Attending Craft Fairs is Important

Credit: Artefact Contemporary Craft Fair at Vessel Gallery 

It is easy to think up reasons for not attending craft events, e.g.:

·        Expense

·        Stocking costs

·        Accommodation and travel

·        Will I be able to sell to people?

·        Is my glass work good enough?

·        Which show is the right one; there are so many?

These are the thoughts we use when trying to avoid something.  There are a number of reasons to make the effort to show your glass at events.  These are some of them.

Feedback

Attending a craft fair enables you to get personal feedback on your work and your prices.  The questions people ask will show the kind of marketing you need to do. By talking to people, you can refine the idea of your ideal client and what they like about your glass.  The things about your work that are not clear indicate what you need to consider about your glass or presentation.

“It’s much better to get feedback from strangers who are interested in design or crafts, rather than asking for feedback from your mum or best friend!”  Patricia Van den Akker

Raise your Profile

Attending the events that fit your glass work can build your profile in a way that on-line cannot.  An event where entrants are selected boosts your confidence, but more importantly, boosts the confidence of the buyer.  You can use this to build your reputation by posting on social media, and even help to get local business awards.  But be sure the event is one which contains your peers, as a poorly chosen show will not improve your profile.

Maintain Contacts

Participation in fairs and other events is an easy way to maintain existing contacts.  It shows how your glass is developing and maintains your profile within the buying community.  It is also a good excuse to connect with the people on your mailing list, and through social media.  An invitation is a welcome reminder to people that you value the client enough to welcome them to your event.

New Clients

While at an event, whether a trade fair, or another kind of event, the people you meet will be those who are interested and willing to buy.  These are your new customers coming to your door.  Get them to sign up to your newsletter online with Mail Chimp or other reputable email provider to ensure you comply with the GDPR legislation on privacy.  Give them information about your social media and website too.

Events Can Help Online Sales 

When promoting your participation in an event, you need to feature your website also.  This enables those who cannot attend the event to look at the site and some will purchase.  Also, when you are following up with people afterwards some will make online purchases although they did not buy at the event. 

Physical Presence 

You stand is a tangible presentation of your glass or collection.  A well-presented stand can have much more impact than an online display.  It is an occasion where people can touch your work and get a tactile impression as well as physical one. This engagement with your glass makes it more likely people will buy from you now or in the future.

Selling creative work is a process and your individual and trade clients go through various steps of getting to know you, like you and trust you before they purchase…   Events play a key role in this buying and commissioning process.  Patricia van den Akker.

Deadlines

Signing up to an event means you have to have things ready. You can‘t put things off, because you have to be there and be prepared.  This makes you direct all your efforts to all of your business needs at once – marketing, promotion, updating the website, pricing, preparing your stand and its display of glass work, etc.  It brings to the fore all the things you may have put on the back burner.

Attending craft fairs and other selling events can bring many benefits in addition to sales – profile, getting feedback, re-connecting with previous customers, finding new customers, and simply putting everything you need to promote your business in a one-time limited occasion.

Vitrification: The Workhorse of Nuclear Waste Management

 

Vitrification: The Workhorse of Nuclear Waste Management

Posted Krista Grayson on Jun 18, 2019

Nuclear power has been used to produce electricity for over 60 years, and is responsible for around 16% of the electrical energy produced worldwide. This percentage is likely to increase, as countries move away from fossil fuels and require a source of energy to make up the shortfall this will cause. 

With more reactors coming online, more fuel will be used, and this presents a problem: there is no conclusive method to handle the spent fuel. Vitrification (the transformation into glass) of nuclear waste is one established solution, but there is still plenty of room for improvement in this method.

The issue of nuclear waste

A key problem with nuclear power is what to do with the waste products generated when the fuel is completely spent. Although it is no longer useful in power generation, this waste is still very dangerous if not stored correctly. 

The most problematic waste, called ‘high level’ nuclear waste (HLW), is highly radioactive, has an extremely long half-life and requires cooling and containment due to the elemental decay, which gives off heat and radiation. 

Additionally, some radioactive isotopes such as Tc-99, Se-79, and I-129 are mobile in water, which requires further measures in order to reduce their ability to move into the groundwater. Secondary waste streams can also present issues as this waste can contain large amounts of molybdenum and noble metals.

Safely storing nuclear waste through vitrification

One method of long term storage and disposal involves the processing and transformation of the spent fuel into a glass, a technique known as vitrification. It has been used for HLW immobilization for over 40 years in most countries that have a nuclear power program, including France, Germany, Belgium, Russia, UK, Japan, and the USA.

Glass is desirable as a long-term storage form as it is a relatively insoluble, compact and solid. In this form it is easier to store and handle, saving space and reducing cost. Glass also possesses high chemical durability, allowing it to remain in a corrosive environment for thousands or even millions of years without failing. While glass is often thought of as a fragile material, a properly treated block of borosilicate glass is incredibly resilient.

