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Mercury Release from Dental Amalgam


The IADR/AADR/CADR 80th General Session (March 6-9, 2002) San Diego, California

http://iadr.confex.com/iadr/2002SanDiego/techprogram/index.html

Dental Materials: VII - Others-Metallic

http://iadr.confex.com/iadr/2002SanDiego/techprogram/session_1455.htm

11:00 AM-12:15 PM San Diego Convention Center Exhibit Hall C, Poster Session

Amalgam

3438 Effect of Composition on Mercury Vapor Release from Pd-Containing Amalgams
A.L. NEME1, J.L. FERRACANE2, and B.B. MAXSON1, 1 University of Detroit Mercy, USA, 2 Oregon Health & Science University, USA
3439 Mercury Vapor Release in Various Capsule Designs
J.T. VETTRAINO, and A.L. NEME, University of Detroit Mercy, USA
3440 Hg Release After Abrasion of Pd-Containing Amalgams with Varied Cu
J.L. FERRACANE1, J.D. ADEY1, and T. OKABE2, 1 Oregon Health & Science University, USA, 2 Baylor College of Dentistry, Texas A&M University System, Health Science Center, USA
3441 The Effect of Bleaching Agents on Mercury Release from Spherical Dental Amalgam
F.J. CERTOSIMO, F.J. ROBERTELLO, M.V. DISHMAN, R.E. BOGACKI, and M. WEXEL, Virginia Commonwealth University, USA
3442 TCLP Analysis and Residual Mercury Levels in Dental Wastewater Lines
M.E. STONE, J.C. KUEHNE, R.S. KARAWAY, J.M. GULLETT, and J.C. RAGAIN, Jr., Naval Dental Research Institute, USA
3443 Evaluation of an amalgam under AFM after Nd:YAG laser appliction
M. TANASIEWICZ, and T. KUPKA, Silesian University of Medicine, Poland
3444 WITHDRAWN
3445 Longitudinal assessments of urinary mercury levels in the Casa Pia Study
M.D. MARTIN1, B.G. LEROUX1, T. BENTON1, J. LEITAO2, M. BERNARDO2, H. SOARES LUIS2, N. BRAVEMAN3, J.S. WOODS1, L. SIMMONDS1, and T.A. DEROUEN1, 1 University of Washington, USA, 2 University of Lisbon, Portugal, 3 National Institute of Dental and Craniofacial Research, USA
3446 Effects of compositional variations of dental gallium alloys on corrosion and mechanical properties
Y.-J. PARK1, Y.-R. LEE1, D.-J. LEE1, B.K. NORLING2, and H.R. RAWLS2, 1 Chonnam National University, South Korea, 2 University of Texas Health Science Center at San Antonio, USA

 

3438 Effect of Composition on Mercury Vapor Release from Pd-Containing Amalgams
A.L. NEME1, J.L. FERRACANE2, and B.B. MAXSON1, 1 University of Detroit Mercy, USA, 2 Oregon Health & Science University, USA

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_13180.htm

The addition of a small amount of Pd has been shown to reduce mercury release from amalgam during setting (Neme, IADR #3218, 2000).

Objective:
The aim of this study was to evaluate the effect of Cu content on Hg release during setting of amalgams with 1.5 wt% Pd using two collection methods; closed bottle (CB) and Intraoral Flow (IOF).

Methods:
Five amalgam alloys produced by Special Metals (Ann Arbor, MI) were evaluated (wt %): CU1=Ag-60.3, Sn-28.2, Cu-10; CU2=Ag-59.1, Sn-28.4, Cu-11; CU3=Ag-57.9, Sn-28.6, Cu-12.0; CU4=Ag-56.8, Sn-28.8, Cu-13; CU5=Ag-55.6, Sn-28.9, Cu-14. Five Class I cavities were restored for each of the alloys and individually placed in 25-mL glass bottles sealed with a rubber septum (CB). Vapor was extracted by a syringe and analyzed using the Jerome 411 Mercury Analyzer at 1, 3, and 5 hrs after trituration and daily for 5 days. An additional 5 Class I cavities were restored for each of the alloys and placed in a typodont. Ten-second vapor readings were taken at 10 min., 0.5, 1, 2, 3 and 5 hrs after trituration using a customized impression tray attached to the mercury analyzer with a flow rate of 125 cc/10 sec (IOF). The data were analyzed by ANOVA and Tukey HSD (a=0.05).

