Urinary Mercury Levels and Predictors of Exposure among a Group of Italian Children

Urinary mercury (Hg) levels are suitable to assess long-term exposure to both elemental and inorganic Hg. In this study, the urinary Hg levels of 250 children (aged 6–11 years) from three areas with different anthropogenic impacts in the Rieti province, central Italy, were assessed. The Hg concentrations were in the range of 0.04–2.18 µg L⁻¹ with a geometric mean equal to 0.18 µg L⁻¹ [95% confidence interval (CI), 0.17–0.20 µg L⁻¹] or 0.21 µg g⁻¹ creatinine (95% CI, 0.19–0.23 µg g⁻¹ creatinine), and a reference value calculated as 95th percentile of 0.53 µg L⁻¹ (95% CI, 0.44–0.73 µg L⁻¹) or 0.55 µg g⁻¹ creatinine (95% CI, 0.50–0.83 µg g⁻¹ creatinine). In all cases, urinary Hg data were below the HBM-I values (7 µg L⁻¹ or 5 µg g⁻¹ creatinine) established for urine, while the 95th percentile was above the German Human Biomonitoring Commission’s RV95 (0.4 µg L⁻¹) set for children without amalgam fillings. A significant correlation (p < 0.05) was found between creatinine-corrected results and residence area, with higher urinary Hg levels in children living in the industrial area. Multiple linear regression analysis showed that creatinine was the main predictor of urinary Hg.

Long-term in-vivo effect of various restorative materials on enamel and dentin of primary molars

OBJECTIVE

To explore the long-term in-vivo effect of different dental restorative materials on the surrounding enamel and dentin, in primary molars.

METHOD AND MATERIALS

Sixteen naturally exfoliated primary molars restored with amalgam, compomer, and glass-ionomer cement were collected after 2 to 5 years of function in the mouth. Four intact molars served as control. The teeth were sliced buccolingually and the ion content in the restorative material, the enamel, and the dentin surrounding the restoration was determined using a scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) program.

RESULTS

Amalgam released copper to the enamel and dentin causing a bluish discoloration. No traces of mercury or other ions were detected in the enamel or dentin. The enamel and dentin surrounding the restoration showed reduced inorganic components and increased organic components. The enamel and dentin surrounding the compomer restoration showed similar to amalgam reduction in inorganic components and increased organic components. Traces of fluoride, aluminum, and silicon were found. The enamel and dentin of teeth restored with glass-ionomer cement showed the least reduction in inorganic components, with higher fluoride content and traces of aluminum, silicon, and strontium.

CONCLUSION

This long-term in-vivo study showed release of copper ions from amalgam material to the enamel and dentin, but no traces of mercury. Amalgam and compomers showed no remineralization effect on the dentin surrounding the restoration. Glass-ionomer restorations showed remineralization effect on the tooth components and migration of inorganic ions from the enamel and dentin to the material.

Electrospun nanofibers decorated with bio-sonochemically synthesized gold nanoparticles as an ultrasensitive probe in amalgam-based mercury (II) detection system

In this study, bio-ultrasound-assisted synthesized gold nanoparticles using Gracilaria canaliculata algae have been immobilized on a polymeric support and used as a glassy probe chemosensor for detection and rapid removal of Hg²⁺ ions. The function of the suggested chemosensor has been explained based on gold-amalgam formation and its catalytic role on the reaction of sodium borohydride and rhodamine B (RhB) with fluorescent and colorimetric sensing function. The catalyzed reduction of RhB by the gold amalgam led to a distinguished color change from red and yellow florescence to colorless by converting the amount of Hg²⁺ deposited on Au-NPs. The detection limit of the colorimetric and fluorescence assays for Hg²⁺ was 2.21 nM and 1.10 nM respectively. By exposing the mentioned colorless solution to air for at least 2 h, unexpectedly it was observed that the color and fluorescence of RhB were restored. Have the benefit of the above phenomenon a recyclable and portable glass-based sensor has been provided by immobilizing the Au-NPs and RB on the glass slide using electrospinning. Moreover, the introduced combinatorial membrane has facilitated the detection and removal of Hg²⁺ ions in various Hg (II)-contaminated real water samples with efficiency of up to 99%.

Characterisation of secondary metal-bearing phases in used dental amalgam and assessment of gastric solubility

Detailed SEM/EDS investigation of used dental amalgams was carried out in order to characterise morphology and chemical composition of secondary metal-bearing phases resulting from long-term exposure of dental amalgam to oral environment, and assess their solubility in gastric environment. The investigation revealed numerous secondary phases, represented by compositionally and morphologically complex Hg-, Cu-, Sn-, Ag-, Zn-bearing sulphides and oxides/hydroxides, while sulphates and phosphates are scarce. Secondary metal-bearing phases mostly occur at the amalgam/tooth interface; however, some phases were found only on the occlusal surfaces of amalgam. Secondary phases mostly form porous aggregates of minute crystallites and micro- or nanocrystalline crusts. In oral environment, these phases are mostly stable and represent trapping media for dissolved potentially toxic metals released during amalgam corrosion. Simplified PHREEQC calculations of solubility of secondary metal-bearing phases in aqueous environment under conditions similar to those in gastric environment showed that secondary phases are more soluble in gastric environment than in oral solutions, which is mostly due to their forms of occurrence. Secondary phases in gastric environment thus act as secondary sources of potentially toxic metals, particularly Sn, Zn and also Cu, which are released both under reducing and oxidising conditions especially in acidic environment. Only very small amounts of Hg are potentially released and should not represent serious threat. Secondary phases that contribute the most to bioaccessibility of these metals are Sn hydroxychlorides, Sn oxides/hydroxides, Sn sulphates/hydroxysulphates, Sn oxides, Zn sulphides and Cu sulphides (Cu₂S).

