The contribution of dental amalgam to urinary mercury excretion in children.

Environ Health Perspect. 2007 Oct;115(10):1527-31

Authors: Woods JS, Martin MD, Leroux BG, DeRouen TA, Leitão JG, Bernardo MF, Luis HS, Simmonds PL, Kushleika JV, Huang Y

BACKGROUND: Urinary mercury concentrations are widely used as a measure of mercury exposure from dental amalgam fillings. No studies have evaluated the relationship of these measures in a longitudinal context in children. OBJECTIVE: We evaluated urinary mercury in children 8-18 years of age in relation to number of amalgam surfaces and time since placement over a 7-year course of amalgam treatment. METHODS: Five hundred seven children, 8-10 years of age at baseline, participated in a clinical trial to evaluate the neurobehavioral effects of dental amalgam in children. Subjects were randomized to either dental amalgam or resin composite treatments. Urinary mercury and creatinine concentrations were measured at baseline and annually on all participants. RESULTS: Treatment groups were comparable in baseline urinary mercury concentration (approximately 1.5 microg/L). Mean urinary mercury concentrations in the amalgam group increased to a peak of approximately 3.2 microg/L at year 2 and then declined to baseline levels by year 7 of follow-up. There was a strong, positive association between urinary mercury and both number of amalgam surfaces and time since placement. Girls had significantly higher mean urinary mercury concentrations than boys throughout the course of amalgam treatment. There were no differences by race in urinary mercury concentration associated with amalgam exposure. CONCLUSIONS: Urinary mercury concentrations are highly correlated with both number of amalgam fillings and time since placement in children. Girls excrete significantly higher concentrations of mercury in the urine than boys with comparable treatment, suggesting possible sex-related differences in mercury handling and susceptibility to mercury toxicity.

PMID: 17938746 [PubMed - in process]

Mercury in human brain, blood, muscle and toenails in relation to exposure: an autopsy study.

Environ Health. 2007;6:30

Authors: Björkman L, Lundekvam BF, Laegreid T, Bertelsen BI, Morild I, Lilleng P, Lind B, Palm B, Vahter M

BACKGROUND: The main forms of mercury (Hg) exposure in the general population are methylmercury (MeHg) from seafood, inorganic mercury (I-Hg) from food, and mercury vapor (Hg0) from dental amalgam restorations. While the distribution of MeHg in the body is described by a one compartment model, the distribution of I-Hg after exposure to elemental mercury is more complex, and there is no biomarker for I-Hg in the brain. The aim of this study was to elucidate the relationships between on the one hand MeHg and I-Hg in human brain and other tissues, including blood, and on the other Hg exposure via dental amalgam in a fish-eating population. In addition, the use of blood and toenails as biological indicator media for inorganic and organic mercury (MeHg) in the tissues was evaluated. METHODS: Samples of blood, brain (occipital lobe cortex), pituitary, thyroid, abdominal muscle and toenails were collected at autopsy of 30 deceased individuals, age from 47 to 91 years of age. Concentrations of total-Hg and I-Hg in blood and brain cortex were determined by cold vapor atomic fluorescence spectrometry and total-Hg in other tissues by sector field inductively coupled plasma-mass spectrometry (ICP-SFMS). RESULTS: The median concentrations of MeHg (total-Hg minus I-Hg) and I-Hg in blood were 2.2 and 1.0 microg/L, and in occipital lobe cortex 4 and 5 microg/kg, respectively. There was a significant correlation between MeHg in blood and occipital cortex. Also, total-Hg in toenails correlated with MeHg in both blood and occipital lobe. I-Hg in both blood and occipital cortex, as well as total-Hg in pituitary and thyroid were strongly associated with the number of dental amalgam surfaces at the time of death. CONCLUSION: In a fish-eating population, intake of MeHg via the diet has a marked impact on the MeHg concentration in the brain, while exposure to dental amalgam restorations increases the I-Hg concentrations in the brain. Discrimination between mercury species is necessary to evaluate the impact on Hg in the brain of various sources of exposure, in particular, dental amalgam exposure.

PMID: 17931423 [PubMed - in process]

[Dental health, mercury and health injuries]

Tidsskr Nor Laegeforen. 2007 Jun 14;127(12):1671

Authors: Aas O, Hilt B

PMID: 17571114 [PubMed - indexed for MEDLINE]

[Health complaints related to dental filling materials]

Tidsskr Nor Laegeforen. 2007 May 31;127(11):1524-8

Authors: Lygre GB, Helland V, Gjerdet NR, Björkman L

BACKGROUND: A wide range of materials is used in dental treatment. To what extent these materials lead to adverse reactions is under dispute. The aim of this study was to investigate whether patients with suspected adverse reactions to dental materials experienced an improvement in health after these materials were replaced. MATERIAL AND METHODS: Information on health complaints related to dental materials was obtained from the Dental Biomaterials Adverse Reaction Unit in Bergen, Norway for 142 patients. A follow-up questionnaire regarding subjective health was sent to these patients 1(1/2) to 2(1/2) years later. A similar questionnaire was sent to a reference group of 800 persons drawn from the general population. RESULTS: The patient group had more health complaints than the reference group (p < 0.001) at baseline. Of the 84 patients who completed the questionnaire (59%) 35 had changed dental materials. Amalgam fillings had been replaced in most of these patients. 23 patients (66%) reported improved health after replacement. Intraoral complaints decreased significantly (p = 0.022), and were most pronounced in patients with lesions in contact with dental materials. The intensity of various health complaints decreased slightly in most patients with replaced dental materials, but the patient group still had significantly higher health complaint indices than the reference group. INTERPRETATION: The intensity of subjective health complaints was reduced after replacement of dental materials, but it was still higher than for a comparable group in the general population. The results indicate that there may be a specific health effect of replacing dental materials, but normal symptom fluctuations over time and placebo effects such as positive effects from expectations and general care from the health personnel may have had an influence.

PMID: 17551559 [PubMed - indexed for MEDLINE]

Analysis of the diametral compressive bond strength between composite resin and amalgam in different stages of oxidation.

Minerva Stomatol. 2007 Apr;56(4):209-13

Authors: Benitez Catirse AB, Oliveira Pagnano V, Da Silva Mello AS, Do Nascimento C, Mardegan Issa JP

AIM: Amalcomp is a technique that combines composite resin to amalgam in restorative procedures to improve esthetics and minimize the negative effects of polymerization on dental tissues. The objective of this in vitro study was to measure the diametral compressive bond strength between Fill Magic composite (Vigodent) versus Permite (DFL) or Velvalloy (SS White) amalgams in different oxidation stages. METHODS: Twenty-four cylinders of each amalgam brand were fabricated using a Teflon matrix and divided into 3 groups according to the immersion period in artificial saliva for oxidation: A (1 day), B (7 days) and C (30 days). After immersion, the amalgam cylinders were bonded to the composite specimens using the Scotch Bond Multi Use Plus (3M) bonding system. Diametral compression assays were then carried out in an EMIC-MEM 2000 universal testing machine set to 0.5 mm/min. Statistical analysis was performed using ANOVA and Tukey's test. RESULTS: The mean recorded strength (MPa) for each oxidation group was: A=9.71, B=8.21 and C=6.98 (A>B = C; P<0.01). Permite (7.24) provided significantly less adhesion to the composite than Velvalloy (9.36; P<0.05). There was no interaction between the factors alloy, resin and time. CONCLUSIONS: Under the conditions of this study, the less oxidized amalgam showed the greatest diametral compressive strength values.

PMID: 17452958 [PubMed - indexed for MEDLINE]

Dental amalgam restorations and children's neuropsychological function: the New England Children's Amalgam Trial.

Environ Health Perspect. 2007 Mar;115(3):440-6

Authors: Bellinger DC, Daniel D, Trachtenberg F, Tavares M, McKinlay S

BACKGROUND: A concern persists that children's exposure to mercury vapor from dental amalgams produces neurotoxicity. OBJECTIVE: Our goal was to compare the neuropsychological function of children, without prior exposure to dental amalgam, whose caries were repaired using either dental amalgam or mercury-free composite materials. METHODS: We conducted a randomized controlled trial involving 534 6- to 10-year-old urban and rural children who were assessed yearly for 5 years using a battery of tests of intelligence, achievement, language, memory, learning, visual-spatial skills, verbal fluency, fine motor function, problem solving, attention, and executive function. RESULTS: Although the mean urinary mercury concentration was greater among children in the amalgam group than the composite group (0.9 vs. 0.6 microg/g creatinine), few significant differences were found between the test scores of children in the two groups. The differences found were inconsistent in direction. Analyses using two cumulative exposure indices--surface years of amalgam and urinary mercury concentration--produced similar results. CONCLUSIONS: Exposure to elemental mercury in amalgam at the levels experienced by the children who participated in the trial did not result in significant effects on neuropsychological function within the 5-year follow-up period.