Results:
A significant difference in Hg vapor release was determined among alloys and time. The alloy with the highest Cu content yielded lower total Hg vapor release (11.7 ng) compared with the alloy with the lowest Cu content (15.2 ng) in the CB method. A similar trend was reported in the IOF method, however not significant.

Conclusion:
In conclusion, Hg vapor release significantly decreased with increasing Cu content in Pd-containing dental amalgams in the CB collection method. Supported in part by NIH/NIDCR grant DE07644.


 

3439 Mercury Vapor Release in Various Capsule Designs
J.T. VETTRAINO, and A.L. NEME, University of Detroit Mercy, USA

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_13205.htm

Since the introduction of capsulated amalgam, some attention has been given to the potential hazards associated with residual mercury in the capsule waste.

Objective:
It was the purpose of this investigation to evaluate the amount of mercury vapor released from different amalgam capsules in a closed system following trituration.

Methods:
Three different capsule designs each with double-spill regular set alloys were evaluated (Dispersalloy, Tytin, and Valiant PhD). Forty capsules of each material were triturated, the amalgam scrap was discarded, and the unsealed waste capsules were placed in 1-gallon jugs and sealed (n=5). Additionally D and T were evaluated with their capsules resealed and stored as above. Vapor was measured using the Jerome 411 Mercury Vapor Analyzer with a 10:1 dilution module. Measurements were taken at baseline (time 0), 1, 2, 3, 24, 48 and 72 hours after trituration. Average mercury vapor levels and total vapor released were calculated and the data were analyzed by ANOVA and Tukey HSD at a=0.05.

Results:
There was no significant difference in total amount of Hg vapor released among materials with open capsules (D=68.67 m g, T=61.02 m g, V=79.66m g). A significant difference was observed between open and closed capsules in both material D and T, however no significant difference was found between closed capsules (D=8.35m g, T=6.98m g).

Conclusions:
In conclusion, although no significant differences were determined among the three capsule designs investigated when unsealed, resealed amalgam capsules released significantly less Hg vapor compared with open capsules of the same design. Funded in part by Kerr Corp.


 

3440 Hg Release After Abrasion of Pd-Containing Amalgams with Varied Cu
J.L. FERRACANE1, J.D. ADEY1, and T. OKABE2, 1 Oregon Health & Science University, USA, 2 Baylor College of Dentistry, Texas A&M University System, Health Science Center, USA

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_13270.htm

Objective:
We recently reported reduced Hg release from Pd-containing amalgams (Adey, IADR:#428, 1999).  The aim of this study was to compare the Hg release after abrasion from 5 amalgams containing 1.5 wt% Pd, and to relate the amount of Sn in the g1 to Hg release and Cu content.

Methods:
Alloys were produced by Special Metals (Ann Arbor, MI)(wt %): CU10=Ag-60.3/Sn-28.2/Cu-10; CU11=Ag-59.1/Sn-28.4/Cu-11; CU12=Ag-57.9/Sn-28.6/Cu-12.0; CU13=Ag-56.8/Sn-28.8/Cu-13; CU14=Ag-55.6/Sn-28.9/Cu-14.  Amalgams  (4mm dia) were made with 42% residual Hg (n=10), aged 1 month and tested for Hg release every 30-60s after abrasion until reaching zero (Jerome 411). Sn wt% was determined with EPMA.  Total Hg release was determined by integration (ng) and compared with Tytin (Kerr).

Results:
Means with the same superscript were not different (ANOVA/Tukey’s; p<.05).