The effect of restorative materials on cytokines in gingival crevicular fluid

OBJECTIVE

Composition of the restorative materials may cause inflammatory responses by monocyte activation and changes in the levels of cytokine released from different cells. Interleukin-6 (IL-6), interleukin-8 (IL-8) and Tumor necrosis factor alpha (TNF-α) are important cytokine for evaluating of the inflammatory process. The aim of this study was to evaluate the different restorative materials used in class V cavities effect on gingival crevicular fluid inflammatory cytokine levels.

DESIGN

60 individuals having Class V carious cavities participated in the study. Cavities were restored with FiltekZ250, DyractXP, Fuji IX, Cavex avalloy restorative materials. Changes in clinical and biochemical parameters were evaluated before restorations, seven and 21days after restorations. Contralateral tooth intact enamel surface was determined as control side. Periotron8000 device was used for detection of GCF volume. Cytokine level of GCF was evaluated by Human ELISA kits. Data were analyzed using Mann-Whitney U test and Wilcoxon signed ranks test. The correlations between clinical parameters and biochemical parameters were examined by Spearman's rank correlation analysis.

RESULTS

After restorative treatments PI and GI scores were decreased compared with baseline evaluations. There was a significant difference in GCF levels between experimental and control sites in all groups. GCF IL-6 levels in all groups except Filtek Z250, GCF IL-8 levels in all groups except Fuji IX, GCF TNF-α level in only Fuji IX showed significant differences between experimental and control sites.

CONCLUSIONS

The obtained data supported that all of the tested materials caused changes in GCF cytokine levels.

[Healing of Amyotrophic Lateral Sclerosis: A Case Report]

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a devastating disease leading to death within 3-5 years in most cases. New approaches to treating this disease are needed. Here, we report a successful therapy.

CASE REPORT

In a 49-year-old male patient suffering from muscle weakness and fasciculations, progressive muscular atrophy, a variant of ALS, was diagnosed after extensive examinations ruling out other diseases. Due to supposed mercury exposure from residual amalgam, the patient's teeth were restored. Then, the patient received sodium 2,3-dimercaptopropanesulfate (DMPS; overall 86 × 250 mg in 3 years) in combination with α-lipoic acid and followed by selenium. In addition, he took vitamins and micronutrients and kept a vegetarian diet. The excretion of metals was monitored in the urine. The success of the therapy was followed by scoring muscle weakness and fasciculations and finally by electromyography (EMG) of the affected muscles. First improvements occurred after the dental restorations. Two months after starting therapy with DMPS, the mercury level in the urine was increased (248.4 µg/g creatinine). After 1.5 years, EMG confirmed the absence of typical signs of ALS. In the course of 3 years, the patient recovered completely.

CONCLUSIONS

The therapy described here is a promising approach to treating some kinds of motor neuron disease and merits further evaluation in rigorous trials.

Mercury Amalgam Diffusion in Human Teeth Probed Using Femtosecond LIBS

In this work the diffusion of mercury and other elements from amalgam tooth restorations through the surrounding dental tissue (dentin) was evaluated using femtosecond laser-induced breakdown spectroscopy (fs-LIBS). To achieve this, seven deciduous and eight permanent extracted human molar teeth with occlusal amalgam restorations were half-sectioned and analyzed using pulses from a femtosecond laser. The measurements were performed from the amalgam restoration along the amalgam/dentin interface to the apical direction. It was possible to observe the presence of metallic elements (silver, mercury, copper and tin) emission lines, as well as dental constituent ones, providing fingerprints of each material and comparable data for checking the consistence of the results. It was also shown that the elements penetration depth values in each tooth are usually similar and consistent, for both deciduous and permanent teeth, indicating that all the metals diffuse into the dentin by the same mechanism. We propose that this diffusion mechanism is mainly through liquid dragging inside the dentin tubules. The mercury diffused further in permanent teeth than in deciduous teeth, probably due to the longer diffusion times due to the age of the restorations. It was possible to conclude that the proposed femtosecond-LIBS system can detect the presence of metals in the dental tissue, among the tooth constituent elements, and map the distribution of endogenous and exogenous chemical elements, with a spatial resolution that can be brought under 100 µm.

Identifying occupational and nonoccupational exposure to mercury in dental personnel

The objective of this study was to investigate the occupational and nonoccupational exposure to mercury (Hg) vapor in dental personnel by examining the relationships between blood mercury, urine mercury, and their ratio with air mercury. The method was performed on 50 occupational exposed and 50 unexposed controls (25 men and 25 women). The mercury concentrations in air and human biological samples were determined based on the National Institute for Occupational Safety and Health (NIOSH) method and standard method (SM) by a new mode of liquid-phase microextraction, respectively. The mean mercury concentrations in urine (μg Hg⁰/g creatinine) and blood were significantly higher than control group, respectively (19.41 ± 5.18 vs 2.15 ± 0.07 μg/g and 16.40 ± 4.97 vs 2.50 ± 0.02 μg/L) (p <.001). The relationships between mercury concentration in blood/urine ratio (r = .380) with dental office air are new indicators for assessing occupational exposure in dental personnel.