How vitrification works

The process of vitrification is quite simple but can be difficult to execute. First, the waste is dried, then heated to convert the nitrates to oxides. Glass-forming additives are added to the waste material and heated again to around 1000 °C. The molten liquid is poured into a suitable containment vessel to cool and form the glass. Once solidified, the final vitreous product has incorporated the waste contaminants in its macro- and micro-structure, and the hazardous waste constituents are immobilized.

The two main types of glass currently used to immobilize nuclear waste are borosilicate and aluminophosphate glasses. Both of these materials allow high waste loadings and can immobilize large amounts of actinides. Borosilicate glasses can accommodate up to 7.2 mass pct of PuO2 for example. 

Advantages and limitations of nuclear waste vitrification

Although vitrification is often the preferred method of waste storage, there are some drawbacks to the current techniques, both with the necessary setup and materials used. Vitrification has a high initial investment cost, high operational cost and complex technology requiring qualified personnel. 

This makes it most economically viable in locations where relatively large volumes of radioactive waste with stable composition are available, such as HLW from nuclear power plants. 

Unfortunately, the current generation of glasses cannot handle large amounts of MoO3 and noble metals that are produced from secondary waste streams. These compounds are poorly soluble in borosilicate glasses and this limits the amount of waste that can be loaded into the material, increasing process time and material costs.

New materials to process molybdenum-rich nuclear waste

It is clear that vitrification is of vital importance for the long term success of nuclear power. Mo-Sci has been working on new types of glass that can immobilize a higher percentage of waste, as well as methods within the processing that can speed up the vitrification.

This includes an iron phosphate waste form able to contain 40 wt% of the simulated molybdenum-rich nuclear waste. This vitrified nuclear waste is prepared by melting the mixture of simulated waste components and iron phosphate glass additives in a commercial-scale cold crucible induction melter (CCIM). When the chemical durability of the waste form was measured, it was found to be as good as or better than that of borosilicate glass.

The CCIM melting technology can also process waste forms faster, safer and at a lower cost than other melting technologies as it removes the metal electrodes that directly contact the molten glass and refractory used to contain the melt. This novel CCIM-processed iron phosphate waste form could drive large savings in time and money in the industry’s need to remediate nuclear waste, and make nuclear power an even more attractive option for the future. 

See our article on iron phosphate waste forms for more information on these new developments.

References

1. Thompson, L. (2010) Vitrification of Nuclear Waste http://large.stanford.edu/courses/2010/ph240/thompson2/
2. Criscenti, L. et al. (2013). An international initiative on long-term behavior of high-level nuclear waste glass. Materials Today, 16 https://doi.org/10.1016/j.mattod.2013.06.008
3. Ojovan, M. I., & Lee, W. E. (2011). Glassy Wasteforms for Nuclear Waste Immobilization, 42 https://doi.org/10.1007/s11661-010-0525-7 
4. Ojovan, M. I. (2007). Glasses for Nuclear Waste Immobilization, WM’07 Conference. https://www.researchgate.net/publication/267700284_Glasses_for_Nuclear_Waste_Immobilization/download 
5. Cheol-Woon, K. (2018) Iron Phosphate Waste Forms for Nuclear Waste Disposal https://mo-sci.com/iron-phosphate-nuclear-waste-disposal

Selling online

Credit: 48HoursLogo.com

Once you have achieved a lot of visits to your website, you need to convert the visits to sales. 

The first thing you need to do is consider your products.  Craft products are more difficult to sell online than mass manufactured items that are completely standard and so have known quality.

Is your product suitable for online selling?

·        The general case is that lower priced gift items are easier to sell than expensive ones. 

·        Is delivery expensive relative to the cost of the item? 

·        Do the items have to be sized, e.g., rings?

·        Are the items easy to post safely without breakage?

·        How much packaging will be necessary?

If the answers are that what you sell is expensive to buy or deliver, must made to a size, or are difficult to post, you may have difficulties in generating sales.  If you have items that are likely to sell less well online, consider the other ways you can sell them – trade events, galleries, shops, wholesale.  Also think about making items that are easier to sell online, but still fall within your style.  This approach will help support your more difficult to deliver or more expensive items that won’t sell well online.

Then

Online selling techniques are not so different from in-person selling, except that you have to rely on text and images to do the selling.  This puts more emphasis on words and images and getting your personality into those two things.

The basics are:

Get the viewer’s attention

Stimulate their interest

Develop their desire for the object

Convert these elements into the purchase.

There are many things that can create these three pre-requisites for a purchase.  

Images

The quality of images is extremely important.  Photographs must be sharp, focused, and with lots of light.  They must be taken to show the quality of craftsmanship.  Multiple pictures of the item help to give a better feeling of the object.  They should be taken from various angles, including the unseen backs of items to show the craftsmanship and help promote the assurance of quality. Lifestyle images bring items to life, but have to be carefully arranged.  This is often done best by a professional photographer.

