Journal List > J Korean Acad Oral Health > v.37(4) > 1057571

Jin, Kim, Woo, Im, Song, and Choi: Impact of amalgam removal on urinary mercury concentration in children: a pilot study

Abstract

Objectives

This pilot study aimed to evaluate the effect of dental amalgam, a restorative material, on children by measuring the mercury concentration in the urine as well as the number of teeth filled with dental amalgam.

Methods

Twenty children enrolled in grades 1-4 of two elementary schools in Daegu participated in this study. One trained dentist performed oral examinations and removed amalgam restorations from the teeth with a high and low speed handpiece. In order to measure the urinary mercury concentrations, urine samples were collected from all participants at baseline and immediately and 24 hours after removal of the dental amalgam restorations.

Results

The mean number of teeth from which the amalgam restorations was removed was 9.8 while the mean urinary mercury concentrations at baseline, immediately, and 24 hours after removal of dental amalgam restorations were 2.66, 2.76, and 2.76 μg/g creatinine, respectively. The mean urinary mercury concentration increased consistently after amalgam restoration removal. For those participants whose removed amalgamated surfaces were more than 11, the mean urinary mercury concentration immediately after amalgam restoration removal and 24 hours after removal increased consistently but showed no significant difference.

Conclusions

This study demonstrated that dental amalgam restoration was related to urinary mercury concentration, and these findings present a possibility of mercury accumulation in the body. Therefore, we suggest future longitudinal studies to ensure the safety of children exposed to mercury by establishing criteria for amalgam removal.

References

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Fig. 1.
Concentration urinary mercury according to the sampling times.
jkaoh-37-194f1.tif
Table 1.
General characteristics of study participants
Characters N (%) Characters N (%)
Gender Income (thousand won)
Boys 13 (65.0) ≤1,990 7 (35.0)
Girls 7 (35.0) >1,990 13 (65.0)
Grade Education*
1 3 (15.0) Father
2 3 (15.0) ≤12 yrs 7 (38.9)
3 6 (30.0) >12 yrs 11 (61.1)
4 8 (40.0) Mother
Fish consumption ≤12 yrs 8 (42.1)
≤1 /weeks 10 (50.0) >12 yrs 11 (57.9)
1< <4 /weeks 8 (40.0) Dental visit (6 month)
≥4 /weeks 2 (10.0) no 12 (60.0)
Toothbrushing frequency yes 8 (40.0)
≤2 9 (45.0) Chewing gum
>2 12 (55.0) Hardly ever 16 (80.0)
Occasionally 4 (20.0)

*There were missing values.

Table 2.
Mean concentration urinary mercury according to general characteristics Mean±SD (mg/g creatinine)
Baseline Post-removal amalgam After 24 hours P-value
Total 2.66±1.51 2.76±2.46 2.76±2.30
Gender
Boys 2.56±0.83 2.84±2.93 2.59±2.48 0.826
Girls 2.84±2.40 2.59±1.41 3.08±2.06
Grade
1 1.92±0.51 5.91±2.97 6.49±2.74 0.025
2 4.00±3.66 2.74±1.90 3.22±2.88
3 2.61±1.00 0.96±0.77 1.18±0.91
4 2.48±0.73 2.93±2.33 2.39±0.94
Fish consumption
≤1 /weeks 2.31±0.95 2.22±2.76 2.01±1.72 0.246
1< <4 /weeks 2.52±0.78 3.34±2.21 3.37±2.66
≥4 /weeks 4.99±4.32 3.10±2.57 4.12±3.43
Toothbrushing frequency
≤2 3.14±1.94 3.29±2.35 3.55±2.85 0.138
>2 2.27±0.98 2.32±2.57 2.12±1.59
Income (thousand won)
≤1,990 2.49±1.07 1.84±1.05 2.13±1.51 0.255
>1,990 2.75±1.74 3.25±2.88 3.10±2.62
Education Father
≤12 yrs 2.65±0.74 3.19±3.56 1.82±1.36 0.675
>12 yrs 2.50±1.93 2.65±1.51 3.60±2.68
Mother
≤12 yrs 2.67±0.99 2.57±2.50 2.08±1.47 0.419
>12 yrs 2.78±1.85 3.04±2.60 3.39±2.74
Dental visit (6 month)
No 2.54±0.93 2.92±2.94 2.17±1.31 0.553
Yes 2.84±2.18 2.51±1.66 3.65±3.18
Chewing gum
Hardly ever 2.46±0.90 2.63±2.65 2.15±1.49 0.086
Occasionally 3.46±3.06 3.25±1.68 5.21±3.53

Repeated Measure ANOVA.

Table 3.
Mean concentration urinary mercury according to number of amalgam surfaces Mean±SD (mg/g creatinine
N Baseline Post-removal amalgam After 24 hours P-value
Amalgam surfaces
≤8 5 3.18±0.84 2.09±3.06 1.19±0.86 0.611
8< <11 8 2.95±2.11 2.29±1.38 2.73±1.81
≥11 7 1.96±0.80 3.64±2.82 3.93±2.96
P-value* 0.319 0.521 0.124

*Repeated Measure ANOVA,

Two-way ANOVA.

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