Proximal Contact Repair of Complex Amalgam Restorations

The carving of a complex amalgam restoration may occasionally result in light proximal contact with the adjacent tooth. The purpose of this study was to investigate the strength of complex amalgam restorations repaired with a proximal slot amalgam preparation. Extracted human third molars of similar coronal size were sectioned 1 mm apical to the height of the contour using a saw and were randomly distributed into 9 groups of 10 teeth each. One pin was placed at each line angle of the flattened dentinal tooth surface. A metal matrix band was placed and an admixed alloy was condensed and carved to create a full crown contour but with a flat occlusal surface. A proximal slot was prepared with or without a retention groove and repaired using a single-composition spherical amalgam 15 minutes, 24 hours, one week, or six months after the initial crown condensation. The specimens were stored for 24 hours in 37°C water before fracture at the marginal ridge using a round-ended blade in a universal testing machine. The control group was not repaired. The mean maximum force in newtons and standard deviation were determined per group. Data were analyzed with a 2-way analysis of variance as well as Tukey and Dunnett tests (α=0.05). Significant differences were found between groups based on type of slot preparation (p=0.017) but not on time (p=0.327), with no significant interaction (p=0.152). No significant difference in the strength of the marginal ridge was found between any repair group and the unrepaired control group (p>0.076). The proximal repair strength of a complex amalgam restoration was not significantly different from an unrepaired amalgam crown. Placing a retention groove in the proximal slot preparation resulted in significantly greater fracture strength than a slot with no retention grooves. Time of repair had no significant effect on the strength of the repair.

Root-end Filling Materials Alter Fibroblast Differentiation

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).

Quantification of Hg excretion and distribution in biological samples of mercury-dental-amalgam users and its correlation with biological variables

This is the first study conducted to quantify the excretion and distribution of mercury (Hg) with time (days) in the biological samples collected from Hg dental amalgam users (MDA). The individuals, with Hg-based dental filling were selected, and their biological samples (red blood cells (RBCs), plasma, urine, hair, and nails) were collected on first, third, and 12th day of fillings. The concentrations of Hg observed in the biological samples of MDA were also correlated with the biological variables such as age, weight, restoration, fish consumption, number, and surface area of fillings. The concentrations of Hg in the biological samples of MDA were found 6-8 times higher than the non-amalgam users (control). The concentrations of Hg in the RBCs (4.39 μg/L), plasma (3.02 μg/L), and urine (22.5 μg/L) on first day of filling were found comparatively higher than the concentrations observed on third day (2.15, 1.46, and 12.3 μg/L for RBCs, plasma, urine, respectively) and 12th day (3.05, 2.5, 9.12 μg/L for RBCs, plasma, urine, respectively), while Hg concentrations were found lower in the hair and nails on third day of fillings (1.53 μg/g for hair and 2.35 μg/g for nails) as compared to the 12th day (2.95 μg/g for hair and 3.5 μg/g for nails). The correlations were found significant (p ˂ 0.05) between Hg concentrations in the biological samples of MDA and biological variables (the number of restoration, fish consumption, number, and surface area of fillings), while no significant (p ˃ 0.05) correlations were observed for Hg concentrations in the biological samples with age and weight of MDA. These observations unveil the fact that the use of Hg-based dental filling is the undesirable exposure to Hg which should be replaced by composite (a safer filling material).

The effects of overhang amalgam restoration on levels of cytokines, gingival crevicular fluid volume and some periodontal parameters

PURPOSE

To evaluate clinical periodontal findings and GCF levels of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin 8 (IL-8) in patients with overhang amalgam restorations before and after overhang restoration removal.

METHODS

22 volunteer subjects (age range: 22-42 years old) with 22 overhang Class II amalgam restorations were selected. GCF samples were obtained from adjacent and contralateral teeth for IL-6, IL-8 and TNF-α measurements and analyzed using enzyme-linked immunosorbent assay (ELISA) kits. The amalgam overhangs were removed and the readings were repeated at the end of 1 week. Clinical periodontal assessments, including gingival index (GI) and plaque index (PI) were performed at baseline and after 1 week. Data were analyzed using the paired t-test and independent sample t-test at a significance level of 0.05. Correlations were investigated using Pearson correlation analysis.

RESULTS

A significant reduction in GI and PI was observed after removal of the overhanging restoration on Day 7. (P< 0.05) However, there was no significant difference between IL-6 (P= 0.857), IL-8 (P= 0.579) and TNF-α (P= 0.958) levels before and after overhang restoration removal. There were no significant correlations between laboratory findings and clinical parameters.

CLINICAL SIGNIFICANCE

Dental restorations may produce periodontal disease and may alter tooth form, surface integrity, relationship with the periodontium and adjacent teeth. The marginal edge located in the gingival sulcus is likely the cause of the inflammatory reaction. This study showed significant improvement in clinical periodontal parameters after removing the overhangs of restorations.

British Society of Prosthodontics Debate on the Implications of the Minamata Convention on Mercury to Dental Amalgam--Should our Patients be Worried?

In 2013, the Minamata Convention on Mercury called for a global phase-down of amalgam use, with a view to reduce environmental mercury pollution. This will significantly impact UK dentistry, given the still extensive use of amalgam in U.K. general dental practice. However, until now there has been little national discussion or debate. In Spring 2015, The British Society of Prosthodontics dedicated a significant part of its Annual Conference to debating the implications of this issue. Clinical case examples were discussed with audience interaction and voting facilitated using innovative Audience Response System Technology. A remarkable range of concerns and opinions were given. The debate elicited specific concerns amongst clinicians regarding the suitability of mercury-free alternatives to amalgam; particularly where cavities are large and extend beneath the gingival anatomy. There are also anecdotal reports of Dental Foundation (DF) dentists not being adequately taught the use of dental amalgam in undergraduate dental schools. CPD/CLINICAL RELEVANCE: Many clinicians, especially those treating patients for whom moisture control is challenging, feel that amalgam should remain available for clinicians to choose in certain clinical circumstances for the restoration of posterior teeth, even in the event of a complete phase-down.

Microleakage in different primary tooth restorations

BACKGROUND

Microleakage may cause tooth sensitivity, secondary caries, discoloration and even failure of the restoration. In order to overcome these potential problems, materials that are able to bind to the tooth structure have been developed, such as composite resin and glass ionomer cement. The purpose of the study was to compare microleakage arising from amalgam (Am), composite resin (CR), glass ionomer (GI), Ketac-Silver (KS), and GI filling with banding (GI+B) when these materials are used for class II restoration of a primary molar.