Get and maintain interest

What you do must be apparent immediately.  Do you have recognisable work or style? Is your business name memorable?  An explanation of what you do and why it is unique is important to maintain interest.  Links from these explanations to relevant individual items or product groups are appropriate to keeping people engaged.

It is important to maintain interest after the initial contact.  Make it easy to find other relevant items. Use links, buttons, suggestions, etc., liberally.

Keep the site alive with case studies. These can be the background to your workday, or events in your business life.   Inside views of the development of new lines shows how you progress from idea to finished work.  You have interesting ways of working, that many people are interested in knowing about. Show your working practices, tell them the story of making.

You need to keep in touch with potential and existing clients.  Direct posts to those you have contact details for, with information on developments keeps you and what you do in customers’ minds.  These must not be direct sales pitches.  You can ask questions of these people to keep them engaged. They may also tell others about you and your work.  General posts to targeted audiences can help spread the word too.  Some paid promotion on social media can help, if targeted to the right people.

Provide information

Explain the potential questions about each item that client may have.  Think about the kinds of questions you ask about non-glass craft products. Use those approaches in stating and answering these questions.

Make the explanations personal and consistent with your site and the glass products you are offering.  In many cases, it is desirable to establish a FAQ section, including terms and conditions.  This can help maintain confidence of the buyer in your ability to make and supply the work.

Purchase

What’s for sale

You need to overcome any difficulties that the client might face in coming to the buying decision.  The website should be immediately clear about what you do and for whom.  Price levels need to be clear, possibly by grouping or sorting. Images need to connect with client desires.  This is where lifestyle images are useful.  Do remember that first impressions are all important.

Develop trust

Development of, or appearance of trustworthiness is essential to buying.  People buy from those they know, like and trust.  Development of this is essential for consistent online sales, as well as anywhere else.  This can be promoted by your presence on a group of platforms that you link between. Good descriptions of products and about yourself are important to maintaining the trust of the client.  Testimonials, if you have them, are useful. 

The website must appear professional.  Knowledge of your location is important to developing confidence in your work. Knowing where else your work is available is also important in validating confidence in your business.  Knowledge of where else your work can be purchased gives creditability to your standing within the craft  buying community. This can include your attendance at craft and trade fairs, as well as any awards or press mentions.

Buying and delivery

Make it easy to purchase.  One-click links can help ease the customer into buying. Use of a known payment provider increases confidence that the purchased item will be delivered and that there is a mechanism to get money back if not.  Make sure you explain about postage and packaging, unless you have included it in the in price.  If P&P is included, make sure that you are clear in the text accompanying the image and description.  If you don’t do that, the price comparisons with those that don’t include P&P are skewed against you.  Include plain English terms and conditions, to engender trust if something were to go wrong.

But

Don’t rely exclusively on online sales. There is enormous competition online, even though it is a means to get your work known to a wide range of people Importantly, it is a way to get year-round sales rather than the summer and autumn craft circuit.  Other sources for consistent sales - without you being present all the time - are galleries, shops and wholesalers.

Think about combining online sales with craft fairs and other selling events.  These face to face events give you the opportunity of getting direct feedback on your work, which will help develop what you do.  Promote your attendance at events on the website and tell about your website at events.  Blog about the events before and after their occurrence on your website and social media.  Tell stories from the events on your social media and in the website, too.

Selling online requires getting attention, stimulating interest and promoting desire to buy.  Some of the things you can do are noted.  But do not put all your effort into online.  You can gain a lot of information by attending face to face selling events.

Are Electric Furnaces the Future of Glass Manufacturing?

 

Are Electric Furnaces the Future of Glass Manufacturing?

Posted Krista Grayson on May 16, 2019

Overview of glass production 

Glass production is typically energy-intensive. Glass furnaces may reach 1300-1550 ºC for the melting and refinement of the raw materials, depending on the formulation required. 

Natural gas and electricity are the main energy sources, however historically, the glass industry has favored gas because it is an established technology, with low price, high purity, ease of control and the fact that there is no requirement for storage facilities. Gas furnaces have long life-times, on average over 12 years and sometimes up to 20 years.

Until recently electric glass melting furnaces have been used for specialty glasses, and particularly glasses with significant volatile constituents such as fluoride opal glasses, borosilicates and lead crystal. Interest is growing in extending its use through the industry.

Electric glass furnace production

The most effective method of electric glass production is to use electrodes immersed in the glass either as electric boosting (providing 5-20 % of total energy input) or all-electric melting. The immersed electrodes are connected to a power supply and transformer, to pass an electric current through the glass. 