 

 

CU10 CU11 CU12 CU13 CU14

Hg release

373(156)a

790(427)a,b

990(400)b

1050(318)b,c

1567(673)c

%Sn in g1

2.62(0.38)

2.17(0.19)

2.15(0.28)

1.80(0.16)

1.57(0.13)

Pd significantly reduced Hg vapor emission for all alloys compared to Tytin (2182 ± 544).   There was a significant correlation between increased Sn in  g1 and lower Hg release (R2=0.932).  EPMA identified a Cu-Pd-Sn phase that increased with higher wt% Cu.  We hypothesize that when Cu content is low, Cu preferentially reacts with Pd (instead of forming Cu-Sn), thus freeing Sn to deposit in the g1.  When Cu content is high, more Sn reacts with Cu and is unavailable for the g1 matrix.

Conclusion:
This study verified that a small amount of Pd (1.5%) in amalgams can significantly reduce Hg release.  The reduction is due to an increased Sn in the g1.   Supported by NIH/NIDCR Grant DE 07644.


 

3441 The Effect of Bleaching Agents on Mercury Release from Spherical Dental Amalgam
F.J. CERTOSIMO, F.J. ROBERTELLO, M.V. DISHMAN, R.E. BOGACKI, and M. WEXEL, Virginia Commonwealth University, USA

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_13606.htm
Objective:
To investigate the effect of carbamide peroxide, hydrogen peroxide and over-the-counter home bleaching products on the release of mercury from spherical dental amalgam (Tytin(R)). 

Methods:
One hundred fifty amalgam specimens were prepared in acrylic blocks, aged for 1 week at 37°C, and placed in individual polystyrene jars containing 20 ml of saline. The specimens were divided into three groups of 50(A, B, and C) and bleached in 8 hour cycles.  The groups were removed from the saline, blotted to remove moisture, and each subgroup of 10 specimens was covered with Opalescence (Op), Day White 2 (Dw), Contrast pm Plus (Pm), or Rembrandt Dazzling White (Rb).  After 8 hours of bleaching, the specimens were cleaned with a toothbrush, rinsed with deionized water, and returned to the saline for 24 hours.  Group A was tested for mercury release after 8 hours of bleaching, Group B after 40 total hours of bleaching, and Group C after 80 total hours of bleaching.  A reducing agent, SnCl2, was added to change mercury in solution to mercury vapor. The headspace was then analyzed with a Gold Film Mercury Vapor Analyzer. 

Results:
Mean (mg/m3) and 95% confidence interval:

  Control Op Dw Pm Rb
8h 0.33(0.23-0.43) 0.29(0.23-0.35) 0.39(0.34-0.44) 0.27(0.22-0.33) 0.32(0.30-0.35)
40h 0.26(0.22-0.31) 0.70(0.64-0.76) 0.83(0.79-0.87) 0.54(0.50-0.58) 0.41(0.33-0.50)
80h 0.32(0.28-0.35) 1.46(1.32-1.59) 1.94(1.86-2.02) 0.73(0.69-0.78) 0.64(0.59-0.70)
ANOVA showed statistically significant variation among groups for each time period (p<0.05). The post hoc Tukey-Kramer HSD test showed that at 8 hours, Dw was significantly greater than Pm (p<0.05).  At 40 hours, all pairs were significantly different from each other (p< 0.05).  And at 80 hours, only Pm and Rb were not significantly different (p< 0.05).

Conclusion:
 
All groups exposed to bleach showed increased mercury release over time.