METHODS

Fifty primary molars were collected and class II cavities were prepared on each tooth. The teeth were randomly divided into five groups (Am, CR, GI, KS, and GI+B), each of which received a different material as part of the restoration. The restored teeth then underwent 100 cycles of thermocycling that consisted of 55°C for 30 seconds, 19°C for 20 seconds, and 5°C for 30 seconds. The teeth were then immersed in 0.5% basic fuchsin solution for 24 hours. Afterwards, the teeth were embedded and sectioned mesiodistally through the center of each restoration. Dye penetration associated with the occlusal and cervical margins of each restoration was then assessed.

RESULTS

Cervical leakage was greater than occlusal leakage in the CR, GI and KS groups (p < 0.05). When leakage on occlusal margin was examined, however, the Am group showed greater leakage than the CR, GI, and GI+B groups (p < 0.05). When leakage on the cervical margin was examined, the Am group showed greater leakage than the GI and GI+B groups, while the KS group showed greater leakage than the GI+B group (p < 0.05).

CONCLUSION

Restorations using GI and GI+B indicated that these materials performed better than the other materials in this study overall. However, none of the materials were entirely devoid of leakage.

Exposures of dental professionals to elemental mercury and methylmercury

Mercury (Hg) exposure, a worldwide public health concern, predominantly takes two forms--methylmercury from fish consumption and elemental Hg from dental amalgam restorations. We recruited 630 dental professionals from an American Dental Association meeting to assess Hg body burden and primary sources of exposure in a dually exposed population. Participants described occupational practices and fish consumption patterns via questionnaire. Hg levels in biomarkers of elemental Hg (urine) and methylmercury (hair and blood) were measured with a Direct Mercury Analyzer-80 and were higher than the general US population. Geometric means (95% CI) were 1.28 (1.19-1.37) μg/l in urine, 0.60 (0.54-0.67) μg/g in hair and 3.67 (3.38-3.98) μg/l in blood. In multivariable linear regression, personal amalgams predicted urine Hg levels along with total years in dentistry, amalgams handled, working hours and sex. Fish consumption patterns predicted hair and blood Hg levels, which were higher among Asians compared with Caucasians. Five species contributed the majority of the estimated Hg intake from fish--swordfish, fresh tuna, white canned tuna, whitefish and king mackerel. When studying populations with occupational exposure to Hg, it is important to assess environmental exposures to both elemental Hg and methylmercury as these constitute a large proportion of total exposure.

The use of bonded partial ceramic restorations to recover heavily compromised teeth

Restorative procedures are accompanied by a reduction of tooth stability, a decrease of fracture resistance, and an increase in deflection of weakened cusps. The choice between a direct or an indirect restorative technique, mainly in posterior areas, is a challenge, and involves biomechanical, anatomical, functional, esthetic, and financial considerations. In this article, the pros and cons of direct restorations are examined, as well as an analysis of indirect restorations and an overview of dental ceramics. In particular, several clinical uses of lithium disilicate overlays with a circumferential adhesive ferrule effect are proposed: heavily compromised vital teeth with thin walls, cracked teeth, and endodontically treated molars. Clinical procedures are described step by step on the basis of data from scientific literature. In conclusion, the use of lithium disilicate in combination with adhesive technologies can lead to a more conservative, economic, and esthetic approach in the restoration of heavily compromised teeth.

Replacing Amalgam Restorations: A Standardized Protocol Based on Analyzing Tissue Physicochemical Modifications

Almost 60% of operative dentistry is devoted to replacing restorations. When practitioners have to replace an amalgam restoration, they tend to opt for an adhesive restoration, as it is conservative of tooth tissues and mimics the natural appearance of teeth. Based on a literature review, the aim of this article is to determine the best tissue approach when replacing an old amalgam by a new adhesive restoration. After analyzing and understanding tissue alterations due to the amalgam corrosion process, the authors propose an analytical approach to managing the situation. Both tissue orientated and specific mechanical approaches are developed and should be implemented to carry out the optimal clinical procedure and achieve the most conservative and durable treatment.

Agreement Among Dental Students, Peer Assessors, and Tutor in Assessing Students' Competence in Preclinical Skills

The aim of this study was to determine the level of agreement regarding assessments of competence among dental students, their student peers, and their clinical skills tutors in a preclinical skills program. In 2012-13 at the University of Edinburgh, second-year dental students learned to perform the following seven cavity preparations/restorations on primary and permanent Frasaco teeth: single-surface adhesive occlusal cavity; single-surface adhesive interproximal cavity; single-surface adhesive labial cavity; multi-surface adhesive cavity; multi-surface amalgam cavity; pre-formed metal crown preparation; and composite resin buildup of a fractured maxillary central incisor tooth. Each student, a randomly allocated student peer, and the clinical skills tutor used standardized descriptors to assign a competency grade to all the students' preparations/restorations. The grades were analyzed by chi-square analysis. Data were available for all 59 second-year students in the program. The results showed that both the students and their peers overestimated the students' competence compared to the tutor at the following levels: single-surface adhesive occlusal cavity (χ(2)=10.63, p=0.005); single-surface adhesive interproximal cavity (χ(2)=11.40, p=0.003); single-surface labial cavity (χ(2)=23.70, p=0.001); multi-surface adhesive cavity (χ(2)=12.56, p=0.002); multi-surface amalgam cavity (χ(2)=38.85, p=0.001); pre-formed metal crown preparation (χ(2)=40.41, p=0.001); and composite resin buildup (χ(2)=57.31, p=0.001). As expected, the lowest levels of agreement occurred on the most complicated procedures. These findings support the need for additional ways to help students better self-assess their work.

