Dental composite materials and renal function in children

Toxicity of resin-matrix composites in a dental clinical setting

The aim of this study was to perform a systematic review to comprehensively explore the factors contributing to the resin-matrix composites' toxicity in patients. A systematic review was performed according to the PRISMA guidelines. The bibliographic review was performed in the following databases: PubMed, Cochrane Central and Web of Science. Inclusion and exclusion criteria were established to retrieve articles published in English over the last 20 years. The research yielded 1261 articles, with 1227 articles remaining after removing duplicates. Following a title and abstract screening, 20 articles underwent full-text review, and 12 in vivo studies were included. Detectable levels of free monomers and potential toxicity exposure were reported in the selected studies on saliva, urine, and blood samples. The selected in vivo studies suggest relatively low local and systemic toxicity although the available methods show technical limitations and therefore further studies are required. Dental operator-dependent factors were also identified. Standard chair-side guidelines on handling of resin-matrix composites placement plays a key role on the properties of the materials. The results reported noticeable changes in samples were not considered significant to affect patient's health, although, manufacturer's instructions must be followed whilst using resin-matrix composites. In fact, adequate light curing parameters maintain a high degree of conversion of the resin-matrix composites  decreasing the release of residual monomers and thus the probability of related  toxicity.

Residual Monomer Release after the Polymerization of Different-Colored Flowable Compomer

BACKGROUND

Compomers are restorative materials commonly used in pediatric dentistry. It is important to investigate the monomer release of materials used especially in pediatric patients. The aim of this study was to evaluate the residual monomer released from different-colored flowable compomers at five polymerization times.

MATERIALS AND METHODS

Three experimental groups were formed: Group 1: pink flowable compomer (Twinky Star, VOCO, Germany), Group 2: blue flowable compomer (Twinky Star, VOCO), Group 3: white flowable compomer, A2 color of Dyract XP (Dentslpy DeTrey, Konstanz, Germany). For each group, samples were prepared using standard cylindrical Teflon molds (n = 10), and the compomers were cured using a light-emitting diode (LED) source in accordance with the manufacturer's recommendations. During each time period, the number of residual monomers: bisphenol-A glycidyl methacrylate (bis-GMA), urethane dimethacrylate (UDMA), hydroxyethyl methacrylate (HEMA), and triethylene glycol dimethacrylate (TEGDMA) were determined with high-performance liquid chromatography (HPLC). All data were analyzed statistically.

RESULTS

In all groups, the amount of residual monomers increased after 1-h release periods (P < 0.05). For 2 weeks, the total residual monomers released were determined at most in Group 3 and at least in Group 1. However, there was no significant difference between the groups in terms of released amounts of monomers (P > 0.05).

CONCLUSIONS

According to the study, when the total amount of residual monomer released from all groups was compared, no difference was found and it was observed that none of them exceeded the toxic dose. Flowable colored compomers can be used as safely as white compomers in pediatric dentistry.

Analytical Methods for Determination of BPA Released from Dental Resin Composites and Related Materials: A Systematic Review

Knowing the impacts of bisphenol A (BPA) on human health, this systematic review aimed to gather the analytical methods for the quantification of BPA release of BPA in dental materials in in vitro and in vivo (biological fluids) studies. A brief critical discussion of the impacts of BPA on human health and the possible association with BPA in dental materials was also presented. The research was carried out by three independent researchers, (according to PRISMA guidelines) in PUBMED and SCOPUS databases, by searching for specific keywords and articles published between January 2011 and February 2022. Seventeen articles met the eligibility criteria and were included in this systematic review: 10 in vitro and 7 in vivo. In in vitro studies, the highest amounts of BPA released were from flowable to conventional resins, followed by resin-modified glass ionomer. In contrast, the smallest amount was released from "BPA-free" composites and CAD-CAM blocks. Regarding in vivo studies, a higher concentration of BPA were found in saliva than urine or blood. The best analytical method for trace quantifying BPA is LC-MS/MS (Liquid Chromatography with Tandem Mass Spectrometry) due to its selectivity, low quantification limits, and the unequivocal identification. However, further studies are required to develop faster and more sensitive methods, in order to obtain more reliable results.

