OBJECTIVETo measure the magnitude of galvanic currents produced by different occluding metallic contact.

METHODSThe circuits of instantly different metallic contact were simulated in artificial saliva, and electrical potential of every couple and 15 currents of instant contact were then measured. After 8 hours' soaking, 15 currents were obtained in addition.

RESULTSGalvanic currents variation produced hy intermittently metallic contact was ruleless. During early soaking, gold/titanium, gold/high zinc-containing amalgam and low/high zinc-containing amalgam exhibited much higher current, and there was significant difference on currents between titanium/high zinc-containing amalgam and other couples (P < 0.05). There was also significant difference on currents between titanium/high zinc containing amalgam, titanium/low zinc-containing amalgam and gold/titanium, gold/low zinc-containing amalgam and gold/high zinc-containing amalgam after 8 hours' soaking (P < 0.05). In contrast with currents produced by couples before and after 8 hours' soaking, only the currents produced by gold/high zinc-containing amalgam proved to be no significant of difference (P > 0.05), while the currents produced by gold/low zinc-containing amalgam and titanium/high zinc-containing amalgam increased. Potential of high zinc-containing amalgam was more negative than other alloys, and it was always under anodic behavior during the experiment corrupted acceleratedly.

CONCLUSIONDentists can't ignore the case that the patient feels normal at the beginning of wearing different occluding metallic restorations. Either of gold/ titatium, gold/high zinc-containing amalgam and low/high zinc-containing amalgam appearing in oral will do harm to the patients' health. Neither of gold/low zinc-containing amalgam nor titanium/high zinc-containing amalgam can coexist in oral. Zinc-free or low zinc-containing amalgam should be selected instead of high zinc-containing amalgam.

Alloys ; Corrosion ; Dental Alloys ; Dental Amalgam ; Electrogalvanism, Intraoral ; Gold ; Humans ; Titanium

OBJECTIVE: The aim of this study was to assess artifacts induced by metallic restorations in three-dimensional (3D) dental surface models derived by cone-beam computed tomography (CBCT). METHODS: Fifteen specimens, each with four extracted human premolars and molars embedded in a plaster block, were scanned by CBCT before and after the cavitated second premolars were restored with dental amalgam. Five consecutive surface models of each specimen were created according to increasing restoration size: no restoration (control) and small occlusal, large occlusal, disto-occlusal, and mesio-occluso-distal restorations. After registering each restored model with the control model, maximum linear discrepancy, area, and intensity of the artifacts were measured and compared. RESULTS: Artifacts developed mostly on the buccal and lingual surfaces. They occurred not only on the second premolar but also on the first premolar and first molar. The parametric values increased significantly with increasing restoration size. CONCLUSIONS: Metallic restorations induce considerable artifacts in 3D dental surface models. Artifact reduction should be taken into consideration for a proper diagnosis and treatment planning when using 3D surface model derived by CBCT in dentofacial deformity patients.
Artifacts* ; Bicuspid ; Cone-Beam Computed Tomography* ; Dental Amalgam ; Dentofacial Deformities ; Diagnosis ; Humans ; Molar

The notion that dental amalgam is a potential source of mercury exposure remains a controversial issue. However, there are few epidemiological analyses that have addressed whether this occurs in children. We aimed in our current study to identify the relationship between dental amalgam filling surfaces and the blood mercury levels in a cohort of 711 South Korean children aged between 8-9 years. Oral examinations were conducted to detect the number of amalgam filling surfaces on the teeth of these individuals. Blood samples were also taken from these children to assess the levels of mercury accumulation in the body. The amalgam filling surfaces were classified into four groups based on their number: 0 (n = 368), 1-5 (n = 219), 6-10 (n = 89), and 11+ (n = 35). The blood mercury levels in the children with more than 10 amalgam surfaces was 0.47 microg/L higher on average than those with no amalgam surfaces after adjusting for the frequency of fish or seafood consumption, age, and gender (P < 0.05). We found from our data that a higher number of dental amalgam fillings correlated with a higher blood mercury level in Korean children. Further studies are needed to investigate whether these elevated mercury levels exert neurotoxic or nephrotoxic effects.
Aged ; Child ; Cohort Studies ; Dental Amalgam ; Diagnosis, Oral ; Humans ; Republic of Korea ; Seafood ; Tooth

OBJECTIVES: The adverse health effects of mercury in dental amalgam have not yet been clarified. This study was conducted to examine the effects of dental amalgam on the concentration of blood mercury in Korean children. METHODS: A total of 1,275 students were enrolled in the elementary school in Seoul, Incheon, and Daegu. The number and location of dental amalgam filling of teeth were ascertained by oral examination. Dietary habits-including frequency of seafood intake-and other demographic factors were obtained from the children's parents. The concentration of blood mercury was measured by an atomic absorption spectrophotometer to which a hydride generator was installed. RESULTS: The geometric mean of blood mercury concentration was 1.91 microg/L. It was found that elementary school students in Seoul and the 4th grade elementary school students have the lowest concentration of blood mercury among the study groups. Both linear and secondary linear increase of the concentration of blood mercury, depending on the number of dental amalgam fillings, were statistically significant (p-trend < 0.01, p-quadratic < 0.01). As a result of multiple regression analysis on the blood mercury concentration of elementary school students, the regression coefficient (beta) of a dental amalgam filling was found to be 0.027 (standard error = 0.014, p = 0.048). CONCLUSIONS: In children, the dental amalgam fillings were significantly contribute to the concentration of blood mercury. To accurately assess the effect of dental amalgam on the concentration of body mercury, further studies using the concentration of urine mercury are needed.
Absorption ; Child ; Demography ; Dental Amalgam ; Diagnosis, Oral ; Humans ; Korea ; Parents ; Seafood ; Tooth