 

3442 TCLP Analysis and Residual Mercury Levels in Dental Wastewater Lines
M.E. STONE, J.C. KUEHNE, R.S. KARAWAY, J.M. GULLETT, and J.C. RAGAIN, Jr., Naval Dental Research Institute, USA

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_14559.htm

Objective:
This study was undertaken to characterize residual mercury content of dental wastewater lines and to determine the leaching potential of mercury and silver utilizing Toxicity Characteristic Leaching Procedure (TCLP) analysis. TCLP extraction determines the mobility of analytes in an acetic acid buffer solution. The concentration of regulated analytes in the extract determines the toxicity characteristic of a sample and therefore whether it is subject to disposal regulations under the Resource Conservation and Recovery Act (RCRA). RCRA limits for mercury and silver are 0.2 mg/liter and 5.0 mg/liter respectively.

Methods:
Segments of dental wastewater lines were obtained from three dental treatment facilities ranging in size from 30 to more than 100 dental chairs. Determination of residual mercury content was done with United States Environmental Protection Agency (USEPA) method 7471, TCLP extraction was done with USEPA Method 1311, mercury analysis of TCLP extracts was done with USEPA method 7470A (Cold Vapor Atomic Absorption Spectrometry), the analysis of Ag concentrations in the TCLP extract was done with USEPA method 6010 (Inductively Coupled Plasma-Atomic Emission Spectrometry, ICP-AES) and the digestion of extracts for ICP-AES analysis was done with microwave assisted acid digestion (USEPA Method 3015).

Results:
Residual mercury content averaged 29.6 grams/kg (range=0.710 grams/kg to 177 grams/kg, sd=55.4). TCLP analysis showed Hg levels in the leachate to average 0.1153 mg/liter (range=0.0179 to 0.396 mg/liter, sd=0.1069). Ag levels ranged from non-detectable levels (<0.05 mg/liter) to 0.537 mg/liter.

Conclusions:
Results show considerable amounts of residual mercury in wastewater lines from large dental clinics. TCLP analysis shows waste lines to be capable of leaching mercury over RCRA limits making them subject to hazardous waste disposal regulations under RCRA. Mercury in waste line sludge can be mobilized by the action of oxidizing line cleanser. This study was supported by a grant from the USEPA, IAG# number: DW17947929-01-0.


 

3443 Evaluation of an amalgam under AFM after Nd:YAG laser appliction
M. TANASIEWICZ, and T. KUPKA, Silesian University of Medicine, Poland

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_14724.htm

Objectives:
The aim of the study was to compare Ra (roughness analysis) and Sa (section analysis) of an experimental silver amalgam Dentinmet (IMN) prior and after Nd:YAG laser application. Methods: 40 undamaged premolar human teeth were randomly assigned to 2 equal groups filled with Dentinmet. The Nd:YAG laser beam was applied to the amalgam surface (power range 1W, 5W, 9W) – 10 filled teeth per one range; the control group of 10 filled premolars without radiation. Research through the AFM method was carried out with the E Nanoscope (Digital Instruments). The results obtained were expressed as an average of 10 measurements and corresponding standard deviations.

Results:
Authors obtained an effect of increase of smoothness of amalgam exposed to 9W laser beam (amalgam Ra: control - 42,05 ± 3,39, SD 4,74; 9W - 41,82 ± 6,66, SD 9,31; amalgam Sa: control - 302,69 ± 53,34, SD 74,57; 9W - 370,13 64,22, SD 89,77).

Conclusions:
The AFM technique seems to be a very useful method enabling high precision three-dimensional analysis exact and visualization. Results obtained might suggest the efficiency of Nd;YAG expositions in the following categories of clinical use: correction of micro-defects of filling material surfaces, micro-correction of occlusion-articulation interdependences in cases of trauma locus.


 

3445 Longitudinal assessments of urinary mercury levels in the Casa Pia Study
M.D. MARTIN1, B.G. LEROUX1, T. BENTON1, J. LEITAO2, M. BERNARDO2, H. SOARES LUIS2, N. BRAVEMAN3, J.S. WOODS1, L. SIMMONDS1, and T.A. DEROUEN1, 1 University of Washington, USA, 2 University of Lisbon, Portugal, 3 National Institute of Dental and Craniofacial Research, USA

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_20128.htm

The Casa Pia Study is a prospective clinical trial (a component of the Children’s Amalgam Trial) sponsored by the NIDCR to examine the health effects of mercury amalgam exposure in children. 