Once Resin Composites and Dental Sealants Release Bisphenol-A, How Might This Affect Our Clinical Management?-A Systematic Review

(1) Background: Bisphenol A (BPA) based dental resins are commonly used in preventive and reparative dentistry. Since some monomers may remain unpolymerized in the application of dental resin, they dissolve in the saliva. (2) Methods: The literature search was carried out in Pubmed, Cochrane and Embase databases. Randomized controlled trials, cohort studies and case-control studies that evaluated BPA levels in human urine, saliva and/or blood were included. (3) Results: The initial search had 5111 results. A total of 20 studies were included in the systematic review. Most studies showed an increase of the levels of bisphenol A 1 h after treatments with composite resins and dental sealants. One week after treatments the levels were decreased. (4) Conclusions: Some clinical precautions should be taken to decrease the release of BPA, namely the use of rubber dam, the immediate polishing of all resins used, or the use of glycerin gel to avoid non-polymerization of the last resin layer, and mouthwash after treatment. Another preventive measure in addition to the above-mentioned is the use of the smallest possible number of restorations or sealants, a maximum of four per appointment. These measures are even more important in children, adolescents and pregnant women.

Urinary metabolites of dibutyl phthalate and benzophenone-3 are potential chemical risk factors of chronic kidney function markers among healthy women

Chronic kidney disease (CKD) is a global health threat of growing concern. Recently, exposure to endocrine disrupting compounds (EDCs) such as phthalates and bisphenol A has been suggested as a risk factor for CKD. However, most epidemiological studies have focused on a limited number of urinary chemicals. This study aimed to identify chemical determinants of the urinary albumin-to-creatinine ratio (ACR), which is a kidney function marker, among multiple major EDCs including phthalate metabolites, bisphenols, and benzophenones in a Korean female population (20-45 years old, n = 441). First, the creatinine-adjusted urinary concentration of each urinary chemical was associated with ACR in a linear regression model (single-pollutant model). Then, compounds with a significant association with ACR in the single-pollutant model were added in a multi-pollutant model and evaluated for their association with ACR. Moreover, to prevent potential reverse causality due to impaired kidney function, quartile analyses were performed for the subjects with healthy renal function (ACR < 9.71 mg/g). In addition to creatinine adjustment, the statistical analysis was also conducted with specific gravity-adjusted concentrations of urinary chemicals, and the results were compared. Several compounds measured in the urine showed a significant association with ACR in the single-pollutant model. In the multi-pollutant model, however, only monobutyl phthalate and benzophenone-1, which are metabolites of dibutyl phthalate and benzophenone-3, respectively, showed significant positive associations. The association of these chemicals remained significant in a couple of the sensitivity analyses with a different adjustment of urine dilution and in a subpopulation with normal ACR. In conclusion, among dozens of urinary chemicals, monobutyl phthalate and benzophenone-1 consistently showed a strong association with urinary ACR. Confirmation of our observation in other human populations and experimental studies is warranted.

Environmental exposures and pediatric kidney function and disease: A systematic review

BACKGROUND

Environmental chemical exposures have been implicated in pediatric kidney disease. No appraisal of the available evidence has been conducted on this topic.

METHODS

We performed a systematic review of the epidemiologic studies that assessed association of environmental exposures with measures of kidney function and disease in pediatric populations. The search period went through July 2016.

RESULTS

We found 50 studies that met the search criteria and were included in this systematic review. Environmental exposures reviewed herein included lead, cadmium, mercury, arsenic, fluoride, aflatoxin, melamine, environmental tobacco, bisphenol A, dental procedures, phthalates, ferfluorooctanoic acid, triclosan, and thallium/uranium. Most studies assessed environmental chemical exposure via biomarkers but four studies assessed exposure via proximity to emission source. There was mixed evidence of association between metal exposures, and other non-metal environmental exposures and pediatric kidney disease and other kidney disease biomarkers. The evaluation of causality is hampered by the small numbers of studies for each type of environmental exposure, as well as lack of study quality and limited prospective evidence.