PMID: 17431496 [PubMed - indexed for MEDLINE]

The effect of disinfectants and line cleaners on the release of mercury from amalgam.

J Am Dent Assoc. 2006 Oct;137(10):1419-25

Authors: Batchu H, Chou HN, Rakowski D, Fan PL

BACKGROUND: Dental practices use disinfectants or line cleaners to flush dental unit wastewater lines to minimize odor generation, remove solid waste particles and remove biofilms in dental unit water lines (DUWLs). METHODS: The authors evaluated 47 disinfectants or line cleaners for their potential to release mercury from amalgam waste. They prepared each product concentration according to the manufacturer's recommendations and gently agitated it along with one amalgam specimen for 24 hours. They filtered the combined decanted liquid and rinse and analyzed it for mercury using modified U.S. Environmental Protection Agency method 245.1. RESULTS: Six preparations released significantly more mercury from amalgam (about 17 to 340 times) than did the deionized water control (P < .001). The amount of mercury released by the other disinfectants/line cleaners was not statistically different from that released by the control. The pH values of all preparations ranged from 1.76 to 12.35. CONCLUSION AND CLINICAL IMPLICATIONS: This study and other published reports have demonstrated that preparations containing chlorine release more mercury from amalgam than did some other products and the deionized water control. As a result, the use of these products is not recommended for treating dental office wastewater lines or DUWLs.

PMID: 17012722 [PubMed - indexed for MEDLINE]

Improvement of eczematous symptoms after removal of amalgam-like metal in alveolar bone.

Bull Tokyo Dent Coll. 2006 Feb;47(1):13-7

Authors: Matsuzaka K, Mabuchi R, Nagasaka H, Yoshinari M, Inoue T

This case report describes a 55-year-old woman with an amalgam-like metal remaining in alveolar bone after root-end sealing in 1964, and who then developed eczematous facial symptoms from 2000 onwards. Removal of the amalgam-like metal material improved the symptoms.

PMID: 16924154 [PubMed - indexed for MEDLINE]

Evaluating amalgam separators using an international standard.

J Am Dent Assoc. 2006 Jul;137(7):999-1005

Authors: Batchu H, Rakowski D, Fan PL, Meyer DM

BACKGROUND: Most amalgam particles generated during placement and removal of amalgam restorations are captured by chair-side traps and suction system traps and filters. Particles not captured can end up in the wastewater discharged from the dental office. Environmental initiatives to reduce the discharge of mercury-containing products such as dental amalgam waste into the environment have sparked interest in the use of amalgam separators. METHODS: The authors used International Organization for Standardization (ISO) Standard 11,143 for Amalgam Separators in a laboratory test to evaluate the amalgam removal efficiency of 13 commercially available amalgam separators and two commercially available filtration devices not marketed as amalgam separators but that have the potential to be used as such. RESULTS: All 13 amalgam separators and the two filtration devices exceeded the ISO Standard 11,143 requirement of 95 percent amalgam removal efficiency. The authors found statistical differences in the efficiency of the separators and filtration devices. No differences were found between the "empty" and "full" conditions for each separator. CONCLUSION AND CLINICAL IMPLICATIONS: This laboratory evaluation shows that amalgam separators and the filtration devices removed at least 97.05 percent of the amalgam in samples with particle-size distribution as specified in ISO Standard 11,143.

PMID: 16803827 [PubMed - indexed for MEDLINE]

Survival of ART and amalgam restorations in permanent teeth of children after 6.3 years.

J Dent Res. 2006 Jul;85(7):622-6

Authors: Frencken JE, Taifour D, van 't Hof MA

The null hypothesis tested was that there is no difference in the survival percentages of all restorations placed through the Atraumatic Restorative Treatment (ART) approach, with high-viscosity glass ionomer, and those produced through the traditional approach, with amalgam (TA), in the permanent dentitions of children after 6.3 years. Using a parallel group design, we randomly assigned a total of 370 children, aged 6 to 9 years, to the ART group and 311 children, also aged 6 to 9 years, to the TA group. Eight dentists placed a total of 1117 single- and multiple-surface restorations. The cumulative survival percentages for ART glass-ionomer restorations were statistically significantly higher than those of amalgam restorations at all time intervals except the first (p < or = 0.044). After 6.3 years, the cumulative survival percentages of ART and amalgam restorations were 66.1% (SE = 3.1%) and 57.0% (SE = 3.3%), respectively. We concluded that the restorations produced with the ART approach, with high-viscosity glass ionomer, survived longer than those produced with the traditional approach, with amalgam, in the permanent teeth of young children.

PMID: 16798862 [PubMed - indexed for MEDLINE]

Mercury(II) ion-selective polymeric membrane sensors for analysis of mercury in hazardous wastes.

Anal Sci. 2006 Jun;22(6):877-81

Authors: Hassan SS, Mahmoud WH, Mohamed AH, Kelany AE

Two novel potentiometric sensors that are highly selective to Hg2+ ions are described. These are based on the use of 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) and tricyclazole (TCZ) as neutral carriers in plasticized poly(vinyl chloride) membranes. Fast Nernstian responses are obtained for Hg2+ ions over the concentration ranges 7.0 x 10(-6) - 1.0 x 10(-2) and 7.7 x 10(-6) - 1.0 x 10(-2) mol l(-1) at pH 1.8 - 3.3 with lower detection limits of 5.0 x 10(-6) and 5.6 x 10(-6) mol l(-1) (approximately 1 microh ml(-1)) and calibration slopes of 30.0 and 29.7 mV decade(-1) with DTNB- and TCZ-based membrane sensors, respectively. Validation of the assay method reveals good performance characteristics, including long life span, good selectivity for Hg2+ ions over a wide variety of other metal ions, long term response stability, and high reproducibility. Applications for direct determination of mercury in hazardous wastes including dental amalgam, mercury bulbs, and fluorescent lamps give results with good correlation with data obtained using cold vapor atomic absorption spectrometry.

PMID: 16772689 [PubMed - indexed for MEDLINE]

Neurobehavioral effects of dental amalgam in children: a randomized clinical trial.

JAMA. 2006 Apr 19;295(15):1784-92

Authors: DeRouen TA, Martin MD, Leroux BG, Townes BD, Woods JS, Leit&#xE3;o J, Castro-Caldas A, Luis H, Bernardo M, Rosenbaum G, Martins IP

CONTEXT: Dental (silver) amalgam is a widely used restorative material containing 50% elemental mercury that emits small amounts of mercury vapor. No randomized clinical trials have determined whether there are significant health risks associated with this low-level mercury exposure. OBJECTIVE: To assess the safety of dental amalgam restorations in children. DESIGN: A randomized clinical trial in which children requiring dental restorative treatment were randomized to either amalgam for posterior restorations or resin composite instead of amalgam. Enrollment commenced February 1997, with annual follow-up for 7 years concluding in July 2005. SETTING AND PARTICIPANTS: A total of 507 children in Lisbon, Portugal, aged 8 to 10 years with at least 1 carious lesion on a permanent tooth, no previous exposure to amalgam, urinary mercury level <10 microg/L, blood lead level <15 microg/dL, Comprehensive Test of Nonverbal Intelligence IQ > or =67, and with no interfering health conditions. INTERVENTION: Routine, standard-of-care dental treatment, with one group receiving amalgam restorations for posterior lesions (n = 253) and the other group receiving resin composite restorations instead of amalgam (n = 254). MAIN OUTCOME MEASURES: Neurobehavioral assessments of memory, attention/concentration, and motor/visuomotor domains, as well as nerve conduction velocities. RESULTS: During the 7-year trial period, children had a mean of 18.7 tooth surfaces (median, 16) restored in the amalgam group and 21.3 (median, 18) restored in the composite group. Baseline mean creatinine-adjusted urinary mercury levels were 1.8 microg/g in the amalgam group and 1.9 microg/g in the composite group, but during follow-up were 1.0 to 1.5 microg/g higher in the amalgam group than in the composite group (P<.001). There were no statistically significant differences in measures of memory, attention, visuomotor function, or nerve conduction velocities (average z scores were very similar, near zero) for the amalgam and composite groups over all 7 years of follow-up, with no statistically significant differences observed at any time point (P values from .29 to .91). Starting at 5 years after initial treatment, the need for additional restorative treatment was approximately 50% higher in the composite group. CONCLUSIONS: In this study, children who received dental restorative treatment with amalgam did not, on average, have statistically significant differences in neurobehavioral assessments or in nerve conduction velocity when compared with children who received resin composite materials without amalgam. These findings, combined with the trend of higher treatment need later among those receiving composite, suggest that amalgam should remain a viable dental restorative option for children. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00066118.

PMID: 16622140 [PubMed - indexed for MEDLINE]

Neuropsychological and renal effects of dental amalgam in children: a randomized clinical trial.

