Dental cavities have been a matter of concern to humankind for the past thousands of years. The earliest evidence of preparing cavities and filling them with dental filling material dates back to at least 13000 years. The history of dental fillings has been analogous to the history of modern dentistry. The American Dental Association describes dentistry as one of the oldest medical professions in the history of mankind. Let's take a look at the timeline and history of dental fillings and their evolution over time from the prehistoric era to modern times.
Paleolithic Bitumen Dental Filling [13000 years back]
In a new report published in the American Journal of Physical Anthropology, the earliest evidence of dental filling material dated back to 13000 years was found in the remains of a late Upper Paleolithic hunter-gatherer who lived in Roparo Ferdian which is now known as modern-day Northern Italy. The researchers discovered holes drilled in the upper central incisors of human remains. The holes bore marks that indicated drilling by sharpened rocks and while the dental filling was no longer present, there was evidence of the remains of bitumen which is a natural tar-like substance. Thus, bitumen came to be known as the first known dental filling material.
Neolithic Beeswax Dental Filling [6500 years back]
The earliest dental filling which has survived enough to be studied dates back to 6500 years ago in the Neolithic human tooth. Researchers discovered a 6500-year-old human mandible from a cave in Trieste, Italy where the cracked canine bore traces of filling with beeswax. It was unclear whether the beeswax was used to fill the crack before or after the death of the individual. It is estimated that if the beeswax filling was done during the lifetime of an individual then it would serve as the earliest known evidence of therapeutic palliative dental filling.
Origin of Dental Amalgam [600AD]
Amalgam which is still used in modern dentistry has origins dating back to 600AD. The amalgam dental filling was first introduced in the year of 659 during the Tang dynasty in the Chinese medical text, Xinxiu Benaco written by Su Gong. The text illustrated using of an amalgamation of tin and silver to fill the cavities in the tooth. The composition of the earliest dental amalgam was published during the Ming dynasty and in a text written by Liu Wentai in 1505, it was stated that the composition consists of "100 shares of mercury, 45 shares of silver and 900 shares of tin."
"100 shares of mercury, 45 shares of silver and 900 shares of tin" was the composition of dental amalgam published in a Chinese medical text during Ming dynasty written by Liu Wentai during 1505.
Advent Of Dental Amalgam 
Amalgam was introduced to the western world during the 1830s. It was in 1833 an Englishman, Edward Crawcour, and his nephew Moses Crawcour brought and introduced dental amalgam to the United States and it was quick to rise in popularity. Though, its use was banned by the American Society of Dental Surgeons due to the health hazards accompanied by amalgam. But dental amalgam rose to popularity again during the period of 1856-1859 when the ASDS was disbanded and the American Dental Association was founded.
Use Of Gold Dental Filling [1700-1800]
The use of gold in dentistry dates back to several thousands of years though its use as dental filling material was not one of them. Gold was used as a replacement for missing teeth or as bands to hold the teeth together which is dated back to Etruscans during the year 201. However, the use of gold dental fillings was not seen till the 1700s when its advent was seen as dental filling material across Europe. In 1855, Robert Arthur invented a cohesive gold foil method that made the filling of cavities easier with the help of metal in soft malleable form.
Modern Dental Filling Materials [21st Century]
Modern dentistry has seen advancements that parallels with the advancements in modern-day dental filling materials. The dental filling materials seen in use in the 21st Century include these following materials:
1. Gold Fillings- Gold dental fillings also known as inlays and onlays are metallic fillings that are an alloy of gold, copper, and other metals. They are highly durable, in fact, the most durable dental filling material and sustainable of all dental filling materials known and can last up to more than 20 years of time. They are resistant to chipping, fracture, and corrosion however one of the advantages of gold fillings is the cost which can be ten times more than that of silver amalgams.
2. Composite Resins- Dental composite resin is a tooth-colored material and is widely used in esthetic restorative dentistry. They are used to replace the decayed portion of tooth structure as well as it is useful for a variety of dental restorations including fillings, veneers, inlays, and crowns. It has esthetic properties since it is more natural looking which serves as a major advantage over dental amalgams. Composite resins have been used as restorative materials for nearly 50 years. National Library of Medicine states that they have been used in over 95% of all anterior teeth direct restorations and in 50% of all posterior teeth direct restorations.
3. Silver Amalgams- Silver amalgam is an alloy composed of silver, tin, copper, and mercury which lasts up to 15-20 years. Silver amalgams have been used as dental filling materials since the 1840s and have been known to be widely used restorative materials to treat dental caries. However, there have been disagreements regarding its use in dentistry due to the presence of mercury in its formulation which has proved to be hazardous in nature by various researches conducted on dental amalgams. Although silver amalgams do produce trace amounts of mercury, it has been widely agreed by dental professionals and associations worldwide that the amount of mercury released poses little to no risk at all.
4. Porcelain Fillings- The porcelain fillings are also known as inlays and onlays and these are the only materials that are free of mercury, metal, or BPA. They are made up of ceramic materials with which crowns and bridges are fabricated in color which matches the natural tooth color. They are highly durable and last up to 15 years and are stain resistant in nature.
5. Glass Ionomer- Glass Ionomer Cement is used in restorative dentistry as a luting cement and a filling material. They are commonly used for temporary restorations, subgingival cavities, and for pediatrics restoration in the milk teeth of children. GIC is made up of silicate glass powder which contains fluoride that attributes to the anticaries activity of GIC cement. However, they are very durable and sustainable in nature because of which they are used as temporary fillings to be replaced later with permanent restorations.