In all-electric furnaces, the melting energy comes from the electrodes (joule heat), with a gas burner being used for the initial start-up, or as an emergency heat source. These furnaces mainly operate ‘cold top’, where the raw material is distributed evenly over the melting surface of the glass, forming an insulating ‘batch blanket’. Melting and refining take place in one vertical process, with glass being drawn through a throat at the bottom of a deep melting tank.

Advantages of electric melting

Electric furnaces offer several advantages over gas furnaces. For example, they have very low direct emissions of CO2, thermal NOx or SOx emissions. With pressure to reduce emissions coming from both customers and legislation, this is a significant benefit. While it is possible to improve conventional gas furnaces to reduce emissions, this can result in more complex technology that results in additional maintenance, the use of non-environmentally friendly chemicals, and limitations to equipment lifespan. 

Another benefit is that heat losses from electric furnaces are much lower. The thermal efficiency of gas furnaces peaks at around 45%. This means more energy is lost as heat than is used to convert the raw materials to molten glass. Heat losses occur from the superstructure of the furnace and in the residual waste gases, even if heat recovery systems are used. In contrast, the electrical approach means that the melting energy is transferred directly into the glass. Thermal efficiency can be over 70% even in a small electric furnace and can reach 85% in a large electric furnace.

All-electric furnaces are also more energy efficient than gas-fired furnaces; they use around 35% less energy. The difference in energy efficiency is particularly important for small furnaces. As furnace size decreases, the energy efficiency of electric furnaces remains very high, whereas the efficiency of gas furnaces drops dramatically and can be less than 20%. 

Electric boosting can be a highly effective way to reduce overall energy consumption. It also means that energy release can be highly focused, helping to determine conditions in the glass bath. In some cases, a well-designed boost system can improve glass quality homogeneity, seed and stone losses. In contrast, in gas furnaces, where focused energy release is not possible, imprecise temperature profiles can be created in the glass. 

A key advantage of the cold-top electric furnace is that everything that goes into the batch stays in the glass, aside from the gases released from the melting process, which permeate out through the batch blanket. Losses of batch constituents such as fluorine, boron, lead, various volatile refining agents and other constituents are almost eliminated. 

Disadvantages of all-electric melting

While electric furnaces have lower capital costs, they have shorter life-times (2-7 years compared to 10-20 years for conventional furnaces) and higher energy costs. The economic viability of electric furnaces is closely related to the cost of electricity compared with gas. Higher thermal and energy efficiencies can offset this cost for smaller furnaces, but this might not be the case for larger furnaces. 

The low environmental impact is only maintained if the furnace can receive power from renewable energy sources and requires a power grid that is reliable and stable. 

There are also operational considerations. For example, the maintenance of electrodes to limit higher resistance caused by wear. It is not possible to melt higher temperature glasses (>1500C) and there is concern of corrosion/erosion of electrode material from certain glass compositions. Further, recycled glass may be an issue that requires new handling methods. 

Conclusion

In most places, it is still environmentally cleaner to burn fossil fuels in a furnace than to use them to generate electricity for electric melting. However, as renewables increase their contribution to electricity production, this situation will change. It also appears that improvements in energy efficiency of fossil fuel combustion technologies have leveled off. As emissions legislation kicks in and consumers increasingly demand materials and technologies that are environmentally friendly, there may be well a swing in glass manufacture from gas to electric energy. The other advantages of electric melting, such as better thermal efficiency and energy consumption, will also count in its favor.

References

1. https://www.eurotherm.com/efficient-future-for-the-glass-industry-is-all-electric 
2. https://www.glassmanevents.com/content-images/speakers/Andy-Reynolds-Fives.pdf 
3. http://www.electroglass.co.uk/articles/2010-09%20Electric%20Melting%20&%20Boosting%20for%20Glass%20Quality%20Improvement.pdf
4. http://ietd.iipnetwork.org/content/electric-melting

Metal inclusions

Two difficulties with metal inclusions in glass are common: stress and bubbles.

Stress

Metal inclusions always create stress in the glass. Different metals have different expansions and different strengths.  They also have different melting points - some so low that they liquify during the fusing process.

The trick in using metals as inclusions is to minimise the amount of stress. Small amounts of stress can be contained within the glass. The thicker or more mass inside the glass, the greater risk of stress breaks. The stronger or more rigid the metal is, the more stress will be generated.

Minimising stress is most easily achieved by using small amounts of the metal.  Thinning the metal as much as possible also reduces stress.  Flattening wire also helps reduce the amount of stress as well as keeping it in the place you want it without rolling away from its placement.

Bubbles

Bubbles often form around inclusions, especially of metals.  Metals that do not melt at fusing temperatures are stiffer than the surrounding glass.  You can see from the table noted above those metals which melt at higher temperatures than fusing.  These metals will create bubbles around their perimeter and elsewhere over the metal wherever there are wrinkles or undulations as the metal holds air in those places.