JAMA. 2006 Apr 19;295(15):1775-83

Authors: Bellinger DC, Trachtenberg F, Barregard L, Tavares M, Cernichiari E, Daniel D, McKinlay S

CONTEXT: No randomized trials have been published that address the concern that inhalation of mercury vapor released by amalgam dental restorations causes adverse health effects. OBJECTIVE: To compare the neuropsychological and renal function of children whose dental caries were restored using amalgam or mercury-free materials. DESIGN AND SETTING: The New England Children's Amalgam Trial was a 2-group randomized safety trial involving 5 community health dental clinics in Boston, Mass, and 1 in Farmington, Me, between September 1997 and March 2005. PARTICIPANTS AND INTERVENTION: A total of 534 children aged 6 to 10 years at baseline with no prior amalgam restorations and 2 or more posterior teeth with caries were randomly assigned to receive dental restoration of baseline and incident caries during a 5-year follow-up period using either amalgam (n=267) or resin composite (n =267) materials. MAIN OUTCOME MEASURES: The primary neuropsychological outcome was 5-year change in full-scale IQ scores. Secondary outcomes included tests of memory and visuomotor ability. Renal glomerular function was measured by creatinine-adjusted albumin in urine. RESULTS: Children had a mean of 15 tooth surfaces (median, 14) restored during the 5-year period (range, 0-55). Assignment to the amalgam group was associated with a significantly higher mean urinary mercury level (0.9 vs 0.6 microg/g of creatinine at year 5, P<.001). After adjusting for randomization stratum and other covariates, no statistically significant differences were found between children in the amalgam and composite groups in 5-year change in full-scale IQ score (3.1 vs 2.1, P = .21). The difference in treatment group change scores was 1.0 (95% confidence interval, -0.6 to 2.5) full-scale IQ score point. No statistically significant differences were found for 4-year change in the general memory index (8.1 vs 7.2, P = .34), 4-year change in visuomotor composite (3.8 vs 3.7, P = .93), or year 5 urinary albumin (median, 7.5 vs 7.4 mg/g of creatinine, P = .61). CONCLUSIONS: In this study, there were no statistically significant differences in adverse neuropsychological or renal effects observed over the 5-year period in children whose caries were restored using dental amalgam or composite materials. Although it is possible that very small IQ effects cannot be ruled out, these findings suggest that the health effects of amalgam restorations in children need not be the basis of treatment decisions when choosing restorative dental materials. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00065988.

PMID: 16622139 [PubMed - indexed for MEDLINE]

Amalgam matrix for class II and class V preparations connected at the proximal box.

J Am Dent Assoc. 2006 Feb;137(2):186-9

Authors: Mamoun JS, Ahmed MK

BACKGROUND: The authors present a technique for placing and reinforcing an amalgam matrix around combined Class II and Class V preparations that connect at the proximal box. OVERVIEW: First, the dentist fills the Class V aspect of the preparation, using a temporary resin-based composite wall at the line angle to support amalgam condensation. The dentist then removes the wall and places a matrix band around the tooth, internally reinforcing the band with smaller pieces of matrix band and resin-saturated cotton balls that are light-polymerized and externally reinforcing the band with fast-polymerizing vinyl polysiloxane. Finally, the dentist condenses the line angle amalgam through the proximal box and condenses the proximal box and occlusal aspects. CONCLUSION: For connected Class II and Class V preparations, this matrix technique permits controlled amalgam condensation, even at the line angle aspect, where it is difficult to condense amalgam without voids or microleakage. CLINICAL IMPLICATIONS: This technique allows dentists to provide a stable, inexpensive direct restoration for teeth with connected Class II and Class V preparations, providing an alternative for patients who do not wish to have crowns placed.

PMID: 16521384 [PubMed - indexed for MEDLINE]

Methylmercury, amalgams, and children's health.

Environ Health Perspect. 2006 Mar;114(3):A149; author reply A149-50

Authors: Guzzi G, Minoia C, Pigatto PD, Severi G

PMID: 16507443 [PubMed - indexed for MEDLINE]

The color differences between different thicknesses of resin veneered over amalgam.

J Contemp Dent Pract. 2005 Nov 15;6(4):38-45

Authors: Al-Jazairy YH, El-Hejazi AA

STATEMENT OF PROBLEM: Composites and compomers are popular in dental practice. However, little is known about their esthetic appearance as veneering restorative materials over amalgam restorations. PURPOSE: This in vitro study was designed to assess the color differences of composite and compomer restorative materials, placed in thicknesses of 1 mm and 2 mm over amalgam. MATERIAL AND METHODS: Thirty six cylindrical Teflon molds were filled with amalgam (13 mm diameter, 2 mm thickness) and stored at 37 degrees C and 100% relative humidity for 7 days. Nine veneers (for each thickness of 1 and 2 mm) were fabricated from four types of tooth-colored restorative material, Dyract AP (DYR), Compoglass F (COMP), Herculite XRV (XRV), and Vitalecense (VIT), over amalgam specimens using Teflon-split molds and following the manufacturers' instructions. A spectrophotometer was used to measure the color difference DeltaE* between the two thicknesses. RESULTS: Color difference DeltaE* values for 1 mm thickness veneers [XRV (2.52), Comp (5.46), VIT (6.73), and DYR (6.88)] were statistically significantly higher than the 2 mm thickness [XRV (1.32), Comp (3.24), VIT (4.89), and DYR (4.83)]. Although the XRV material had the lowest DeltaE* values, no statistically significant difference was found between the two thicknesses. The color measurements at L*, a*, and b* showed most materials became darker in color at either thickness. CONCLUSION: The thicker veneer specimens were found to be closer in color to the controls than the thinner specimens. Only XRV had color differences (DeltaE*) small enough to be considered clinically acceptable (2.52 and 1.32 at 1 mm and 2 mm, respectively). CLINICAL IMPLICATIONS: In this in vitro study the color of XRV was affected the least when veneered on amalgam. Opaquers may be needed to be used with thinner veneers to minimize the effect of amalgam background.

PMID: 16299605 [PubMed - indexed for MEDLINE]

Disinfectants' effect on mercury release from amalgam.

J Am Dent Assoc. 2005 Jul;136(7):915-9

Authors: Roberts HW, Marek M, Kuehne JC, Ragain JC

BACKGROUND: Mercury environmental discharge is under increased scrutiny by the U.S. Environmental Protection Agency (EPA). Dental amalgam should be processed properly to prevent an additional environmental burden. Some processing agencies require that submitted amalgam be noninfectious. Investigations have demonstrated that oxidizing disinfectants mobilize mercury from amalgam into solution and add mercury to the environmental burden if it is disposed of improperly. The authors conducted a study to evaluate the effect of representative disinfectants on amalgam mercury release. METHODS: The authors sized a high-copper spherical amalgam alloy to match that typically found in dental unit suction traps. They exposed 20 grams of the alloy to several disinfectant solutions and evaluated the filtered supernatant solution for mercury content. RESULTS: Chlorine disinfectant materials discharged the most mercury ions, followed by bromide, iodophor, peroxide/peracetic acid and phenolic disinfectants. The quaternary ammonium compound did not discharge mercury ions above the detection limit (0.2 parts per billion) into solution. CONCLUSIONS: A quaternary ammonium compound did not mobilize mercury ions into solution when used as a disinfectant agent for amalgam. Chlorine disinfectants mobilized mercury ions the most, followed by bromide, iodophor, peroxide/peracetic acid and phenolic disinfectants. CLINICAL IMPLICATIONS: Dentists are obligated to be good environmental stewards and should follow practices that reduce environmental mercury release. Dental personnel should be aware that oxidizing disinfectants mobilize mercury ions into solution, which will be added to the environment if they are processed improperly. If required by processing, dental personnel should consider the different oxidizing effects of commonly used disinfectants.

PMID: 16060472 [PubMed - indexed for MEDLINE]

Teeth with large amalgam restorations and crowns: factors affecting the receipt of subsequent treatment after 10 years.

J Am Dent Assoc. 2005 Jun;136(6):738-48; quiz 805-6

Authors: Kolker JL, Damiano PC, Caplan DJ, Armstrong SR, Dawson DV, Jones MP, Flach SD, Warren JJ, Kuthy RA

BACKGROUND: The authors evaluated the factors associated with the receipt of subsequent treatment by teeth restored with a large amalgam restoration or a large amalgam restoration and crown restoration after 10 years. METHODS: The authors used retrospective data from the University of Iowa College of Dentistry (Iowa City, Iowa) administrative database and patient records to evaluate patient and tooth factors for their association with the two primary outcomes: receipt of any subsequent treatment and receipt of catastrophic treatment (extraction, endodontic therapy). RESULTS: The authors followed 518 teeth over a 10-year period (49 percent with large amalgam restorations and 51 percent with crowns). Sixty-four percent of the large amalgam restorations and 32 percent of the crowns received subsequent treatment during the 10 years. In addition to restoration type, the patient's sex, history of grinding teeth and having a broken tooth were related to the tooth's receiving subsequent treatment. Twenty-two percent of large amalgam restorations and 12 percent of crowns received catastrophic treatment with the odds of teeth with large amalgam restorations receiving a catastrophic treatment being 2.1 times the odds of teeth with crowns receiving catastrophic treatment. CONCLUSIONS: Teeth with crowns were less likely to receive any treatment or catastrophic treatment over 10 years than were teeth with large amalgam restorations. Patient and tooth factors also were related to a tooth experiencing subsequent treatment. CLINICAL IMPLICATIONS: Teeth with crowns received less subsequent treatment than teeth with large amalgam restorations. This could be related to both the difference in longevity between the two restorations, as well as how appropriately treatment was planned for each procedure. Cost differences between the two restorations need to be factored into the decision-making process.

