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PubMed1994

Mechanical retention versus bonding of amalgam and gallium alloy restorations.

The retention of amalgam and gallium alloy restorations in proximal box forms was measured in vitro, and three different adhesives to conventional undercuts were compared. For control, restorations were placed without undercuts or adhesives. No significant difference was found between amalgam and gallium alloys with each of the five methods of retention used. Alloys placed without retention or adhesives were significantly less retentive than all other groups. When Tytin alloy was used, no difference was found in retention among the restorations retained with Panavia or All-Bond adhesive or an occlusal dovetail and retention grooves, but Amalgambond adhesive was less retentive than all three of these methods. When gallium alloy was used, both Panavia and All-Bond adhesive were more retentive than undercuts, but the effect of Amalgambond adhesive was more retentive than undercuts, but the effect of Amalgambond adhesive was comparable to that of undercuts. The results of this study indicate that adhesives could be used in place of traditional undercuts to retain amalgam and gallium alloys, thus saving a considerable amount of tooth structure.

Acid Etching, Dental↗

PubMed1991

Evidence for arsenic as the immunosuppressive component of gallium arsenide.

Gallium arsenide (GaAs) has been shown previously to suppress the in vivo antibody-forming cell (AFC) response to sheep erythrocytes (SRBC) when administered intratracheally at concentrations between 50 and 200 mg/kg. In the present studies, direct addition of GaAs to in vitro-generated antibody cultures resulted in dose-dependent suppression of the primary antibody response, and was only seen when GaAs was added within 36 hr following immunization. Using atomic absorption spectrophotometry on tissue samples from mice exposed to 200 mg/kg GaAs, arsenic concentrations were found to peak in the spleen at 24 hr and decline, whereas gallium concentrations continue to rise through 14 days. Concentrations of each metal in the spleen at 24 hr are comparable to the concentrations achieved for each metal when GaAs is added at 25 microM to the in vitro model system. The 24 hr time point was chosen for comparison because all in vivo-in vitro studies were conducted using spleens from mice 24 hr after GaAs exposure. NaAsO2 and Ga(NO3)3 suppressed the AFC response dose-dependently, and in a time-dependent manner similar to GaAs when added to the in vitro system. However, based on IC50 values for each salt, the role of the gallium component in the immunosuppression appears weak. Oxalic acid (OA) and meso-2,3-dimercaptosuccinic acid (DMSA), chelators of gallium and arsenic respectively, were added to cultures with GaAs to confirm that arsenic was the primary immunosuppressive component. DMSA dose-dependently blocked GaAs-induced immunosuppression in vitro, while OA had no effect. The metal-binding compounds were determined to be specific for the metals used in these studies and did not cross-react with one another. DMSA was evaluated for its ability to prevent suppression of the AFC response in splenocytes from GaAs-exposed mice and was able to block GaAs-induced suppression of the AFC response when given sc every 4 hr beginning 1 hr prior to GaAs exposure. These data indicate that the arsenic component of GaAs is the major contributor to the GaAs-induced immunosuppression and that this effect occurs within the first 36 hr of the 5-day culture period in a concentration-dependent manner.

Animals↗

PubMed1993

Anodic polarization behavior and microstructure of a gallium-based alloy.

A gallium-based alloy (GA) that was developed as a substitute for dental amalgam was investigated for anodic polarization behavior in deoxygenated Ringers solution, 37 degrees C. The related microstructures were examined and microanalyses were conducted. Four polarization tests were conducted by scanning from -300mV to +1,000 mV (vs. SCE) at 2 mV/s. Polarization of the first sample (GA-1) was stopped after the first anodic dissolution peak (-100 mV, 1.5-2.0 x 10(-3) A/cm2). The fourth sample (GA-4) was interrupted at the secondary peak (+1000 mV, 0.3 A/cm2). It was found that (1) the early stage of the first peak is related to selective dissolution of divalent tin ions, followed by a dissolution of Ga. Transmission electron diffraction (TED) identified the brown corrosion product as Ga2O3; (2) the GA-4 sample was covered with the white corrosion product of mainly Sn+4, identified as SnO2. In addition, the current density of the GA sample when coupled with a high-copper dental amalgam was 0.03 A/cm2 (with +1,000 mV) at the second peak which was about a ten times lower value than for the uncoupled sample; (3) the uncoupled gallium alloy and gallium alloy coupled with a high-copper dental amalgam showed 10(3)-10(4) times higher anodic current density than that of an uncoupled high-copper dental amalgam, suggesting that the gallium alloy is more corrosion prone.

