitus, as implied by the relation of this disease to arsenic in drinking water in a recent study from Taiwan. METHODS: A case-referent analysis on death records of 5498 individuals in the art glass producing part of southeastern Sweden was performed. Out of all the enrolled subjects, 888 were glass workers. According to occupational title, glassblowers, foundry workers, and unspecified workers were regarded as potentially exposed to arsenic. Persons with a diagnosis of diabetes mellitus either as an underlying or contributing cause of death were considered cases. Referents were decedents without any indication of cancer, cardiovascular disease, or diabetes. RESULTS: A slightly elevated risk [Mantel-Haenszel odds ratio (MH-OR) 1.2, 95% confidence interval (95% CI) 0.82-1.8] was found for diabetes mellitus among the glassworks employees, especially in combination with cardiovascular disease (MH-OR 1.4, 95% CI 0.81-2.3). For the glassblowers, other foundry workers and unspecified glassworkers probably exposed to arsenic, the M-H odds ratio was 1.4 (95% CI 0.92-2.2). Unspecified glass workers, who probably included persons with high exposure, carried the higher risk (MH-OR 1.8, 95% CI 1.1-2.8). CONCLUSIONS: The observations from this study provide limited support for the possibility that occupational arsenic exposure could play a role in the development of diabetes mellitus. Many other metallic compounds are also used in art glass production, however, and there is a possibility of confounding.

Age Distribution↗
PubMed1979

Glass laceration injuries and prevention.

Accidents involving glass in doors, sidelights, specially vulnerable windows, and shower screens are an important cause of injury, and occasionally death. Most of the injuries are superficial cuts and abrasions, but many involve deep lacerations of tendons, nerves and muscles. The accidents occur mainly in children and young adults with the highest rate being among males aged from 15 to 19 years. The number and severity of these injuries could be reduced through the wider use of appropriate forms of safety glazing: laminated glass or toughened glass in new installlations, and the application of a plastic safety film to existing glass.

Adolescent↗
PubMed2006

A comparison of glass and plastic blood collection tubes for routine and specialized coagulation assays: a comprehensive study.

CONTEXT: Blood collection tubes made from plastic are beginning to replace glass tubes. Coagulation test results can be influenced easily by preanalytic factors, including exposure to surfaces that activate the clotting cascade. OBJECTIVE: To compare the effects of the blood collection tube material on 22 coagulation assays performed in clinical laboratories. DESIGN: Paired blood samples from 28 healthy volunteers were drawn into BD Vacutainer Glass Citrate Tubes and BD Vacutainer Plus Plastic Citrate Tubes, and the results of coagulation assays were determined in parallel. RESULTS: No statistically significant differences were observed between glass and plastic for 14 assays: prothrombin time (and international normalized ratio); activated partial thromboplastin time; activated protein C resistance; antithrombin activity; factors II, V, VIII, and IX; alpha2-antiplasmin; plasminogen activity; von Willebrand factor antigen; ristocetin cofactor; thrombin time; and reptilase time. Statistically significant differences were found for fibrinogen; chromogenic protein C activity; protein S activity; PTT-LA lupus anticoagulant-sensitive activated partial thromboplastin time; and factors VII, X, XI, and XII. Mean differences ranged from 0.4% to 5.5% and were unlikely to be of clinical significance. CONCLUSIONS: The results of this study suggest that plastic tubes can be used in place of glass tubes for a wide variety of coagulation assays.

Blood Coagulation Tests↗