PMID: 16022038 [PubMed - indexed for MEDLINE]

Urinary mercury concentrations associated with dental restorations in adult women aged 16-49 years: United States, 1999-2000.

Occup Environ Med. 2005 Jun;62(6):368-75

Authors: Dye BA, Schober SE, Dillon CF, Jones RL, Fryar C, McDowell M, Sinks TH

BACKGROUND: Mercury amalgam dental restorations have been used by dentists since the mid 19th century and issues on safety continue to be periodically debated within the scientific and public health communities. Previous studies have reported a positive association between urine mercury levels and the number of dental amalgams, but this relation has never been described in a nationally representative sample in the United States. AIMS AND METHODS: Using household interview, dietary interview, dental examination, and laboratory data from the 1999-2000 National Health and Nutrition Examination Survey (NHANES), the association between mercury concentrations and dental restorations was examined in US women of reproductive age. RESULTS: In women of childbearing age, approximately 13% of all posterior dental surfaces were restored with amalgams and the average urinary mercury level in women was low (1.34 microg/l). It is estimated that an increase of 1.8 microg/l in the log transformed values for mercury in urine would occur for each 10 dental surfaces restored with amalgam. CONCLUSIONS: Although the findings do not address the important issues of adverse health effects at low thresholds of mercury exposure, they do provide important reference data that should contribute significantly to the ongoing scientific and public health policy debate on the use of dental amalgams in the USA.

PMID: 15901883 [PubMed - indexed for MEDLINE]

Mercury from dental amalgam: looking beyond the average.

Occup Environ Med. 2005 Jun;62(6):352-3

Authors: Barregard L

PMID: 15901879 [PubMed - indexed for MEDLINE]

Periapical surgery using the ultrasound technique and silver amalgam retrograde filling. A study of 71 teeth with 100 canals.

Med Oral Patol Oral Cir Bucal. 2005;10 Suppl 1:E67-73

Authors: Mart&#xED;-Bowen E, Peñarrocha-Diago M, García-Mira B

INTRODUCTION: Periapical surgery using ultrasound allows the treatment of root canals of difficult access, with the sacrifice of little root tissue. As a result, periapical disorders which were condemned to treatment failure in the past can now be dealt with successfully. MATERIAL AND METHODS: In 71 teeth presenting 100 root canals treated with ultrasound and subjected to retrograde filling with silver amalgam, the course and short-term success of management was evaluated in relation to lesion size, the magnitude of apical resection, and the size of the retrograde filling cavity. The duration of follow-up was one year, with post-treatment controls after 6 and 12 months. RESULTS: After 6 months, the percentage clinical and radiological success was 92% and 58%, respectively. One year after periapical surgery the corresponding percentages were 95% and 80%. Global success after 6 months was 63%, versus 84.2% after 12 months. No statistically significant relation was observed between treatment success and the size of the periapical lesion, the amount of apex resected, or the size of retrograde filling. CONCLUSION: Periapical surgery using ultrasound and retrograde filling with silver amalgam affords a high success rate after 12 months.

PMID: 15800469 [PubMed - indexed for MEDLINE]

Mercury exposure from dental filling placement during pregnancy and low birth weight risk.

Am J Epidemiol. 2005 Apr 15;161(8):734-40

Authors: Hujoel PP, Lydon-Rochelle M, Bollen AM, Woods JS, Geurtsen W, del Aguila MA

Several European countries have guidelines suggesting that women should not receive mercury-containing dental amalgam fillings during pregnancy. One concern raised by several studies is that mercury exposure during pregnancy may lead to decreased birth weight. A population-based, case-control study was designed to investigate whether placement of mercury-containing fillings in 1993-2000 during pregnancy increased the low-birth-weight risk. Cases and controls were sampled from enrollees of a dental insurance plan with live singleton births in Washington State; 1,117 women with low-birth-weight infants (< 2,500 g) were compared with a random sample of 4,468 women with infants weighing 2,500 g or more. The results indicated that 13% of a dentally insured population had one or more restorative procedures during pregnancy that, regardless of chemical composition, did not increase the low-birth-weight risk (odds ratio = 0.96, 95% confidence interval: 0.88, 1.05). The 4.9% of the women (n = 249) who had at least one mercury-containing amalgam filling during pregnancy were not at an increased risk for a low-birth-weight infant (odds ratio = 0.75, 95% confidence interval: 0.45, 1.26) and neither were women who had 4-11 amalgam fillings placed (odds ratio = 1.00, 95% confidence interval: 0.27, 3.68). This study found no evidence that mercury-containing dental fillings placed during pregnancy increased low-birth-weight risk.

PMID: 15800265 [PubMed - indexed for MEDLINE]

Longevity of posterior tooth dental restorations.

J Am Dent Assoc. 2005 Feb;136(2):201-3

Authors: Christensen GJ

Several forms of restorative techniques are used for posterior teeth. They vary significantly in cost and longevity. The following restorative concepts are the most commonly used: amalgam, resin-based composite, PFM, cast gold alloy restorations and all-ceramic restorations. I suggest that patients be informed about the potential longevity of restorative treatment for posterior teeth as they make decisions about treatment for their oral restorative needs.

PMID: 15782524 [PubMed - indexed for MEDLINE]

Immunolocalization of HLA-DR and metallothionein on amalgam tattoos.

Braz Dent J. 2004;15(2):99-103

Authors: Leite CM, Botelho AS, Oliveira JR, Cardoso SV, Loyola AM, Gomez RS, Vaz RR

Despite studies concerning toxic reactions related to amalgam components in the literature, few studies have been devoted to evaluate local noxious effects of amalgam tattoos (AT) on biological tissues. In addition, little is known about activation of inflammatory cells by mucosa-implanted amalgam debris. Tissue reaction to AT depends on the particle size. Human leukocyte antigen DR (HLA-DR) is an activation marker of inflammatory cells associated with antigen presentation. Metallothioneins (MT) are proteins involved with metal detoxication, including mercury and silver. The purpose of the present study was to investigate the immunolocalization of HLA-DR and MT in AT with large or powdered particles. Paraffin-embedded AT tissue blocks were sectioned and subjected to immunohistochemistry for HLA-DR and MT localization. The results demonstrated a dense mononuclear inflammatory infiltrate associated with large and powdered debris and positivity for HLA-DR and MT in inflammatory cells. While blood vessel walls and connective fibers impregnated with powdered particles were negative for HLA-DR, they were positive for MT. In addition, wherever epithelial basement membrane impregnation by powdered amalgam particles was observed, a strong positivity for MT was detected. These findings demonstrate that residual elements of AT still have noxious local effects over tissues.

PMID: 15776190 [PubMed - indexed for MEDLINE]

Oral lichen planus and allergy to dental amalgam restorations.

Arch Dermatol. 2004 Dec;140(12):1434-8

Authors: Laeijendecker R, Dekker SK, Burger PM, Mulder PG, Van Joost T, Neumann MH

OBJECTIVES: To determine contact allergies in patients with oral lichen planus and to monitor the effect of partial or complete replacement of amalgam fillings following a positive patch test reaction to ammoniated mercury, metallic mercury, or amalgam. DESIGN: In group A (20 patients), the oral lesions were confined to areas in close contact with amalgam fillings. In group B (20 patients), the lesions extended 1 cm beyond the area of contact with amalgam fillings. In group C (20 patients), the oral lesions had no topographic relationship with amalgam fillings. Partial or complete replacement of amalgam fillings was recommended if there was a positive patch test reaction to ammoniated mercury, metallic mercury, or amalgam. Control group D (20 patients) had signs of allergic contact dermatitis. RESULTS: Amalgam fillings were replaced in 13 patients of group A, with significant improvement. Dental amalgam was replaced in 8 patients of group B, with significant improvement. In group C, amalgam replacement in 2 patients resulted in improvement in 1 patient. These results were evaluated after 3 months. No positive patch test reactions to mercury compounds were found in patients with concomitant cutaneous lichen planus and in group D. CONCLUSIONS: Contact allergy to mercury compounds is important in the pathogenesis of oral lichen planus, especially if there is close contact with amalgam fillings and if no concomitant cutaneous lichen planus is present. In cases of positive patch test reactions to mercury compounds, partial or complete replacement of amalgam fillings will lead to a significant improvement in nearly all patients.