CONCLUSION

There is a need for well-designed epidemiologic studies of environmental chemical exposures and kidney disease outcomes.

Bisphenol A Release: Survey of the Composition of Dental Composite Resins

BACKGROUND

Bisphenol A (BPA) is an endocrine disruptor with potential toxicity. Composite resins may not contain pure BPA, but its derivatives are widely used. Several studies found doses of BPA or its derivatives in saliva or urine of patients after composite resin placement.

OBJECTIVE

The aims of this study were to establish an exhaustive list of composite resins marketed in Europe and their composition, and to assess the extent of BPA derivatives used.

METHODS

A research on manufacturers' websites was performed to reference all composite resins marketed in Europe, then their composition was determined from both material safety data sheets and a standardized questionnaire sent to manufacturers. Manufacturers had to indicate whether their product contained the monomers listed, add other monomers if necessary, or indicate "not disclosed".

RESULTS

160 composite resins were identified from 31 manufacturers and 23 manufacturers (74.2%) responded to the survey. From the survey and websites, the composition of 130 composite resins (81.2%) was: 112 (86.2%) based on BPA derivatives, 97 (74.7%) on bis-GMA, 17 (13.1%) without monomer derived from BPA (UDMA, sometimes with TEGDMA) and 6 (4.6%) with UDMA (only); 1 (0.8%) did not contain a BPA derivative or UDMA or TEGDMA. Pure BPA was never reported.

CONCLUSION

This work has established a list of 18 composite resins that contain no BPA derivative. Manufacturers should be required to report the exact composition of their products as it often remains unclear or incomplete.

Summary of: dental composite materials and renal function in children

OBJECTIVE

To examine whether greater exposure to resin-based composite materials, which may intra-orally release bisphenol A (BPA), is associated with worse renal function outcomes in children.

DESIGN

Prospective multi-centre study.

SETTING

Community health dental clinics in Boston and Maine from 1997-2005.

SUBJECTS AND METHODS

Five hundred and thirty-four New England Children's Amalgam Trial participants aged six to ten years were randomised to treatment with amalgam or resin-based composite restorations over five years of follow-up.

INTERVENTIONS

Restorations were placed according to treatment arm, and sealants placed per standard of care. Cumulative composite exposure was calculated using surface-years (each treated surface weighted by number years present).

MAIN OUTCOME MEASURES

Urinary excretion of albumin, gamma-glutamyl transpeptidase (gamma-GT), and N-acetyl-β-D-glucosaminidase (NAG) were available for 417 children.

RESULTS

Analysis of covariance showed no association between exposure to dental composites, polyacid-modified compomer, or flowable composite dental sealants and preventative resin restorations with levels of renal function. There was no association between composite materials and thresholds indicating renal damage in logistic regression models.

CONCLUSIONS

This study found no harmful associations between dental composite materials and renal function in children. Therefore, concerns about renal function need not be a consideration in the choice of dental restoration material or placement of preventative dental sealants.

The effects of environmental chemicals on renal function

The global incidence of chronic kidney disease (CKD) is increasing among individuals of all ages. Despite advances in proteomics, genomics and metabolomics, there remains a lack of safe and effective drugs to reverse or stabilize renal function in patients with glomerular or tubulointerstitial causes of CKD. Consequently, modifiable risk factors that are associated with a progressive decline in kidney function need to be identified. Numerous reports have documented the adverse effects that occur in response to graded exposure to a wide range of environmental chemicals. This Review summarizes the effects of such chemicals on four aspects of cardiorenal function: albuminuria, glomerular filtration rate, blood pressure and serum uric acid concentration. We focus on compounds that individuals are likely to be exposed to as a consequence of normal consumer activities or medical treatment, namely phthalates, bisphenol A, polyfluorinated alkyl acids, dioxins and furans, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Environmental exposure to these chemicals during everyday life could have adverse consequences on renal function and might contribute to progressive cumulative renal injury over a lifetime. Regulatory efforts should be made to limit individual exposure to environmental chemicals in an attempt to reduce the incidence of cardiorenal disease.