Corrosion↗

PubMed1995

The physical properties of a gallium alloy restorative material.

OBJECTIVES: This study was conducted to compare the physical properties of a gallium alloy restorative material and a widely used mercury-containing dental amalgam. METHODS: Although the specimens were not prepared according to ISO specifications, specimens of both materials were subjected to ISO standard (ISO 1559; 1986) tests. The results were analyzed by ANOVA, Mann-Whitney U test and Student's t-test. RESULTS: The gallium alloy showed setting expansion which was greater than that for the other amalgam and greater than the upper limit set by the ISO standard. For other properties, gallium alloy performed as well as, and in the case of creep, was superior to that of the amalgam. SIGNIFICANCE: The gallium alloy proved difficult to manipulate even when using the PTFE coated instruments recommended by the manufacturer. It is suggested that while the material may prove to be a viable alternative to conventional dental amalgam, a considerable improvement in its handling characteristics would be required before it would gain widespread acceptance for clinical use.

Alloys↗

PubMed1990

Use of gallium to treat Paget's disease of bone: a pilot study.

The effects of gallium nitrate on bone turnover were evaluated in four patients with active Paget's disease. Treatment with gallium nitrate (100 mg/m2 daily for 5 days, intravenously in 5% glucose) significantly reduced serum calcium, serum phosphate, urinary calcium, and the ratio of maximum tubular reabsorption of phosphate to glomerular filtration rate in each patient. Serum parathyroid hormone levels rose. The findings suggest that the fall in serum calcium caused secondary hyperparathyroidism, resulting in a fall in serum phosphate. Serum alkaline phosphatase and urinary hydroxyproline levels fell substantially, showing that gallium effectively suppressed bone turnover. The fall in hydroxyproline excretion preceded that in serum alkaline phosphatase, suggesting that suppression of bone resorption by osteoclasts preceded that of bone formation by osteoblasts. Alkaline phosphatase levels remained low throughout follow-up (85-141 days), so the effect of gallium seems to be long-lasting.

Aged↗

PubMed2005

Mid- and post-ABVD gallium scanning predicts for recurrence in early-stage Hodgkin's disease.

PURPOSE: To determine the efficacy of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) for patients with Hodgkin's disease and to identify predictors of outcome with this regimen. METHODS: Between 1987 and 1998, 175 patients with Stage I-IV Hodgkin's disease received ABVD as part of initial treatment. Overall survival (OS), freedom-from-treatment-failure (FFTF), and progression-free survival (PFS) were calculated using the Kaplan-Meier technique. Log-rank tests were used to identify univariate predictors of OS, FFTF, and PFS. Specifically, restaging gallium scan results and clinical response after chemotherapy were separately evaluated. RESULTS: The median follow-up time was 64 months. The 5-year OS, FFTF, and PFS rates were 90%, 85%, and 82%, respectively. For Stage I-II patients, restaging gallium scan results and clinical response after chemotherapy were highly predictive of OS, FFTF, and PFS (p < 0.0001). Other significant predictors for higher OS included age <50 (p = 0.002), female gender (p = 0.047), and absence of B symptoms (p = 0.043). Of the 20 patients with a positive restaging gallium scan, 4 received high-dose therapy and 16 continued with conventional-dose therapy or received no further treatment. Of these 16 patients, 11 (69%) were disease-free at last follow-up. CONCLUSIONS: Although a positive mid- or postchemotherapy gallium scan was an adverse prognostic factor for OS, FFTF, and PFS, continued treatment with conventional-dose therapy may be adequate in selected patients with positive scans.

Adolescent↗

PubMed2004

Therapeutic potential of monoisoamyl and monomethyl esters of meso 2,3-dimercaptosuccinic acid in gallium arsenide intoxicated rats.