PMID: 15611418 [PubMed - indexed for MEDLINE]

Lichenoid reaction associated to amalgam restoration.

Med Oral Patol Oral Cir Bucal. 2004 Nov-Dec;9(5):423-4; 421-3

Authors: Segura-Egea JJ, Bull&#xF3;n-Fernández P

Hypersensitivity to mercury associated with amalgam restorations may occur and present in one of two different ways. Most commonly it presents as an oral lichenoid reaction affecting oral mucosa in direct contact with an amalgam restoration and represents a delayed, type IV, cell mediated immune response to mercury or one of the other constituents of the dental amalgam. We report a case of oral lichenoid reaction associated to amalgam restoration. A 38 year-old woman presented a caries lesion of tooth #37. A Blacks class I preparation was performed and filled with amalgam. After 19 months, intra-oral examination revealed atrophic lesion, lightly erythematous, affecting the left buccal mucous. The lesion contacted directly with the amalgam restoration in the lower first molar. The right buccal mucosa was normal. His medical history was unremarkable, he was taking no medication and had no known allergies. However, the patient had felt certain rare sensation in that zone when eating sharp meals. Biopsy showed histological changes compatible with oral lichen planus. The patient decided not to change again the restoration, because she did not have important annoyances and she did not wish to be treated again. Other restorations were performed with composite resins, and no reaction was evidenced in the mucosa.

PMID: 15580119 [PubMed - indexed for MEDLINE]

The timing of subsequent treatment for teeth restored with large amalgams and crowns: factors related to the need for subsequent treatment.

J Dent Res. 2004 Nov;83(11):854-8

Authors: Kolker JL, Damiano PC, Jones MP, Dawson DV, Caplan DJ, Armstrong SR, Flach SD, Kuthy RA, Warren JJ

Crowns and large amalgams protect structurally compromised teeth to various degrees in different situations. The aim of this investigation was to evaluate the survival of teeth with these two types of restorations and the factors associated with better outcomes. Retrospective administrative and chart data were used. Survival was defined and modeled as: (1) receipt of no treatment and (2) receipt of no catastrophic treatment over five- and 10-year periods. Analyses included: Kaplan-Meier survival curves, Log-Rank tests, and Cox proportional hazards regression modeling. Crowns survived longer with no treatment and with no catastrophic treatment; however, mandibular large amalgams were least likely to have survived with no treatment, and maxillary large amalgams were least likely to have survived with no catastrophic treatment. Having no adjacent teeth also decreased survival. Crowns survived longer than large amalgams, but factors such as arch type and the presence of adjacent teeth contributed to the survival of large amalgams.

PMID: 15505235 [PubMed - indexed for MEDLINE]

The prevalence of oral mucosal lesions in U.S. adults: data from the Third National Health and Nutrition Examination Survey, 1988-1994.

J Am Dent Assoc. 2004 Sep;135(9):1279-86

Authors: Shulman JD, Beach MM, Rivera-Hidalgo F

BACKGROUND: Most reports of oral lesion prevalence are based on studies of atypical populations. There are no published studies on oral mucosal lesion prevalence in U.S. adults that are based on a national probability sample. METHODS: The Third National Health and Nutrition Examination Survey, or NHANES III, employed a complex, multistage sample of 33,994 civilian, noninstitutionalized people from 19,528 households. Dentist examiners were trained to recognize, classify and record in a standardized manner the clinical characteristics of each of the 48 conditions of interest to include diagnosis, size, location, surface morphology, color consistency, pain, duration and history using procedures based on the World Health Organization's Guide to Epidemiology and Diagnosis of Oral Mucosal Diseases. RESULTS: Examinations were performed on 17,235 people aged 17 years and older, of whom 4,801 (27.9 percent) had a total of 6,003 lesions. Denture-related lesions (stomatitis, hyperplasia, ulcers, inflammation and angular cheilitis) composed 8.4 percent and tobacco-related lesions (smokeless tobacco-related and nicotinic stomatitis) composed 4.7 percent of all lesions. Discounting denture-related lesions, amalgam tattoos were the most prevalent lesions (3.30 percent), followed closely by cheek/lip bites (3.05 percent) and frictional white lesions (2.67 percent). Smokeless-tobacco users (odds ratio, or OR, = 3.90) and removable denture wearers (OR = 3.57) had the highest odds of having a lesion. CONCLUSION: Lesion prevalences differed significantly by age, sex, race/ethnicity, denture wearing and tobacco use. When lesion-specific prevalences are cited in the literature, they should be stratified by covariates known to be associated with them.

PMID: 15493392 [PubMed - indexed for MEDLINE]

Prevalence of cusp fractures in teeth restored with amalgam and with resin-based composite.

J Am Dent Assoc. 2004 Aug;135(8):1127-32; quiz 1164-5

Authors: Wahl MJ, Schmitt MM, Overton DA, Gordon MK

BACKGROUND: Complete cusp fracture in restored teeth is a common problem observed in general dental practice. Many dentists believe that teeth restored with amalgam are more likely to be associated with cusp fractures than are those restored with resin-based composite. METHODS. The authors noted the condition of 10,869 posterior teeth with amalgam or resin-based composite restorations with at least one cusp present, unrestored or missing in 1,902 consecutively seen adult patients in a private general dental practice. For each patient, the authors recorded age, type of restorations, number of surfaces of each restoration, and presence or absence of a complete cusp fracture and of caries. RESULTS: There was a lower percentage of cusp fractures in younger subjects than in older subjects and in teeth with a single restored surface than in those with more than one restored surface. There was no significant difference in the prevalence of cusp fracture rates in amalgam-restored teeth versus composite-restored teeth in subjects aged 18 through 54 years. In subjects aged 55 through 96 years, there was a marginally significantly greater cusp fracture rate in composite-restored teeth than in those restored with amalgam. Overall, there was no significant difference in the prevalence of cusp fracture in teeth restored with amalgam (1.88 percent) versus composite-restored teeth (2.29 percent). CONCLUSIONS: The prevalence of cusp fractures in amalgam-restored teeth and resin-based composite-restored teeth is not significantly different. Teeth with more than one surface restored with either resin-based composite or amalgam and teeth in older subjects were more likely to suffer a cusp fracture. CLINICAL IMPLICATIONS: Teeth restored with amalgam and with resin-based composite exhibited equally low cusp fracture prevalence. When choosing between amalgam and resin-based composite in consideration of the likelihood of a future cusp fracture, either restorative material is acceptable.

PMID: 15387051 [PubMed - indexed for MEDLINE]

Health effects of dental amalgam exposure: a retrospective cohort study.

Int J Epidemiol. 2004 Aug;33(4):894-902

Authors: Bates MN, Fawcett J, Garrett N, Cutress T, Kjellstrom T

BACKGROUND: Whether dental amalgam fillings (containing mercury) are hazardous is a long-standing issue, with few epidemiological investigations. Allegations have particularly involved nervous system disorders, such as multiple sclerosis, Alzheimer's disease, and chronic fatigue syndrome. This retrospective cohort study, the largest of its kind, contained people in the New Zealand Defence Force (NZDF) between 1977 and 1997. The NZDF has its own dental service, providing all personnel with regular and consistent treatment. Comprehensive treatment records are maintained and archived. METHODS: Yearly dental treatment histories, including amalgam filling placements, were compiled from individual records. To minimize amalgam exposure misclassification the cohort was restricted to people who, at NZDF entry, were aged <26 years and had all their posterior teeth. The cohort was linked with morbidity records. Data were analysed with a proportional hazards model, using a time-varying exposure unit of 100 amalgam surface-years. RESULTS: The final cohort contained 20 000 people, 84% males. Associations with medical diagnostic categories, particularly disorders of the nervous system and kidney, were examined. Of conditions allegedly associated with amalgam, multiple sclerosis had an adjusted hazard ratio (HR) of 1.24 (95% CI: 0.99, 1.53, P = 0.06), but there was no association with chronic fatigue syndrome (HR = 0.98, 95% CI: 0.94, 1.03), or kidney diseases. There were insufficient cases for investigation of Alzheimer's or Parkinson's diseases. CONCLUSIONS: Results were generally reassuring, and provide only limited evidence of an association between amalgam and disease. Further follow-up of the cohort will permit investigation of diseases more common in the elderly.

PMID: 15155698 [PubMed - indexed for MEDLINE]

Occupational hazards among clinical dental staff.