OBJECTIVES: Dental amalgam is a widely used filling material for oral cavity. The released mercury vapor from amalgam could have systemic adverse effects potentially. The purpose of this study is to evaluate the relationship between dental amalgam and urinary mercury levels in children during a 6-month timespan. METHODS: A total of 525 elementary school children participated in this study. Oral examination was carried out from one dentist. Urine samples collected at baseline and at 6 month were analyzed for mercury and creatinine excretion. Additionally, general characteristics of subjects were surveyed by a questionnaire. The statistical analysis was performed using the SPSS 18.0. RESULTS: Greater amalgam surfaces were associated to higher urinary mercury levels; this tendency was similar at the 6-month observation after the correct baseline data. In the multivariable model, urinary mercury excretion was only associated with amalgam surfaces positively. CONCLUSIONS: Even a small amount of mercury uptake from dental amalgam has been associated to increase the mercury concentration of urine.
Child ; Creatinine ; Dental Amalgam ; Dentists ; Diagnosis, Oral ; Follow-Up Studies ; Humans ; Mouth ; Surveys and Questionnaires

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 microg/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.
Child* ; Creatinine ; Daegu ; Dental Amalgam ; Dentists ; Diagnosis, Oral ; Humans ; Longitudinal Studies ; Pilot Projects* ; Tooth

PURPOSE: The present study aimed to evaluate which of the following imaging methods best assessed misfit at the tooth-restoration interface: (1) bitewing radiographs, both conventional and digital, performed using a photostimulable phosphor plate (PSP) and a charge-coupled device (CCD) system; (2) panoramic radiographs, both conventional and digital; and (3) cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Forty healthy human molars with class I cavities were selected and divided into 4 groups according to the restoration that was applied: composite resin, composite resin with liner material to simulate misfit, dental amalgam, and dental amalgam with liner material to simulate misfit. Radiography and tomography were performed using the various imaging methods, and the resulting images were analyzed by 2 calibrated radiologists. The true presence or absence of misfit corresponding to an area of radiolucency in regions subjacent to the esthetic and metal restorations was validated with microscopy. The data were analyzed using a receiver operating characteristic (ROC) curve, and the scores were compared using the Cohen kappa coefficient. RESULTS: For bitewing images, the digital systems (CCD and PSP) showed a higher area under the ROC curve (AUROC) for the evaluation of resin restorations, while the conventional images exhibited a larger AUROC for the evaluation of amalgam restorations. Conventional and digital panoramic radiographs did not yield good results for the evaluation of resin and amalgam restorations (P < .05). CBCT images exhibited good results for resin restorations (P>.05), but showed no discriminatory ability for amalgam restorations (P < .05). CONCLUSION: Bitewing radiographs (conventional or digital) should be the method of choice when assessing dental restoration misfit.
Biomedical and Dental Materials ; Cone-Beam Computed Tomography ; Dental Amalgam ; Humans ; Methods ; Microscopy ; Molar ; Radiographic Image Enhancement ; Radiography ; ROC Curve ; Tooth

OBJECTIVETo assess effects of different class II cavities on stresses of amalgam and composite resin restoration.

METHODSFive kinds of class II MO cavities were prepared on the first molars of mandibles. The cavities were filled by amalgam and composite resin, respectively. The stresses were analyzed by using three-dimensional finite element method, after vertical and lateral pressures were loaded on the teeth.

RESULTSThe stresses were greater in traditional cavities than those in reformed cavities when 100 N vertical and lateral pressures were loaded on the teeth. But the pressing stress and shearing stress in cavities filled by amalgam were smaller in traditional cavities than those in reformed cavities. The stresses were smaller in cavities filled by resin than those in cavities filled by amalgam significantly, when the cavities were designed with slot retention groove, without slot retention groove and as plate form. The stresses were smaller in two kinds of slot and plate cavities than those in traditional and reformed cavities.

CONCLUSIONIt is better to design cavity with slot retention groove for amalgam restoration and to design cavity without slot retention groove for composite resin restoration.

Composite Resins ; standards ; Dental Amalgam ; standards ; Dental Cavity Preparation ; methods ; Dental Models ; Dental Restoration, Permanent ; methods ; Dental Stress Analysis ; methods ; Finite Element Analysis ; Humans ; Mandible ; Molar

Considerable effort has been made to address the issue of occupational health and environmental exposure to mercury. This review reports on the current literature of mercury exposure and health impacts on dental personnel. Citations were searched using four comprehensive electronic databases for articles published between 2002 and 2015. All original articles that evaluated an association between the use of dental amalgam and occupational mercury exposure in dental personnel were included. Fifteen publications from nine different countries met the selection criteria. The design and quality of the studies showed significant variation, particularly in the choice of biomarkers as an indicator of mercury exposure. In several countries, dental personnel had higher mercury levels in biological fluids and tissues than in control groups; some work practices increased mercury exposure but the exposure levels remained below recommended guidelines. Dental personnel reported more health conditions, often involving the central nervous system, than the control groups. Clinical symptoms reported by dental professionals may be associated with low-level, long-term exposure to occupational mercury, but may also be due to the effects of aging, occupational overuse, and stress. It is important that dental personnel, researchers, and educators continue to encourage and monitor good work practices by dental professionals.
Aging ; Biomarkers ; Central Nervous System ; Dental Amalgam ; Environmental Exposure ; Humans ; Occupational Diseases ; Occupational Health ; Patient Selection ; Research Personnel

Dental Amalgam ; adverse effects ; therapeutic use ; Dental Caries ; therapy ; Dentists ; legislation & jurisprudence ; Dissent and Disputes ; legislation & jurisprudence ; Humans ; Impetigo ; etiology ; Liability, Legal ; Psoriasis ; etiology