Impact of Technique-Specific Operative Videos on First-Year Dental Students' Performance of Restorative Procedures

The aim of this study was to examine the impact of psychomotor operative video demonstrations on first-year dental students who are performing specific procedures for the first time in a preclinical setting. The class was randomly divided into two groups, and three restorative procedures were selected. On the date on which each procedure was to be performed in the preclinical laboratory for the first time, one group (experimental, n=50) was shown a technique video for that specific procedure immediately before commencing the exercise; the control cohort (n=50) did not view the video. Technical performance on procedures was evaluated by students and two calibrated and blinded examiners. The students' perceptions of the experience were also collected in a survey. All first-year students participated in the study, for a 100% response rate. A Mann-Whitney U test did not show any group differences in technical performance (mean values on preparation: 77.1 vs. 77.8; amalgam: 82.7 vs. 82.8; composite: 79.7 vs. 78.0). A Spearman rho test revealed a significantly higher correlation in 13 out of 25 evaluation categories between student self-assessment and blinded examiner assessment for the experimental group. A chi-square test of questionnaire responses revealed a positive student perception of administering these videos for the preparation (X(2)=4.8, p<0.03), the amalgam restoration (X(2)=12.4, p<0.001), and the composite restoration (X(2)=11.3, p<0.001). The psychomotor video demonstrations did not immediately improve student performance on preclinical operative procedures, but they were well received by students and augmented self-assessment ability. These findings suggest that videos can be a useful teaching aid in a preclinical environment, especially regarding comprehension of concepts.

The Influence of Parenting Style and Child Temperament on Child-Parent-Dentist Interactions

PURPOSE

This study aimed to investigate the interaction between parenting style and child's temperament as modulators of anxiety and behavior in children during the dental procedure.

METHODS

Healthy four- to six-year-olds (n equals 288), with carious primary molars scheduled to receive amalgam fillings were selected. The Primary Caregivers Practices Report was used to assess the parenting style, and the Children's Behavior Questionnaire-Very Short Form was used to evaluate child temperament. Children were managed using common behavior management strategies. Child behavior and anxiety during the procedure were assessed using the Frankl behavior rating scale and the verbal skill scale, respectively. Spearman's correlation coefficient was used to examine the correlation among variables.

RESULTS

Authoritative parenting style was positively related to positive child's behavior (P<.05) and negatively related to child's anxiety (P<.05). A positive relationship existed between permissive subscale and negative behaviors (P<.05) and child's anxiety (P<.05). There was a significant direct effect of authoritative parenting style on the effortful control trait (P<.05) and permissive parent style on the child negative affectivity (P<.05).

CONCLUSIONS

Parenting style appeared to mediate child temperament and anxiety, and was related to the child's behavior. Parenting style should be considered in the selection of behavior guidance techniques.

Is apical periodontitis in root filled teeth associated with the type of restoration?

OBJECTIVE

To study the association between type of restoration and apical periodontitis (AP) in root filled teeth.

MATERIALS AND METHODS

The present study used data from surveys conducted in 1983, 1993 and 2003. In 1983, 130 randomly selected subjects aged 3-80 years in the city of Jönköping, Sweden, were invited for a clinical and radiological examination. The study was repeated in 1993 and 2003. New participants were, thus, recruited with the same sampling criteria and sample size in the same geographical area in 1993 and 2003, respectively. In the present study, only dentate individuals aged 20-70 years with ≥1 root filled tooth were included, yielding a sample of 788 subjects with 2634 root filled teeth. Apical periodontitis on the tooth level was the dependent variable. Periapical status was assessed according to Periapical Index (PAI). Independent variables were root filling quality, recurrent caries, type of restoration, number of teeth with apical periodontitis, age and gender. Root fillings appearing homogenous and ending within 2 mm from radiographic apex were regarded as adequate, otherwise inadequate. All radiographs were re-studied by one observer regarding periapical status and root filling quality. Risk was analyzed by means of a GEE model.

RESULTS

Type of restoration, root filling quality, number of teeth with apical periodontitis within the individual and age were found to be predictors of AP in root filled teeth. Presence of recurrent caries and gender were not found to be associated with AP.

CONCLUSIONS

According to the present study, root filling quality and type of restoration may be predictive of AP in root filled teeth.

The use of amalgam in pediatric dentistry: new insights and reappraising the tradition

The debate on amalgam led to its being phased out in some countries. Results of clinical trials report failure rates of amalgams ranging from 12 percent to over 70 percent. Treatment of caries should meet the needs of each particular patient, based on his/her caries risk. In general, for small occlusal lesions, a conservative preventive resin restoration would be more appropriate than the classic Class I amalgam preparation. For proximal lesions, amalgam would be indicated for two-surface Class II preparations that do not extend beyond the line angles of primary teeth. This recommendation might not be appropriate for high-risk patients or restoring primary first molars in children four years old and younger where stainless steel crowns have demonstrated better longevity. Currently, amalgam demonstrates the best clinical success for Class II restorations that extend beyond the proximal line angles of permanent molars. The need to reduce the use of amalgam as a mercury-containing material is inevitable when aiming to reduce environmental contamination. It is important always to praise prevention and constantly search for biologically safe materials regarding health, clinical work, and environment. The purpose of this report was to summarize several factors that affect the effectiveness, advantages, and disadvantages of using dental amalgam in primary teeth.

In situ bacterial accumulation on dental restorative materials. CLSM/COMSTAT analysis

PURPOSE

To evaluate the influence of different restorative materials on the biofilm structure accumulated in situ.

METHODS

15 discs of each material (ceramic; resin composite; resin-modified and conventional glass-ionomers; amalgam) were adapted to palatal devices in order to accumulate biofilm in situ, under a cariogenic challenge (20% sucrose solution, 10x/day). After 7 days, the specimens were carefully removed and visualized by confocal laser scanning microscopy (CLSM). The images were analyzed qualitatively (descriptive analysis about cell viability and architecture) and quantitatively using COMSTAT software (area, bio-volume, mean thickness, maximum thickness and roughness coefficient of the biofilm). The statistical analysis was performed by using the Kolmogorov-Smirnov and Kruskal-Wallis tests (P ≤ 5%).