J Contemp Dent Pract. 2004 May 15;5(2):134-52

Authors: Fasunloro A, Owotade FJ

Although identification of risks to dental healthcare workers has been explored in several industrialized nations, very little data is available from developing countries. This paper examines the occupational hazards present in the dental environment and reports survey results concerning attitudes and activities of a group of Nigerian dental care providers. A survey on occupational hazards was conducted among the clinical dental staff at the Dental Hospital of the Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife in Osun State, Nigeria. Thirty eight of the forty staff responded, yielding a response rate of 95%. Subject ages ranged from 26 to 56 years with approximately 25% in the 31-46 year old bracket. All of the staff were aware of the occupational exposure to hazards, and the majority had attended seminars/workshops on the subject. Only five staff members (13.2%) owned a health insurance policy and 26 (68.4%) had been vaccinated against Hepatitis B infection. All dentists (24) had been vaccinated compared with only two non-dentists; this relationship was significant (p= 30.07, chi2=0.000). Fourteen members of the clinical staff (36.8%) could recall a sharp injury in the past six months, and the majority (71.1%) had regular contact with dental amalgam. Wearing protective eye goggles was the least employed cross infection control measure, while backache was the most frequently experienced hazard in 47% of the subjects. The need for Hepatitis B vaccinations for all members of the staff was emphasized, and the enforcement of strict cross infection control measures was recommended. The physical activities and body positions that predispose workers to backaches were identified and staff education on the prevention of backaches was provided.

PMID: 15150641 [PubMed - indexed for MEDLINE]

Examiner agreement in the replacement decision of Class I amalgam restorations.

J Contemp Dent Pract. 2004 May 15;5(2):81-92

Authors: Ermis RB, Aydin U

The aim of this study was to investigate interexaminer and intraexaminer agreement in the replacement decision for Class I amalgam restorations. Three examiners evaluated the restorations clinically and with bitewing radiographs. One hundred and twelve restorations were evaluated for secondary caries, body fracture, deficient anatomic form (contour), ditched margins, and marginal overhangs. After one month, the assessments were repeated by the same examiners under the same conditions. Cohen's Kappa analysis was used to analyze the data. The number of replacement decisions varied from 12 to 27 and from 6 to 14 at the first and second evaluations, respectively. The Kappa statistics indicated "moderate" to "substantial" consistency for interexaminer and intraexaminer agreement in the replacement decisions based on clinical and radiographical examinations. Restorations with deficient anatomic form and marginal overhangs presented the most frequent diagnostic difficulties and lead to disagreement among examiners. The most frequently mentioned reasons for replacement were the restorations had ditched margins at both clinical evaluation periods and secondary caries was detected during radiographical evaluations. In the absence of agreement among examiners, clinical and radiographic guidelines are necessary for replacing Class I amalgam restorations.

PMID: 15150636 [PubMed - indexed for MEDLINE]

Evaluation of the mercury exposure of dental amalgam patients by the Mercury Triple Test.

Occup Environ Med. 2004 Jun;61(6):535-40

Authors: Hansen G, Victor R, Engeldinger E, Schweitzer C

AIMS: To establish and analyse reference data for the mercury burden of patients with and without amalgam fillings. METHODS: Atomic absorption spectroscopy was used to quantify Hg concentrations in the scalp hair and urine (before and after application of dimercaptopropane sulphonate), and Hg release from dental amalgams (using a newly developed, amalgam specific chew test), in 2223 subjects. RESULTS: 50th centiles were 1.3 microg Hg/g creatinine in basal urine, 32 microg Hg/g creatinine after DMPS application, 454 ng Hg/g in hair, and 27 microg Hg per g of chewing gum, which corresponds to about 1 micro g Hg released per minute of chewing. Total Hg intake (from ambient air, drinking water, food, and amalgams) of most patients is well below the provisioned tolerable weekly intake (PTWI) defined by the WHO, unless extremely Hg rich food is consumed on a regular basis. However, for patients exceeding the 75th centile in chew tests, total Hg intake exceeds the PTWI by about 50%, even at the low limit of intake from food. In the absence of occupational exposure, significant Hg release from dental amalgams is a necessary but insufficient condition to obtain a high long term body burden. After removal of dental amalgams, chew tests no longer exhibit oral Hg exposure, while basal urine Hg content and DMPS induced excretion display a exponential decrease (half life about 2 months in both cases). CONCLUSIONS: A standardised procedure for evaluation of the magnitude and origin of the Hg burden of individuals has been developed, which, by comparison with the database presented here for the first time, can serve as a diagnostic tool.

PMID: 15150394 [PubMed - indexed for MEDLINE]

Root-end filling materials alter fibroblast differentiation.

J Dent Res. 2004 May;83(5):408-13

Authors: Bonson S, Jeansonne BG, Lallier TE

Root-end filling materials are commonly used following endodontic surgical procedures; however, their effect on adjacent soft tissues is poorly understood. We predict that, due to the differences in their chemical composition, these materials will have profoundly different effects on the survival and differentiation of fibroblasts. Many of the root-end filling materials examined were initially cytotoxic to both PDL and gingival fibroblasts in co-culture experiments; however, this was reduced after the materials were washed in either mineral trioxide aggregate (MTA) or hybrid ionomere composite resin (HICR) for 2 wks. Additionally, PDL fibroblasts displayed enhanced proliferation on MTA and survival on amalgam when compared with gingival fibroblasts. MTA preferentially induced alkaline phosphatase expression and activity in both PDL and gingival fibroblasts. In contrast, HICR inhibited alkaline phosphatase expression and activity. In addition, MTA and HICR repressed pleiotrophin in PDL fibroblasts, while HICR repressed periostin in both fibroblasts. Thus, root-end filling materials differentially affect periodontal fibroblast differentiation. Abbreviations: mineral trioxide aggregate (MTA), zinc-oxide eugenol cement (ZOEC), hybrid ionomer composite resin (HICR), reverse-transcriptase polymerase chain-reaction (RT-PCR).

PMID: 15111634 [PubMed - indexed for MEDLINE]

Susceptibility of metallothionein-null mice to the behavioral alterations caused by exposure to mercury vapor at human-relevant concentration.

Toxicol Sci. 2004 Jul;80(1):69-73

Authors: Yoshida M, Watanabe C, Satoh M, Yasutake A, Sawada M, Ohtsuka Y, Akama Y, Tohyama C

While recent human studies suggested adverse neurobehavioral outcomes of low-level exposure to mercury vapor (Hg0) as found among those having dental amalgam fillings and dental personnel, past animal experiments only dealt with exposure at much higher mercury concentrations. The present study aimed to examine neurobehavioral effects of prolonged, low-level Hg0 exposure in mice and to evaluate the protective role of metallothionein-I,II (MT-I,II) against Hg0-induced neurotoxicity, using a knock-out strain of mice. Adult female metallothionein-I,II-null (MT-null) and wild-type OLA129/C57BL6 mice were exposed to 0.06 mg/m3 of Hg0 for 8 h per day for 23 weeks. Neurobehavioral effects were evaluated at 12 and 23 weeks of exposure using open-field test and passive avoidance test. Subcellular distribution of mercury and the induction of MT were also assessed. The Hg0 exposure resulted in significantly enhanced locomotion in the open-field test and poorer performance in the passive avoidance test at a brain Hg concentration less than 1 ppm. These effects were slightly exaggerated in MT-null mice, which showed less induction of MT, lower brain Hg concentration, and lower calculated concentration of MT-unbound cytosolic Hg. The results showed, for the first time, that a concentration of Hg0 relevant to human exposure level could cause neurobehavioral effects in adult mice. The higher susceptibility of MT-null mice suggested that MT-I,II have protective roles in the metal-induced neurobehavioral toxicity, which cannot be entirely explained by kinetic mechanisms, thus suggesting an involvement of nonkinetic mechanisms.

PMID: 15071173 [PubMed - indexed for MEDLINE]

[Evaluation of the safety of the dental amalgam]

Shanghai Kou Qiang Yi Xue. 2001 Dec;10(4):369-71

Authors: Wang J, Liu Z

PMID: 14993976 [PubMed]

Effectiveness of single-surface ART restorations in the permanent dentition: a meta-analysis.

J Dent Res. 2004 Feb;83(2):120-3

Authors: Frencken JE, Van 't Hof MA, Van Amerongen WE, Holmgren CJ

Over the past few years, there has been an increase in the number of studies reporting on various aspects of the Atraumatic Restorative Treatment (ART) approach. Five randomized clinical trials in which ART restorations with glass ionomers were compared with amalgam restorations in permanent teeth for a maximum period of 3 yrs constituted the database. This meta-analysis divided the publications into 'early' (1987-1992) and 'late' (1995-) studies on the basis of improvements in the approach. The analysis showed that, in the 'early' studies, single-surface amalgam restorations survived statistically significantly longer than comparable ART restorations after 1, 2, and 3 yrs. This trend did not continue into the late group of studies; no statistically significant difference between the 2 types of restorations was found. Based on the available data, it appears that there is no difference in survival results between single-surface ART restorations and amalgam restorations in permanent teeth over the first 3 yrs.