The dose dependent effects of monoisoamyl and monomethyl esters of meso 2,3-dimercaptosuccinic acid (DMSA) (0.1, 0.3 and 0.5 mmol kg(-1), intraperitoneally (i.p.) once daily for 5 days) to offset the characteristic biochemical, immunological, oxidative stress consequences and DNA damage (based on DNA fragmentation and comet assay) following sub-chronic administration of gallium arsenide and the mobilization of gallium and arsenic were examined. The effects of these chelators alone in normal animals too were examined on above-mentioned variables. Male Wistar rats were exposed to 10 mg kg(-1), GaAs, orally once daily for 12 weeks and were administered DMSA or two of its monoesters (monoisoamyl or monomethyl) for 5 consecutive days. DMSA was used as a positive control. DMSA and its derivatives, when given alone, generally have no adverse effects on various parameters. After 5 days of chelation therapy in GaAs pre-exposed rats, MiADMSA was most effective in the reduction of inhibited blood delta-aminolevulinic acid dehydratase (ALAD) activity and zinc protoporphyrin level while, all three chelators effectively reduced urinary ALA excretion, compared to GaAs alone exposed rats. MiADMSA was also effective, particularly at a dose of 0.3 mmol kg(-1), in enhancing the inhibited hepatic transaminase activities. Parameters indicative of oxidative stress responded less favorably to the chelation therapy, however, three chelators significantly restored the altered immunological variables. MiADMSA was relatively more effective than the other two chelators. GaAs produced significant DNA damage in the liver and kidneys and the chelation treatment had moderate but significant influence in reducing DNA damage. All three chelators significantly reduced arsenic concentration and, however, MiADMSA was more effective than the other two chelators in depleting arsenic concentration from blood and other soft tissues. A dose of 0.3 mmol kg(-1) was found to be relatively better than the other two doses examined. Gallium contents of blood and soft tissues remained uninfluenced by the chelation therapy. Significant loss of copper after MiADMSA administration, however, is of concern and requires further exploration. Additionally, further studies are required for the choice of appropriate dose, duration of treatment and possible toxic/side effects. Keeping in view the promising role of MiADMSA in the treatment of GaAs poisoning, these data will be needed for the registration of this chelating agent as licensed drug for the treatment of gallium arsenide intoxication.

Aminolevulinic Acid↗

PubMed1978

Role of gallium 67 in inflammatory disease.

Gallium 67 has been found to be extremely useful for detection of inflammatory disease. In the skeletal system it complements the 99m Tc-phosphate compounds in differentiating periatricular osteomyelitis, septic arthritis, and cellulitis. Gallium is particularly useful in documenting successful treatment of bone infection because the phosphate scan remains positive for much longer periods of time. In a variety of chest disorders gallium uptake has been found to correlate well with the active inflammatory state. One of the most frequent uses of gallium imaging has been for localization of inflammatory foci in postoperative patients as well as in patients who present with fever of undetermined origin. Neutrophilic labeling followed by migration to the inflammatory area appears to be the major mechanism of localization of radiogallium. For this reason leukopenic patients constitute a group in which false negative results may be encountered.

Abdomen↗

PubMed1997

Gallium nitrate optic neuropathy.

PURPOSE: To report a patient with visual loss after systemic administration of gallium nitrate. METHOD: Case report. RESULTS: After receiving intravenous gallium nitrate, a 77-year-old man developed bilateral visual loss and optic neuropathy with central scotomas on visual field testing and diminished P2-wave amplitude on visual evoked potential examination. The condition worsened after oral corticosteroid therapy. Partial recovery of optic nerve function in both eyes was present after 12 months of oral ferrous sulfate administration. CONCLUSIONS: Partially reversible bilateral optic neuropathy may occur after administration of gallium nitrate in the absence of other chemotherapeutic agents. Ophthalmic examinations are indicated in patients who receive gallium nitrate.

Adenocarcinoma↗

PubMed1999

Selenium effects on gallium arsenide induced biochemical and immunotoxicological changes in rats.

The influence of selenium (6.3 and 12.6 micromol/kg, intraperitoneally) on the disposition of gallium and arsenic and a few gallium arsenide (GaAs) sensitive biochemical variables was studied in male rats. Concomitant administration of Se and GaAs (70 micromol/kg, orally, 5 days a week for 4 weeks) significantly prevented the accumulation of arsenic while, the gallium concentration reduced moderately in the soft organs. The biochemical (haematopoietic and liver) and immunological variables however, responded less favorably to selenium administration. Most of the protection was however observed with the dose of 12.6 micromol rather than at 6.3 micromol. The results thus suggest a few beneficial effects of selenium in preventing the appearance of signs of GaAs toxicity like preventing inhibition of blood delta-aminolevulinic acid dehydratase (ALAD), hepatic malondialdehyde (MDA) formation and the accumulation of gallium and arsenic concentration.

Animals↗

PubMed1980

Gallium scanning in lymphoma.

