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

Do affluent nations value a clean environment and preserve it? Evaluating the N-shaped environmental Kuznets curve

Since industrialization, the world has been under great strain from rising temperatures. Economies work hard to boost economic growth by sacrificing natural surroundings that are degrading owing to increased carbon emissions from unsustainable production and consumption. The race-to-the-bottom strategy is seen in different parts of the globalized world, corroborating the pollution haven concept and energy-related emissions. The study assumed that once affluent nations reached a particular economic level, they would concentrate on environmental reforms to safeguard environmental and natural resources. The study built a model of the emissions-growth nexus by controlling inward FDI, information and communication technology, research and development expenditures, and renewable energy using aggregated data from high-income nations from 1976 to 2019. The study verified the N-shaped environmental Kuznets curve using a three-degree polynomial factor of per capita income. On the other hand, inward FDI was assessed as having the potential to support the pollution haven hypothesis (PHH) by increasing carbon emissions. The data show that the square and cubic forms of per capita income have a significant negative and positive effect on carbon emissions in the long run, corroborating the short-peak V-shaped EKC hypothesis. However, the N-shaped EKC hypothesis between income and emissions is verified in the short run. The PHH confirmed that more inward FDI is associated with higher long-term carbon emissions. For decreasing global carbon emissions and unclean production, stringent and incentive-based regulations are preferable.

Managing the phase-down of amalgam amongst Nigerian dental professionals and students: A national survey

BACKGROUND

Amalgam is one of the most reliable dental restorative materials. Health and environmental concerns associated with the mercury content of amalgam have necessitated an amalgam phase-down in clinical practice.

OBJECTIVES

This study investigated the level of awareness and preparedness for the planned amalgam phase-down recommended by the Minamata Convention amongst Nigerian dental students and dentists.

METHODS

This cross-sectional national survey was performed across all geopolitical zones of Nigeria. Data regarding awareness, practice and level of preparedness for amalgam phase-down were obtained using a questionnaire that was distributed amongst clinical dental students and dentists of different cadres, who routinely place dental restorations, in public and private practice. The questionnaires were administered online or were hand delivered. Data were analysed using the chi-square test and Spearman's rank correlation coefficient. A p value ≤ 0.05 was considered statistically significant.

RESULTS

Notably, 845 dental students and dentists participated in the survey. Mean age (±standard deviation) of participants was 30.15 ± 7.67 years, 33.8% were students, and 66.2% were dentists (most dentists [77.1%] were employed at public hospitals). A significant percentage of respondents had poor knowledge of the Minamata Convention (87.7%) and lacked training in the use of alternatives to amalgam (72.0%). Amalgam continues to be commonly used by 39.1% and 31.3% of dental students and dentists, respectively. Only 4.7% of the respondents admitted to following good amalgam phase-down practices. Awareness (P = 0.013) and amalgam phase-down practices (P = 0.011) were significantly higher amongst dentists than amongst dental students.

CONCLUSION

We observed low levels of awareness regarding the Minamata Convention, amalgam phase-down, mercury hygiene practices and training in alternatives to amalgam use amongst Nigerian dental professionals and students.

Physical Properties of Glass Ionomer Cement Containing Pre-Reacted Spherical Glass Fillers

The aim of this study was to assess the effect of different commercial liquid phases (Ketac, Riva, and Fuji IX) and the use of spherical pre-reacted glass (SPG) fillers on cement maturation, fluoride release, compressive (CS) and biaxial flexural strength (BFS) of experimental glass ionomer cements (GICs). The experimental GICs (Ketac_M, Riva_M, FujiIX_M) were prepared by mixing SPG fillers with commercial liquid phases using the powder to liquid mass ratio of 2.5:1. FTIR-ATR was used to assess the maturation of GICs. Diffusion coefficient of fluoride (DF) and cumulative fluoride release (CF) in deionized water was determined using the fluoride ion specific electrode (n=3). CS and BFS at 24 h were also tested (n=6). Commercial GICs were used as comparisons. Riva and Riva_M exhibited rapid polyacrylate salt formation. The highest DF and CF were observed with Riva_M (1.65x10-9 cm2/s) and Riva (77 ppm) respectively. Using SPG fillers enhanced DF of GICs on average from ~2.5x10-9 cm2/s to ~3.0x10-9 cm2/s but reduced CF of the materials on average from ~51 ppm to ~42 ppm. The CS and BFS of Ketac_M (144 and 22 MPa) and Fuji IX_M (123 and 30 MPa) were comparable to commercial materials. Using SPG with Riva significantly reduced CS and BFS from 123 MPa to 55 MPa and 42 MPa to 28 MPa respectively. The use of SPG fillers enhanced DF but reduced CF of GICs. Using SPG with Ketac or Fuji IX liquids provided comparable strength to the commercial materials.

Direct technique premolar coronal restorations: From metallic material to "complete adhesive restoration"

Introduction:

The choice of restorative materials has for a long time been determined by the tooth position. Thus, premolar restoration depended on the practitioner's clinical assessment and practical experience in regard to the material to be handled.

Aim:

The objective of this study was to assess, in the students' practice, the change in the choice of materials used for premolars restoration.