Thin metals

One possibility to reduce the bubbles is to thin the metal by hammering flat or use foil thicknesses of the metal.  Many specialist metal suppliers have very thin metals, often called shims.  They are increasingly available in online shops.

Weight

Another is to use enough glass on top to flatten the metal.  You should flatten the metal in the cold state as much as you can.  Then the weight of the glass presses down on the metal both in the cold and heated states. With a good long bubble squeeze, you can force more air out to the sides than with less covering glass.

Placing

A third possibility is placement. The further the metal inclusion is from the edges the more air is likely to be trapped to form bubbles.  If the air has less distance to travel, more is likely to escape.

Pressing

Supporting the edges or corners allows the centre to drop before the edges are sealed.  The weight of glass helps to press the air out to the sides.  Thicker glass (6mm/0.25") on top of the metal inclusion can help push the air away from the metal. You can also provide - within the design - paths for the air to escape. This can be elements such as powder, stringers and other glass accessories that can hold the glass up during the bubble squeeze process, but become invisible at fusing temperatures.

Fire in stages

A fifth possibility is to fire differently.  You can place the metal on a kiln shelf which is covered with fibre paper and put the glass on top of the metal and fire to a rounded tack fuse at the minimum.  To avoid dog-boning, you should cut the capping piece several centimetres larger than the final piece, so you can cut off the distorted edges. Clean the bottom and dry very well after firing and put the base under the top piece that has the metal attached.  Fire the combined piece slowly with a good bubble squeeze.  This can be applied to included vegetable matter too. 

Further information is available in the ebook Low Temperature Kiln Forming.

Inclusions often produce stress and bubbles.  There are some things that can reduce both when encasing metals or vegetation.

Glass Ionomers in Dental Restorations and Fillings

 

Glass Ionomers in Dental Restorations and Fillings

Posted Krista Grayson on Mar 27, 2019

It is widely known that eating sugary foods leads to a build-up of bacteria which can result in dental caries (tooth decay). The incidence of dental caries has fallen significantly since fluoride, which makes teeth more resilient to decay, was added to toothpaste. Nonetheless, the majority of dentist visits are still for the repair of teeth damaged by tooth decay. Indeed, in the US, 92% of adults and 21% of children have had dental caries in their permanent teeth.1

Tooth decay is caused by the acid produced by bacteria while they consume the sugars found in food and drink. This acid dissolves the protective enamel coating of teeth and then the dentine below. If the resultant cavity is not treated it can become painful, and this potentially leads to infection and even tooth loss.

The most common corrective action for tooth decay is to remove the decayed tooth tissue and fill the cavity with a filling material. There are several types of filling material currently available, including a variety of composite fillings, and the traditional silver amalgam. Composite filling materials are increasingly popular as many people prefer tooth-colored fillings that are less conspicuous. Composite dental materials can also be used for dental restorations to rebuild chipped or broken teeth. Most recently glass ionomer cements, which can be used in much the same way as composite materials, have been introduced as an additional alternative material for dental restoration.

The quality of a filling material is a key factor in determining the effectiveness of a repair. If the filling material is not durable it will be worn away during eating, and if it is prone to shrinkage bacteria will colonize the gap between the tooth and the filling giving rise to secondary caries. 

The Materials used in Tooth Fillings

In the early days of modern dentistry (1800s), teeth were filled with any metal soft enough to mold into the cavity, eg, tin, silver. This advanced to dental amalgams containing a combination of metals including tin, silver, copper, and mercury as technology improved during the nineteenth century. By the end of the first quarter of the twentieth century silicate dental cements had been developed for both dental filling and the bonding of other dental restorations.2

Amalgam is still the most commonly used filling material today. Even after concerns were raised about the toxic effects of mercury, amalgam fillings continued to be used due to the inferior quality of alternatives. However, now that there are effective alternatives, which have the added aesthetic advantage of being tooth-colored, the proportion of amalgam fillings is steadily declining. 

Today, there are several types of dental filling materials available, including silver amalgam, gold, porcelain, composite resins and glass ionomers. Although effective dental filling materials, gold and porcelain are rarely used due to their high costs. The other main options are compared below.

Amalgam

Amalgam is the least expensive of the dental filling materials and can be applied most quickly.2 It has the added benefit of being highly durable, lasting at least 10?15 years. There are, however, several drawbacks to the use of amalgam fillings, the most concerning of which is the potential toxicity from exposure to mercury during placement and removal of the amalgam, and also whilst in situ if an individual routinely grinds their teeth. The use of amalgam fillings also requires removal of some healthy tooth in order to create a space large enough to hold the amalgam. Lastly, the propensity of amalgam to expand and contract with changing temperature makes it more likely to crack or fracture and damage the surrounding tooth as a consequence of drinking hot and cold liquids.