The findings on gallium-67 scans were compared with the findings of standard techniques (X-ray chest, lymphangiography, clinical examination, and laparotomy findings) in patients with lymphoma, mainly at presentation, but sometimes on follow-up. The objective was to ascertain the reliability of this non-invasive technique in detecting lymphomatous deposits, and to assess its place in the battery of investigations which may be used in clinical staging of lymphomas. One hundred and sixty-six patients were studied, in whom 198 gallium-67 scans were performed. The results indicated that detection of mediastinal and upper para-aortic node involvement was the most significant function, and such detection might alter clinical staging, and, therefore, therapy. Gallium-67 was unhelpful in splenic scanning, being positive usually only in cases which had clinically detectable involvement. Unsuspected lung and bone lesions were found occasionally, and this was of considerable importance. Gallium-67 scanning is regarded as an important, non-traumatic additional investigation, clinically useful in staging lymphomas.

Abdominal Neoplasms↗

PubMed1981

Gallium-67 scanning in the painful total hip replacement.

Pain following total hip replacement is a significant clinical and diagnostic problem. Technetium scanning has proved a sensitive indicator of infection or loosening but does not differentiate between them. This study assessed the value of gallium-67 to aid this differentiation. Thirty patients underwent revision surgery. Fourteen were proven to be infected and 13 had positive gallium scans as also did two patients without infection. The implications of these false interpretations are discussed. Increased gallium activity was correlated with the patterns of the 99mTc scans and arthrographic appearances. It is concluded that gallium-67 scanning is a valuable adjunct to the assessment of the painful hip replacement when infection is suspected.

Aged↗

PubMed2003

Gallium nitrate in multiple myeloma: prolonged survival in a cohort of patients with advanced-stage disease.

Multiple myeloma is characterized by bone destruction mediated by osteoclastic bone resorption. Skeletal complications of myeloma, including bone pain, fractures, spinal cord compression and hypercalcemia, result in significant morbidity. Gallium nitrate was shown in a small, randomized trial to attenuate the rate of bone loss in patients with myeloma treated with chemotherapy. In a retrospective analysis, we found that patients with advanced multiple myeloma treated with chemotherapy plus gallium nitrate had markedly prolonged median survival compared with similar patients treated with chemotherapy alone (87+ months v 48 months, respectively). These data suggest that gallium nitrate may have a positive, indirect benefit on survival in myeloma by decreasing the rate of bone resorption. Further evaluation of gallium nitrate to attenuate progression of disease in patients with multiple myeloma is warranted.

Antineoplastic Agents↗

PubMed2003

Gallium nitrate in the treatment of bladder cancer.

For over 15 years, the MVAC regimen (methotrexate/vinblastine/doxorubicin/cisplatin) has been standard chemotherapy for patients with unresectable or metastatic bladder cancer. The taxanes and gemcitabine have provided new treatment options, but development of more effective regimens is needed. Gallium nitrate has significant activity as a single agent in the treatment of advanced bladder cancer, including activity in heavily pretreated patients and patients previously treated with MVAC or single-agent cisplatin. At a dosage of 300 mg/m(2) daily by continuous infusion for 5 to 7 days every 3 weeks, toxicity has been acceptable in the treatment of patients with refractory disease. Gallium nitrate is also active in combination regimens for advanced bladder cancer. Because it has a different mechanism of action, minimal myelosuppression, and activity in previously treated patients, gallium nitrate may be useful as a single agent in patients with advanced bladder cancer who fail front-line chemotherapy regimens. Evaluation of gallium nitrate in combination with newer agents such as the taxanes or gemcitabine may also be warranted given its activity, different mechanism of action, and non-overlapping toxicity profile.

Antineoplastic Agents↗

PubMed1995

A study of the apical microleakage of a gallium alloy as a retrograde filling material.

The feasibility of utilizing mercury-free Gallium alloy GF for retrograde filling was investigated by comparing apical microleakage in 184 extracted human teeth. The teeth were divided into four experimental and two control groups. Three experimental groups were apical cavity retrofillings with the Gallium alloy GF, a mercury-containing amalgam, and a glass ionomer. The fourth experimental group was filled with gutta-percha and heat-burnished after apicoectomy. After 24 h, 1 wk, 4 wk, and 12 wk immersion in dye solution, the roots were vertically sectioned, and the deepest point of dye penetration was recorded. The glass ionomer showed the least leakage, followed by the amalgam group and the gallium group (no significant difference). The gutta-percha heat-burnished group displayed the greatest leakage. Gallium alloy GF was shown to have an equivalent sealing potential to dental amalgam for a retrograde filling material.