Objectives:
To examine the differences between those subjects assigned to the alternate materials vs. mercury amalgam treatment groups over time, as well as to compare the urinary mercury (HgU) levels for subjects in the amalgam group who received amalgams only at baseline vs. those who required additional treatment during follow-up periods.

Methods:
Children were enrolled at age 8 to 12 (n=507), randomly assigned to amalgam or alternate materials (composites) treatment groups, and are periodically evaluated over time for neurobehavioral, neurological or renal effects. HgU levels are assessed annually. To date, baseline through the third year of follow-up assessments are complete.

Results:
As previously reported, children in the amalgam group had higher HgU levels than children in the composite group after 1 year (2.49 ug/L vs. 1.29 ug/L, p<.01). The present analysis shows that this difference persisted through years 2 (3.24 ug/L vs 1.52 ug/L, p<.01) and 3 of follow-up (4.22 ug/L vs. 1.82 ug/L, p<.01). Amalgam treatment group subjects who received no additional amalgams during year 1 and 2 showed a mean HgU of 2.52 ug/L at the beginning of year 3 follow-up (when urine samples are taken) vs those who did receive additional amalgams, 4.26 ug/L, p=.03.

Conclusions:
There are measurable exposures to mercury from dental amalgam which persist over at least two years beyond placement, and additional exposures do result in increased measurable HgU levels. These findings are consistent with current metabolic models of low level Hg exposure and excretion but do not reflect anything about the health effects of low level Hg exposure in children with no previous exposure to any restorative material.


 

3446 Effects of compositional variations of dental gallium alloys on corrosion and mechanical properties
Y.-J. PARK1, Y.-R. LEE1, D.-J. LEE1, B.K. NORLING2, and H.R. RAWLS2, 1 Chonnam National University, South Korea, 2 University of Texas Health Science Center at San Antonio, USA

http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_20471.htm

Objectives:
This study was performed to evaluate the effects of compositional variations of dental gallium alloys on their corrosion and mechanical behavior.

Methods:
60Ag-28Sn-12Cu wt% (ST group) was prepared by atomization. ST-Pd and ST-Pt groups were prepared by substituting part of the Sn with Pd (2 wt%) or Pt (0.05 wt%), respectively. Low- and high-copper amalgam alloys (LCA and HCA) were also prepared by the atomization method for comparison. Alloy powders of each group were mixed with a liquid gallium alloy composed of 61.98Ga-24.99In-12.98Sn-0.05Bi wt%. Corrosion behavior was evaluated by the potentiodynamic anodic polarization test, together with XRD and FE-SEM/EDS. 24-hour compressive strengths and dimensional changes were also measured.

Results: 
The ST-Pd group exhibited the most anodic behavior, with a corrosion potential (Ecorr) of -707 mV (vs. SCE). This is a significant shift in the noble direction from the -883 mV (vs. SCE) of the ST group (p < 0.05). The LCA group showed the lowest corrosion resistance, having Ecorr of -896 mV. Set specimens had multi-phase microstructures. Sn(Cu)-Cl corrosion products having various morphologies were formed on corroded surfaces. The ST-Pd group had less deposition of corrosion product compared to other groups. The LCA specimens corroded more than the HCA specimens. 24-hour compressive strengths were: ST-Pd (309.8 MPa) >> ST (282.9 MPa) > ST-Pt (280.0 MPa) > HCA (278.8 MPa) > LCA (258.7 MPa). 24-hour setting expansions were ST-Pd (0.24%) << LCH (0.43%) < ST-Pt (0.51%) < ST (0.56%) << HCA (1.33%).

Conclusions:
Substituting 2 wt% palladium for 2 wt% tin in the alloy powder improved the corrosion resistance and compressive strength, and reduced the setting expansion. A high-copper content induced excessive setting expansion.

 

 

 

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