Resin Composites

Dental composites can vary in formulation but all include a synthetic resin making them similar to plastics in composition. Initially, composite materials lacked the strength and durability of amalgam, but advances in their production mean that they can now be both strong and durable. Their main benefit is that they chemically bond to the tooth structure, providing further support and reducing the marginal gap that encourages bacterial colonization and increases the risk of secondary tooth decay. There is however a risk of subsequent shrinkage that can lead to gap development. Composite fillings are also aesthetically more pleasing since, unlike amalgam fillings, they blend in with the natural tooth surface. Unfortunately, composite materials are still considerably more expensive than amalgam (although still less expensive than gold or porcelain) and are more time-consuming to apply.2 Furthermore, the successful application of composite fillings is very technique sensitive and requires the area to be kept dry during placement. 

Glass Ionomer Dental Cements

Glass ionomer cements (GIC) can have a variety of compositions, but the principal constituents are silica, alumina, and calcium. A source of fluoride, such as fluorite, is also commonly added to provide protection against tooth decay. Additional minerals can also be incorporated into the GIC to promote remineralisation and/or prevent acidification. The glass ionomer may be combined with resin for added strength, and to reduce the sensitivity to the presence of moisture on placement.3 GIC represent a very flexible dental restoration solution since the physical properties of GIC can be modified to meet a specific dental application by adjusting the ratios of the constituent chemicals.2

GIC, like resin composites, are tooth-colored and so have cosmetic appeal. The primary benefit of GIC is their chemical adhesion to enamel and dentin, which improves the strength of the restoration and eliminates the need for a bonding agent during placement.2,4 The bond strength of this adhesion is typically increased by addition of polycarboxylic acid. GIC have been reported to exhibit a contact-free area wear that is five times higher than that of amalgam and three times higher than for resin composite materials.2 Furthermore, in contrast to other restoration materials that can suddenly fail due to mechanical fatigue, GIC become stronger over time as water is absorbed and are thus less prone to failure.2

Most recently, GIC has been created using bioactive glass.5 Resin-modified GIC containing bioactive glass has been shown to result in a thick uniform layer of mineralization on the restoration-dentin interface,6 improve the mechanical properties of a filling,7 and reduced the incidence of secondary tooth decay at restoration margins.8

Conclusion

Despite silver amalgam being the mainstay dental filling material for many decades, there has been a desire to reduce its use due to toxicity concerns. Now that the alternative products available can provide comparable efficacy, the proportion of dental caries being corrected with amalgam fillings is declining. Advances in the formulations of composite and glass ionomer dental materials have given them the required strength and durability to make them effective products for tooth restoration. Although fillings with these newer materials are more expensive and take longer to place, they are often the preferred choice due to their improved aesthetics and low risk of toxicity. 

Glass ionomer cements have the added benefits of flexibility in their physical characteristics, strong adhesion to the tooth surface and lower failure rate. The properties of both composite and glass ionomer dental materials can be improved by the inclusion of bioactive glass. 

Mo-Sci produces a range of high quality glass and bioactive glass powders suitable for use as a dental filling materials and for the fixation or coating of dental implants.9 The precise composition of their glass products can be tailored to suit a specific application. Contact us for for more information.

References & Further Reading

1. National Institutes of Health. NIDCR Data & Statistics. Dental Caries (Tooth Decay) in Adults (Age 20 to 64). Available at: https://www.nidcr.nih.gov/DataStatistics/FindDataByTopic/DentalCaries/DentalCariesAdults20to64.htm
2. Lohbauer U. Dental Glass Ionomer Cements as Permanent Filling Materials? — Properties, Limitations Future Trends. Materials 2010, 3(1), 76-96; doi:10.3390/ma3010076
3. Gao W, et al. Demineralization and remineraliza-tion of dentine caries, and the role of glass ionomer cements. Int Dent J. 2000;50(1):51–56.
4. Benelli EM, et al. In situ anticariogenic potential of glass ionomer cement. Caries Res. 1993;27(4):280–284.
5. Matsuya S, et al. Structure of bioactive glass and its application to glass ionomer cement. Dent Mater J. 1999 Jun;18(2):155–166.
6. Prabhakar AR, et al Comparative Evaluation of the Remineralizing Effects and Surface Micro hardness of Glass Ionomer Cements Containing Bioactive Glass (S53P4):An in vitro Study. Int J Clin Pediatr Dent. 2010 May-Aug;3(2):69-77. doi: 10.5005/jp-journals-10005-1057. Available at https://www.ncbi.nlm.nih.gov/pubmed/27507915.
7. Chatzistavrou X, et al. Fabrication and characterization of bioactive and antibacterial composites for dental applications. Acta Biomater. 2014;10:3723–3732. Available at https://www.ncbi.nlm.nih.gov/pubmed/24050766
8. Khvostenko D, et al. Bioactive glass fillers reduce bacterial penetration into marginal gaps for composite restorations. Dental materials 2016;32(1):73–81. Available at http://www.demajournal.com/article/S0109-5641(15)00437-6/pdf
9. Mo Sci Corporation website. http://www.mo-sci.com/en/products