RESULTS

The medians of the biofilm parameters analyzed showed no statistical difference regarding different materials. However, qualitatively, glass-ionomer cements and amalgam showed visually a prevalence of non-viable cells forming small clusters distributed by the biofilm, and voids were presented in smaller proportion in the biofilm volume compared to composite and ceramic.

Electrical Pulp Testing: Sources of Error

INTRODUCTION

Accurate identification and assessment of an inflamed or necrotic tooth is essentialfor endodontic treatment. The purpose of this research was to investigate possible sources of error associated with the use of the electric pulp tester (EPT).

METHODS

Forty-six intact teeth (23 tooth pairs) in 22 patients were evaluated in vivo. For the tooth pairs, one tooth had to have been previously endodontically treated and restored with a class II amalgam restoration. The restoration was required to have proximal contact with a class II amalgam of another vital posterior tooth. EPT was performed on pulpless and vital teeth for experimental groups (enamel, restoration, contacting, or isolated).

RESULTS

The highest rate of false positive responses (82%) was found in the pulpless restored contacting group, suggesting that EPT impulses are able to travel through proximal metallic contacts and stimulate teeth distant from the EPT probe. All vital tooth groups had a high rate of positive responses with no significant diferences.

CONCLUSIONS

If a tested tooth contains an interproximal restoration contacting adjacent restorations or the gingival, the teeth must be isolated (rubber dam) and the EPT probe should be placed in a region suspected to have uninterrupted tubule paths to the pulp.

Metals as a common trigger of inflammation resulting in non-specific symptoms: diagnosis and treatment

BACKGROUND

The multiple symptoms of chronic fatigue syndrome (CFS) and fibromyalgia resemble those described in patients suffering from autoimmune/inflammatory syndrome induced by adjuvants (ASIA). It has been suggested that chronic metal-induced inflammation might play a role both in CFS and fibromyalgia as well as in ASIA. Humans are exposed to metals mainly through the release of metal ions from corroding dental restorations and orthopedic implants, food, vaccines and jewelry. Metals readily bind to sulphur and other groups in the mitochondria, enzymes and cell proteins. Metal-bound proteins are recognized by the immune system of susceptible subjects and might trigger an abnormal immune response, including allergy and autoimmunity.

OBJECTIVES

To study three subjects with CFS and two with fibromyalgia, all of whom suspected metal exposure as a trigger for their ill health.

METHODS

We measured delayed-type hypersensitivity to metals (metal allergy) using a validated lymphocyte transformation test, LTT-MELISA. All patients except one were sensitized to metals present in their dental restorations. The remaining patient reacted to metals in his skull implant. The removal of sensitizing metals resulted in long-term health improvement. Nine healthy controls matched for gender and age showed only marginal reactivity to the metals tested.

CONCLUSIONS

Patients with CFS and fibromyalgia are frequently sensitized to metals found in the environment or used in dentistry and surgery. This allergy to metals might initiate or aggravate non-specific symptoms in metal-sensitized patients.

Finite element analysis of different restorative materials in primary teeth restorations

AIM

The purpose of this finite element analysis (FEA) study is to evaluate and compare the stress distributions at the primary molars and restorative materials according to the material used.

MATERIALS AND METHODS

A total of 12 3D models of Class II cavities in primary molars plus one control model were analysed. Study design: Three-dimensional FEA was used to compare stress distribution on enamel, dentin and restoration surfaces of cavities.

STATISTICS

Stresses occurring under occlusal forces were compared with the von Mises criterion.

RESULTS

The highest von Mises stress values at the enamel and restoration of restored tooth 84 were computed. On the basis of these results, all materials were ranked on enamel stress as: flowable composite resin (FCR)> compomer > resin modified glass ionomer cement (RMGIC) > giomer composite resin (GCR) > hybrid composite resin (HCR) > amalgam. Moreover, ranking of materials on restoration stress was FCR < compomer < RMGIC < GCR < amalgam < HCR.

CONCLUSION

A restorative material with appropriate elasticity module, able to balance stress concentrations, should be used to increase the survival rate of both the hard tissue of the tooth and the restoration material.

Differences between reported and actual restored caries lesion depths: results from The Dental PBRN

OBJECTIVE

The objectives of this research were to: (1) quantify the discordance between the caries lesion depth at which dentists restored initial lesions during a clinical study ("actual depth") and the lesion depth that they reported during a hypothetical clinical scenario ("reported depth"); (2) test the hypothesis that certain practitioner, practice, patient, and caries lesion characteristics are significantly associated with this discordance.

METHODS

Practitioner-investigators who perform restorative dentistry in their practices completed an enrollment questionnaire and participated in 2 consecutive studies on caries diagnosis and treatment. The first study was a survey asking about caries treatment. The second study collected data on restorations placed in routine clinical practice due to caries in patients over 19 years of age on occlusal surfaces only or proximal surfaces only. We report results on 2,691 restorations placed by 205 dentists in 1,930 patients with complete data.

RESULTS

Discordance between actual depth and reported depth occurred in only about 2% of the restorations done due to proximal caries, but about 49% of the restorations done due to occlusal caries. Practice type, restorative material used and the diagnostic methods used were significantly associated with discordance.

CONCLUSION

Dentists frequently restored occlusal caries at a shallower depth as compared to their reported depth, but the discordance was very small for proximal lesions. Discordance for occlusal caries was more common when radiographs were not taken or if a resin restoration was placed.

Dentists' perspectives on caries-related treatment decisions

OBJECTIVE

To assess the impact of patient risk status on Colombian dentists' caries related treatment decisions for early to intermediate caries lesions (ICDAS code 2 to 4).