PMID: 14742648 [PubMed - indexed for MEDLINE]

The inhibition of mercury absorption by dietary ethanol in humans: cross-sectional and case-control studies.

Occup Environ Med. 2004 Feb;61(2):e8

Authors: Martin MD, Naleway C

BACKGROUND: Since the inhibition of mercury absorption by ethanol was serendipitously discovered in 1965,(1) a limited number of small number studies with both animal and human subjects have reported results consistent with this finding. AIMS: To investigate this phenomenon in a large scale human study with low level Hg exposed dentists. METHODS: Data were collected for a sample of 1171 dentists, and both cross sectional and case-control methods were utilised to examine the data. RESULTS: Abstainers (n = 345) had significantly higher urinary mercury concentrations (HgU) than drinkers (n = 826): 5.4 microg/l v 4.8 microg/l. Multiple linear regression showed a significant effect of ethanol dose on HgU after adjusting for potential confounders. A case-control analysis in which cases were defined as those individuals with urinary Hg concentrations of > or =15 microg/l (approximately top 5%), and controls as those with concentrations of <1.0 microg/l ( approximately bottom 5%), showed a clear protective dose-response relation; there was a decreasing risk of being a "case" (having an HgU > or =15 microg/l) with increasing ethanol consumption. The significance of the adjusted model is p<0.001, and the chi2 test for trend across ethanol consumption categories in the adjusted model is p<0.05, confirming the dose-response relation. CONCLUSION: We believe that this straightforward investigation provides the first specific confirmation in a large scale human study of the inhibitory effect of ethanol on urinary mercury concentration, and by inference, on mercury absorption.

PMID: 14739392 [PubMed - indexed for MEDLINE]

An in vitro study into the corrosion of intra-oral magnets in the presence of dental amalgam.

Eur J Orthod. 2003 Dec;25(6):615-9

Authors: Noar JH, Evans RD, Wilson D, Costello J, Ioannou E, Ayeni A, Mordan NJ, Wilson M, Pratten J

The aim of this investigation was to study the corrosion behaviour and products of uncoated neodymium-iron-boron magnets in the presence of dental amalgam. Microcosm plaques were grown on discs of neodymium-iron-boron magnets or amalgam in a constant depth film fermentor. The biofilms were supplied with artificial saliva and growth was determined by viable counting. The results showed that the neodymium-iron-boron magnets corroded with an average daily weight loss of 0.115 +/- 0.032 per cent. However, when the magnets were in close proximity to the amalgam the amount of corrosion was reduced to a daily loss of 0.066 +/- 0.023 per cent. The highest loss of constituent elements from the corrosion products of the magnets was observed for iron. The composition of the microcosm plaques altered markedly between the two materials with less streptococci and more Veillonella spp. present in the biofilms grown on magnets in the presence of amalgam. The corrosion of neodymium-iron-boron magnets is limited and in the presence of amalgam is reduced further. This suggests that amalgam present in the mouth will not cause an increased clinical risk in terms of biocompatibility with neodymium-iron-boron magnets.

PMID: 14700268 [PubMed - indexed for MEDLINE]

Dental mercury hygiene recommendations.

J Am Dent Assoc. 2003 Nov;134(11):1498-9

Authors:

BACKGROUND: The ADA has long recognized the importance of observing proper mercury hygiene practices for the safety of dental professionals. In 1999, the ADA Council on Scientific Affairs adopted mercury hygiene recommendations to provide guidance to dentists and their staff members for safe handling of mercury and dental amalgam. These mercury hygiene recommendations have been developed to update those previously adopted by the Council. OVERVIEW: In addition to discussing sources of mercury in the dental office, this Council report describes office engineering considerations and hygiene recommendations to be used during preparation and placement of dental amalgam restorations. New information included in this report covers the management of mercury spills. PRACTICE IMPLICATIONS: These recommendations are intended to provide guidance to the dental practitioner in ensuring the safety of personnel who handle dental amalgam and in minimizing the release of mercury into the dental office environment.

PMID: 14664270 [PubMed - indexed for MEDLINE]

Galvanic interaction between gold and amalgam: effect of zinc, time and surface treatments.

J Am Dent Assoc. 2003 Nov;134(11):1463-7

Authors: Walker RS, Wade AG, Iazzetti G, Sarkar NK

BACKGROUND: Previous studies have investigated the electrolytic action of oral electrogalvanism. However, the reasons why certain treatments or materials are successful in reducing galvanic current have not been addressed fully. This study assessed galvanic current with several materials, surface conditions and treatments. METHODS: The authors measured galvanic currents between a type 3 cast gold alloy and Dispersalloy Dispersed Phase Alloy (zinc) (Dentsply Caulk, Milford, Del.) under different surface conditions using a zero-resistance-ammeter technique in a synthetic saliva solution for 10 hours. In addition, the galvanic currents between the same gold and Tytin alloy (non-zinc) (Kerr, Orange, Calif.), experimental zinc alloy (same makeup as that of Tytin, with the addition of zinc) and non-zinc dispersed-phase experimental alloy (essentially the same physical and chemical makeup as that of Dispersalloy, with the exclusion of zinc) were measured. Triplicate tests were performed for each condition. RESULTS: The statistical analysis indicated that electrogalvanic activity is reduced significantly when the amalgam surface is treated with tin oxide or silver nitrate. Both zinc-containing amalgams in their as-carved condition exhibited higher anodic charge densities than did their zinc-free counterparts. Galvanic current measured in Dispersalloy was reduced with the passage of time after carving. CONCLUSION: Galvanic interaction between cast gold and amalgam is reduced with time and surface treatments, but is increased considerably when the amalgam contains zinc. CLINICAL IMPLICATIONS: Amalgam restorations containing zinc that are in contact with gold restorations occasionally elicit galvanic pain. Selection of a non-zinc-containing amalgam will reduce the level of galvanic interaction. Galvanic pain from occlusal contact is reduced or eliminated when the restoration is brushed with tin oxide immediately after carving or is treated with 2 percent silver nitrate. Some patients may benefit from having their teeth separated with nonconducting rubber dam material.

PMID: 14664264 [PubMed - indexed for MEDLINE]

[The effect of pit and fissure sealants in teeth filling with silver amalgam]

Shanghai Kou Qiang Yi Xue. 2003 Jun;12(3):237-8

Authors: Yu YM, Liu XH, Li DL

PMID: 14661344 [PubMed - indexed for MEDLINE]

Dynamic maneuvers in local staging of head and neck malignancies with current imaging techniques: principles and clinical applications.

Radiographics. 2003 Sep-Oct;23(5):1201-13

Authors: Henrot P, Blum A, Toussaint B, Troufleau P, Stines J, Roland J

Imaging has been widely demonstrated to be important in local staging of head and neck malignancies as a complement to clinical examination, including endoscopy. Recent developments in multidetector row computed tomography (CT) provide better anatomic resolution within a shorter acquisition time and wider anatomic coverage. However, in many cases lesions still remain undefined. In such cases, performance of dynamic maneuvers could provide useful information about the local extent of a tumor. The usefulness of dynamic maneuvers has increased with the improvement in temporal and spatial resolution that resulted from the most recent techniques of multidetector row CT. The puffed cheek technique and the modified Valsalva maneuver allow evaluation of a lesion that was poorly demonstrated owing to apposition of mucosal surfaces. In some cases, phonation improves demonstration of small lesions of the vocal cords and allows more precise anatomic localization. The open mouth technique allows demonstration of a lesion that was previously overlooked due to dental amalgam artifacts.

PMID: 12975510 [PubMed - indexed for MEDLINE]

Purchasing, installing and operating dental amalgam separators: practical issues.

J Am Dent Assoc. 2003 Aug;134(8):1054-65

Authors: McManus KR, Fan PL

BACKGROUND: Growing environmental concern over the accumulation of mercury in some fish has led some state and local environmental agencies to pursue stricter regulation of mercury in wastewater. Dental offices are an identifiable source of mercury in the form of dental amalgam. Although mercury in dental amalgam is not immediately bioavailable (that is, it has not been shown to contribute significantly to the problem of mercury in fish tissue), environmental agencies in some locales are asking dental offices to install amalgam separators in an effort to reduce amalgam discharges beyond those already achieved through chairside traps and vacuum filters. Field experience indicates that the configuration and operation of the dental office infrastructure can significantly affect the choice of separator, as well as the operation and maintenance of the installed equipment. OVERVIEW: The authors review factors related to office infrastructure and operation that dentists should consider when investing in an amalgam separator. They also provide a cost-analysis worksheet and checklist that may be useful to dentists who are considering purchasing a separator. CONCLUSIONS AND CLINICAL IMPLICATIONS: Before purchasing or installing an amalgam separator, dentists should consider factors specific to the available models, including size and maintenance requirements. In addition, office-specific actors should be considered (such as the plumbing configuration, available space for installation and subsequent access to that space for equipment replacement and maintenance). Dentists also should research whether any local or state regulations exist that might influence product selection or installation. Dentists should consider the effect an amalgam separator could have on existing suction equipment. Finally, dentists will want to consider the short- and long-term costs (including maintenance and parts replacement) of the available options.