Reducing Implant-Related Infection with Bioactive Glass

 

Reducing Implant-Related Infection with Bioactive Glass

Posted Krista Grayson on Feb 13, 2019

Disease, trauma or serious infection may result in extensive bone damage or bone loss which exceeds the body’s capacity to repair itself. In such cases, implants are needed to promote satisfactory healing. These may take the form of screws, plates, or rods to immobilize broken bones in the correct alignment, reinforce weak bones or correct skeletal deformities. Similarly, diseased joints can be replaced with prosthetic joints to restore normal, pain-free movement. 

Despite ongoing medical advances and improvements in materials and procedures, there remains a substantial risk of implanted devices becoming infected. In addition to microbes being introduced into the body during surgery, there is the risk of bacteria transported in the blood from other parts of the body colonizing the surface of an implant. It has been estimated that as many as 2.5% of primary hip and knee replacements and to 10% of joint revision surgeries are complicated by infection.1 Infected implanted devices represent a significant clinical challenge. Typically, despite lengthy antibiotic treatments, it is often necessary for the infected implant to be surgically removed. This not only increases patient morbidity and dissatisfaction, but is also associated with substantial cost.2 

Antibiotics continue to be the mainstay strategy for both the prevention and treatment of implant infections. However, the power of antibiotics in the fight against infection is diminishing as many strains of potent bacteria are developing resistance to even the strongest antibiotics. Consequently, the risk of implanted devices becoming infected is on the rise and researchers are investigating novel ways to reduce such infections.

One strategy is based on the discovery that the majority of bacteria live in surface-bound microbial communities, rather than as free-swimming entities. On binding to the surface, bacteria secrete adhesion proteins that provide an irreversible attachment.3 Such bacterial biofilms account for over 80% of clinical microbial infections.2 It was therefore proposed that making the surface of implants unsuitable for bacterial colonization would dramatically lower infection rates. This can be achieved by coating the implant with bioactive glass.

The Antimicrobial Properties of Bioactive Glass

Bioactive glass is a type of glass made from high-purity chemicals, such as silica, calcium, and boron, which induce specific biological activity.4 Bioactive glass, by virtue of its high strength, low weight and biocompatibility, has been widely used in a range of biomedical applications, including tissue engineering, bone grafting, dental reconstruction and wound healing.5 

Such clinical experience has shown that borate bioactive glass possesses antimicrobial properties against a wide range of bacteria, including MRSA and E-coli.6,7 The antimicrobial efficacy is achieved though an increase in pH of the surrounding body fluids (which is stressful for bacteria) and because any bacteria that do approach are unable to adhere to bioactive glass and so cannot create microfilms on its surface.8,9 In vitro studies have confirmed that bioactive glass has strong anti-staphylococcal and anti-streptococcal activity.10,11

Since the antimicrobial action of bioactive glass arises from it creating an environment that is hostile to bacteria rather than requiring direct contact with the invading microbe in order to kill it, it is effective across a wide range of bacteria. Furthermore, the bacteria cannot adapt to such effects, and so no bacteria have been found to develop resistance to the antimicrobial effects of bioactive glass.9 

Coating Implants with Bioactive Glass

Initial technical challenges have been overcome and a range of titanium implants have been successfully coated with bioactive glass.12 Clinical use of implants coated with bioactive glass has given promising results in both orthopedic and dental applications. There was no evidence of the coated implants causing any adverse effects or inflammatory response in the surrounding tissue. Furthermore, the implants coated with bioactive glass were found to accelerate cell attachment and mineralization of the extracellular matrix, promoting more rapid bone growth. In addition, the proportion of bone-to-implant contact was significantly greater for implants coated with bioactive glass compared with traditional implants.13-15

Enhancing the Antimicrobial Efficacy of Bioactive Glass

Bioactive glass has good antimicrobial action, being effective against a broad spectrum of aerobic and anaerobic bacteria.9 However, the antimicrobial effects can be further enhanced to increase the range of antimicrobial activity, by the addition of ions, such as boron, copper, silver, yttrium, and iodine, or organic nanoparticles.16,17 The chosen antimicrobial agent is incorporated into the bioactive glass during its production and released once the bioactive glass is in an aqueous solution, creating an environment inhospitable for microbial life. The bioactive glass can thus be used as a delivery system for antimicrobials.18

The advantage of ions and nanoparticles over antibiotics is that their efficacy depends solely on contact with the bacterial cell wall; they do not need to enter the cell. Consequently, their lethal effect is delivered irrespective of the specific genetics of the target bacteria and is unaffected by the resistance mechanisms used by bacteria to evade antibiotics.

