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  • David Silverberg

Breaking down the various types of fillings

Updated: Jan 4, 2022

Written By David Silverberg

We all have heard the term “fillings” even if we sport pearly whites as flawless as a Scarlett Johansson. But do you know exactly what it is and which materials dentists use for fillings?  If there’s any one blog post to act as a one-stop hub for all your questions on fillings, including an overview of ground-breaking research on next-gen fillings, you’re reading it! First we told you about dental scrap but now here’s a primer for all things related to fillings.

What is a filling? To treat a cavity a dentist will remove the decayed part of the tooth and then “fill” the area on the tooth where the decayed material was removed.

Also, a dentist may give patients local anesthetic by “freezing” the affected area. Fillings help make sure the tooth is protected from further degradation and assist in preserving the tooth so it remains functional.

There was a time when you had only one choice for fillings—silver amalgam. But, today’s dental technology has opened the door to far more attractive and versatile options.

Types of Fillings

The most common fillings type is amalgam, which you notice by its silver shine.  They are created by mixing mercury and a silver alloy (50% mercury, 35% silver, and 15% tin, copper and other metals). Amalgam lasts a long time and has been used in fillings for at least 150 years. The material is economical to use and it’s not unusual for an amalgam filling to last 15 to 20 years.

Mercury usage has been controversial in the past 10 years, as mercury has been discovered to be a potential cancer-causing compound. Over the years, some people have expressed concern about the materials used in amalgam fillings, especially mercury. However, according to the American Dental Association (ADA), the mercury in fillings is safe because, once mixed with the other metals, the mercury is stable and rarely leaves the filling. The ADA reports there have been so significant studies that show harm from amalgam fillings. It should be noted that a downside of amalgam fillings is that they can create a grayish hue to the surrounding tooth structure. Also, cracks and fractures may crop up, since, while all teeth expand and contract in the presence of hot and cold liquids, which can cause the tooth to crack or fracture, amalgam material may experience a wider degree of expansion and contraction and lead to a higher incidence of cracks and fractures.

Gold inlays can be used in most areas of the mouth. An inlay is often small and placed within the biting surface of the tooth. An onlay can cover a bigger area of the tooth. Gold is the most long-lasting and hard-wearing filling material and will remain as is for many years, and its advantages include not tarnishing and offering great strength as a filling. After the gold inlay or onlay has been made, a dentist will fix it in place with dental cement and due to this process and the price of gold compared to mercury, this type of filling is more expensive than amalgam.

Composite fillings are known to be durable, but may not be as hard wearing as amalgam fillings. Composite fillings come out tooth-coloured and are made from powdered glass quartz, silica or other ceramic particles added to a resin base.  After the tooth is ready to be filled, the filling is bonded onto the area and a light shone onto it to set it. The dentist then selects a shade to match a patient’s teeth. The Canadian Dental Association breaks down the pros and cons of this popular filling: - Advantages

  • These fillings will be the same colour as your natural teeth.

  • They cost less than gold fillings.

  • They are direct fillings, so they can be done in one appointment, in most cases.

- Disadvantages

  • This kind of filling can break more easily than amalgam or gold fillings, and may not last as long.

  • Composite fillings cost more than amalgam fillings.

  • Recurrent decay is more of a problem than with amalgam or gold fillings.

Porcelain materials are another common option for dentists. They are hard and brittle since porcelain and metal can be combined to make a strong, tooth-coloured crown. Unless the patient has a bad tooth-grinding habit or some other issue, a combination of porcelain and metal can be used anywhere in the mouth.

Platinum also can be found in some fillings, but it’s not as common as other material since it can be quite hard, inflexible and difficult to form into foil. Yet it can still be valuable to some services that collect dental scrap, such as Muzeum Dental Refining. Platinum is currently priced at $971 US an ounce.

Another material, palladium, can be found in some fillings, as well in bridges, crowns, inlays and gold restoration. Palladium is known as a soft silver-white metal that isn’t too far off from platinum, but it is the least dense and exhibits the lowest melting point of the platinum group metals. Palladium can still be lucrative to dentists looking to sell scrap dental gold, as it’s currently priced at $2,259 US an ounce. The fillings process Most fillings are carried out in two ways:

  1. Direct Filling - These fit right into the cavity, after the dentist has cleaned out the decay. They harden quickly and most often, patients will be able to have a direct filling put in place in one appointment. 

  2. Indirect Filling - Examples of this type of filling are often crowns (or caps) and inlays. They are made custom in a lab to fit  a patient’s profile. The dentist cements the filling in place, and these types of fillings could take two or more appointments to complete.

What does the future hold for fillings?

Last year, a team of researchers created a filling material supposedly two times more resistant to breakage than standard fillings, and made from the compound used to strengthen car bumpers.

Earlier research found that graphene, a super durable material, can be a viable fillings candidate. Typical metal fillings can degrade over time and composite fillings are not very strong. But with graphene, it’s 200 times stronger than steel and doesn't corrode, giving it potential to be an ideal replacement for the usual dental fillings material. Bioactive glass could also be a filling compound of the future. Oregon researchers found that "bioactive" glass, a type of crushed glass that can interact with the body, could help reduce the ability of bacteria to attack composite tooth fillings.  “This type of glass is only beginning to see use in dentistry, and our research shows it may be very promising for tooth fillings,” said Jamie Kruzic, a professor and expert in advanced structural and biomaterials in the OSU College of Engineering, in a press release. “The bacteria in the mouth that help cause cavities don't seem to like this type of glass and are less likely to colonize on fillings that incorporate it. This could have a significant impact on the future of dentistry.” As a fun addendum, in case you were curious about the first filling ever, it took place 6,500 years ago and was made from beeswax. As New Scientist writes, the recipient of the treatment was “most likely a 24 to 30-year-old man, living in what is now Slovenia. His fossilized jawbone was found early last century near the village of Lonche. At the time, the find – one of the oldest human bones ever found in the region – was described, catalogued and filed away in a museum in nearby Trieste, Italy.” Dental fillings and dental scrap is one of Muzeum Dental’s specialties, so if you have questions about receiving a free dental scrap kit or how our refining and assessment process works, contact us anytime.

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