METHODS

A web-based questionnaire assessed dentists' views on the management of early/intermediate lesions. The questionnaire included questions on demographic characteristics, five clinical scenarios with randomised levels of caries risk, and two questions on different clinical and radiographic sets of images with different thresholds of caries.

RESULTS

Questionnaires were completed by 439 dentists. For the two scenarios describing occlusal lesions ICDAS code 2, dentists chose to provide a preventive option in 63% and 60% of the cases. For the approximal lesion ICDAS code 2, 81% of the dentists chose to restore. The main findings of the binary logistic regression analysis for the clinical scenarios suggest that for the ICDAS code 2 occlusal lesions, the odds of a high caries risk patient having restorations is higher than for a low caries risk patient. For the questions describing different clinical thresholds of caries, most dentists would restore at ICDAS code 2 (55%) and for the question showing different radiographic thresholds images, 65% of dentists would intervene operatively at the inner half of enamel. No significant differences with respect to risk were found for these questions with the logistic regression.

CONCLUSION

The results of this study indicate that Colombian dentists have not yet fully adopted non-invasive treatment for early caries lesions.

Evaluation of four different optimized magnetic-resonance-imaging sequences for visualization of dental and maxillo-mandibular structures at 3 T

OBJECTIVES

The purpose of this study was to evaluate four in-house optimized, non-contrast enhanced sequences for MRI-investigation of maxillo-mandibular and dental structures by use of 3 T.

METHODS

12 volunteers with different dental status were examined by using a 3 T MRI with a 20-channel standard head-and-neck coil. All images performed were evaluated by using 3D-techniques, with different slice-thicknesses, in 3D T1- and T2-weighted sequences, as well as by using new techniques of image depictions. In addition phantom measurements were performed to estimate the extent of image artefacts caused by retainers and metal implants.

RESULTS

Mean age of the participants was 33 years (range, 25.5-62.75 years), and the sex ratio was 5 females to 7 males. We identified different techniques to improve osseous and dental structures, despite problems caused by dental implants, tooth crowns or braces.

CONCLUSION

The sequences evaluated offered excellent visualization in 2D and 3D of osseous and dental structures. Anatomical, osseous and dental structures were described at their ROI, in relation to patients with dental and head and neck pathologies. The ability to detect and distinguish pathological processes as soon as possible in 3D with excellent image quality avoiding ionizing radiation remains a challenging domain.

Mercury poisoning dentistry: high-level indoor air mercury contamination at selected dental sites

Mercury (Hg), also known as quick silver, is an essential constituent of dental amalgam. It is a toxic substance of global concern. Children are more at risk from mercury poisoning which affects their neurological development and brain. In the past, a number of studies at dental sites in many countries have been carried out and reported. The present report briefly describes and discusses our recent investigations carried out at 34 dental sites (teaching institutions, hospitals and private clinics) in Pakistan. It is evident from the data that at many sites the indoor mercury vapor levels exceed far above the permissible limit recommended for safe physical and mental health. At these sites, public in general and the medical, paramedical staff and vulnerable population in particular, are at most serious risk to health resulting from exposure to toxic and hazardous mercury. To minimize such risk, some of the recommendations are, best in-house environmental practices for occupational health and safety, mercury contaminated waste reduction at source, mercury specific legislation and ratification of Minamata convention on mercury by Pakistan and other world governments at the earliest time possible.

Dental amalgam: is this the end?

Dental amalgam is a reliable and effective restorative material with a well-established role in modern dentistry. Throughout the years its mercury content and the risks posed to human health were main topics of interest for many scientists. This paper offers a review of the scientific literature on the health and environmental impact of mercury in dentistry published over the last decade. A variety of peer-reviewed, epidemiological and large-scale clinical studies on dental amalgam, as well as published reports of professional and governmental bodies, were organised thematically and analysed. The most relevant findings of the aforementioned literature are reported. No reliance has been placed on unpublished work or publicly available opinions that are not scientifically based. In order to offer an appropriate view on the topic the toxicology, health impacts and possible environmental threats are briefly presented in relation to the relevant literature published in the last ten years. It is almost unanimously accepted that dental amalgam is a safe material, with little or insignificant adverse effect on general health. However, current and mostly unfounded environmental concerns may result in the implementation of new across the board legislation that could lead to a global dental amalgam "phase out".

Metallic profile of whole blood and plasma in a series of 106 healthy volunteers

In 2003, we simultaneously quantified 27 metals by inductively coupled plasma-mass spectrometry (ICP-MS) in the whole blood, plasma and urine of 100 healthy volunteers. We again determined the metallic profile in whole blood and plasma during 2012. ICP-MS validated multielementary method was performed for metals in whole blood and plasma. Whole blood vanadium and chromium were quantified using ICP-MS collision cell technology. The aims of the study were to compare and assess any changes in this profile, particularly due to the environment. Healthy male/female staff volunteers (n = 106) with no professional exposure to metals, or medication containing lithium, strontium; or food supplements with trace elements and vitamins and with no metal prosthesis were included. Tobacco consumption and the number of dental amalgams were recorded. Our results demonstrated a blood lead level that had drastically decreased, i.e. reduced by half, during this period (12.5 versus 26.3 µg/L, P < 0.0001). Known differences were observed between males and females for copper and zinc; cadmium and lead were higher in smokers. Median plasmatic mercury, a specific test for dental amalgam exposure, did not significantly increase (0.38 versus 0.28 µg/L, P = 0.11). The ICP-MS metallic profile is a very practical concept that is useful for clinical, forensic and environmental toxicology, including industrial hygiene monitoring.