Analysis of Variance↗

PubMed1999

Galvanic interaction between titanium and gallium alloy or dental amalgam.

OBJECTIVES: The objective was to examine in vitro the galvanic interaction between titanium and a high-copper dental amalgam or a gallium-based direct filling alloy at different area ratios, and to relate the observed interactions to the electrochemical characteristics of the alloys. METHODS: The tested materials were cast titanium, a single-composition, spherical high-copper amalgam, and a gallium-based direct filling alloy. Polarization curves were recorded. The galvanic couples were prepared at Ti/filling alloy ratios of 1:1, 2:1, 4:1 and 6:1. The couples were exposed to synthetic saliva at 37 degrees C and the galvanic currents and potentials were measured as a function of time. The results were analyzed by ANOVA and Tukey tests (p < or = 0.05). RESULTS: Freshly abraded titanium initially was anodic to both the amalgam and the gallium alloy, but the polarity reversed after a period of exposure. The galvanic potential and current density increased with the increasing Ti/alloy area ratio. The potential increase was smaller and the current increase larger for the Ga alloy than for the amalgam. The difference was consistent with the polarization characteristics. The galvanic current density was of the order of 10(-8) A/cm2 for the Ti/amalgam couple, and 10(-7) to 10(-6) A/cm2 for the Ti/gallium alloy couple. SIGNIFICANCE: The results show that the galvanic interaction between titanium and direct filling alloys is small. High copper dental amalgams should suffer little galvanic corrosion when in contact with Ti. For gallium direct filling alloys, the galvanic interaction may be more detrimental because of the inherently lower corrosion resistance.

Analysis of Variance↗

PubMed2000

Clinical evaluation and microstructural analysis of a direct placement gallium restorative alloy.

OBJECTIVES: The objective of this study was to assess the clinical performance of a direct placement gallium alloy sealed with an established dentine adhesive system. In addition, microanalysis of a few gallium restorations that failed in clinical service was performed. Clinical factors such as pulpal sensitivity, fracture of the restoration and of the tooth, marginal deterioration, and tarnish were assessed. METHODS: Sixty-five restorations of Galloy and 62 of Tytin (49 and 51 Class II restorations, respectively) were placed according to a predetermined scheme for randomisation in 37 patients by two operators using rubber dam isolation. For the Galloy restorations, the enamel and dentine were etched, and then sealed with PAAMA 2 dentine adhesive according to the manufacturer's instructions. After carving, PAAMA 2 was applied to the Galloy and light-cured. Cavity preparations for Tytin received no adhesive sealer. All restorations were polished at least 24 h post-operatively. Microstructural analysis of retrieved fragments of failed restorations was conducted using electron probe microanalysis. RESULTS: At 1 year, only one Tytin restoration was found to have failed due to an isthmus fracture. The remaining restorations of Tytin were intact with no reported sensitivity. Of the 65 Galloy restorations placed, 28 had to be removed, including restorations in teeth, which were symptomatic, non-vital and/or fractured, and teeth with fractured restorations. Tarnish was present on many of the Galloy restorations. Retrieved fragments of failed Galloy restorations exhibited a dark surface at the pulpal wall interface and small cracks were observed in that surface. Internal cracks and extensive corrosion was observed using the microprobe. Gallium oxides and chlorides were identified as the predominant corrosion products. CONCLUSIONS: The gallium alloy, Galloy, sealed with PAAMA 2 dentine adhesive system demonstrated a high clinical failure rate.

Dental Alloys↗

PubMed1998

Interaction of gallium nitrate with other inhibitors of ribonucleotide reductase: effects on the proliferation of human leukemic cells.

Ribonucleotide reductase, a key enzyme in deoxyribonucleotide synthesis, is an important target for cancer chemotherapy. Drugs that inhibit its individual components may act synergistically to block DNA synthesis. Prior work has established that gallium inhibits the R2 subunit of ribonucleotide reductase. We show that gallium acts synergistically with the ribonucleotide reductase inhibitors gemcitabine and hydroxyurea to inhibit the proliferation of CCRF-CEM cells. In contrast, combinations of gallium with the ribonucleotide reductase inhibitors amidox, didox, or trimidox produced antagonistic effects on cell growth. Spectroscopy analysis revealed that as a result of their metal-binding properties, amidox, didox and trimidox formed complexes with gallium, thus negating potential synergistic actions. Our results have important implications in the design of clinical trials using these ribonucleotide reductase inhibitors in combination.

Antineoplastic Agents↗