Materials and Methods:

This was a retrospective study based on the available care records in the department of conservative dentistry and endodontics of a dental school. Variables analyzed included the year of restoration, the type of material, the premolar position in the arch, and the coronal restoration site (occlusal, proximal, and cervical). Data collected were processed with the SPSS software version 22 (SPSS Inc., Chicago, IL, USA; 2013). The statistical significance threshold was set at 5% for Pearson's Chi-square test.

Results:

Between 1994 and 2017, 1738 restored premolars were identified. Over the years, amalgam restorations declined from 99.2% in 1994 to 1.3% in 2017, contrary to composite whose frequency increased from 0.6% to 88.6%. Maxillary premolars were exclusively restored with composite in 2017 when amalgam was still, somewhat, used for mandibular premolars.

Conclusion:

The reversal in the choice of materials in favor of composites reflects the global trend. This seems to be related to the current awareness of the prohibition, among others, of medical devices containing mercury.

Amalgam phase down: baseline data preceding implementation in Nigeria

OBJECTIVE

The Minimata Convention on mercury includes amalgam phase-down and eventual phase-out from dentistry. To aid its subsequent evaluation it is important to have baseline data of amalgam use in a locality prior to implementing a phase-down.

METHODOLOGY

Records of patients spanning 5 years from January 2011 to January 2016 were analysed to determine and the compare frequency of amalgam usage with other dental materials for carious teeth restorations in a Nigerian university teaching hospital. Classes of cavities restored and cadres of operators who employed the different materials were included. Institutional ethics committee approval was obtained prior to commencing the study.

RESULTS

2,058 patients' records were retrieved, 59% females and 41% males. Their ages ranged 19-80 years, mean 33.5 ± 12.7 years, young adults 20-39 years old were the majority (62.9%). Filling materials included 57.5% amalgam, 17.6% glass ionomer cement (GIC) and 24.9% resin composite. Class I restorations constituted 70.5% of amalgam restorations, while Class II restorations made up 29.4% and Class V restorations accounted for 0.1%. Undergraduate dental students placed most of the amalgam restorations (60.5%), and 78.9% of all their restorations were amalgam. Less experienced dentists used all materials equally; the more experienced dentists placed more composite resin and GIC (43.3%).

CONCLUSION

Amalgam fillings constituted nearly 60% of the restorations of carious teeth. Training of dental students in placement of non-mercury alternatives to amalgam and Minimum Intervention Dentistry needs to be emphasized in dental schools. Phase-down of amalgam should be intensified in Nigeria with the ultimate aim of a phase-out in line with the Minamata Convention.

Complex Dentistry in General Practice - What Would You Do?

In 2019, in a world of instant gratification, what are the expectations of patients and dentists? Is training sufficient to meet these expectations? Decision-making in dentistry impacts the treatment choices patients are given, and may influence the outcomes of such treatment. It is therefore important to ensure as much standardisation as possible. In order to achieve this, it is important to know the current standard and the views of dentist as this will influence dental treatment planning. Clinical Relevance: This paper captures the treatment planning dilemmas of dentists, specifically of those in their Foundation training year, in order to aid targeting of training and development. Objective Statement: To understand treatment decisions of general dental practitioners and specialists.

Dental Composites with Calcium / Strontium Phosphates and Polylysine

Purpose

This study developed light cured dental composites with added monocalcium phosphate monohydrate (MCPM), tristrontium phosphate (TSrP) and antimicrobial polylysine (PLS). The aim was to produce composites that have enhanced water sorption induced expansion, can promote apatite precipitation and release polylysine.

Materials and Methods

Experimental composite formulations consisted of light activated dimethacrylate monomers combined with 80 wt% powder. The powder phase contained a dental glass with and without PLS (2.5 wt%) and/or reactive phosphate fillers (15 wt% TSrP and 10 wt% MCPM). The commercial composite, Z250, was used as a control. Monomer conversion and calculated polymerization shrinkage were assessed using FTIR. Subsequent mass or volume changes in water versus simulated body fluid (SBF) were quantified using gravimetric studies. These were used, along with Raman and SEM, to assess apatite precipitation on the composite surface. PLS release was determined using UV spectroscopy. Furthermore, biaxial flexural strengths after 24 hours of SBF immersion were obtained.

Results

Monomer conversion of the composites decreased upon the addition of phosphate fillers (from 76 to 64%) but was always higher than that of Z250 (54%). Phosphate addition increased water sorption induced expansion from 2 to 4% helping to balance the calculated polymerization shrinkage of ~ 3.4%. Phosphate addition promoted apatite precipitation from SBF. Polylysine increased the apatite layer thickness from ~ 10 to 20 μm after 4 weeks. The novel composites showed a burst release of PLS (3.7%) followed by diffusion-controlled release irrespective of phosphate addition. PLS and phosphates decreased strength from 154 MPa on average by 17% and 18%, respectively. All formulations, however, had greater strength than the ISO 4049 requirement of > 80 MPa.

Conclusion

The addition of MCPM with TSrP promoted hygroscopic expansion, and apatite formation. These properties are expected to help compensate polymerization shrinkage and help remineralize demineralized dentin. Polylysine can be released from the composites at early time. This may kill residual bacteria.