Evaluation of various concentrations of alkaline surface treatment on interfacial bond strengths of amalgam bonded to amalgam

This study was done to assess the influence of alkaline surface modification on interfacial bond strength of existing fractured (old) amalgam restoration bonded to fresh amalgam. Old and Fresh amalgam interfaced samples were prepared by applying a 4-methacryloyloxyethy trimellitate anhydride (4-META) containing adhesive. The adhesive used was Amalgabond (Parkell, Farmingdale, NY 11735, USA). Four concentrations of calcium hydroxide Ca(OH)2 solutions were used as a surface modifiers for old amalgam to increase the pH of the amalgam surfaces. The concentrations used were 2.5, 5, 10 and 15%. Direct measurement of the interfacial bond strength was carried out using an electromechanical universal tensile testing machine at crosshead speed of 10mm per minute. Results show that all the calcium hydroxide modified samples produced the increased tensile bond strength (TBS) as compared to their control group. The highest values of bond strength were achieved using 15% Ca(OH)2 solution as surface modifier. Pretreatment of fractured amalgam with calcium hydroxide improves the bond strength of 4-META adhesives. Its use in repair of amalgam may therefore be considered.

Relationship of estimated dietary intake of n-3 polyunsaturated fatty acids from fish with peripheral nerve function after adjusting for mercury exposure

BACKGROUND

Some clinical studies have suggested that ingestion of n-3 polyunsaturated fatty acids (PUFA) has neuroprotective effects on peripheral nerve function. However, few epidemiological studies have examined the effect of dietary n-3 PUFA intake from fish consumption on peripheral nerve function, and none have controlled for co-occurrence of methylmercury exposure from fish consumption.

OBJECTIVES

We evaluated the effect of estimated dietary n-3 PUFA intake on peripheral nerve function after adjusting for biomarkers of methylmercury and elemental mercury in a convenience sample of 515 dental professionals.

METHODS

We measured sensory nerve conduction (peak latency and amplitude) of the median, ulnar and sural nerves and total mercury concentrations in hair and urine samples. We estimated daily intake (mg/day) of the total n-3 PUFA, n-3 docosahexaenoic acid (DHA), and n-3 eicosapentaenoic acid (EPA) based on a self-administrated fish consumption frequency questionnaire. We also collected information on mercury exposure, demographics and other covariates.

RESULTS

The estimated median intakes of total n-3 PUFA, n-3 EPA, and n-3 DHA were 447, 105, and 179 mg/day, respectively. The mean mercury concentrations in urine (1.05 μg/L) and hair (0.49 μg/g) were not significantly different from the US general population. We found no consistent association between n-3 PUFA intake and sensory nerve conduction after adjusting for mercury concentrations in hair and urine although some positive associations were observed with the sural nerve.

CONCLUSIONS

In a convenience sample of dental professionals, we found little evidence suggesting that dietary intake of n-3 PUFAs from fish has any impact on peripheral nerve function after adjustment for methylmercury exposure from fish and elemental mercury exposure from dental amalgam.

New insight into biomarkers of human mercury exposure using naturally occurring mercury stable isotopes

Human exposure to methylmercury (MeHg) and elemental mercury vapor (Hg(0)(g)) are often estimated using total Hg concentrations in hair and urine, respectively. We investigated whether Hg stable isotopes could be used to better distinguish between exposure to Hg(0)(g) versus MeHg. We found that hair from North American dental professionals was characterized by high positive Δ(199)Hg values (mean = 1.86‰, 1 SD = 0.12‰, n = 11). This confirms that among people who regularly consume fish, total Hg concentrations in hair reflect exposure to MeHg. In contrast, we found that urine from the same individuals was characterized by a range of Δ(199)Hg values (0.29 to 1.77‰, 2 SD = 0.06‰, n = 12) that were significantly correlated to the number of dental amalgams in each individual's mouth. We hypothesize that fish-derived MeHg is demethylated within the body, causing mass-dependent fractionation and the excretion of inorganic Hg in urine. Mercury in urine therefore represents a mixture of demethylated fish-derived MeHg and amalgam-derived inorganic Hg. We estimate that the majority (>70%) of Hg in urine from individuals with <10 dental amalgams is derived from ingestion of MeHg in fish. These data suggest that within populations that consume fish, urine total Hg concentrations may overestimate Hg exposure from personal dental amalgams.

Mercury biomarkers and DNA methylation among Michigan dental professionals

Modification of the epigenome may be a mechanism underlying toxicity and disease following chemical exposure. Animal and human data suggest that mercury (Hg) impacts DNA methylation. We hypothesize that methylmercury and inorganic Hg exposures from fish consumption and dental amalgams, respectively, may be associated with altered DNA methylation at global repetitive elements (long interspersed elements, LINE-1) and candidate genes related to epigenetic processes (DNMT1) and protection against Hg toxicity (SEPW1, SEPP1). Dental professionals were recruited at Michigan Dental Association (MDA) meetings in 2009 and 2010. Subjects (n=131) provided survey data (e.g. exposure sources, demographics) and biological samples for Hg measurement and epigenetic analysis. Total Hg was quantified via atomic absorption spectrophotometry in hair and urine, indicative of methylmercury and inorganic Hg exposures, respectively. Global repetitive and candidate gene methylation was quantified via pyrosequencing of bisulfite converted DNA isolated from buccal mucosa. Hair Hg (geometric mean (95% CI): 0.37 (0.31-0.44) µg/g) and urine Hg (0.70 (0.60-0.83) µg/L) were associated with sources of exposure (fish consumption and dental amalgams, respectively). Multivariable linear regression revealed a trend of SEPP1 hypomethylation with increasing hair Hg levels, and this was significant (P<0.05) among males. The trend remained when excluding non-dentists. No significant relationships between urine Hg and DNA methylation were observed. Thus, in a limited cohort, we identified an association between methylmercury exposure and hypomethylation of a potentially labile region of the genome (SEPP1 promoter), and this relationship was gender specific.