PMID: 12956345 [PubMed - indexed for MEDLINE]

Radiation dose to the lens of eye and thyroid gland in paranasal sinus multislice CT.

Br J Radiol. 2003 Jun;76(906):418-20

Authors: Zammit-Maempel I, Chadwick CL, Willis SP

CT has become an established examination in the evaluation of the paranasal sinuses. Until recently this was achieved by the direct coronal technique on conventional and single slice helical scanners. With the advent of multislice technology, thin slice axial CT with excellent coronal and sagittal reconstructions is now the norm. We describe a study designed to evaluate the radiation dose to the lens of the eye and thyroid gland in the axial and coronal planes on a Siemens Volume Zoom quad slice scanner at 140 kV and effective mAs of 100 using 1 mm collimation. Thermoluminescent dosimeters were placed on the eyelid and thyroid gland of 29 patients scanned axially in the supine position and a further 28 patients scanned coronally in the prone position with gantry tilt. The results show mean doses of 35.1 mGy (lens) and 2.9 mGy (thyroid gland) in the coronal plane compared with 24.5 mGy (lens) and 1.4 mGy (thyroid gland) in the axial plane. Results obtained from a head phantom and from using the ImPACT CT dose calculator were comparable. The kV and mAs were then reduced to 120 and 40, respectively, and the axial study repeated using the head phantom and predicted doses using the ImPACT CT dose calculator. The low dose scanning technique revealed a lens dose of 9.2 mGy and thyroid dose of 0.4 mGy. The eye dose on a multislice scanner is still substantially less than the threshold dose of 0.5-2 Gy for detectable lens opacities. These results indicate that, in addition to the established perceived advantages of multislice axial sinus CT, i.e. patient comfort, no artefact from dental amalgam and reproducible true coronal images, should be included a decreased radiation dose to both the eye lens and thyroid gland compared with direct coronal scanning.

PMID: 12814929 [PubMed - indexed for MEDLINE]

Direct and indirect restorative materials.

J Am Dent Assoc. 2003 Apr;134(4):463-72

Authors:

BACKGROUND: In recent years, dentistry has benefited from a marked increase in the development of esthetic materials, including ceramic and plastic compounds. But the advent of these new materials has not eliminated the usefulness of more traditional restorative materials such as gold, base metal alloys and dental amalgam. OVERVIEW: This report outlines important features of direct and indirect restoratives, with an emphasis on the safety and efficacy of each material. CONCLUSIONS AND PRACTICE IMPLICATIONS: This article was developed to help dentists explain to their patients the relative pros and cons of various materials used in dental restorations, which include fillings, crowns, bridges and inlays. The weight of the scientific evidence indicates that all of these materials are safe and effective for their intended use. Patients, in consultation with their dentists, are free to choose the most appropriate among them for their particular needs.

PMID: 12733780 [PubMed - indexed for MEDLINE]

Mercury derived from dental amalgams and neuropsychologic function.

Environ Health Perspect. 2003 May;111(5):719-23

Authors: Factor-Litvak P, Hasselgren G, Jacobs D, Begg M, Kline J, Geier J, Mervish N, Schoenholtz S, Graziano J

There is widespread concern regarding the safety of silver-mercury amalgam dental restorations, yet little evidence to support their harm or safety. We examined whether mercury dental amalgams are adversely associated with cognitive functioning in a cross-sectional sample of healthy working adults. We studied 550 adults, 30-49 years of age, who were not occupationally exposed to mercury. Participants were representative of employees at a major urban medical center. Each participant underwent a neuropsychologic test battery, a structured questionnaire, a modified dental examination, and collection of blood and urine samples. Mercury exposure was assessed using a) urinary mercury concentration (UHg); b) the total number of amalgam surfaces; and c) the number of occlusal amalgam surfaces. Linear regression analysis was used to estimate associations between each marker of mercury exposure and each neuropsychologic test, adjusting for potential confounding variables. Exposure levels were relatively low. The mean UHg was 1.7 micro g/g creatinine (range, 0.09-17.8); the mean total number of amalgam surfaces was 10.6 (range, 0-46) and the mean number of occlusal amalgam surfaces was 6.1 (range, 0-19). No measure of exposure was significantly associated with the scores on any neuropsychologic test in analyses that adjusted for the sampling design and other covariates. In a sample of healthy working adults, mercury exposure derived from dental amalgam restorations was not associated with any detectable deficits in cognitive or fine motor functioning.

PMID: 12727600 [PubMed - indexed for MEDLINE]

[Mercury and health in the dental practice]

Rev Saude Publica. 2003 Apr;37(2):266-72

Authors: Morales Fuentes I, Reyes Gil R

Mercury is a heavy metal widely used by man. It is considered very toxic causing conditions in the central nervous system, behavior disturbances, and renal and sexual disorders. For a century, mercury has been used in the dental practice for its capacity of joining metals (amalgamate), its low cost and its rapid fixing in dental pieces repair. Currently, there is much controversy about the safety of dental amalgams and it has been demonstrated it poses occupational risks to dental practitioners and their assistants. The objective of this study is review aspects related to metallic mercury toxicity for personnel involved in the dental practice and patients with dental amalgams. Routes of mercury exposure in dentistry, occupational risks and measures to prevent mercury poisoning are presented here. A literature review was conducted mostly on data from Biological Abstracts and the Science Citation Index for the period between 1990 and 2000.

PMID: 12700853 [PubMed - indexed for MEDLINE]

Methyl mercury and inorganic mercury in Swedish pregnant women and in cord blood: influence of fish consumption.

Environ Health Perspect. 2003 Apr;111(4):637-41

Authors: Bj&#xF6;rnberg KA, Vahter M, Petersson-Grawé K, Glynn A, Cnattingius S, Darnerud PO, Atuma S, Aune M, Becker W, Berglund M

We studied exposure to methyl mercury (MeHg) in Swedish pregnant women (total mercury [T-Hg] in hair) and their fetuses (MeHg in cord blood) in relation to fish intake. The women were recruited at antenatal care clinics in late pregnancy to participate in an exposure study of environmental pollutants. Fish consumption was evaluated using food frequency questionnaires including detailed questions on fish consumption. In addition, we determined inorganic mercury (I-Hg) and selenium (Se) in cord blood. On average, the women consumed fish (all types) 6.7 times/month (range 0-25 times/month) during the year they became pregnant. They reported less consumption of freshwater fish--species that might contain high concentrations of MeHg--during than before pregnancy. T-Hg in maternal hair (median 0.35 mg/kg; range 0.07-1.5 mg/kg) was significantly associated (R2 = 0.53; p < 0.001) with MeHg in cord blood (median 1.3 microg/L; range 0.10-5.7 microg/L). Both hair T-Hg and cord blood MeHg increased with increasing consumption of seafood (r = 0.41; p < 0.001 and r = 0.46; p < 0.001, respectively). Segmental hair analysis revealed that T-Hg closer to the scalp was lower and more closely correlated with MeHg in cord blood than T-Hg levels in segments corresponding to earlier in pregnancy. We found a weak association between Se (median 86 microg/L; range 43-233 microg/L) and MeHg in cord blood (r = 0.26; p = 0.003), but no association with fish consumption. I-Hg in cord blood (median 0.15 microg/L; range 0.03-0.53 microg/L) increased significantly with increasing number of maternal dental amalgam fillings.

PMID: 12676628 [PubMed - indexed for MEDLINE]

Works in progress: a comparison of dental school experiences between passing and failing NERB candidates, 2001.

J Dent Educ. 2003 Mar;67(3):311-6

Authors: Ranney RR, Wood M, Gunsolley JC

The purpose of this report is to compare outcomes on the North East Regional Board of Dental Examiners (NERB) clinical examination to selected measures of academic performance in one U.S. dental school. The data came from results of the spring 2001 NERB examination at that school. Five measures of academic performance--number of Class II amalgam restorations completed, number of Class III/IV composite restorations completed, fixed prosthodontic units performed, fourth-year class rank, and GPA-were compared between those who passed and those who failed NERB's restorative exercise (RESTOR) and provisional fixed partial denture exercise (SIM). Analyses could not confirm a positive relationship between the school performance measures and the NERB outcome of passing RESTOR on the first attempt. On the other hand, those who passed SIM on the first attempt had, on the average, performed more amalgams, composites, and fixed prosthodontic units as students than those who failed; they also had, on average, better class rank and higher GPA. Therefore, only performance on SIM related to performance in school. However, both RESTOR and SIM had a similar number of failures from the top as well as the bottom portions of the class. These preliminary data from one dental school class raise questions about the validity of the NERB clinical examination for licensure decisions.

PMID: 12665060 [PubMed - indexed for MEDLINE]