Conclusion

Infection of medical implants is an increasingly serious clinical and socioeconomic burden. Furthermore, the situation is likely to worsen with the increasing prevalence of bacteria with multi-drug resistance. 

Bioactive glass has inherent antimicrobial activity and does not elicit a toxic response to surrounding tissues. Consequently, coating implants with bioactive glass represents an attractive option for reducing the risk of infection. The antimicrobial properties of bioactive glass can be further enhanced by loading it with antimicrobial agents, such as ions or antibacterial nanoparticles. Such a strategy would reduce the need for prophylactic antibiotic use, whereby protecting against the development of further strains of antibiotic-resistant bacteria. 

Since bacteria cannot adapt to the hostile environment created by bioactive glass or its biofilm-resistant surface, they are unlikely to develop resistance to the antimicrobial action of bioactive glass. 

In addition, the coating of implants with bioactive glass has been shown to speed up the fusion of the implant with bone, accelerating a patient’s recovery.

The use of bioactive glass, either alone or doped with antimicrobial agents, as a coating for orthopedic and dental implants is thus likely to improve the success rate and enhance patient outcomes across a range of reparative and restorative surgeries by promoting rapid healing and minimizing the occurrence of infection. 

Mo-Sci produces high quality bioactive glass powders, the precise composition of which can be tailored to meet specific requirements. They produce bioactive glass suitable for coating orthopedic and dental implants.

References & Further Reading

1. Lentino JR. Prosthetic joint infections: Bane of orthopedists, challenge for infectious disease specialists. Clin Infect Dis. 2003;36:1157–61. doi: 10.1086/374554.
2. Hall-Stoodley L, et al. Bacterial biofilms: from the natural environment to infectious diseases. Nature Reviews Microbiology2004;2(2): 95–108.
3. Davey ME and O’Toole GA. Microbial biofilms: from ecology to molecular genetics. Microbiology and Molecular Biology Reviews2000;64(4):847–867.
4. Brauer DS. Bioactive Glasses—Structure and Properties. Angew Chem Int Ed 2015;54: 4160–4181.
5. Rahaman MN, et al. Bioactive glass in tissue engineering. Acta Biomaterialia 2011;7:2355?2373.
6. Ottomeyer M, et al. Broad-Spectrum Antibacterial Characteristics of Four Novel Borate-Based Bioactive Glasses. Advances in Microbiology 2016;6:776?787.
7. Khvostenko D, et al. Bioactive glass fillers reduce bacterial penetration into marginal gaps for composite restorations. Dental materials 2016;32(1):73–81. Available at http://www.demajournal.com/article/S0109-5641(15)00437-6/pdf
8. Zhang D, et al. Factors Controlling Antibacterial Properties of Bioactive Glasses. Key Engineering Materials 2007;330-332:173?176.
9. Drago L, et al. Recent Evidence on Bioactive Glass Antimicrobial and Antibiofilm Activity: A Mini-Review Materials 2018;11:326?337.
10. Misra SK, et al. Poly(3-hydroxybutyrate) multifunctional composite scaffolds for tissue engineering applications. Biomaterials 2010;31:2806–2815.
11. Rivadeneira J, et al. In vitro antistaphylococcal effects of a novel 45S5 bioglass/agar-gelatin biocomposite films. J Appl Microbiol 2013;115,604–612.
12. Lopez-Esteban S, et al. Bioactive glass coatings for orthopedic metallic implants. Journal of the European Ceramic Society 2003;23:2921–2930.
13. Mehdikhani-Nahrkhalaji M, et al. Biodegradable nanocomposite coatings accelerate bone healing: In vivo evaluation. Dent Res J (Isfahan). 2015;12(1):89?99.
14. Chen Q, et al.Cellulose Nanocrystals–Bioactive Glass Hybrid Coating as Bone Substitutes by Electrophoretic Co-deposition: In Situ Control of Mineralization of Bioactive Glass and Enhancement of Osteoblastic Performance. ACS Appl Mater Interfaces. 2015 Nov 11;7(44):24715?25.
15. van Oirschot BA, et al. Comparison of different surface modifications for titanium implants installed into the goat iliac crest. Clin Oral Implants Res. 2016;27(2):e57?67.
16. Kaur G, et al D. Review and the state of the art: Sol–gel and melt quenched bioactive glasses for tissue engineering. J Biomed Mater Res B Appl Biomater 2016;104, 1248–1275.
17. Karwowska E. Antibacterial potential of nanocomposite-based materials – a short review. Nanotechnology Reviews 2016;6(2):243?254.
18. Rivadeneira J and Gorustovich J. Bioactive glasses as delivery systems for antimicrobial agents. Journal of Applied Microbiology 2016;122, 1424–1437.
19. Mo Sci Corporation website. http://www.mo-sci.com/en/products